Submitted to: Virus Research
Publication Type: Peer reviewed journal
Publication Acceptance Date: 4/16/2002
Publication Date: 7/1/2002
Citation: Interpretive Summary: Infection with bovine viral diarrhea viruses (BVDV) are a source of major economic loss to U.S. cattle producers. Variation among BVDV impacts upon the study and control of BVDV outbreaks. On one hand, efforts to detect and prevent BVDV infection are hampered by the variation observed among BVDV strains. On the other hand, unique strain variations can be used to tract and identify the origin of BVDV outbreaks. Comparing BVDV from different geographic locations reveals whether there are distinct strains of virus existing in different areas. Differences that correlate with geographic locations can be used to study the traffic of viral strains between locations. In this study we compared BVDV type 2 strains from South America to BVDV type 2 strains from North America. We found that there were distinct differences between viral strains isolated from the two continents. This information will be used to design better detection and control programs.
Technical Abstract: Bovine viral diarrhea virus (BVDV) isolates are divided into two genotypes (BVDV-1 and BVDV-2). The BVDV1 genotype has been further divided into subgenotypes (BVDV1a and BVDV1b). To date subgenotypes of BVDV2 have not been identified. In this study, we demonstrate that four Brazilian BVDV2 isolates cluster to a separate genetic group within BVDV2, thus representing a distinct subgenotype. The 5'UTR sequence homology between the Brazilian group of viruses and representative BVDV2 from North America, Europe and Asian (81.7%) is lower than the homology used to segregate BVDV1 into BVDV1a and BVDV-1b (83.6%). Most nucleotide differences observed between the two subgroups of BVDV2 were concentrated in two regions, which also harbor most of the differences seen between BVDV1a and BVDV1b. To determine if the segregation of Brazilian BVDV-2 to a separate subgroup was real, an additional analysis was performed comparing NS2/3 sequences from the Brazilian viruses with North American BVDV2s. Analysis of the NS2/3 coding region also segregated the Brazilian BVDV2 to a separate group. The sequence homology between the two subgroups (86.3%) was higher than the homology in the 5'UTR (81.7%), with mean sequence homologies of 91% and 87.2% within the Brazilian and the other group, respectively. In contrast with the 5'UTR, alignment of the NS2/3 sequences revealed nucleotide differences distributed across the region. These results demonstrate that the Brazilian viruses cluster to a genetically distinct group within BVDV2.