Summary
Bovine
viral diarrhoea virus 2 (BVDV-2) strains demonstrated in cattle,
sheep and adventitious contaminants of biological products were
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 taxonomic status.
Variation in conserved genomic sequences was used as a parameter
for the epidemiological evaluation of the species in relation to
geographic distribution, animal host and virulence. Four genotypes
were identified within the species. Taxonomic segregation corresponded
to geographic distribution of genotype variants. Genotype 2a was
distributed worldwide and was also the only genotype that was circulating
in sheep and cattle. Genotypes 2b, 2c and 2d were restricted to
South America. Genotypes 2a and 2d were related to the contamination
of biological products. Genetic variation could be related to the
spread of BVDV-2 species variants in different geographic areas.
Chronologically, the species emerged in North America in 1978 and
spread to the United Kingdom 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 to a haemorrhagic
syndrome. These observations suggest that the evaluation of genomic
secondary structures, by identifying markers for expression of virus
biological activities and species evolutionary history, may be a
useful tool for the epidemiological evaluation of BVDV-2 species
and possibly of other species of the genus Pestivirus.
Keywords
Bovine
viral diarrhoea, BVDV-2, Palindromic nucleotide substitutions, Pestivirus,
5-untranslated region, Virus.
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