|Rieder, Aida - Elizabeth|
Submitted to: Virology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/16/2007
Publication Date: 3/17/2008
Citation: Hollister, J.R., Vagnozzi, A., Knowles, N., Rieder, A.E. 2008. Molecular and Phylogenetic Analyses of Bovine Rhinovirus Type 2 Shows it is Closely Related to Foot-and-Mouth Disease Virus. Virology. Vol 373/2: 411-425. Interpretive Summary: Bovine rhinovirus type 2 (BRV2) is a picornavirus associated with common cold in cattle. Like many other respiratory viruses (such as the major and minor group of human rhinoviruses), BRV2 targets the upper respiratory tract and grows well at 33 degrees C. There is lack of information in the literature regarding the biology of BRV-2, or the incidence and frequency of the disease induced by this virus in cattle. Moreover, there is not published data on their genome organization and RNA sequence. In the current study, we have generated a nearly full-length genome sequence for BRV2 that included most of non-translated regions and the protein coding sequence. The results surprisingly showed that BRV2 shares more genomic similarities with foot-and-mouth disease virus (FMDV) an aphtovirus that causes vesicular disease, than with rhinoviruses or other picornaviriruses. Considering the similarity in genome structure and organization, overall amino acid identity and the results of the phylogenetic analysis, we propose that BRV2 be re-classified a member of the aphthovirus genus of the family Picornaviridae along with FMDV and equine rhinovirus.
Technical Abstract: Bovine rhinovirus 2 (BRV2), a causative agent of respiratory disease in cattle, is currently an unclassified species tentatively assigned to the genus rhinovirus in the family Picornaviridae. A nearly full-length cDNA of the BRV2 genome was cloned and the nucleotide sequence from the poly(C) to the poly(A) determined. Alignment of the predicted BRV2 polyprotein demonstrated more similarities to foot-and-mouth disease virus (FMDV) than to the rhinoviruses. Specifically, BRV2 possesses a putative leader proteinase, a small 2A protein and a poly(C) tract, which are characteristic of Aphthoviruses. Examination of the amino acids immediately flanking the predicted cleavage sites within the polyprotein revealed conservation between BRV2 and FMDV in most cases. A single putative VPg (3B) protein encoded by BRV2 is also more similar to the 3rd VPg found in FMDV serotypes than those of rhinoviruses. Alignment of BRV-2 EC11 and FMDV A24 polyproteins showed that 41% of the amino acids are identical within the P1 region. Furthermore, amino acids in 2A, 2C, 3B3, 3C and 3D are as much as 67%, 52%, 52%, 50%, and 64% identical, respectively. Using in vitro translation analysis, we determined that BRV2 leader protein is rapidly released from the viral polyprotein at a rate similar to the autocatalytic release of FMDV leader proteinase. In addition, expression of BRV2 leader protein in bovine kidney (BK-LF) cell extracts resulted in the cleavage of eIF4G and produced cleavage products that co-migrated with those induced by FMDV leader proteinase, suggesting a functional relationship between the leader protein in these viruses. The sequence similarities combined with the results from phylogenetic and biochemical analysis suggest that BRV2 is closely related to FMDV and should therefore be considered as a new species within the genus Aphthovirus.