Genus: Nyavirus


Genus: Nyavirus

Distinguishing features

The genus Nyavirus includes three species. Based on the genomic structure and phylogeny, Sierra Nevada virus (SNVV), Nyamanini virus (NYMV), and Midway virus (MIDWV) are closely related (Mihindukulasuriya et al., 2009, Rogers et al., 2014). Based on PASC analysis, the SNVV genomic sequence is about 50% identical to NYMV and MIDWV genomes, whereas the identity between NYMV and MIDWV is closer (≈63%).

Virion

Morphology

Virions are enveloped and spherical with a diameter of 100–130 nm (Figure 1.Nyamiviridae). 

Nucleic acid

Unsegmented, single stranded, negative sense RNA.

Proteins

Nyavirus genomes encode six structural proteins. Among them, the nucleocapsid protein (N), glycoprotein (G), and RNA-dependent RNA polymerase (L) protein are identified on the basis of sequence similarity and structural properties shared with mononegavirus homologues. The functions of the other encoded proteins are largely unknown, but may be those of matrix and polymerase cofactor proteins (Mihindukulasuriya et al., 2009).

Genome organization and replication

Nyavirus negative-sense, single-stranded RNA genomes range from 11.6–11.8 kb (Figure 2.Nyamiviridae). Nyaviruses have unsegmented genomes with six ORFs that encode the structural proteins (Mihindukulasuriya et al., 2009, Rogers et al., 2014). Knowledge of nyavirus replication is limited. Nyamanini virus replicates in the nucleus of infected cells (Herrel et al., 2012).

Antigenicity

SNVV is antigenically distinct from MIDWV and NYMV when tested in complement fixation tests, whereas MIDWV and NYMV are serologically related (Mihindukulasuriya et al., 2009, Rogers et al., 2014).

Biology

Although NYMV and MIDWV have been isolated from birds of different species and their ticks, it is unclear whether SNVV can also infect birds.

Species demarcation criteria

The SNVV genome is about 50% similar to those of NYMV and MIDWV genomes, whereas the nucleotide sequence identity between NYMV and MIDWV is closer (≈63%).

Derivation of names

Genus: acronym of the first three letters of “Nyamanini Pan” (place of isolation of Nyamanini virus in South Africa); and -virus (ending denoting a virus genus); Neo-Lat. n. neut. sg. Nyavirus  – the genus of nyaviruses. Species: named after the location where species members were first identified.

Member Species

SpeciesVirus name(s)Exemplar isolateExemplar accession numberExemplar RefSeq numberAvailable sequenceOther isolatesOther isolate accession numbersVirus abbreviationIsolate abbreviation
Midway nyavirusMidway virusRML47153FJ554525NC_012702Complete genomeMIDWV
Nyamanini nyavirusNyamanini virustick 39FJ554526NC_012703Complete genomeNYMV
Sierra Nevada nyavirusSierra Nevada virusKF530058NC_024376Complete genomeSNVV

Virus names, the choice of exemplar isolates, and virus abbreviations, are not official ICTV designations.
Download GenBank/EMBL query for sequences listed in the table here.