Subfamily: Alpharhabdovirinae
Genus: Uniorhavirus
Distinguishing features
Viruses assigned to the genus Uniorhavirus form a distinct monophyletic group based on well-supported Maximum Likelihood or Maximum Clade Credibility trees inferred from complete L sequences. Killamcar 1 virus 1 (KILLV1; species Uniorhavirus killamcar), currently the only virus assigned to the genus, was detected in a freshwater mollusc.
Virion
Morphology
Virion morphology is unknown.
Nucleic acid
The KILLV1 genome consists of a single molecule of negative-sense, single-stranded RNA of approximately 11.9 kb (Goldberg et al., 2023).
Proteins
The KILLV1 N, P, M, and L proteins share sequence homology and/or structural characteristics with the cognate proteins of other rhabdoviruses. G1 and G2 are class I transmembrane glycoproteins.
Genome organisation and replication
The KILLV1 genome includes the four canonical rhabdovirus structural protein genes (N, P, M, and L) (Figure 1 Uniorhavirus). In addition, between the M and L genes, there are two consecutive genes encoding class I transmembrane glycoproteins (Goldberg et al., 2023). These appear to have agisen by gene duplication. As it is not yet established which of these encodes the virion surface glycoprotein, they have been designated as G1 and G2.
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| Figure 1 Uniorhavirus. Schematic representation of the killamcar virus 1 genome shown in reverse (positive-sense) polarity. The genome contains long open reading frames (ORFs) in the N, P, M, and L genes (open arrows) along with two additional ORFs encoding class I transmemverane glycoproteins (G1 and G2) between M and L. |
Biology
KILLV1 was discovered by viral metagenomic sequencing of hemolymph from freshwater mussels collected in Indiana, USA in 2019 (Goldberg et al., 2023). No isolate of the virus has yet been reported.
Species demarcation criteria
There is only one species in the genus. For viruses to be assigned to additional species in the genus, several of the following characteristics would have to be observed: A) minimum amino acid sequence divergence of 10% in the N proteins; B) minimum amino acid sequence divergence of 10% in the L proteins; C) minimum amino acid sequence divergence of 15% in the G proteins; D) significant differences in genome organisation as evidenced by numbers and locations of ORFs; E) they can be distinguished in virus neutralisation tests; and F) they occupy different ecological niches as evidenced by differences in vertebrate hosts and or arthropod vectors.