RESUMEN
Bovine rhinitis viruses (BRVs) cause mild respiratory disease of cattle. In this study, a near full-length genome sequence of a virus named RS3X (formerly classified as bovine rhinovirus type 1), isolated from infected cattle from the UK in the 1960s, was obtained and analyzed. Compared to other closely related Aphthoviruses, major differences were detected in the leader protease (L(pro)), P1, 2B, and 3A proteins. Phylogenetic analysis revealed that RS3X was a member of the species bovine rhinitis A virus (BRAV). Using different codon-based and branch-site selection models for Aphthoviruses, including BRAV RS3X and foot-and-mouth disease virus, we observed no clear evidence for genomic regions undergoing positive selection. However, within each of the BRV species, multiple sites under positive selection were detected. The results also suggest that the probability (determined by Recombination Detection Program) for recombination events between BRVs and other Aphthoviruses, including foot-and-mouth disease virus was not significant. In contrast, within BRVs, the probability of recombination increases. The data reported here provide genetic information to assist in the identification of diagnostic signatures and research tools for BRAV.
RESUMEN
The role of non-structural protein 3A of foot-and-mouth disease virus (FMDV) on the virulence in cattle has received significant attention. Particularly, a characteristic 10-20 amino acid deletion has been implicated as responsible for virus attenuation in cattle: a 10 amino acid deletion in the naturally occurring, porcinophilic FMDV O1 Taiwanese strain, and an approximately 20 amino acid deletion found in egg-adapted derivatives of FMDV serotypes O1 and C3. Previous reports using chimeric viruses linked the presence of these deletions to an attenuated phenotype in cattle although results were not conclusive. We report here the construction of a FMDV O1Campos variant differing exclusively from the highly virulent parental virus in a 20 amino acid deletion between 3A residues 87-106, and its characterization in vitro and in vivo. We describe a direct link between a deletion in the FMDV 3A protein and disease attenuation in cattle.