NAL Call No.: 475 Ex7
Descriptors: effects of stressors on mortality, mouse model, cold and isolation stressors, viral encephalitis enhancement.
Abstract: The effect of cold or isolation stress on mortality rate and brain virus level were investigated in mice infected with West Nile virus (WNV). Exposure of mice for 5 min/day to cold water (1 0.5 degrees C) for 8-10 days resulted in 92% mortality as compared to 47% in control mice (p less than 0.001). Mice housed in individual cages (isolation stress) were also more susceptible to WN viral infection, as shown by increased mortality rate reaching 85% as compared to 50% in mice housed 6 per cage (p less than 0.01). Cold or isolation stress increased blood brain and spleen virus levels as early as 2 days after inoculation. After 8 days of isolation or cold stress, mice inoculated with WNV had 8.9 and 9.0 log10 plaque forming units in the brain, respectively, as compared to 6.9 in the control (p less than 0.01-0.001). Furthermore, lymphoid organs such as spleen and thymus showed severe mass loss. These data suggest that physical or non-physical stress situations enhance WNV encephalitis by accelerating virus proliferation and increase mortality in mice.
Blackburn, N.K.; A. Shepherd; B. Paterson; T. Besselaar. Susceptibility of the dog tick Haemaphysalis leachii Audouin (Acarina: Ixodidae) to West Nile virus. Journal of the Entomological Society of Southern Africa. Mar 1990. v. 53 (1) p. 11-16. ISSN: 0013-8789.
NAL Call No.: 420 EN86
Descriptors: dogs, Haemaphysalis leachii, ticks, West Nile virus, susceptibility, disease transmission, South Africa.
Mathiot, CC; Georges, AJ; Deubel, V. Comparative analysis of West Nile virus strains isolated from human and animal hosts using monoclonal antibodies and cDNA restriction digest profiles. Research in Virology. 1990 Sep-Oct; 141(5): 533-43. ISSN: 0923-2516.
NAL Call No.: QR355 A44
Descriptors: strain comparisons, 17 strains, humans, birds, mosquitoes, ticks, genetic strain typing, transmission factors, pathgenicity for humans.
Abstract: Three West Nile (WN) virus strains isolated in Bangui, Central African Republic (CAR), from patients with hepatitis were analysed comparatively with the prototype WN virus strain and 7 WN strains previously isolated from birds (2 strains), mosquitoes (3 strains) and ticks (2 strains) in CAR. The comparison was based on two techniques: an epitopic analysis by indirect immunofluorescence assay using a panel of 9 monoclonal antibodies to WN virus, and an analysis of HaeIII and TaqI restriction digest profiles of cDNA to infected cell RNA. Similar results were obtained with both techniques: the 3 human strains were found to be identical to each other and identical or very close to mosquito and tick strains, whereas prototype WN virus and bird strains were significantly different from the human strains. As "classical" infections due to WN virus without hepatic involvement were also reported during the period of isolation of the arthropod strains, we concluded that the same virus subtype may have been the cause of different infection patterns. A new definition of the disease spectrum of WN virus, including the possibility of liver involvement, should be established. Clearly, the Egyptian prototype WN virus represents a different topotype. Bird strains also appear to be different from human and arthropod strains, raising the question of their transmissibility and pathogenicity for man, and of the role of birds in the natural cycle of WN virus.
Morvan, J; Besselaar, T; Fontenille, D; Coulanges, P. Antigenic variations in West Nile virus strains isolated in Madagascar since 1978. Research in Virology. 1990 Nov-Dec; 141(6): 667-76. ISSN: 0923-2516.
NAL Call No.: QR355 A44
Descriptors: 52 isolates, immunofluorescent techniques, monoclonal antibodies, 5 groups of variants, human, birds, mosquitoes, bird migration, dissemination and transmission.
Abstract: The antigenic interrelationship between 52 Madagascan West Nile isolates and two prototype viruses (Eg101 and G2266) was assessed by an immunofluorescent technique using monoclonal antibodies. This analysis enabled us to define 5 groups of variants, 4 of which were closer to the Egyptian strain (Eg101) than to the Indian prototype (G2266). Groups II and V were dominant whereas strains of groups I and IV were less numerous. One strain belonging to group III was antigenically similar to the Indian strain. Antigenic variations were observed among viruses isolated from man, birds and different mosquito genera. Geographic variations were also observed. Exchanges exist between Madagascar and the African continent by means of migratory birds which seem to be instrumental in disseminating the virus and introducing the antigenic variants.
Morvan, J; Fontenille, D; Besselaar, TG; Coulanges, P. Utilisation des anticorps monoclonaux pour l'analyse antigenique des souches de virus West Nile isolees a Madagascar. Apport pour la comprehension du cycle epidemiologique. [Use of monoclonal antibodies for the antigenic analysis of West Nile viral strains isolated in Madagascar. Contribution to the understanding of the epidemiological cycle]. Archives de l'Institut Pasteur de Madagascar. 1990; 57(1): 167-81. ISSN: 0020-2495. In French.
Descriptors: 53 isolates, antigen comparisons, immunofluorescent techniques, monoclonal antibodies, 5 groups of variants, human, birds, mosquitoes, bird migration, dissemination and transmission.
Abstract: The antigenic relationship of 53 MADAGASCAR West Nile isolates to each other and to the two prototype viruses (Eg 101 and G 2266) was assessed using monoclonal antibodies. In MADAGASCAR exist 5 antigenic groups: 4 which are much closer to the Egyptian strain Eg 101 than to the Indian, and antigenically distinct from South african H 442 strain. One other is closely related to Indian strain G 2266. Antigenic variations are observed in every periods of transmission cycle. Some differences between strains isolated in a same region are also observed. MADAGASCAR is an exchange place for West Nile virus through the instrumentality of migratory birds.
Olaleye, OD; Omilabu, SA; Ilomechina, EN; Fagbami, AH. A survey for haemagglutination-inhibiting antibody to West Nile virus in human and animal sera in Nigeria. Comparative Immunology, Microbiology and Infectious Diseases. 1990; 13(1): 35-9. ISSN: 0147-9571.
NAL Call No.: QR180.C62
Descriptors: hemagglutination inhibition antibody, sera survey, humans, camels, goats, cattle, sheep, prevalence levels, yellow fever virus antigens, Potiskum virus antigens, Nigeria, Africa.
Abstract: A survey for West Nile virus (WNV) haemagglutination-inhibition (HI) antibody was carried out in humans and domestic animals. Human sera were collected from Ibadan, while the animal sera were collected from both Ibadan and Maiduguri. Out of 304 human sera tested, 123 were positive (40%). There was a higher prevalence of HI antibody in adults than children. Sex distribution of positive sera showed that 37% of males and 43% of females had WNV HI antibody. There was no significant difference in the prevalence of HI antibody in both sexes. On the 123 WNV HI positive sera tested, 104 (85%) and 78 (75%) had yellow fever and Potiskum HI antibody respectively. Monotypic WNV virus reactions were frequently found in children while polytypic reactions were frequently found in adults. A total of 200 animal sera were examined, 50 camels, 50 goats, 49 cattle and 51 sheep. The highest prevalence of HI antibody was found in camels (26%), followed by sheep (20%). Percentage of positive sera in other species were: goat (18%) and cattle (6%). Of the 35 WNV HI positive animal sera, 26 and 20% reacted with Yellow fever and Potiskum virus antigens respectively.
Wiederhold, A.H.; P. Jupp; J. Alexander. Sindbis and West Nile viruses: an electron microscope study of salivary gland infection in the vector mosquito Culex univittatus. Journal of the Entomological Society of Southern Africa. Sept 1990. v. 53 (2) p. 141-149. ISSN: 0013-8789.
NAL Call No.: 420 EN86
Descriptors: Culex univittatus, salivary glands, Sindbis virus, West Nile virus, infection, electron microscopy, disease vectors, South Africa.