Genoepidemiological Evaluation of Bovine viral diarrhea virus 2 Species Based on Secondary Structures in the 5' Untranslated Region

Abstract

Bovine viral diarrhea virus 2 (BVDV-2) strains demonstrated in cattle, sheep, and adventitious contaminants of biological products have been evaluated by the palindromic nucleotide substitutions (PNS) method at the three variable loci (V1, V2 and V3) in the 5' untranslated region (UTR), to determine their taxonomical status. Variation in conserved genomic sequences was used as parameter for epidemiological evaluation of the species in relation with geographical distribution, animal host and virulence. Four genotypes, BVDV-2a, BVDV-2b, BVDV-2c, and BVDV-2d have been identified within the species. Taxonomical segregation corresponded to geographical distribution of genotype variants. Genotype 2a was present worldwide, and was the only circulating also in sheep, in addition to cattle. Genotypes 2b, 2c and 2d were restricted to South America. Contamination of biological products was related to genotypes 2a and 2d. Genetic variation could be related with chronological diffusion of the BVDV-2 species variants in different geographic areas. Chronologically, the species emerged in North America in 1978, spreading in UK and Japan, continental Europe, South America and New Zealand. Correlation between clinical features related with isolation of BVDV-2 strains and genetic variation indicated that subgenotype 1, variant 4 of genotype 2a was related with hemorrhagic syndrome. These observations suggest that evaluation of genomic secondary structure, by identifying markers for expression of virus biological activities and species evolutionary history, may be applied as useful tool for epidemiological evaluation of the BVDV-2 species, and possibly for other species of the genus Pestivirus.