Although many viruses have been classified into genera in this Report, a significant number have not yet been assigned to a recognized genus, or been sufficiently distinguished from recognized genera so as to form a new genus. Some examples are listed here. These are viruses for which certain key characteristics are known but which are as yet unplaced; poorly characterized viruses are excluded. The listing is not exhaustive but contains examples that illustrate that the task of devising a universally applicable virus taxonomy is not yet complete.
Araguari virus was isolated from a Philander opossum collected in 1969 at Serra do Navio, T.F. Amapa, Brasil. Virions are enveloped and contained 8 RNA species and 3 major polypeptides (67 103, 58 103, 30 103; 1:2:3), 2 minor polypeptides (43.5 103, 35 103); 67 103 and 30 103 proteins which appear to be glycoproteins (i.e., not similar to arenaviruses). This virus is pathogenic for certain laboratory vertebrates and cell cultures. See Zeller, Karabatsos, Calisher, Digoutte, Murphy and Shope, 1989 and Karabatsos, 1985.
Johnston Atoll virus [related to Quaranfil virus, vide infra] was isolated from Ornithodoros capensis ticks collected in 1969 at Sand Island, Johnston Atoll, Pacific Ocean; all subsequent isolates have been obtained from O. capensis from Australasia. It is pathogenic for certain laboratory vertebrates and cell cultures. Virions are enveloped and contain three major polypeptides (67 103, 58 103, 30 103; 1:2:3), 2 minor polypeptides (43.5 103, 35 103); the 30 and 67 103 proteins appear to be glycoproteins (i.e., not similar to arenaviruses) See Karabatsos, 1985.
The virus was first isolated from Bubulcus ibis (cattle egret) collected in 1957 in South Africa and since has been isolated from cattle egrets and ticks in Africa. It is pathogenic for certain laboratory vertebrates and cell cultures. Virions are enveloped and contain RNA. See Karabatsos, 1985.
Quaranfil virus [related to Johnston Atoll virus, vide infra] was isolated from Argas (Persicargus) arboreus ticks collected in 1953 near Cairo, Egypt. Subsequent isolates have been obtained from humans (febrile illnesses), ibis and pigeons, and ticks in Egypt, South Africa, Afghanistan, Nigeria, and Iran. Electron microscopy (numerous attempts) has been inconclusive. Virions are enveloped. QRFV is pathogenic for a wide variety of laboratory hosts. See Karabatsos, 1985.
Acute Bee Paralysis Virus (ABPV)
Isolated from the honeybee Apis mellifera, the unenveloped virions are approximately 30 nm in diameter in negative stained preparations. The virion contains four capsid polypeptides of Mr 35, 33 and 24 and 9 103. The genome comprises ssRNA of around Mr 3.1 106. The virus produces rapid paralysis in adult honeybees after injection but is generally only found to cause disease in bee colonies when in association with other pathogens/parasites, most notably the parasitic mite Varroa jacobsoni. See Bailey and Ball, 1991.
Acyrthosiphon Pisum Virus (APV)
Acyrthosiphon pisum virus particles are icosahedral, 31 nm in diameter. The virus was isolated from Acyrthosiphon pisum but was able to infect many other Aphis species. The virus capsid is composed of a major protein of Mr 34 103 and three minor proteins of 23, 24, and 66 103. The genome consists of a polyadenylated ssRNA molecule of approximately 10 kb containing two large ORFs. ORF2 overlaps ORF1 and is putatively expressed by a -1 translational frameshift. The capsid proteins are encoded by the 3-end of ORF1 and the 5-end of ORF2. The ORF1 product contains motifs characteristic of RNA-dependent RNA polymerases, helicases and cysteine proteases. See Van der Wilk, Dullemans, Verbeek and van den Heuvel, 1997.
Aphid Lethal Paralysis Virus (ALPV)
The virus was originally isolated from the aphid Rhopalosiphum padi collected in the Western Province of South Africa. The virions are isometric with a diameter of 26 nm and comprise three major polypeptides of Mr 34, 32 and 31 103 and nimor polypeptide of Mr 41 103. The genome is composed of positive sense ssRNA of approximately Mr 3.3 106 that is polyadenylated at the 3-end. Naturally occurs in laboratory populations of several aphid species and can be vertically and horizontally transmitted between individuals. See Williamson, Rybicki, Kasdorf and von Wechmar, 1988.
The virus was originally isolated from pollen gathered from honey bee hives in Arkansas. The virus has a diameter of around 30 nm and contains a single segment of ssRNA of Mr 1.8 106. The buoyant density of the virions is 1,37 g/ml and the virus contains only one major coat protein of Mr 41 103. See Bailey and Woods, 1974.
The virus was first isolated from honeybees in the United Kingdom. The virions are around 35 nm in diameter and contain an RNA genome. The single major capsid protein is Mr 52 103 and the virus shows a distant serological relationship to BYV. BXV and BYV may be the same virus species. The virus is only transmissible per os to adult honey bees but it is found commonly in Great Britain but also present in mainland Europe. See Bailey and Woods, 1974.
The virus was originally isolated from honey bees in the United Kingdom. The virus shows a distant serological relationship to BXV but has a major capsid protein of Mr 50 103. Like BXV, BYV has virions of 35 nm in diameter, an RNA genome is only transmissible per os to adult honey bees. The virus has been found more widely in honey bee colonies (including North America and Australasia) than BXV. See Bailey, Carpenter, Govier and Woods, 1980.
The virus was isolated from honeybees in California during studies on Arkansas bee virus. The 30 nm virions contain a single species of ssRNA of Mr 2.8 106. The virus has three major capsid proteins of Mr 37, 35 and 32.5 103. See Lommel, Morris and Pinnock, 1985.
Commonly found as an infection of pupae and prepupae of honeybee queens. The virions are isometric, approximately 30 nm in diameter and contain a ssRNA genome of approximately Mr 2.3 106. The virus has four major capsid polypeptides of Mr 34, 32, 29 and 6 103. Frequently occurs as a symptomless infection of worker honeybees and often in association with the protozoan pathogen Nosema apis. See Bailey and Ball, 1991.
Chronic Bee Paralysis Virus (CBPV)
The virus was first isolated from honeybees in the United Kingdom. The virions have an unusual anisometric shape and are polymorphic in size-usually of approximately 60nm in length but ranging in diameter from 20 to 30 nm. Purified virion preparations contain several ssRNA species ranging is size from 1.35 to 0.35 kb. Virions contain a single structural protein of 2.5 kDa. The virus is readily transmitted to adult honey bees per os and has been identified in colonies almost everywhere that honey bees are maintained. See Bailey and Ball, 1991.
The virus was originally isolated from honeybees during studies on other honeybee viruses. The virions are around 17 nm in diameter and contain a single segment of RNA of around Mr 0.45 106. The virus has a single capsid protein of Mr 19 103 and a buoyant density of 1.38 g/ml. See Bailey, Ball, Carpenter and Woods, 1980.
Originally isolated from a laboratory colony of the Mediterranean fruit fly, Ceratitis capitata in France. The isometric virus particles are 24 nm in diameter and contain three major capsid proteins of Mr 39, 34 and 27 103. No serological relationship to Drosophila A, C or P viruses. See Plus, Veyrunes and Cavalloro, 1981.
The virus was isolated from diseased adult honeybees collected in Japan. The virions are 30 nm in diameter and contain an RNA genome. The virus shows some serological relationship to Egypt bee virus. See Bailey and Ball, 1991.
Originally isolated from a laboratory colony of Drosophila melanogaster in France, it has subsequently been found widely distributed in laboratory and natural populations of Drosophila spp. from arround the world. The virions are 30 nm in diameter and contain a ssRNA genome polyadenylated at the 3-end. Three coat proteins reported of Mr 73, 44 and 32 103 - although not present in equimolar amounts. Serologically distinct from Drosophila C and P viruses. Readily transmitted both horizontally and vertically (transovarially). See Christian and Scotti, 1998.
Isolated from Drosophila melanogaster the virions of DPV are approximately 30 nm in diameter. The virions contain a single species of ssRNA and three major proteins of Mr 48, 30 and 26 103 in non-equimolar amounts. Serologically related to a virus isolated from Drosophila immigrans. Readily transmitted both horizontally and vertically (transovarially). See Christian and Scotti, 1998.
The virus was isolated from European honeybees collected in Egypt in the spring of 1977. The virions contain RNA, are 30 nm in diameter and compromise three major capsid proteins of Mr 41, 30 and 25 103. The virus is serologically distinct from all other viruses of domesticated bees. See Bailey, Carpenter and Woods, 1979.
Galleria Cell Line Virus (GmCLV)
Originally isolated from a cell line derived from the lepidopteran Galleria mellonella after challenging with the unassigned RNA-containing maize stem borer virus (MSBV). The virions are 29 nm in diameter and contain a ssRNA of Mr 2.9 106 that is polyadenylated at its 3-end. The capsid contains two major polypeptides of Mr 34.5 and 32.5 103 in equimolar amounts. The virus replicates in cultured Galleria mellonella cells and after injection into G. mellonella larvae. See Lery, Fediere, Taha, Salah and Giannotti, 1997.
Gonometa Podocarpi Virus (GpV)
The virus was isolated from insects collected during an epizootic in populations of the lepidoperan Gonometa podocarpi in pine plantations in Uganda in September of 1963. The isometric 32 nm diameter virions contain a single segment of ssRNA and four major polypeptides of Mr 37, 32, 2 and 12 103. Minor amounts of a Mr 48 103 protein are also present in the virion. A similar virus was also found to be present in another lepidopteran present at the epizootic site (Pacymetana sp.). See Harrap, Longworth, Tinsley and Brown, 1966.
Heliothis zea virus 1 was isolated as a persistent virus of an insect cell line derived from Heliothis zea. Although the virus can infect a number of insect (lepidopteran) cell lines, infection of an insect has not been observed. The virion of HzV-1 is composed of an enveloped rod-shaped nucleocapsid. Virions are released from infected cells by cell lysis. HzV-1 genome consists of a single molecule of circular dsDNA, approximately 240 kbp in length. HzV-1 was previously classified as a non-occluded member of the family Baculoviridae. See Burand, 1991.
Infectious Flacherie Virus (IFV)
The disease caused by IFV was recognized in the mid 1800’s although the aetiologix agent was not isolated and identified until this century. The virus has been isolated primarily from the silkworm Bombyx mori but has also been found the Mulberry pyralid Glyphodes pyloalis. The virions are approximately 27 nm in diameter and contain a single species of ssRNA of Mr 2.4 106 that is polyadenylated at the 3-end and has a covalently linked protein (VPg) at it’s 5-end. The virus has four major structural proteins of Mr 35, 33, 31 and 12 103. Sequence analysis of the complete genome [AB000906] has shown that it is organized in a similar fashion to the picornaviruses with a single ORF encoding a single polyprotein. The 5 portion of the ORF contains the structural proteins and the 3 portion the non-structural proteins. See Isawa, Asano, Sahara, Lizuka and Bando, 1998.
Originally isolated from the Asiatic hive bee, Apis cerana, KBV has subsequently been found in both the European honeybee, Apis mellifera and the European Wasp, Vespa germanica. The virions are approximately 30 nm in diameter, contain ssRNA and have four major structural polypeptides of Mr 31, 37, 25 and 6 103. The virus is transmissible per os to larvae, infected individuals becoming persistently infected adults. The virus is not usually associated with disease symptoms, but in association with other parasites/pathogens a disease state may be induced. Several serologically distinct strains of KBV have been reported. See Bailey and Ball, 1991.
Kawino virus was first isolated from the mosquito Mansonia uniformis collected near the village of Kawino in Kenya in 1973. The virus particles are 28 nm in diameter and contain four major structural polypeptides of Mr 33, 30, 27 and 7 103 with a minor component of Mr 36 103. The genome comprises a single segment of ssRNA of Mr 2.6 106. The virus replicates in several mosquito cell lines but was not found to replicate in a tick cell line or several mammalian cell lines. See Pudney, Newman and Brown, 1978.
The virus was originally isolated from the kelp fly, Chaetocoelopa sydneyensis, collected in New South Wales, Australia. The virus has isometric particles of 29 nm in diameter that have surface projections that give the particles the appearance of small reovirus particles. The virions contain ssRNA of around Mr 3.5 106 and two major capsid proteins of Mr 73 and 29 103. The virions have a buoyant density of 1.43 g/ml in neutral CsCl. See Scotti, Gibbs and Wrigley, 1976.
Latoia Viridissima Virus (LvV)
The virus was isolated from the lepidopteran palm pest Latoia viridissima in the Ivory Coast and are approximately 30 nm in diameter. The genome comprises a single segment of ssRNA of Mr 2.9 106 and the virions appear to contain two major structural polypeptides of Mr 31 and 30 103. Stoichiometry of the structural proteins suggests that there may acutally be two proteins of Mr 30 103. The virus is serologically related to a virus isolated from the limacodid banana pest, Teinorhynchha umbra. See Zeddam, Phillippe, Veyrunes, Fediere, Mariau and Bergoin, 1990.
The virus was isolated from the lepidopteran pine pest Lymantria ninayi collected during an epizootic in pine plantations in Papua New Guinea. The virions contain a polyadenylated ssRNA of around Mr 2.8 106, three major capsid proteins of Mr 38, 33 and 32 103 and a minor capsid ccomponent of Mr 43 103. The virus shows some serological cross-reaction with antisera to a Drosophila C virus isolate. See Pullin, Black, King, Entwistle and Moore, 1984.
The virus was isolated from larvae of the maize stem borer Sesamia cretica in Egypt. The virions are isometric with a diameter of 30 nm and contain one segment of ssRNA of 9.4 kb that is polyadenylated at the 3-end. The virus has three major polypeptides of Mr 60, 54 and 28 103 in non-equimolar amounts and a minor component of Mr 58 103. The virus is highly pathogenic per os. See Fediere, Taha, Lery, Giannotti, Monsarrat and Abol-Ela, 1991.
Nezara Viridula Virus-1 (NVV-1)
The virus was originally isolated from a diseased laboratory colony of the green stinkbug Nezara viridula and has isometric virions of 29 nm in diameter. The genome comprises a single segment of ssRNA of approximately Mr 3.1 106 and the virions contain three major structural proteins of Mr 32, 32 and 31 103. The virus is transmitted both vertically and horizontally and has significant effects on the longevity and fecundity of infected individuals. See Williamson and von Wechmar, 1992.
Oryctes Rhinoceros Virus (OrV)
The Oryctes rhinoceros virus is a pathogenic virus of invertebrates, that infects a number of coleopteran insects in the family Scarabaeidae. The mature virion of Oryctes rhinoceros virus consists of an enveloped, rod-shaped nucleocapsid and contains a unique tail-like structure protruding from one end. The mature virion is produced by virus budding from the plasma membrane and contains two unit membranes. The genome is a single supercoiled circular dsDNA of approximately 130 kbp. Although these viruses were previously classified as members of the family Baculoviridae, they differ in several respects including virion morphology and the lack of an occlusion body. See Crawford, 1994.
Pectinophora Gossypiella Virus (PgV)
The virus was isolated from naturally occurring dead larvae of the pink bollworm Pectinophora gossypiella. The icosahedral virions are 27 nm in diameter and contain RNA. Three capsid proteins of Mr 47, 33 and 32 103 have been identified but are present in non-equimolar amounts. The virus is infectious but not highly pathogenic to larvae of Pectinophora gossypiella exposed per os and can be vertically transmitted from infected adults to their progency. See Monsarrat, Abol-Ela, Abdel-Hamid, Fediere, El Husseini and Gianotti, 1995.
Pteroteinon Laufella Virus-1 (PlV-1)
The virus was isolated from the lepidopteran pest of oil palms Pteroteinon laufella in the Ivory Coast. Two viruses were isolated one of 40 nm (P. laufella virus-1) and one of 30 nm (P. laufella virus-2). The virions of P. laufella virus-1 contain RNA and have one major capsid peptide of Mr 53 103 and minor polypeptides of Mr 63 and 34 103. The virus shows no serological relationship to CrPV or small RNA-containing viruses from Latoia viridissima or Teinorhyncha umbra. See Herder, Fediere, Kouassi, Lery, Kouevidjin, Phillippe and Mariau, 1994.
Queensland Fruit Fly Virus (QFFV)
The virus was originally isolated from a laboratory culture of the Queensland fruitfly Bactrocera (Dacus) tryoni. The isometric virions have a diameter of 30 nm and contain three major structural proteins of Mr 42, 37 and 31 103. The genome compromises one segment of ssRNA of approximately Mr 2.9 106 and is polyadenylated at its 3-end. The virus is serologically unrelated to other insect picorna-like viruses including Ceratitis V virus. See Bashiruddin, Martin and Reinganum, 1988.
The aetiological agent of sacbrood disease of honeybees was identified as a virus as long ago as 1917. However, it was not until 1964 that the virus was first isolated and characterized. The 30 nm virions contain a ssRNA genome of around Mr 2.6 106 and three major structural proteins of Mr 32, 28 and 25 103. The virus causes a characteristic disease of honeybee larvae and is found in colonies the world over. Transmission is horizontal with virus being transmitted to larvae by inapparently infected adult workers bees. A serologically distinct strain of Sacbrood virus has also been isolated from the Asiatic hive bee, Apis cerana. See Bailey and Ball, 1991.
The virus was isolated from laboratory cultures of the aphids Sitibion avenae and Metopolophium dirhodum maintained in the United Kingdom. The virions are 30 nm in diameter and comprised of a ssRNA genome and a single capsid protein of Mr 29 103. The virus is readily transmitted horizontally between individuals and is serologically unrelated to Rhopalosiphum padi virus and Aphid lethal paralysis virus. See Allen and Ball, 1990.
Slow Bee Paralysis Virus (SBPV)
The virus was first isolated from adult honey bees in Britain. Although capable of causing paralysis after injection into adult honeybees it does not appear to be associated with any natural disease symptoms. The virions are 30 nm in diameter and contain ssRNA. The virus has three major capsid polypeptides of Mr 46, 29 and 27 103. See Bailey and Ball, 1991.
The virus was isolated from a laboratory population of the vertebrate haematophage Triatoma infestans in Argentina. The isometric virions are 30 nm in diameter and contain a single segment of ssRNA of approximately Mr 3 106. The capsid comprises three major polypeptides of Mr 39, 37, and 33 103 with a minor component of Mr 45 103. The virus may be transmitted both horizontally and vertically. Present in natural populations throughout Argentina at a frequency of about 10%. See Muscio, La Torre and Schodeller, 1988.
Turnaca Rufisquamata Virus (TrV)
The virus was isolated from larvae of the palm defoliating insect Turnaca rufisquamata collected during a disease epizootic in the Ivory Coast. The 30 nm diameter virion are reported to contain four proteins of Mr 41, 33, 30, and 12 103. The genome comprises a single segment of ssRNA of 9.4 kb. See Fédière, Lery, Kouassi, Herder, Veyrunes and Mariau, 1992.
Agaricus Bisporus Virus 1 (ABV-1)
Particles are isometric, about 25 nm in diameter and sediment at 90-100S. The single Mr 25 103 coat protein encapsidates two dsRNA species of about 2 kb. See Barton and Hollings, 1979.
Allomyces Arbuscula Virus (AAV)
Particles are isometric, about 40 nm in diameter and sediment as 67S and 75S components. Particles consist of proteins, with Mr of 38 103, 34 103, 28 103 and 21 103, and dsRNA of 3.6 kbp, 2 kbp and 1.6 kbp. See Khandjian, Turian and Eisen, 1977.
Aspergillus Foetidus Virus F (AFV-F)
Particles are isometric, 40-42 nm in diameter and sediment as 164S and 145S components. Particles contain a major Mr 87 103 protein and minor species of Mr 125 103 and 100 103. The ds RNA are 3.8 kbp, 2.7 kbp, 2.5 kbp, 2.1 kbp and 1.8 kbp. See Buck and Ratti, 1975.
Colletotrichum Lindemuthianum Virus (CLV)
Particles are isometric, 30 nm in diameter and sediment as 110S and 85S components. Particles contain a major Mr 52 103 protein and a minor species of Mr 45 103. The dsRNAs are 3.6 kbp, 1.6 kbp and 1.5 kbp. See Rawlinson, Carpenter and Muthyalu, 1975.
Gaeumannomyces Graminis Virus 45/101-C (GGV-45/101C)
Particles are isometric, 29 nm in diameter and sediment at 127S. They consist of a Mr 66 103 protein and a ds RNA of 1.8 kbp. See Buck, 1984.
Helminthosporium Maydis Virus (HMV)
Particles are isometric, 48 nm in diameter and sediment at 283S. Particles consist of a Mr 121 103 protein and ds RNA of 8.3 kbp. See Bozarth, 1977.
Particles are isometric, 39 nm in diameter and contain 1 dsRNA of 6.5 kbp. See Ushiyama and Nakai, 1982.
LaFrance Isometric Virus (LFIV)
Particles are isometric, 36 nm in diameter and contain dsRNA species of 3.6 kbp, 3 kbp, 2.8 kbp, 2.7 kbp, 2.5 kbp, 1.6 kbp, 1.4 kbp, 0.9 kbp, and 0.8 kbp. See Goodin, Schlagnhaufer and Romaine, 1992.
Perconia Circinata Cirus (PeCV)
Particles are isometric, 32 nm in diameter and sediment as 150S and 140S components. Particles contain dsRNA of 2.5 kbp, 2 kbp, 1.8 kbp, 1.6 kbp, 0.7 kbp and 0.6 kbp. See Dunkle, 1974.
Black Raspberry Necrosis Virus (BRNV)
Particles are isometric and about 28 nm in diameter. They sediment as a 50S component that is not infective and probably does not contain nucleic acid, or a 130S component that is infective. The genome is thought to be ssRNA. BRNV is transmitted by raspberry aphids in nature and by other species experimentally. It is not seed-transmitted. See Jones, 1988.
Brachypodium Yellow Streak Virus (BYSV)
Particles are isometric, about 32 nm in diameter, sediment at about 122S and have a density in CsCl solutions of about 1.35 g/cm3. They comprise a single ssRNA component with an Mr of about 1.67 106 and a coat protein of about 38 103. See Edwards, Cooper, Massalskì and Green, 1985.
Cassava Ivorian Bacilliform Virus (CsIBV)
Particles are bacilliform, 18 nm in diameter and 42 nm, 49 nm and 76 nm in length, and sediment as three components. Particles contain three RNA components that, if ssRNA, would be about 2.7 kb, 3 kb and 4 kb in size, and protein with an Mr of 22 103. No vector is known. A tentative, though distant, relationship has been proposed between CsIBV and the genus Alfamovirus. See Fargette, Roberts and Harrison, 1991 and Fargette and Harrison, 1998.
Chara Australis Virus (CAV; formerly Chara Corallina Virus)
The virions of CAV, like those of tobamoviruses, are rod-shaped and 17 nm in diameter, but are 532 nm long. The ssRNA genome is of about 10000 nts. The virion protein has a Mr of 18,500, is serologically distantly related to those of tobamoviruses, and its gene is clearly homologous with the virion protein genes of tobamoviruses. Some other parts of the genome show clear sequence homology with parts of the Beet necrotic yellow vein virus and Hepatitis virus E genomes (Keese, P., Mackenzie, A., Torronen, M. and Gibbs, A.J., pers. com.). The vector has not been identified. See Skotnicki, Gibbs and Wrigley, 1976.
No particles have been detected in diseased tissue. The genome is thought to be dsRNA and the probable vector is Pythium sp. See Haber, Kim, Gillespie and Tekauz, 1990 and Haber, Barr, Chong, Tekauz and Kim, 1993.
Particles are isometric and about 30 nm in diameter. They either lack RNA or contain ssRNA of about 7.5 kb. Coat protein has an Mr of about 28 103. Particles are found only in phloem tissue and are not mechanically transmissible. The natural vector in not known. See Boulila, Boscia, Di Terlizzi, Castellano, Minafra, Savino and Martelli, 1990.
Hart’s Tongue Fern Mottle Virus (HTFMoV)
Particles are rod-shaped, 22 nm in diameter and either 135 nm or 320 nm in length. The genome is probably of ssRNA. The virus is probably soil-transmitted. See Hull, 1968.
Maize White Line Mosaic Virus (MWLMV)
Particles are isometric about 35 nm in diameter and contain ssRNA of about 4 kb. Coat protein has an Mr of about 33 103. Virus is soil-borne; transmission may be by fungi but is not possible mechanically. See de Zoeten and Reddick, 1984.
Nicotiana Velutina Mosaic Virus (NVMV)
Particles are rod-shaped, about 18 nm in diameter and have a modal length of about 125 to 150 nm. Particles contain ssRNA molecules of either 3 kb or 8 kb. The smaller RNA contains a triple gene block that encodes proteins somewhat similar to the translation products of analogous genes in some definitively classifed viruses. The virus is mechanically transmissible, but no vector is known. NVMV has been linked to furoviruses in the past but may be no more like these viruses than viruses in other genera. See Randles, 1978 and Randles and Rohde, 1990.
Preparations of purified virus contain bacilliform and non-enveloped particles of 150 40 nm diameter. Enveloped particles are sometimes seen in infected plant tissues. The genome comprises 2 molecules of 6413 nts (RNA-1) and 6001 nts (RNA-2). The RNA have conserved and complementary terminal sequences. RNA-1 contains 5 ORFs, and RNA-2 encodes a single ORF. Some of the encoded proteins have sequences similar to those of proteins of rhabdoviruses. OFV was previously classified as a tentative rhabdovirus, but differs from viruses in the family Rhabdoviridae in having a bipartite genome. See Doi, 1977 and Kondo, Maeda, Tamada and Shirako, 1998.
Particles are isometric and are about 27 nm in diameter. They sediment at about 128S and have a buoyant density in CsCl solutions of about 1.45 g/cm3. Particles contain about 36% RNA and have a coat protein with an Mr of about 22 103. The virus is mechanically transmissible. See Bos, Huttinga and Maat, 1979.
Pelargonium Zonate Spot Virus (PZSV)
Particles are quasi-isometric 25-35 nm in diameter, and sediment as three components. Nucleic acid is ssRNA of about 4.4 kb and about 3.3 kb. Coat protein has an Mr of 44 103. The virus is readily transmitted by sap inoculation. Natural transmission is by thrips. See Gallitelli, Quacquarelli and Martelli, 1983.
Vicia Faba 447 Cytolasmic Male Sterility-Associated Virus (VfCMSaV)
Plants affected by VfCMSaV are male-sterile and contain a 17.6 kbp dsRNA specific to the condition. No virions are present in affected tissues, although cytoplasmic membraneous vesicles are present that contain dsRNA. These are absent if plants have been “restored” to male fertility. The plus-sense strand of the dsRNA is nicked 2735 nt from the 5 end. The larger 3 fragment encodes motifs characteristic of domains with helicase and RNA- dependent RNA polymerase functions. VfCMSaV resembles ds RNA found in rice tissues, but both differ from the superficially similar viruses in the genus Hypovirus in genome arrangement and in gene sequences. See Pfeiffer, 1998.
Watercress Yellow Spot Virus (WYSV)
Particles are isometric and about 37 nm in diameter. They comprise a 43.5 103 protein and ssRNA with an Mr of about 1.6 106. Particles are unstable and show no serological relationship to carmoviruses, dianthoviruses or tombusviruses. A possible vector is Spongospora subterranea f. sp. nasturtii. See Walsh and Clay, 1993.
The virus is mechanically transmissible but no virus particles are detectable. Infective RNA is single-stranded and lacks detectable poly(A). dsRNA of 6.8, 3.5 and 3.3 kbp were detected in infected plants and the RNA was infective after heating. See Gardiner, Pearson, Hopcroft and Forster, 1995.
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