Evidence for recombination in neboviruses.

Neboviruses are bovine enteric caliciviruses (genus Nebovirus) associated with enteric diseases in calves. By screening the stools of calves collected from Italian herds using primers targeted to a conserved stretch in calicivirus RNA-dependent RNA-polymerase (RdRp), nebovirus RNA was detected in calves with enteritis (13.1%) but not in overtly health animals. Upon sequence analysis of the RdRp fragment, the Italian viruses formed a tightly conserved group and resembled closely the nebovirus prototype Nebraska/80/US. The sequence of a 2.2kb ORF1 fragment, spanning the 3' end of the RdRp and the full-length capsid coding region, of two nebovirus strains was determined, revealing marked genetic heterogeneity in the capsid protein, as the two Italian viruses were classified into two distinct capsid lineages, and suggesting a recombination event downstream the highly conserved shell (S) domain.