Subfamily: Alpharhabdovirinae

Genus: Alphanemrhavirus

Distinguishing features

Viruses assigned to the genus Alphanemrhavirus form a distinct monophyletic group based on well-supported Maximum Likelihood or Maximum Clade Credibility trees inferred from complete L sequences. Viruses assigned to the genus have been detected in parasitic nematodes (roundworms of the phylum Nematoda).

Virion

Morphology

Viruses assigned to the genus have not yet been isolated or visualized by transmission electron microscopy.

Nucleic acid

Alphanemrhavirus genomes consist of a single molecule of negative-sense, single-stranded RNA and range from approximately 10.7–11.7 kb (Shi et al., 2016, Hause et al., 2020, Wu et al., 2021).

Proteins

Alphanemrhavirus N, P, M, G and L proteins share sequence homology and/or structural characteristics with the cognate proteins of other rhabdoviruses. In Xinzhou nematode virus 4 (XzNV-4; species Alphanemrhavirus xinzhou), ORF Mx overlaps the M ORF and encodes a putative 67 amino acid (7.6 kDa) protein of unknown function. This putative protein has not yet been identified in infected cells and it is not known if it is expressed.

Genome organisation and replication

Alphanemrhavirus genomes include five genes (N, P, M, G and L) encoding the structural proteins and concise intergenic regions (Figure 1.Alphanemrhavirus). In XzNV-4, an additional ORF (Mx) overlaps the end of the M ORF within the M gene.

Figure 1.Alphanemrhavirus. Schematic representation of alphanemrhavirus genomes shown in reverse (positive-sense) polarity. N, P, M, G and L represent ORFs encoding the structural proteins. ORF Mx of Xinzhou nematode virus 4, overlapping the end of the M ORF, is highlighted (grey).

Biology

Alphanemrhaviruses have been detected only by high-throughput sequencing of pooled mixtures of parasitic nematodes (roundworms) (Shi et al., 2016) or from the tissues of bats or rodents. Xingshan nematode virus 4 (species Alphanemrhavirus xingshan) was detected in a pool of spirurian nematodes (subclass Spiruria) that includes important mammalian parasites. XzNV-4 was detected in a pool of snake-associated nematode parasites (Shi et al., 2016). Each was detected in China. Rattus tanezumi rhabdovirus 1 (species Alphanemrhavirus bangkok) was detected in lung tissue of Asian house rats (Rattus tanezumi) collected in Thailand (Wu et al., 2021). Sodak rhabdovirus 1 (species Alphanemrhavirus sodak) was detected by in visceral homogenates from big brown bats (Eptesicus fuscus) collected in the USA (Hause et al., 2020).

Species demarcation criteria

Viruses assigned to different species within the genus Alphanemrhavirus have several of the following characteristics: 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 organization as evidenced by numbers and locations of ORFs; E) can be distinguished in virus neutralisation tests; and F) occupy different ecological niches as evidenced by differences in vertebrate hosts and or arthropod vectors.

Related, unclassified viruses

Virus names and virus abbreviations are not official ICTV designations.

* Coding region sequence incomplete