An overview of calf diarrhea - infectious etiology, diagnosis, and intervention

Cho, Yong-il; Yoon, Kyoung-Jin

Neboviruses belong to the newly established genus Nebovirus in the family Caliciviridae [14] . The viral genome is approximately 7.4 kb in length and contains two ORFs: ORF1 (encoding nonstructural proteins and capsid protein) and ORF2 (encoding small basic proteins with unknown functions) [100, 124] . Newbury agent-1 and Nebraska-like bovine calicivirus form two distinct genotypes that were associated with calf diarrhea cases in the UK (1978) and Nebraska, USA (1980), respectively [100, 124, 143] . Since then, the presence of Nebovirus has been reported in other countries including France (2011), Italy (2011), and Korea (2008) [28, 66, 107] . The reported prevalence of Neboviruses in diarrheic calves ranges from 7% to 28.0% depending upon geographic location [19, 28, 66, 100, 107] . There is no evidence of zoonotic transmission. Genetic diversity has been reported to exist among Neboviruses along with identification of a novel genotype [66] . Similar to BNoVs, lesions caused by Nebovirus are observed mainly in the jejunum and ileum with villi atrophy, loss of villi enterocyte, and crypt hyperplasia when gnotobiotic calve are challenged with the virus [51, 124] .