103.
|
Type Species |
(GLV) |
Virions are isometric, 36 nm in diameter (Fig. 3).
Physicochemical and Physical Properties
Virion buoyant density in CsCl is 1.368 g/cm3.
Virions contain a single molecule of dsRNA, 7.0 kbp in size.
Virions contain a single major capsid protein, Mr of 100 103.
None reported.
None reported.
Genome Organization and Replication
The virus is found in the nuclei of infected G. lamblia. Virus replicates without inhibiting the growth of G. lamblia trophozoites. Virus is also extruded into the culture medium and the extruded virus can infect many virus-free isolates of the protozoan host. There are isolates of the protozoan parasite, however, that are resistant to infection by GLV. A single-stranded copy of the viral dsRNA genome is present in infected cells. The concentration of the ssRNA observed during the time course of GLV infection is consistent with a role as a viral replicative intermediate or mRNA. The ssRNA does not appear to be polyadenylated.
The virus infects many isolates of G. lamblia, a flagellated protozoan human parasite. The virus does not seem to be associated with the virulence of the parasite. It is not observed in the cyst form of the parasite and it is not known whether it can be carried through the transformation between cyst and trophozoite. The virus is infectious as purified particles and can infect uninfected G. lamblia.
List of Species Demarcation Criteria in the Genus
According to the virus species definition, viruses found only in distinct host species are for that reason different species. Totiviruses generally replicate stably within the cell as the cells grow. Virus strains of the same species are expected to segregate relative to each other as the cells grow, whereas those of different species should be stably co-maintained. Viruses of the same species should be similarly affected by host chromosomal mutations. Viruses that can recombine or exchange segments with each other to give viable progeny should be considered the same species. Although these biological criteria are the prime determinant of species, sequence criteria are also used. Less than 50% sequence identity at the protein level generally reflects a species difference. None of the above criteria is absolute, but totiviruses described so far leave little doubt about species demarcation.
Official virus species names are in italics. Tentative virus species names, alternative names ( ), strains or serotypes are not italicized. Virus names, genome sequence accession number [ ], and assigned abbreviations ( ) are:
|
Giardia lamblia virus |
[L13218] |
(GLV) |
Tentative Species in the Genus
|
Trichomonas vaginalis virus |
(TVV) |
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