Family: Caliciviridae

Genus: Nebovirus

Distinguishing features

The strains in this genus form a distinct clade within the family Caliciviridae (Figure 4. Caliciviridae). 

Virion

See discussion under family description. 

Genome organization and replication

The nebovirus genome is 7.4 kb and is organized into two major ORFs. ORF1 encodes the non-structural polyprotein with the major structural capsid protein (VP1) gene in frame with the non-structural polyprotein. VP2 is frameshifted +2 and begins 2 nucleotides after the termination of ORF1. 

Biology

Neboviruses cause endemic acute gastroenteritis in calves and the severity of disease in experimentally infected calves is considered equal or worse than that caused by genogroup 3 bovine noroviruses (see Norovirus section). Neboviruses cannot be grown in cell culture and therefore information on their biological properties is limited. There appear to be two phylogenetically distinct polymerase types but the VP1 sequence is conserved between the two prototype viruses, Newbury 1 and Nebraska (NB) bovine enteric calicivirus. This suggests that, like other enteric caliciviruses, neboviruses may undergo recombination. 

Species demarcation criteria

Not applicable as only one species is currently recognized. Additional characterization of the viruses in this genus will be required in order to delineate species criteria. 

Related, unclassified viruses 

Virus names and virus abbreviations are not official ICTV designations. 

* (Alkan et al., 2015)