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00.029.0.03.004. African cassava mosaic virus

Cite this publication as: ICTVdB Management (2006). 00.029.0.03.004. African cassava mosaic virus. In: ICTVdB - The Universal Virus Database, version 4. Büchen-Osmond, C. (Ed), Columbia University, New York, USA

Cite this site as: ICTVdB - The Universal Virus Database, version 4. http://www.ncbi.nlm.nih.gov/ICTVdb/ICTVdB/

Table of Contents

Host of Isolate and Habitat Details
Source of isolate: Manihot esculenta.

Natural host and symptoms
Manihot esculenta, Jatropha multifida — severe mosaic.

Hewittia sublobata — mosaic (probably the natural host of the Kenya coast strain; Bock et al., 1981).

Laportea (=Fluerya) aestuans — bright chlorosis (possibly the natural host in Nigeria; Anon., 1979).

Manihot glaziovii — mosaic.

Reference to Isolation Report
Warburg (1894, see also Storey and Nichols (1938, Harrison et al. (1977, Bock et al. (1978).

Classification

This is a description of a plant virus at the species level with data on all virus properties from morphology to genome, replication, antigenicity and biological properties.

ICTVdB Virus Code: 00.029.0.03.004. Virus accession number: 29003004. Obsolete virus code: 29.0.3.0.004; superceded accession number: 29030004.
NCBI Taxon Identifier NCBI Taxonomy ID: 10817.

Name, Synonyms and Lineage

Synonym(s): cassava latent virus, cassava mosaic virus, cassava African mosaic virus. ICTV approved acronym: ACMV. Virus is an ICTV approved species of the genus 00.029.0.03. Begomovirus in the family 00.029. Geminiviridae.

Virion Properties

Morphology

Virions consist of a capsid. Virus capsid is not enveloped. Capsid is elongated and exhibits icosahedral symmetry. The capsid is geminate and has a diameter of 20 nm. Capsids appear slightly hexagonal in outline. The capsomer arrangement is not obvious. With a length of the dimer is 30 nm.






















Electron micrograph of Geminiviridae by R.G. Milne, Istituto di Virologia, CRN, Torino, Italy.

Electron microscopic preparation and references: Virus preparation contains few virions. Virions best detected by immunosorbent electron microscopy. Reference for electron microscopic methods: Sequeira and Harrison (1982).

Physicochemical and Physical Properties

There are 2 sedimenting component(s) found in purified preparations. The sedimentation coefficient is of the fastest (main) component 76 S20w; of the other(s) are 50 S20w. The thermal inactivation point (TIP) is at 55°C. The longevity in vitro (LIV) is 2-4 days. Although the titer is dependent on the host, the decimal exponent (DEX) of the dilution end point is usually around 3 (type strain in sap of Nicotiana clevelandii). The infectivity is not changed by treatment with ether; decreased when deproteinized with proteases; retained when deproteinized with phenol or detergent (isolated DNA is 1-50% as infective as the same amount of DNA in virions).

Nucleic Acid

The Mr of the genome constitutes 22% of the virion by weight. The genome is segmented and consists of two segments of (similar,) circular, ambisense, single-stranded DNA. Minor species of non-genomic nucleic acid are also found in virions. The complete genome is 5503 nucleotides long. The DNA-1 is fully sequenced, complete sequence is 2779 nucleotides long. Sequence has the accession number
[J02057] Em(40)_vi:GE1G Gb(84)_vi:CLV1G Cassava latent virus (West Kenyan 844), DNA 1 of complete genome. 4/90 2,779bp.
[X17095] Em(40)_vi:GEN1G Gb(84)_vi:GEN1G African cassava mosaic virus (Nigerian strain) DNA 1. 9/93 2,781bp.
[X17096] Em(40)_vi:GEN2G Gb(84)_vi:GEN2G African cassava mosaic virus (Nigerian strain) DNA-2. 9/93 2,725bp.
[X68318] Em(40)_vi:ACPPCR6 Gb(84)_vi:ACPPCR6 African Cassava Mosaic Virus gene for coat protein (clone pPCR6). 7/93 852bp.
[X68319] Em(40)_vi:ACPPCR5 Gb(84)_vi:ACPPCR5 African Cassava Mosaic Virus gene for coat protein (clone pPCR5). 7/93 852bp.
[X68320] Em(40)_vi:ACPPCR4 Gb(84)_vi:ACPPCR4 African Cassava Mosaic Virus gene for coat protein (clone pPCR4). 7/93 852bp. 5 sequences.
DNA-B is fully sequenced, complete sequence is 2724 nucleotides long and has the accession number
[J02058] Em(40)_vi:GE2G Gb(84)_vi:CLV2G Cassava latent virus (west kenyan 844), dna 2 of complete genome. 4/90 2,724bp. The genome has a base ratio of 23.5 % guanine (DNA-1 24.6%, DNA-2 22.3%, 27.7 % adenine (DNA-1 26.9%, DNA-2 28.8%, 18.6 % cytosine (DNA-1 19.9%, DNA-2 17.3%, 30.2 % thymidine (DNA-1 28.5%, DNA-2 31.9%). Reference to nucleotide sequence Stanley and Gay (1983, Stanley (1983, Harrison et al. (1977, Sequeira et al. (1983).

GenBank records for nucleotide sequences; complete genome sequences.

Proteins

Proteins constitute about 78% of the particle weight.

The viral genome encodes structural proteins and non-structural proteins. Virions consist of 1 structural protein(s).

Structural Proteins: Reference to method of preparation: Bock et al. (1977, Sequeira (1982).

Reference to amino acid sequence or composition Stanley et al. (1985).

Non-Structural Proteins: Virus-coded non-structural proteins have been identified by sequence analysis and 5 non-structural protein(s) are found.

Lipids

Lipids are not reported.

Genome Organization and Replication

By itself, genomic nucleic acid is infectious (cloned DNA is infective).

Transcription: Sub-genomic RNA is derived from DNA-2 present in infected cells.

Replication cycle Features: the genome has the two circular genome DNA species share a sequence of 193 nucleotides which contains a stem and loop structure of 33 nucleotides. Transcription in both directions. DNA-1 encodes one protein of more than 15 kDain the plus (virion DNA) sense and three proteins more than 15 kDain the minus sense. DNA-2 encodes one protein more than 15 kDain each sense. Possible promoter and terminator and polyadenylation signals are found in all six ORFs. RNA transcripts of the expected sizes are found.

Antigenicity

The virus is serologically related to bean golden mosaic (SDI:2) (Sequeira and Harrison, 1982), squash leaf curl (Cohen et al., 1983), tomato golden mosaic (SDI:2) (Stein et al., 1983), euphorbia mosaic (Roberts et al., 1984) and many other whitefly transmitted geminiviruses (M. Aiton and BD. Harrison, unpublished information).

There are sequence homologies between the larger genome part (DNA-1) of African cassava mosaic virus and the DNA of bean golden mosaic, tomato golden mosaic, tobacco leaf curl and tomato leaf curl viruses (Roberts et al., 1984). DNA-1 of African cassava mosaic virus shows clear sequence similarities with bean golden mosaic virus in coding regions, but little in non-coding regions (Hamilton et al., 1984; Harrison, 1985). No serological relationship or genome homology has been found between African cassava mosaic virus and any monogeminiviruses.

The close serological relationship between biologically distinct geminiviruses can lead to difficulties in virus identification, especially when plant species not previously recorded as hosts are infected. However, African cassava mosaic virus does not infect Phaseolus vulgaris or Cucurbita pepo whereas bean golden mosaic and squash leaf curl viruses do. In hybridization tests, African cassava mosaic virus DNA-2 probes do not react with extracts of plants infected with bean golden mosaic, tobacco golden mosaic or tobacco leaf curl and allied geminiviruses (Roberts et al., 1984).

Diagnostics and Reference Collections

The best tests for diagnosis are African cassava mosaic virus is the only virus reported from cassava in Africa. However, in South America, similar symptoms are caused by cassava common mosaic virus which also causes local lesions in Chenopodium amaranticolor and Gomphrena globosa and is not transmitted by Bemisia tabaci (Costa and Kitajima, 1972). Viruses associated with two other mosaic diseases of cassava in Colombia are not sap-transmissible to Nicotiana benthamiana. Indian cassava mosaic virus is now considered to be a separate virus.

Biological Properties

Natural Host

Domain
Viral hosts belong to the Domain Eucarya.

Domain Eucarya
Kingdom Plantae.

Kingdom Plantae
Phylum Magnoliophyta (Angiosperms, Class Magnoliopsida (Dicotyledonae).

Class Magnoliopsida (Dicotyledonae)
Subclass ROSIDAE.

Severity and Occurrence of Disease

Host: Signs and symptoms persist and vary cyclically over a few weeks.

Transmission and Vector Relationships

Virus is transmitted by a vector. Virus is transmitted by mechanical inoculation (with difficulty to cassava (Bock and Woods, 1983) but more readily to Nicotiana benthamiana, transmitted by grafting; not transmitted by seeds.

Vector Transmission:
Virus is transmitted by arthropods, by insects of the order Hemiptera, family Aleyrodidae; Bemisia tabaci (Chant, 1958; Dubern, 1979). Virus is transmitted in a persistent manner; retained when the vector moults; not transmitted congenitally to the progeny of the vector (Dubern, 1979).

Experimental Hosts and Symptoms

Under experimental conditions susceptibility to infection by virus is found in few families. Susceptible host species are found in the Family Convolvulaceae, Euphorbiaceae, Solanaceae, Urticaceae. The following species were susceptible to experimental virus infection: Datura ferox, Datura stramonium, Hewittia sublobata, Jatropha multifida, Laportea aestuans, Manihot esculenta, Manihot glaziovii, Nicandra physalodes, Nicotiana benthamiana, Nicotiana clevelandii, Nicotiana debneyi, Nicotiana glutinosa, Nicotiana rustica, Nicotiana tabacum, Solanum nigrum.

Host:
Experimentally infected hosts mainly show symptoms of chlorotic local lesions, systemic mosaic, leaf curling.

Experimentally infected insusceptible Hosts: Families containing insusceptible hosts: Amaranthaceae, Chenopodiaceae, or Convolvulaceae, Cucurbitaceae, Euphorbiaceae, Gramineae, or Leguminosae-Papilionoideae, Malvaceae, Solanaceae (7 /17). Species inoculated with virus that do not show signs of susceptibility: Atriplex hortensis, Beta vulgaris, Capsicum frutescens, Chenopodium amaranticolor, Chenopodium quinoa, Citrullus lanatus, Cucumis melo, Cucumis sativus, Cucurbita maxima, Cucurbita pepo, Datura metel, Gomphrena globosa, Gossypium hirsutum, Ipomoea setosa, Lycopersicon esculentum, Macroptilium lathyroides, Petunia x hybrida, Phaseolus vulgaris, Physalis peruviana, Ricinus communis, Solanum melongena, Solanum tuberosum, Spinacia oleracea, Zea mays.

Diagnostic Hosts

Diagnostic host species and symptoms:

Manihot esculenta — bright mosaic 3-5 weeks after inoculation by whitefly or by grafting. Leaves with symptoms may alternate with leaves showing few or no symptoms.

Nicotiana benthamiana — diffuse chlorotic lesions then systemic leaf curling, malformation and blotching.

Nicotiana clevelandii — the type strain may induce chlorotic local lesions then severe malformation, and irregular yellow veinbanding and blotching. The Kenya coast strain is milder and less readily transmitted.

Datura stramonium — type strain induces chlorotic and necrotic local lesions then systemic veinbanding, leaf curling and malformation.

Diagnostic host: insusceptible host species Cucurbita pepo, Chenopodium amaranticolor, Gomphrena globosa, Phaseolus vulgaris.

Maintenance and Propagation Hosts

Most commonly used maintenance and propagation host species are Manihot esculenta, Nicotiana benthamiana.

Assay Hosts

Host: Assay hosts (for Local lesions or Whole plants):
Datura stramonium (L) for type strain; Nicotiana benthamiana (W) for Kenya coast strain.

References to host data: Storey and Nichols (1938, Bock and Woods (1983, Bock (1983, Bock et al. (1978, Bock et al. (1981, Anon. (1979, Dubern (1979).

Histopathology: Virus can be best detected in mesophyll, epidermis, phloem and companion cells. Virions are found in the nucleus.

Cytopathology: Inclusions are present in infected cells. Inclusion bodies in the host cell are found in the cytoplasm, or nucleus. Inclusions are a granular material. Inclusions contain mature virions. Other cellular changes include the production of fibrillar rings in the nuclei of phloem parenchyma cells (Horvat and Verhoyen, 1981; Adejare and Coutts, 1982).

Geographical Distribution

The virus spreads in Africa. The virus occurs in Angola, Kenya, Nigeria, and the Seychelles.

Ecology, Epidemiology and Control

Studies reported by Bock and Guthrie (1982, Bock (1984, Robertson (1984). Incidence often exceeds 80%, but only a quarter of the cuttings of infected susceptible cassava cultivars yield healthy plants (Bock, 1983). Virus-free cassava plants can be produced by heat treatment and meristem-tip culture. Some cassava genotypes resist infection. Two methods of control are advocated; in Kenya (Bock and Guthrie, 1982; Bock, 1983) and the Ivory Coast (Fargette et al., 1985), virus-free planting material of cultivars with moderate resistance to infection is used, whereas in Nigeria cultivars with superior resistance to, and tolerance of, infection are favoured (Hahn et al., 1980).

List of Strains and Isolates in the Species

Type strain isolate 844 (Bock et al., 1978, Kenya coast (C) strain (Bock et al., 1981), Angola defective isolates (Sequeira and Harrison, 1982).

References

Adejare, G.O. and Coutts, RHA (1982). Phytopath. Z. 103: 87.

Anon. (1979). Rep. Int. Inst. Trop. Agric. 1978, p.107.

Bock, K.R. (1983). In: Plant Virus Epidemiology, p. 337; eds R.T. Plumb and J.M. Thresh. Oxford, Blackwell Scientific Publications.

Bock, K.R. (1984). ODA Crop Virol. Res. Proj. Kenya Agric. Res. Inst., Final Report. Overseas Development Administration, London.

Bock, K.R. and Guthrie, E.J. (1982). Trop. Pest Manag. 28: 219.

Bock, K.R. and Harrison, BD. (1985). CMI/AAB Descr. Pl. Viruses No. 297, 6 pp.

Bock, K.R. and Woods, R.D. (1983). Plant Dis. 67: 994.

Bock, K.R., Guthrie, E.J. and Figueiredo, G. (1981). Ann. appl. Biol. 99: 151.

Bock, K.R., Guthrie, E.J. and Meredith, G. (1978). Ann. appl. Biol. 90: 361.

Bock, K.R., Guthrie, E.J., Meredith, G. and Barker, H. (1977). Ann. appl. Biol. 85: 305.

Chant, S.R. (1958). Ann. appl. Biol. 46: 210.

Cohen, S., Duffus, JE, Larsen, R.C., Liu, H.Y. and Flock, R.A. (1983). Phytopathology 73: 1669.

Costa, AS. and Kitajima, E.W. (1972). CMI/AAB Descr. Pl. Viruses No. 90, 4 pp.

Dubern, J. (1979). Phytopath. Z. 96: 25.

Fargette, D., Fauquet, C. and Thouvenel, J.-C. (1985). Ann. appl. Biol. 106: 285.

Hahn, S.K., Terry, E.R. and Leuschner, K. (1980). Euphytica 29: 673.

Hamilton, W.D.O., Stein, VE, Coutts, RHA and Buck, KW (1984). EMBO J. 3: 2197.

Harrison, BD. (1985). Ann. Rev. Phytopath. 23: 55.

Harrison, BD., Barker, H., Bock, K.R., Guthrie, E.J., Meredith, G. and Atkinson, M. (1977). Nature, Lond. 270: 760.

Horvat, F. and Verhoyen, M. (1981). Parasitica 37: 27119.

Kaiser, W.J. and Louie, R. (1982). Plant Dis. 66: 475.

Roberts, I.M., Robinson, D.J. and Harrison, BD. (1984). J. gen. Virol. 65:1723.

Robertson, I.A.D. (1984). Cassava Whitefly Proj. Crop Virol. Res. Proj. Kenya Agric. Res. Inst., Final Report. Overseas Development Administration, London.

Sequeira, JC (1982). Ph.D. Thesis, University of Dundee, U.K.

Sequeira, JC and Harrison, BD. (1982). Ann. appl. Biol. 101: 33.

Sequeira, J.C., Harrison, BD and Duncan, GH (1983). Rep. Scottish Crop Res. Inst. 1982, p. 193.

Stanley, J. and Gay, MR (1983). Nature, Lond 301: 260.

Stein, VE, Coutts, RHA and Buck, KW (1983). J. gen. Virol. 64: 2493.

Storey, HH and Nichols, RFW (1938). Ann. appl. Biol. 25: 790.

Townsend, R., Stanley, J., Curson, SJ and Short, M.N. (1985). EMBO J. 4:33.

Warburg, O. (1894). Mitt. Deutsch. Schutzgeb. 7: 131.

The following generic references are cited in the most recent ICTV REport .

PubMed References.

VIDEdB, the plant virus database developed at the Australian National University by Adrian J. Gibbs and collaborators, contains an earlier description with the number 166 by C. Büchen-Osmond, 1987. Revised by B.D. Harrison, 1989. A description of the virus is found in DPV, a database for plant viruses developed by the Association of Applied Biologists (AAB), with the number 297.



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ICTVdB - The Universal Virus Database, developed for the International Committee on Taxonomy of Viruses (ICTV) by Dr Cornelia Büchen-Osmond, is written in DELTA. The virus descriptions in ICTVdB are coded by ICTV members and experts, or by the ICTVdB Management using data provided by the experts, the literature or the latest ICTV Report. The character list is the underlying code. All virus descriptions are based on the character list and natural language translations from the encoded descriptions are automatically generated and formatted for display on the Web.

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