West Nile Virus

2004

Abutarbush, Sameeh M.; O'Connor, Brendan P.; Clark, Chris; Sampieri, Francesca; Naylor, Jonathan M. Clinical West Nile virus infection in 2 horses in western Canada. Canadian Veterinary Journal / La Revue Veterinaire Canadienne. 2004 Nov; 45(4): 315-317. ISSN: 0008-5286.

NAL call no.: 41.8 R3224

Descriptors: horses, West Nile virus infection, ataxia, recumbency, detected by polymerase chain reaction.

Abstract: Two horses had a history of ataxia and weakness or recumbency. One recovered and was diagnosed with West Nile virus (WNV) infection by serologic testing. The other was euthanized; it had meningoencephalomyelitis, WNV was detected by polymerase chain reaction. West Nile virus infection is an emerging disease. Year 2002 is the first year in which cases have been seen in Saskatchewan.

Anonymous. Equine WNV cases drop. Journal of Equine Veterinary Science. 2004 Apr; 24(4): 142-143. ISSN: 0737-0806.

NAL call no.: SF951.J65

Descriptors: USDA approved vaccine--West Nile Innovator/Encephalomyletis combination, Fort Dodge Animal Health, effective in horses, effective disease prevention, horses, West Nile virus, 13 million protected with vaccine, forecast fewer cases due to prevention via vaccine.

Anonymous. Getting out into the field, and forest. Editorial. Lancet Infectious Diseases. 2004; 4(3): 127. ISSN: 1473-3099.

Descriptors: influenza, severe acute respiratory syndrome, rabies virus, Ebola virus, West Nile virus.

Anonymous. Recombinant DNA vaccine technology. Edited from Merial literature. Journal of Equine Veterinary Science. 2004; 24(2): 64-67. ISSN: 0737-0806.

NAL call no.: SF951.J65

Descriptors: animals, horses, Aedes, Culicidae, Diptera, Equidae, Chordata, Flaviviridae, antibodies, disease vectors, experimental infection, genetic engineering, immunity, recombinant DNA, recombinant vaccines, seroconversion, vaccination, vaccine development, vaccines, West Nile fever.

Anonymous. West Nile virus vaccine. Journal of Equine Veterinary Science. 2004 Jan; 24(1): 12-13. ISSN: 0737-0806.

NAL call no.: SF951.J65

Descriptors: West Nile virus, horses, vaccine for equines.

Anonymous. West Nile virus 2003. Journal of Equine Veterinary Science. 2004 Mar; 24(3): 100-101. ISSN: 0737-0806.

NAL call no.: SF951.J65

Descriptors: West Nile virus, horses, epidemiology, levels of the disease in equines.

Apperson, Charles S.; Hassan, Hassan K.; Harrison, Bruce A.; Savage, Harry M.; Aspen, Stephen E.; Farajollahi, Ary; Crans, Wayne; Daniels, Thomas J.; Falco, Richard C.; Benedict, Mark; Anderson, Michael; McMillen, Larry; Unnasch, Thomas R. Host feeding patterns of established and potential mosquito vectors of West Nile virus in the eastern United States. Vector Borne and Zoonotic Diseases. 2004 Spring; 4(1): 71-82. ISSN: 1530-3667.

NAL call no.: RA639.5.V43

Descriptors: mosquitos, vector capacity, degree of vector and vertebrate reservoir contact, host feeding habits of vectors, vector feeding preferences, serological and polymerase chain reactions for host–feeding patterns, 21 mosquito species, vector species for West Nile virus may prefer certain avian hosts, mammalophilic mosquito species, New Jersey, New York.

Abstract: An important variable in determining the vectorial capacity of mosquito species for arthropod-borne infections is the degree of contact of the vector and the vertebrate reservoir. This parameter can be estimated by examining the host-feeding habits of vectors. Serological and polymerase chain reaction based methods have been used to study the host-feedings patterns of 21 mosquito species from New York, New Jersey, and Tennessee, 19 of which previously have been found infected with West Nile virus. Mammalophilic mosquito species in New Jersey and New York fed primarily upon white-tailed deer, while those from Memphis, Tennessee, fed mainly upon domestic dogs. A total of 24 different avian host species were detected among the avian-derived blood meals. American Robin, Northern Cardinal, Northern Mockingbird, Tufted Titmouse, and Brown-headed Cowbird were common avian hosts, while blood meals derived from the American Crow were relatively rare. Although the majority of common host species were potentially among the most abundant birds at each location, the proportion of blood meals from the most commonly fed upon avian species was greater than was predicted based upon the likely abundance of these species alone. These findings suggest that vector species for West Nile virus may preferentially feed upon certain avian hosts.

Austgen, Laura E.; Bowen, Richard A.; Bunning, Michel L.; Davis, Brent S.; Mitchell, Carl J.; Chang, Gwong-Jen J. Experimental infection of cats and dogs with West Nile virus. Emerging Infectious Diseases. 2004 Jan; 10(1): 82-86. ISSN: 1080-6040.

NAL call no.: RA648.5.E46

Descriptors: dogs and cats readily infected with WNV, viremia peak titers, carnivores infected by eating WNV infected prey, no-clinical sign of disease, oral transmission.

Abstract: Domestic dogs and cats were infected by mosquito bite and evaluated as hosts for West Nile virus (WNV). Viremia of low magnitude and short duration developed in four dogs but they did not display signs of disease. Four cats became viremic, with peak titers ranging from 10(3.0) to 10(4.0) PFU/mL. Three of the cats showed mild, non-neurologic signs of disease. WNV was not isolated from saliva of either dogs or cats during the period of viremia. An additional group of four cats were exposed to WNV orally, through ingestion of infected mice. Two cats consumed an infected mouse on three consecutive days, and two cats ate a single infected mouse. Viremia developed in all of these cats with a magnitude and duration similar to that seen in cats infected by mosquito bite, but none of the four showed clinical signs. These results suggest that dogs and cats are readily infected by WNV. The high efficiency of oral transmission observed with cats suggests that infected prey animals may serve as an important source of infection to carnivores. Neither species is likely to function as an epidemiologically important amplifying host, although the peak viremia observed in cats may be high enough to infect mosquitoes at low efficiency.

Austin, Ronald J.; Whiting, Terry L.; Anderson, Robert A.; Drebot, Michael A. An outbreak of West Nile virus-associated disease in domestic geese (Anser anser domesticus) upon initial introduction to a geographic region, with evidence of bird to bird transmission. Canadian Veterinary Journal / La Revue Veterinaire Canadienne. 2004 Feb; 45(2): 117-123. ISSN: 0008-5286.

NAL call no.: 41.8 R3224

Descriptors: death of domestic geese, breeding farm, 6-week-old goslings severely affected, seroreaction exceeds expectation of mosquito transmission, Manitoba, Canada.

Abstract: West Nile virus activity in Manitoba was documented for the first time by the collection of an infected crow found on July 8, 2002, in Winnipeg. West Nile virus was identified as the cause of death for a large number of domestic geese at a single farm in southern Manitoba in August. Of the 5 differently aged cohorts on the affected farm, which included 2 breeding flocks and 3 growing flocks, the 6-week-old cohort was most severely affected with 692 of 2731 goslings dying within a 10-day period. Seroprevalence of West Nile virus in 2 clinically affected and recovered juvenile cohorts was 98% and 100%. In breeding geese without clinical disease, seroprevalence was 90% for 15-month-old birds and 10% for 5-year-old birds. Seroreaction in 3 of 4 cohorts tested exceeded what would be expected by mosquito transmission alone.

Ayres, Kenneth; Bandy, Utpala; Drew, Helen; Fulton, John P.; Hayes, Gregory; Getman, Alan; Gurba, Kristen; Hanofin, Christofer; Lopes-Duguay, Liz; Marshall, Robert J.; Mehta, Shashi; Powell, Stephanie. Control of West Nile virus, Rhode Island, 2003. Medicine and Health, Rhode Island. 2004 Mar; 87(3): 84-86. ISSN: 1086-5462.

Descriptors: immunized domestic animals reduces WNV burden, active surveillance in the wild and with domestic animals, educating the public, systematic larviciding, destruction of backyard mosquito habitats, public health issues, surveillance and control efforts, history of exposure of human cases, Rhode Island.

Abstract: Thanks largely to systematic larviciding by the State's 39 municipalities, and aided by the public's destruction of "backyard" mosquito habitats and adoption of personal protective measures (clothing, repellant), Rhode Island minimized the potential human burden of WNV during the 2003 mosquito season (six serious WNV cases, one death, and no reports of WNV-tainted blood donations). The potential burden of WNV on domestic animals was also reduced through immunization. Nonetheless, the State's first WNV death reminds us of the danger this disease poses for the very young, for elders, and for people of all ages who are immune-compromised. Similarly, the widespread location of birds positive for WNV signifies the ubiquity of risk. All mosquitoes must be avoided. Based on its experience with WNV control over the past few years, the State will continue and enhance its surveillance and control efforts in 2004. Once again, systematic larviciding by municipalities and continuing public education through multiple channels will form the backbone of control, supported by active surveillance for the virus in the wild, in domestic animals, and in humans. For the latter effort, the vigilance of the health care community is of signal importance to the protection of the public. Every human case is investigated thoroughly, to establish as accurately as possible the time and place of exposure. DEM and HEALTH use this information to assess potential weaknesses in WNV control efforts, and to take corrective action, as necessary. Health care providers also play an essential role in public education, reminding patients (all patients, but especially the very young, elders, and the immune-compromised) to avoid mosquito bites. Discussing the avoidance of mosquito bites with patients who engage in regular outdoor activity is especially important. School physicians and the medical directors of nursing homes are well-positioned to keep mosquito control and avoidance on the agenda of their respective institutions. Together, we can control the burden of this disease among domestic animals and humans, if we continue to pursue mosquito control and personal protection aggressively. If we don't, the potential for tragedy is tremendous, as evidenced by the recent experience of other regions of the country.

Banet-Noach, Caroline; Gantz, Adi Y.; Lublin, Avishai; Malkinson, Mertyn. A twelve-month study of West Nile virus antibodies in a resident and a migrant species of kestrels in Israel. Vector Borne and Zoonotic Diseases. 2004 Spring; 4(1): 15-22. ISSN: 1530-3667.

NAL call no.: RA639.5.V43

Descriptors: common and lesser kestrel species, blood sampling for antibodies, continuous serological sampling over time, limited number of avian species (flags), forecast timing and dispersion of WNV, Israel.

Abstract: Two species of kestrel, the common and lesser, were caught each month at three geographically defined locations in Israel over a 12-month period, and a total of 306 blood samples were examined for West Nile virus neutralizing antibodies. The prevalences and mean antibody titers were analyzed statistically by the multiple linear regression model and were shown to be significantly affected by two of the independent variables, location and age of the bird. The season had no overall effect on prevalence and titer but a comparison of the mean monthly titers revealed that April was highest and July and August the lowest statistically for the common kestrel which is a resident species. In contrast, the migrating lesser kestrel was caught only in the spring months and principally at the Jerusalem location, where eight out of 29 birds were seropositive. By comparing the serology of the non-migrating, common kestrel with the migrating, lesser kestrel, the effect of seasonality was evaluated in relation to their ecological patterns and yielded evidence for the entry in April of a small number of previously infected common kestrels into Israel. This serological approach based on continuous sampling over an extended period could be used to forecast in the coming years the timing and dispersion of West Nile virus in both Old and New Worlds if surveys are based on a limited number of informative (flag) species.

Beasley, D.W.C.; Davis, C.T.; Whiteman, M.; Granwehr, B.; Kinney, R.M.; Barrett, A.D.T. Molecular determinants of virulence of West Nile virus in North America. Archives of Virology. Supplementum. 2004; 18: 35-41. ISSN: 0939-1983.

NAL call no.: QR355.A72

Descriptors: mouse and hamster models, U.S. West Nile virus strains highly neurovirulent and neuroinvasive, WNV Ethiopia 76a non-neuroinvasive, comparative nucleotide sequencing, strains differ by 5 amino acids in the envelope (E) protein, loss includes glycosylation site, comparison of 27 WNV strains indicates glycosylation site corelates with mouse neuroinvasiveness.

Abstract: West Nile virus (WNV) is a mosquito-borne flavivirus that until very recently had not been found in the Americas. In 1999, there was an outbreak of West Nile encephalitis in New York and surrounding areas, involving 62 human cases, including 7 fatalities. The virus has subsequently become established in the United States of America (U.S.) with 4156 human cases, including 284 deaths, in 2002. The WNV strains found in the U.S. are members of "lineage I", a genetic grouping that includes viruses from Europe, Asia and Africa. Molecular epidemiologic studies indicate that two genetic variants of WNV emerged in 2002. The major genetic variant is found in most parts of the U.S., while the minor genetic variant has been identified only on the southeast coast of Texas. Investigation of WNV in mouse and hamster models demonstrated that strains from the U.S. are highly neurovirulent and neuroinvasive in these laboratory rodents. Other strains, such as Ethiopia 76a from lineage I, are not neuroinvasive and represent important viruses which can be used to elucidate the molecular basis of virulence and attenuation of WNV. To identify putative molecular determinants of virulence and attenuation, we have undertaken comparative nucleotide sequencing of Ethiopia 76a and strains from the U.S. The results show that the two viruses differ by 5 amino acids in the envelope (E) protein, including loss of the glycosylation site. Comparison of our panel of 27 WNV strains suggests that E protein glycosylation is a major determinant of the mouse neuroinvasive phenotype.

Ceccaldi, P.E.; Lucas, M.; Despres, P. New insights on the neuropathogenicity of West Nile virus. FEMS Microbiology Letters. 2004 Apr; 233(1): 1-6. ISSN: 0378-1097.

NAL call no.: QR1.F44

Descriptors: mouse model, murine neural cell cultures, WNV variant “Isr90/NY99” experimental infections, selective infection of neurons and physiopathological changes demonstrated, North America.

Abstract: West Nile virus (WNV) is a mosquito-borne disease that emerged in North America where it caused in 2002 the largest arboviral meningoencephalitis outbreak ever recorded in this area. The viral variant responsible of this outbreak has been found to share 99.7% identity over the entire genome with the viral variant that caused the epizootic in Israel in 1998 and has been referred as "Isr98/NY99". It has been shown to exhibit an increased neurovirulence in humans, as well as in experimental infections in different animal models. Mouse model has allowed to demonstrate the preferential infection of neurons within the central nervous system and to point out the genetic determinism of host susceptibility to WNV. In murine neural cell cultures, the selective infection of neurons was accompanied by physiopathological changes and a cytopathic effect, showing the direct effect of infection of neurons as one of the causes of WNV neuropathogenicity.

Cheng, Ying; King, Nicholas J.C.; Kesson, Alison M. Major histocompatibility complex class I (MHC-I) induction by West Nile virus: involvement of 2 signaling pathways in MHC-I up-regulation. Journal of Infectious Diseases. 2004 Feb; 189(4): 658-668. ISSN: 0022-1899.

NAL call no.: 448.8 J821

Descriptors: mouse embryo fibroblasts (MEFs), WNV infection induced activation of a p65/p50 heterodimer of nuclear factor (NF)kappa B, induced up-regulation of cell surface expression of major histocompatibility complex class I (MHC-I), demonstrate 2 pathways for WNV-induced up-regulation of MHC-I.

Abstract: Type 1 interferon (IFN) receptor gene knockout (IFNAR(-/-)) mouse embryo fibroblasts (MEFs) are more susceptible to and productive of West Nile virus (WNV) and produce less type 1 IFN than WNV-infected wild-type (wt) MEFs. WNV infection of IFNAR(-/-) MEFs induced activation of a p65/p50 heterodimer of nuclear factor (NF)- kappa B and up-regulation of cell-surface expression of major histocompatibility complex class I (MHC-I) molecules. WNV infection of wt MEFs resulted in a greater up-regulation of MHC-I than did infection of IFNAR(-/-) MEFs because of the action of endogenous type 1 IFN production. IFN- beta -treatment of wt MEFs did not activate NF- kappa B but did up-regulate cell-surface MHC-I expression. The WNV-induced NF- kappa B activation was partially abrogated by the serine protease inhibitor N-benzoyl-l-tosyl-l-phenylalanine, which also abrogated the up-regulation of MHC-I. Thus, we demonstrate 2 pathways for WNV-induced up-regulation of MHC-I, a WNV-induced NF- kappa B-dependent, IFN-independent pathway and an NF- kappa B-independent, IFN-dependent pathway.

Couzin, Jennifer. Genetics. Hybrid mosquitoes suspected in West Nile virus spread. Science. 2004 Mar 5; 303(5663): 1451. ISSN: 0036-8075.

NAL call no.: 470 Sci2

Descriptors: animals, birds, Culex, hybridization of mosquito vectors, West Nile fever transmission, physiology, virology, epidemiology, insect bites and stings, United States.

Couzin, J. Erratum: Hybrid mosquitoes suspected in West Nile virus spread. Science. 2004 Mar 26; 303(5666): 1077. ISSN: 0036-8075.

NAL call no.: 470 Sci2

URL: www.sciencemag.org

Descriptors: error, erratum, article correction.

D'Agostino, Jennifer J.; Isaza, Ramiro. Clinical signs and results of specific diagnostic testing among captive birds housed at zoological institutions and infected with West Nile virus. Journal of the American Veterinary Medical Association. 2004 May; 224(10): 1640-1643, 1606. ISSN: 0003-1488.

NAL call no.: 41.8 AM3

Descriptors: captive exhibit birds infected with WNV, diagnostic testing, death or euthanasia within 3 days of clinical symptom onset, WNV infection difficult to diagnose before death, zoo collections, Kansas.

Abstract: During 2002, West Nile virus (WNV) infection was diagnosed in 11 birds housed in outdoor exhibits at 5 zoological institutions in Kansas. Eight birds were examined because of neurologic abnormalities; 2 died suddenly without any clinical signs of disease. Results of CBCs and serum biochemical testing were nonspecific. Results of a plaque reduction neutralization test to detect circulating antibodies against WNV were positive for 2 of 8 birds. Results of a reverse transcriptase-polymerase chain reaction assay of an oral cavity swab specimen for WNV RNA were positive for 4 of 5 birds. One bird survived; the remaining 10 died or were euthanatized, with 9 of the 10 dying or being euthanatized within 3 days of the onset of clinical signs. In all 10 birds that died or were euthanatized, WNV infection was confirmed on postmortem examination by means of specific testing. Findings in these birds suggest that West Nile virus infection can be difficult to diagnose antemortem because clinical signs mimic those associated with other more common avian diseases. Neither of the antemortem diagnostic tests was definitive for diagnosing WNV infection in these cases.

Docherty, D.E.; Long, R.R.; Griffin, K.M.; Saito, E.K. Corvidae feather pulp and West Nile virus detection. Emerging Infectious Diseases. 2004; 10(5): 907-909. ISSN: 1080-6040.

NAL call no.: RA648.5.E46

Descriptors: Corvidae, West Nile flavivirus, virus detected in cloaca, kidney and spleen of carcass.

Eisler, Diane L.; McNabb, Alan; Jorgensen, Danielle R.; Isaac-Renton, Judith L. Use of an internal positive control in a multiplex reverse transcription-PCR to detect West Nile virus RNA in mosquito pools. Journal of Clinical Microbiology. 2004; 42(2): 841-843. ISSN: 0095-1137.

NAL call no.: QR46.J6

Molecular Sequence Databank no.: GENBANK/AF196835

Descriptors: field collected mosquito RNA, multiplex real time Taqman RT PCR, WNV Armored RNA detection of false negative results, British Columbia, Alberta, Manitoba Canada.

Abstract: We report on the use of West Nile virus Armored RNA as an internal positive control (IPC) for the extraction and reverse transcription-PCR (RT-PCR) of RNA extracted from field-collected mosquitoes and on a multiplex real-time Taqman RT-PCR to simultaneously detect the 3' noncoding region of West Nile virus and the West Nile virus NS5-2 region comprising the IPC. Mosquito pools from the province of British Columbia, Canada (n = 635), were tested in duplicate and found to be negative for West Nile virus and positive for the IPC. Known West Nile virus-positive supernatants from mosquito pools from the provinces of Alberta and Manitoba were tested in duplicate and found to be positive for both regions of the West Nile virus genome. The mean cycle threshold (Ct) value for the IPC in batch extraction controls +/- 2 standard deviations was found to be 36.43 +/- 1.78 cycles. IPCs of 98.4% (624) of West Nile virus-negative pools fell within this range, indicating the reproducibility of RNA extraction and RT-PCR for pools varying in mosquito genus and number. A comparison of mosquito pool genera revealed no significant genus effect on the Ct value of the IPC. The incorporation of West Nile virus Armored RNA as an IPC allows monitoring of RNA extraction and RT-PCR and detection of false-negative results due to failures in these processes or to PCR inhibition, respectively.

Farfan-Ale, Jose A.; Blitvich, Bradley J.; Lorono-Pino, Maria A.; Marlenee, Nicole L.; Rosado-Paredes, Elsy P.; Garcia-Rejon, Julian E.; Flores-Flores, Luis F.; Chulim-Perera, Luis; Lopez-Uribe, Mildred; Perez-Mendoza, Gerardo; Sanchez-Herrera, Ingrid; Santamaria, Waldemar; Moo-Huchim, Jose; Gubler, Duane J.; Cropp, Bruce C.; Calisher, Charles H.; Beaty, Barry J. Longitudinal studies of West Nile virus infection in avians, Yucatan State, Mexico. Vector Borne and Zoonotic Diseases. 2004 Spring; 4(1): 3-14. ISSN: 1530-3667.

NAL call no.: RA639.5.V43

Descriptors: migratory and resident birds, surveillance for WNV infection of many individuals and species of birds, enzyme linked immunosorbent assay, plaque reduction neutralization test, evidence of WNV bird-bird transmission in Yucatan Peninsula.

Abstract: Following the introduction of West Nile virus (WNV) into North America in 1999, surveillance for evidence of infection with this virus in migratory and resident birds was established in Yucatan State, Mexico in March 2000. Overall, 8611 birds representing 182 species and 14 orders were captured and assayed for antibodies to WNV. Of these, 5066 (59%) birds were residents and 3545 (41%) birds were migrants. Twenty-one (0.24%) birds exhibited evidence of flavivirus infection. Of these, 8 birds had antibodies to WNV by epitope-blocking enzyme-linked immunosorbent assay. Five (0.06%) birds (gray catbird, brown-crested flycatcher, rose-breasted grosbeak, blue bunting and indigo bunting) were confirmed to have WNV infections by plaque reduction neutralization test. The WNV-infected birds were sampled in December 2002 and January 2003. The brown-crested flycatcher and blue bunting presumably were resident birds; the other WNV seropositive birds were migrants. These data provide evidence of WNV transmission among birds in the Yucatan Peninsula.

Fonesca, Dina M.; Keyghobadi, Nusha; Malcolm, Colin A.; Mehmet, Ceylan; Schaffner, Francis; Mogi, Motoyoshi; Fleischer, Robert C. Emerging vectors in the Culex pipiens complex. Science. 2004 March 5; 303(5663): 1421-1564. ISSN: 0036-8075.

NAL call no: 470 Sci2

Descriptors: Culex pipiens, Culex molestus, vectors of West Nile Virus, common mosquito in urban areas of US, can transmit the virus transovarially, bite both humans and birds, bridge vectors, examination of different populations world wide, divergent array of physiological and behavioral traits, underground and above ground populations, tested genetic relationship via 8 microsatellite loci, US populations clustered separately, all US specimens include hybrids, vectorial capacity, affects of introductions.

Fox, J.L. US West Nile virus epidemic continues to expand westward. American Society of Microbiology. 2004 Jan; 70(1): 9-10. ISSN: 0044-7897.

NAL call no.: QR1.A85

Descriptors: WNV, birds, mosquitos, expansion from East to West, North America.

Gould, L. Hannah; Fikrig, Erol. West Nile virus: a growing concern? Journal of Clinical Investigation. 2004 Apr; 113(8): 1102-1107. Many references. ISSN: 0021-9738.

NAL call no.: 448.8 J8295

Descriptors: epidemiology, ecology, treatments, vaccines, review paper, control and treatments, North America.

Abstract: West Nile virus was first detected in North America in 1999 and has subsequently spread throughout the United States and Canada and into Mexico and the Caribbean. This review describes the epidemiology and ecology of West Nile virus in North America and the prospects for effective treatments and vaccines.

Harvey, Tracey J.; Liu, Wen Jun; Wang, Xiang Ju; Linedale, Richard; Jacobs, Michael; Davidson, Andrew; Le Thuy, T.T.; Anraku, Itaru; Suhrbier, Andreas; Shi, Pei-Yong; Khromykh, Alexander A. Tetracycline-inducible packaging cell line for production of flavivirus replicon particles. Journal of Virology. 2004 Jan; 78(1): 531-538. ISSN: 0022-538X

NAL call no.: QR360.J6

Descriptors: mice, hamsters, flavivirus, virus assembly, Vero cells, genetics, replicon vectors from Kunjin, immune responses, BHK packinaging cell line—tetKUNCprME, tetracycline-inducible promoter, cell production system, transfected cells, West Nile Virus, pathogenicity, development of the noncytopathic Kunjin virus replicon-based gene expression system.

Abstract: We have previously developed replicon vectors derived from the Australian flavivirus Kunjin that have a unique noncytopathic nature and have been shown to direct prolonged high-level expression of encoded heterologous genes in vitro and in vivo and to induce strong and long-lasting immune responses to encoded immunogens in mice. To facilitate further applications of these vectors in the form of virus-like particles (VLPs), we have now generated a stable BHK packaging cell line, tetKUNCprME, carrying a Kunjin structural gene cassette under the control of a tetracycline-inducible promoter. Withdrawal of tetracycline from the medium resulted in production of Kunjin structural proteins that were capable of packaging transfected and self-amplified Kunjin replicon RNA into the secreted VLPs at titers of up to 1.6 x 10(9) VLPs per ml. Furthermore, secreted KUN replicon VLPs from tetKUNCprME cells could be harvested continuously for as long as 10 days after RNA transfection, producing a total yield of more than 10(10) VLPs per 10(6) transfected cells. Passaging of VLPs on Vero cells or intracerebral injection into 2- to 4-day-old suckling mice illustrated the complete absence of any infectious Kunjin virus. tetKUNCprME cells were also capable of packaging replicon RNA from closely and distantly related flaviviruses, West Nile virus and dengue virus type 2, respectively. The utility of high-titer KUN replicon VLPs was demonstrated by showing increasing CD8(+)-T-cell responses to encoded foreign protein with increasing doses of KUN VLPs. A single dose of 2.5 x 10(7) VLPs carrying the human respiratory syncytial virus M2 gene induced 1,400 CD8 T cells per 10(6) splenocytes in an ex vivo gamma interferon enzyme-linked immunospot assay. The packaging cell line thus represents a significant advance in the development of the noncytopathic Kunjin virus replicon-based gene expression system and may be widely applicable to the basic studies of flavivirus RNA packaging and virus assembly as well as to the development of gene expression systems based on replicons from different flaviviruses.

Heinz-Taheny, Kathleen M.; Andrews, John J.; Kinsel, Michael J.; Pessier, Allan P.; Pinkerton, Marie E.; Lemberger, Karin Y.; Novak, Robert J.; Dizikes, George J.; Edwards, Eric; Komar, Nicholas. West Nile virus infection in free-ranging squirrels in Illinois. Journal of Veterinary Diagnostic Investigation. 2004 May; 16(3): 186-190. ISSN: 1040-6387.

NAL call no.: SF774.J68

Descriptors: gray and fox squirrels, first report of WNV infection lesions, gliosis throughout the brain, WNV antigen present in the brain, spleen, heart and kidney, immunohistochemistry.

Abstract: West Nile virus (WNV) infection was diagnosed in 13 gray squirrels (Sciurus carolinensis) and 3 fox squirrels (Sciurus niger) that were observed with neurologic signs before death or found dead. All 16 had gliosis throughout all sections of the brain. Most had lymphoplasmacytic encephalitis or meningoencephalitis, many with admixed neutrophils. Neuronal necrosis and neuronophagia were also prominent features. West Nile virus antigen was demonstrated in the brain, spleen, heart or kidney in 10 of 13 gray squirrels and 3 of 3 fox squirrels by immunohistochemistry. Nucleic acid amplification tests (NAATs) confirmed the presence of WNV in the brain or spinal cord of 10/10 gray squirrels and 1/3 fox squirrels tested. Viral levels were quantified in various tissues of selected gray squirrels, and titers were highest in spleen and brain, with no virus detected in serum. This is the first description of lesions associated with WNV infection in gray and fox squirrels.

Higgs, Stephen; Snow, Keith; Gould, Ernest A. The potential for West Nile virus to establish outside of its natural range: a consideration of potential mosquito vectors in the United Kingdom. Transactions of the Royal Society of Tropical Medicine and Hygiene. 2004 Feb; 98(2): 82-87. ISSN: 0035-9203.

NAL call no.: 448.9 R813

Descriptors: migrating birds, horses, potential of British mosquitoes to transmit WNV, culicine and anopheline mosquitoes, WNV, sporadic outbreaks in Europe, equine and human dead end hosts.

Abstract: Outbreaks of West Nile virus (WNV) infection have occurred sporadically in Europe, apparently due to the migration of infected birds and the subsequent establishment of a transmission cycle involving culicine and anopheline mosquitoes. Both human and equine species become infected, but are considered as dead end hosts since they play an insignificant role in the maintenance of the cycle. Following the introduction of WNV into the United States in 1999 it is increasingly apparent that the virus has an extraordinary ability to infect a very broad range of arthropod species. Here we consider the potential for British mosquitoes to transmit WNV in the event that it is introduced into the UK.

Keyghobadi, Nusha; Matrone, Michael A.; Ebel, Gregory D.; Kramer, Laura D.; Fonseca, Dina M. Microsatellite loci from the northern house mosquito (Culex pipiens), a principal vector of West Nile virus in North America. Molecular Ecology Notes. 2004 Mar; 4(1): 20-22. ISSN: 1471-8278.

NAL call no.: QH541.15.M632

Descriptors: Culex pipiens, microsatellite isolates, markers of epidemiological characterization, intraspecific variation in epidemiological characteristics.

Abstract: Microsatellites were isolated and characterized in the northern house mosquito, Culex pipiens, a widespread pest species and important vector of diseases such as West Nile virus. An enrichment protocol yielded 150 positive clones. We designed primers to amplify 17 unique (GT)n microsatellites, eight of which amplified cleanly and were polymorphic. A survey of 29 individuals showed that these loci are highly variable with the number of alleles ranging from seven to 19 and expected heterozygosity ranging from 0.66 to 0.93. These markers will be useful for studies of population structure and intraspecific variation in epidemiological characteristics of Cx. pipiens.

Kleiboeker, Steven B.; Loiacono, Christina M.; Rottinghaus, Audrey; Pue, Howard L.; Johnson, Gayle C. Diagnosis of West Nile virus infection in horses. Journal of Veterinary Diagnostic Investigation. 2004 Jan; 16(1): 2-10. ISSN: 1040-6387.

NAL call no.: SF774.J68

Descriptors: horses, WNV epizootic caused horse morbidity and mortality, diagnosis, diagnostic sensitivity of reverse transcriptase polymerase chain reaction (RT PCR) low compared to immunoglobulin M immunosorbent assay.

Abstract: The North American West Nile virus (WNV) epizootic, which began in 1999, has caused significant morbidity and mortality in horses. Because experimental infection has failed to consistently produce encephalitis in inoculated horses, investigation of naturally occurring cases was used to optimize strategies for diagnosis of this disease. Although WNV RNA could be detected by reverse transcriptase-polymerase chain reaction (RT-PCR) performed on whole blood collected from both clinically affected horses and unaffected herdmates, the diagnostic sensitivity of this approach was low compared with IgM-capture enzyme-linked immunosorbent assay. In addition, it was observed that 18.5% of herdmates of clinically ill horses seroconverted to WNV yet exhibited no overt clinical signs of WNV encephalitis. West Nile viral RNA was detected in neural tissue of 46 of 64 dead horses that were suspected of having WNV encephalitis. Some of these animals were IgM negative or had not been tested serologically. A primary cause of death other than WNV encephalitis was identified in 15 of the 64 cases, whereas the final diagnosis for 3 of these cases remains unresolved. Quantitative RT-PCR analysis of neural tissue from WNV RNA-positive horses demonstrated that the medulla contained the highest mean concentration of viral RNA and that WNV RNA could be detected in samples extracted from formalin-fixed neural tissue. A comparison of WNV RT-PCR amplification strategies found that nested RT-PCR improved diagnostic sensitivity only slightly over a single round of amplification and that a quantitative (TaqMan) assay had sensitivity and specificity that were equivalent to those of nested amplification.

Lawrie, C.H.; Uzcategui, N.Y.; Gould, E.A.; Nuttall, P.A. Ixodid and Argasid tick species and West Nile virus. Emerging Infectious Diseases. 2004; 10(4): 653-657. ISSN: 1080-6040.

NAL call no.: RA648.5.E46

Descriptors: tick-borne WNV transmission, Ixodes ricinus and Ornithodoros moubata, rodent viremic hosts, ticks unlikely play major role in WNV transmission, some species likely reservoir.

Lis, H. Rozwoj i przebieg zapalenia mozgu Zachodniego Nilu w USA. [Outbreak of West Nile virus encephalitis in the USA (in 1999).] Zycie Weterynaryjne. 2004; 79(2): 110. ISSN: 0137-6810. Note: In Polish.

NAL call no.: SF604.Z9

Descriptors: WNV, emerging disease, disease surveys, encephalitis, epidemiology, public health concerns, zoonotic diseases, birds, horses, humans, United States.

Liu Wei-bin; Liang Guo-dong. [Advances in research of West Nile virus.] Virologica Sinica. 2004 Feb; 19(1): 92-96. ISSN: 1003-5125. Note: In Chinese with no summary.

NAL call no.: QR355.P5

Descriptors: West Nile virus, single strand RNA virus, Flavivirdae, West Nile fever.

Luechtefeld, L. West Nile transmitted from alligator to human. Veterinary Practice News. 2004; 16(1): 14. ISSN: 1528-6398.

NAL call no.: SF601.V5

Descriptors: alligators, Idaho farm, juvenile alligators from Florida developed WNV symptoms, high mortality before virus identified, man infected via handling infected animals.

Lvov, D.K.; Butenko, A.M.; Gromashevsky, V.L.; Kovtunov, A.I.; Prilipov, A.G.; Kinney, R.; Aristova. V.A.; Dzharkenov, A.F.; Samokhvalov, E.I.; Savage, H.M.; Shchelkanov, M.Y.; Galkina, I.V.; Deryabin, P.G.; Gubler, D.J.; Kulikova, L.N.; Alkhovsky, S.K.; Moskvina, T.M.; Zlobina, L.V.; Sadykova, G.K.; Shatalov, A.G.; Lvov, D.N.; Usachev, V.E.; Voronina, A.G. West Nile virus and other zoonotic viruses in Russia: examples of emerging-reemerging situations. Archives of Virology. Supplementum (Austria). 2004; 18: 85-96. ISSN: 0939-1983.

NAL call no.: QR355.A72

Descriptors: vertebrates, humans, ecological groups of viruses, 24 new viruses identified, newly recognized infections described, West Nile virus, Crimean-Congo hemorrhagic fever (CCHF) Northern Eurasia.

Abstract: Studies of the interactions of vertebrates, viruses and arthropod vectors of these viruses were monitored in terms of different ecological groups of viruses transmitted by mosquitoes and ticks in Northern Eurasia in an area encompassing more than 15 million km2. About 90 viruses were isolated, including 24 new to science. Newly recognized infections of vertebrates, including humans, were described. Many unusual epidemic situations were analysed. Permanent efforts were established to prevent bioterrorist activities and their consequences. Extensive epidemic outbreaks of West Nile fever (WNF; i.e., fever caused by West Nile virus) and Crimean-Congo hemorrhagic fever (CCHF) with unusual high mortality appeared in the last four years in southern Russia. We determined infection rates in humans, domestic and wild animals, mosquitoes and ticks from natural and synanthropic biocenoses [Editorial note: "synanthropic" means, roughly, all species living with (c.f. lice, fleas) or near people, such as in houses (c.f. house mice), parks (c.f. Rattus spp.), and the like, rather like "peridomestic", but not strictly so; "biocenosis" is the biome, the "totality of living populations in a particular habitat, which itself is only a part of the ecosystem".]. CCHF virus strains were phylogenetically similar to strains isolated in this area 35 years ago but different from Central-South-Asian and African strains. Before the outset of the current emergence of epidemic WNF, three genetic variants of this virus had been isolated in USSR, two African and one Indian. Phylogenetic analysis of complete genome sequences of epidemic strains demonstrated considerable similarity to strains from USA and Israel and differences from strains isolated in the same USSR areas 20-30 years before. In addition to strains of genotype 1, we isolated strains of second and third lineages and a strain of a fourth genetic variant. Nucleotide differences of these strains from all three genotypes was about 30%. The emerging WNF situation in Russia for the last 4 years probably has been the result of not only natural and social factors, but also to introduction of more virulent strains or by evolution of the virus.

Minke, J.M.; Siger, L.; Karaca, K.; Austgen, L.; Gordy, P.; Bowen, R.; Renshaw, R.W.; Loosmore, S.; Audonnet, J.C.; Nordgren, B. Recombinant canarypoxvirus vaccine carrying the prM/E genes of West Nile virus protects horses against a West Nile virus-mosquito challenge. Archives of Virology. Supplementum (Austria). 2004; 18: 221-230. ISSN: 0939-1983.

NAL call no.: QR355.A72

Descriptors: horses, WNV vaccine for horses, vCP2017 vaccine with prM/E genes from NY1999 WNV isolates synthesized and assessed, dose titration study of antibody response and duration, protection onset determined, challenged with WNV infected Aedes albopictus mosquitoes, two doses provides immunity in horses.

Abstract: An ALVAC (canarypoxvirus)-based recombinant (vCP2017) expressing the prM and E genes derived from a 1999 New York isolate of West Nile virus (WNV) was constructed and assessed for its protective efficacy in horses in two different experiments. In the first trial, a dose titration study was conducted to evaluate both serum neutralising antibody responses to WNV and duration of immunity. In the second trial the onset of protection was determined. Twenty-eight adult horses received two doses of vCP2017 administered intramuscularly at 5-week intervals and sixteen horses comprised age-matched non-vaccinated controls. Individual sera were taken periodically and tested for neutralising antibodies against WNV. Horses were challenged by allowing WNV-infected Aedes albopictus mosquitoes to feed on them two weeks (second trial) or one year (first trial) after the second vaccination. After challenge, horses were monitored for clinical signs of disease, and blood samples were collected for detection of WNV viremia and antibody. In both trials, all vaccinated horses developed neutralising antibodies against WNV. None of the vaccinated or control horses developed clinical signs of WNV disease upon challenge. None of the nine horses challenged 2 weeks after primary vaccination and only one of the ten vaccinated horses challenged 1 year after vaccination developed detectable viremia after challenge, whereas more than 80% of the controls became infected. Results from these studies demonstrated that a primary course of two doses of vCP2017 provides both antibody response and an early immunity in horses against WNV viremia.

Nelson, D.M.; Gardner, I.A.; Chiles, R.F.; Balasuriya, U.B.; Eldridge, B.F.; Scott, T.W.; Reisen, W.K.; Maclachlan, N.J. Prevalence of antibodies against Saint Louis encephalitis and Jamestown Canyon viruses in California horses. Comparative Immunology Microbiology and Infectious Diseases. 2004 May; 27(3): 209-215. ISSN: 0147-9571.

NAL call no.: QR180.C62

Descriptors: horses, seroprevalence of SLE and JC viruses, predicts wider distribution of West Nile virus, California.

Olberg, R.A.; Barker, I.K.; Crawshaw, G.J.; Bertelsen, M.F.; Drebot, M.A.; Andonova, M. West Nile virus encephalitis in a Barbary macaque (Macaca sylvanus). Emerging Infectious Diseases. 2004; 10(4): 712-714. ISSN: 1080-6040.

NAL call no.: RA648.5.E46

Descriptors: Barbary ape, WNV diagnosed, brain lesions, reverse transcriptase polymerase chain reaction, immunohistochemistry and virus isolation, Toronto.

Palmer, Mitchell V.; Stoffregen, William C.; Rogers, Douglas G.; Hamir, Amir N.; Richt, Juergen A.; Pedersen, Douglas D.; Waters, W. Ray. West Nile virus infection in reindeer (Rangifer tarandus). Journal of Veterinary Diagnostic Investigation. 2004 May; 16(3): 219-222. ISSN: 1040-6387.

NAL call no.: SF774.J68

Descriptors: reindeer, first known clinical WNV Cervidae infection, nucleotide sequence of 768-bp region of WNV E-glycoprotein gene, 1 mutation substitution of serine with glycine, compared with WNV-NY99 Bronx zoo flamingo 382-99 isolates.

Abstract: West Nile virus (WNV) infection in 4 reindeer (Rangifer tarandus) resulted in lymphohistiocytic encephalomyelitis within the medulla oblongata and cervical spinal cord. Immunohistochemistry revealed WNV antigen within neurons and among mononuclear cell infiltrates. These represent the first known cases of clinical WNV infection in Cervidae. Clinical signs and lesions were similar to those described in horses. Nucleotide sequence of a 768-bp region of the WNV E-glycoprotein gene revealed 1 nucleotide mutation, which resulted in a single amino acid substitution from a serine to a glycine (position 227 of E-glycoprotein) when compared with the prototype WNV-NY99strain (isolated from Bronx zoo flamingo 382-99).

Papin, James F.; Vahrson, Wolfgang; Dittmer, Dirk P. SYBR green-based real-time quantitative PCR assay for detection of West Nile virus circumvents false-negative results due to strain variability. Journal of Clinical Microbiology. 2004 Apr; 42(4): 1511-8. ISSN: 0095-1137.

NAL call no.: QR46.J6

Descriptors: West Nile virus, point mutations, sequence variations, TaqMan Assay, failure rate, more efficient SYBR green-based assay

Abstract: Real-time quantitative PCR is used routinely for the high-throughput diagnosis of viral pathogens, such as West Nile virus (WNV). Rapidly evolving RNA viruses present a challenge for diagnosis because they accumulate mutations that may render them undetectable. To explore the effect of sequence variations on assay performance, we generated every possible single point mutation within the target region of the widely used TaqMan assay for WNV and found that the TaqMan assay failed to detect 47% of possible single nucleotide variations in the probe-binding site and was unable to detect any targets with more than two mutations. In response, we developed and validated a less expensive assay with the intercalating dye SYBR green. The SYBR green-based assay was as sensitive as the TaqMan assay for WNV. Importantly, it detected 100% of possible WNV target region variants. The assay developed here adds an additional layer of protection to guard against false-negative results that result from natural variations or drug-directed selection and provides a rapid means to identify such variants for subsequent detailed analysis.

Parida, Manmohan; Posadas, Guillermo; Inoue, Shingo; Hasebe, Futoshi; Morita, Kouichi. Real-time reverse transcription loop-mediated isothermal amplification for rapid detection of West Nile virus. Journal of Clinical Microbiology. 2004 Jan; 42(1): 257-63. ISSN: 0095-1137.

NAL call no.: QR46.J6

Descriptors: West Nile virus assay, gene amplification, TR LAMP assay, agarose gel electrophoresis, turbidity, 10-fold higher sensitivity than RT PCR, rapid comprehensive WNV surveillance, isolation, serology.

Abstract: A one-step, single tube, real-time accelerated reverse transcription loop-mediated isothermal amplification (RT-LAMP) assay was developed for detecting the envelope gene of West Nile (WN) virus. The RT-LAMP assay is a novel method of gene amplification that amplifies nucleic acid with high specificity, efficiency, and rapidity under isothermal conditions with a set of six specially designed primers that recognize eight distinct sequences of the target. The whole procedure is very simple and rapid, and amplification can be obtained in less than 1 h by incubating all of the reagents in a single tube with reverse transcriptase and Bst DNA polymerase at 63 degrees C. Detection of gene amplification could be accomplished by agarose gel electrophoresis, as well as by real-time monitoring in an inexpensive turbidimeter. When the sensitivity of the RT-LAMP assay was compared to that of conventional RT-PCR, it was found that the RT-LAMP assay demonstrated 10-fold higher sensitivity compared to RT-PCR, with a detection limit of 0.1 PFU of virus. By using real-time monitoring, 10(4) PFU of virus could be detected in as little as 17 min. The specificity of the RT-LAMP assay was validated by the absence of any cross-reaction with other, closely related, members of the Flavivirus group, followed by restriction digestion and nucleotide sequencing of the amplified product. These results indicate that the RT-LAMP assay is extremely rapid, cost-effective, highly sensitive, and specific and has potential usefulness for rapid, comprehensive WN virus surveillance along with virus isolation and/or serology.

Phalen, D.N.; Dahlhausen, B. West Nile virus. Seminars in Avian and Exotic Pet Medicine. 2004 Apr; 13(2): 67-78. ISSN: 1055-937X.

NAL call no.: SF994.2.A1S36

Descriptors: 200 species of birds, WNV mortality, chickens and turkeys refractory to WNV, horse encephalitis due to WNV, WNV infection reported in many species of mammals, Europe, Israel, United States, Canada, Mexico, Caribbean.

Prince, Harry E.; Lape'-Nixon, Mary; Moore, Ronald J.; Hogrefe, Wayne R. Utility of the focus technologies West Nile virus immunoglobulin M capture enzyme-linked immunosorbent assay for testing cerebrospinal fluid. Journal of Clinical Microbiology. 2004 Jan; 42(1): 12-15. ISSN: 0095-1137.

NAL call no.: QR46.J6

Descriptors: WNV assay, enzyme linked immmunosorbent assay (ELISA), cerebrospinal fluid immunoglobulin M, accurate qualitative WNV IgM detection.

Abstract: Focus Technologies has developed an immunoglobulin M (IgM) capture enzyme-linked immunosorbent assay (ELISA) kit that utilizes recombinant West Nile virus (WNV) antigens to detect WNV IgM in serum. We evaluate here the utility of the kit for detecting WNV IgM in cerebrospinal fluid (CSF). The sensitivity was evaluated by using 52 CSF specimens from the 2002 WNV season that were positive in both the Public Health Service Laboratories WNV IgM ELISA and an in-house WNV IgM ELISA with native WNV antigen. The specificity was evaluated with two groups of specimens: (i). 73 CSF specimens submitted for in-house WNV IgM ELISA testing from February through April 2003 and yielding a negative WNV IgM result and (ii). 60 CSF specimens determined to be positive for another virus by PCR testing. Using these 185 CSF specimens at a screening dilution of 1:2, the kit was determined to be 100% sensitive and 100% specific. Endpoint titers were determined for 20 IgM-positive CSF specimens by testing serial twofold dilutions and ranged from 1:8 to 1:512. Index values (specimen absorbance value/calibrator absorbance value) for the screening dilution (1:2) showed no correlation with IgM titers, whereas index values for higher dilutions showed significant correlation with IgM titers. CSF screening dilutions of greater than 1:2 are not recommended, however, due to the risk of obtaining false-negative results. These findings show that the Focus Technologies WNV IgM capture ELISA, when utilized as recommended, offers accurate qualitative detection of WNV IgM in CSF specimens.

Quirin, R.; Salas, M.; Zientara ,S.; Zeller, H.; Labie, J.; Murri, S.; Lefranc(cedil)ois, T.; Petitclerc, M.; Martinez, D. West Nile virus, Guadeloupe. Emerging Infectious Diseases. 2004; 10(4): 706-708. ISSN: 1080-6040.

NAL call no.: RA648.5.E46

Descriptors: horses, chickens, WNV infection, immunosorbent assay, seroneutralization tests, 2002, six months later high rate of seroconversion observed.

Ratterree, Marion S.; Gutierrez, Robin A.; Travassos da Rosa, Amelia P.A.; Dille, Bruce J.; Beasley, David W.C.; Bohm, Rudolf P.; Desai, Suresh M.; Didier, Peter J.; Bikenmeyer, Larry G.; Dawson, George J.; Leary, Thomas P.; Schochetman, Gerald; Phillippi-Falkenstein, Katherine; Arroyo, Juan; Barrett, Alan D.T.; Tesh, Robert B. Experimental infection of rhesus macaques with West Nile virus: level and duration of viremia and kinetics of the antibody response after infection. Journal of Infectious Diseases. 2004 Feb 15; 189(4): 669-676. ISSN: 0022-1899.

NAL call no.: 448.8 J821

Descriptors; rhesus macaques, WNV experimentally infected, levels of viremia, nested reverse transcription polymerase chain reaction, most sensitive method for detecting viral RNA in blood, WNV antibodies identified in second week with immunosorbent assay, both nucleic acid and serological testing may be needed to identify potential blood donors.

Abstract: Reports of transfusion-associated cases of West Nile virus (WNV) infection indicate the need for sensitive screening methods to identify WNV-infected blood products. We experimentally infected 5 rhesus macaques with WNV, to determine the level and duration of viremia, the kinetics of the humoral immune response, and the sensitivity of various assay systems for detecting WNV in blood. All macaques developed subclinical infections with low levels of viremia; nested reverse-transcription polymerase chain reaction was the most sensitive method for detecting virus or viral RNA in blood. Specific WNV antibodies appeared during the second week of infection; the results of an IgM enzyme-linked immunosorbent assay became positive on the ninth or tenth day after infection, followed in 1-2 days by hemagglutination-inhibiting and neutralizing antibodies. Our results suggest that both nucleic acid and serological testing may be needed to determine exposure to WNV and to identify potentially infected blood donors.

Reeves, W.K.; Korecki, J.A. Ochlerotatus japonicusjaponicus (Theobald) (Diptera: Culicidae), a new invasive mosquito for Georgia and South Carolina. Proceedings of the Entomological Society of Washington. 2004; 106(1): 233-234. ISSN: 0013-8797.

NAL call no.: 420 W27

Descriptors: West Nile virus, new possible mosquito vector, Ochlerotatus japonicusjaponicus, exotic species, Georgia and South Carolina.

Romi, R.; Pontuale, G.; CIufolini, M. G.; Fiorentini, G.; Marchi, A.; Nicoletti, L.; Cocchi, M.; Tamburro, A. Potential vectors of West Nile virus following an equine disease outbreak in Italy. Medical and Veterinary Entomology. 2004 Mar; 18(1): 14-19. ISSN: 0269-283X.

NAL call no.: RA639.M44

Descriptors: race horses WNV infected, equine encephalomyelitis, 11 species of mosquitoes identified, WNV transmission by migratory birds to non-migratory birds, Culex pipiens broader host range more likely to transmit WNV to horses.

Abstract: In the late summer of 1998, an outbreak of equine encephalomyelitis due to West Nile virus (WNV) occurred in the Tuscany region of central Italy. The disease was detected in 14 race horses from nine localities in four Provinces: Firenze, Lucca, Pisa and Pistoia. The outbreak area included Fucecchio wetlands (1800 ha), the largest inland marsh in Italy, and the adjacent hilly Cerbaie woodlands with farms breeding horses. To detect potential vectors of WNV, entomological surveys of Fucecchio and Cerbaie were undertaken during 1999-2002 by collecting mosquito larvae from breeding sites and adult mosquitoes by several methods of sampling. Among 6023 mosquitoes (Diptera: Culicidae) collected, 11 species were identified: Aedes albopictus (Skuse), Ae. vexans (Meigen), Anopheles atroparvus Van Thiel, An. maculipennis Meigen s.s., An. plumbeus Stephens, Culex impudicus Ficalbi, Cx. pipiens L., Culiseta longiareolata Macquart), Ochlerotatus caspius (Pallas), Oc. detritus (Haliday) and Oc. geniculatus (Olivier). In Fucecchio marshes, Cx. impudicus predominated with seasonal peak densities in spring and autumn: its greatest abundance during early spring coincides with arrival of migratory birds from Africa. In Cerbaie hills, Cx. pipiens predominated with peak population density in late summer. No viruses were isolated from 665 mosquitoes processed. These findings, plus other data on Italian mosquito bionomics, suggest a possible mode of WNV transmission involving the most abundant Culex in the Fucecchio-Cerbaie areas. Culex impudicus, being partly ornithophilic, might transmit WNV from migratory to non-migratory birds during springtime; Cx. pipiens, having a broader host range, would be more likely to transmit WNV from birds to horses and, perhaps, to humans by late summer.

Tewari, Deepanker; Kim, Hyun; Feria, Willard; Russo, Brigite; Acland, Helen. Detection of West Nile virus using formalin fixed paraffin embedded tissues in crows and horses: quantification of viral transcripts by real-time RT-PCR. Journal of Clinical Virology. 2004 Aug; 30(4): 320-325. ISSN: 1386-6532.

Descriptors: crows, horses, WNV infected, RT PCR assay, NS5 gene assay, highest amounts of virus in the intestines of crows and brains of horses.

Abstract: West Nile virus (WNV) RNA was quantified in WNV infected crows and horses with the help of a real-time reverse transcriptase-PCR assay. A 5' nuclease assay, based on NS5 gene detection with a fluorescent probe was used for quantifying WNV RNA using formalin fixed paraffin embedded tissue specimens. Quantitative detection of WNV RNA showed the presence of a higher amount of the viral RNA in crow tissues compared to equine tissues and these results correlated well with the detection of WNV antigen by immunostaining. In crows, the highest amount of virus was seen in the intestine and in horses in the brain.

Verne, T.G. Diagnosis of zoonotic viral encephalitis Archives of Virology. 2004; 18: 231-244. ISSN: 0304-8608.

NAL call no.: 448.3 Ar23

Descriptors: humans, animals, West Nile virus, precise identification of arboviruses, surveillance and transmission control, use of DNA microarrays, extend range of viruses detected in a single test, various methods discussed, ELISA, immunochromatographic rapid tests for IgM, virus isolation, molecular assays validation issues.

Wang, Yang; Lobigs, Mario; Lee, Eva; Mullbacher, Arno. Exocytosis and Fas mediated cytolytic mechanisms exert protection from West Nile virus induced encephalitis in mice. Immunology and Cell Biology. 2004 Apr; 82(2): 170-173. ISSN: 0818-9641.

NAL call no.: QR180.I43

Descriptors: C57BL/6 mice mice, experimental infection, WNV induces T-cell responses, virus-host immune reactions assessed individually, cytolytic effector functions.

Abstract: Infection of mice with the flaviviruses West Nile virus (WNV) and Murray Valley encephalitis (MVE) induces cytolytic T-cell responses which are highly cross-reactive on target cells infected with heterologous flaviviruses. Of C57BL/6 mice infected with low doses (10(2)-10(6) PFU) of either virus, 30-40% develop encephalitis and die within 10-12 days. Mice with defects in the Fas or granule exocytosis (perforin and granzymes A and B) pathway of cellular cytotoxicity display reduced mortality and increased survival time when infected with MVE and are protected from encephalitis when deficient in both pathways. This contrasts with infection with WNV where defects in these cytolytic mechanisms increase the percentage of mice that succumb to encephalitis. Thus, no generalizations as to protective or detrimental effects of cytolytic effector functions in recovery from closely related flavivirus infections can be made. Virus-host immune interactions have to be assessed individually and cannot be generalized.

Watson, J.T.; Jones R.C.; Gibbs, K.; Paul, W. Dead crow reports and location of human West Nile virus cases, Chicago, 2002. Emerging Infectious Diseases. 2004; 10(5): 938-940. ISSN: 1080-6040.

NAL call no.: RA648.5.E46

Descriptors: crow deaths, high early season incidence, high human case incidence.

Wonham, Marjorie J.; de-Camino-Beck, Tomas; Lewis, Mark A. An epidemiological model for West Nile virus: invasion analysis and control applications. Proceedings of the Royal Society of London. Series B. Biological Sciences. 2004 Mar 7; 271(1538): 501-507. ISSN: 0962-8452.

NAL call no.: 501 L84B

Descriptors: birds, mosquitoes, model of WNV infection, a single season susceptible-infectious-removed (SIR) model of WNV cross infection between birds and mosquitoes, predict disease levels consistent with independent data.

Abstract: Infectious diseases present ecological and public health challenges that can be addressed with mathematical models. Certain pathogens, however, including the emerging West Nile virus (WN) in North America, exhibit a complex seasonal ecology that is not readily analysed with standard epidemiological methods. We develop a single-season susceptible-infectious-removed (SIR) model of WN cross-infection between birds and mosquitoes, incorporating specific features unique to WN ecology. We obtain the disease reproduction number, R0, and show that mosquito control decreases, but bird control increases, the chance of an outbreak. We provide a simple new analytical and graphical method for determining, from standard public health indicators, necessary mosquito control levels. We extend this method to a seasonally variable mosquito population and outline a multi-year model framework. The model's numerical simulations predict disease levels that are consistent with independent data.

Yaeger, Michael; Yoon, Kyoung-Jin; Schwartz, Kent; Berkland, Loretta. West Nile virus meningoencephalitis in a Suri alpaca and Suffolk ewe. Journal of Veterinary Diagnostic Investigation. 2004 Jan; 16(1): 64-66. ISSN: 1040-6387.

NAL call no.: SF774.J68

Descriptors: WNV, first report in 1Suffolk ewe, 1 alpaca, clinical signs, diagnosis, reverse transcription-polymerase chain reaction assays and immunohistochemistry on the brain, sporatic fatal nonsuppurative meningoencephalitis.

Abstract: The first confirmed cases of West Nile virus (WNV) in the Western Hemisphere were reported in the state of New York in 1999. Since then, the virus has spread throughout the eastern and central United States and continues to extend westward. This report describes clinical signs and microscopic lesions associated with WNV infection in a Suffolk ewe and an alpaca, 2 species in which the disease has not been reported previously. In late August 2002, a 4.5-year-old female alpaca developed an acute onset of clinical signs characterized by torticollis, hyperesthesia, ataxia, recumbency, and altered mentation. The animal died 3.5 days after the onset of clinical signs. Microscopic examination of the brain revealed a mild to moderate, diffuse, lymphoplasmacytic meningoencephalitis. In early September 2002, a 3-year-old Suffolk ewe developed a rapidly progressive illness characterized by ataxia and convulsions. The apparent duration from onset of clinical signs until death was less than 8 hours. The ewe had a moderate, diffuse, lymphoplasmacytic meningoencephalitis with focal gliosis. Reverse transcription-polymerase chain reaction assays and immunohistochemistry on the brain were positive for WNV in both animals. These cases demonstrate that WNV is capable of causing sporadic, fatal, nonsuppurative meningoencephalitis in alpacas and sheep.

Yaremych, S.A.; Warner, R.E.; Mankin, P.C.; Brawn, J.D.; Raim, A.; Novak, R. West Nile virus and high death rate in American crows. Emerging Infectious Diseases. 2004; 10(4): 709-711. ISSN: 1080-6040.

NAL call no.: RA648.5.E46

Descriptors: mosquitos, Culex and Anopheles, crow mortality, antibody prevalence, WNV kills more than 33% of American crows, local ecological effects are dramatic during new exposure.

Yoda, T.; Rakue, Y.; Mizota, T. Integrated pest management and surveillance of West Nile virus infection in Louisiana, USA. Journal of Tokyo Medical University. 2004; 62(2): 212-217. ISSN: 0040-8905.

Descriptors: domestic and wild birds, horses; humans, first appearance of WNV infection in 1999, encephalitis in humans and horses, animal mortality, mosquito control programs, “Integrated Pest Management” (IPM) developed in 1964, reduced WNV infection by 80% in Louisiana, IPM consists of: source reduction, public health education, biological control, chemical control and surveillance systems, New Orleans, Louisiana, United States.

Yu Shaoning, Wuu Alice; Basu, Reneeta; Holbrook, Michael; Barrett, Alan; Lee, J. Ching. Protein stability and structural dynamics in Domain III of vector-specific strain of West Nile envelope protein. Biophysical Journal. 2004 Jan; 86(1): 502a. ISSN: 0006-3495. Note: Meeting abstract.

NAL call no.: 442.8 B5238

Descriptors: Omsk hemorrhagic fever (OHF), WNV, envelope protein WN-D3 and OHF-D3 compared, biochemistry, molecular biophysics, infection methods and techniques, circular dichroism, spectrum analysis, fluorescence quenching, infrared spectroscopy, hydrogen-deuterium exchange.

Zeller, H.G.; Schuffenecker, I. West Nile virus: an overview of its spread in Europe and the Mediterranean basis in contrast to its spread in the Americas. European Journal of Clinical Microbiology and Infectious Diseases. 2004, Mar; 23(3): 147-156. ISSN: 0934-9723.

Descriptors: birds, horses, humans, WNV mosquito transmitted flavivirus, birds amplifying hosts transmission cycle, humans and horses dead end hosts, 1950 fatal WNV encephalitis in Israel, fatal human and equine WNV encephalitis in 1996-2000 in Mediterranean basin, 1998 virulent strain of WNV identified in migrating storks and domestic geese in Israel, 1999 nearly identical strain of WNV appeared in New York killing birds and some humans, outbreaks of WNV unpredictable, pathogenicity potential.

Abstract: West Nile (WN) virus is a mosquito-transmitted flavivirus. It is widely distributed in Africa, the Middle East, Asia, and southern Europe and was recently introduced to North America. Birds are involved in the cycle of transmission as amplifying hosts. Humans and horses are considered accidental dead-end hosts. WN fever was initially considered a minor arbovirosis, usually inducing a nonsymptomatic or a mild flu-like illness in humans, but some cases of encephalitis associated with fatalities were reported in Israel in the 1950s. After two silent decades, several human and equine outbreaks of fatal encephalitis occurred from 1996 to 2000 in Romania, Morocco, Tunisia, Italy, Russia, Israel, and France. In Romania, a few cases of WN encephalitis in humans are noticed every year, and in France, recent WN infections have been detected in monitored sentinel birds in 2001 and 2002. Phylogenetic studies have shown two main lineages of WN strains. Strains from lineage I are present in Africa, India, and Australia and are responsible for the outbreaks in Europe and in the Mediterranean basin, and strains from lineage II have been reported only in sub-Saharan Africa. In 1998, a virulent WN strain from lineage I was identified in dying migrating storks and domestic geese showing clinical symptoms of encephalitis and paralysis in Israel. A nearly identical WN strain suddenly emerged in New York in 1999, killing thousands of native birds and causing fatal cases in humans. The virus is now well established in the New World, and it disseminates rapidly. New modes of transmission through blood donations, organ transplants, and the intrauterine route have been reported. In Europe, an enhanced surveillance of WN infection in humans, horses, birds, and vectors may reveal the presence of the virus in different locations. Nevertheless, outbreaks of WN virus remain unpredictable. Further coordinated studies are needed for a better understanding of the ecology and the pathogenicity of the WN virus.

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December 15, 2003