Characterisation of genotypes among bovine viral diarrhoea virus 2 strains according to palindromic nucleotide substitutions in the 5 untranslated genomic region.
Pestivirus bovine viral diarrhea virus 2 (BVDV-2) strains from 61 isolates from cattle and sheep, and from some adventitious contaminants of biologicals, have been assessed using the palindromic nucleotide substitutions (PNS) method at three variable loci (V1, V2 and V3) located delin the 5' untranslated region (UTR) of genomic RNA. This genotyping procedure is new, simple and practical. Two characteristics of the base pairings common to BVDV-2 species, a C-G or U-A pairing at the V1 locus, and a G*U pairing at the V2 locus, were observed in isolates tested. The PNS method showed six genotypes: BVDV-2a, BVDV-2b, BVDV-2c, BVDV- 2d, BVDV-2e and BVDV-2f. Twenty-five strains showed the BVDV-2a genotype specific combination of three base pairings (A-U in position 1 and C-G or U*G in position 18 in V1 and U-A or U*G in position 4 in V2). Ten strains were identified by a single C-G pairing in position 4 from the bottom of the V2 stem region, characteristic to genotype BVDV-2b. Three strains were assigned to genotype BVDV-2c, due to their recognition by a G*U pairing at the bottom of the V1 stem region. A U-A pairing, characteristic of the BVDV-2d genotype when found in position 18 of the V1 stem region, was observed in fourteen strains. Genotype BVDV- 2e, present in only six South American cattle isolates, was characterized by G-C pairing in position 12, by U-A pairing in position 16 and G_G or G-_A bulges in position 18 in the V1 region. One strain from Argentina was classified as genotype BVDV-2f, showing: A-U pairing in position 9 and 12, U-A in position 16 and G_A bulge in position 18 in V1 region. Two strains were not characterized due to incomplete sequence of V1 locus.
Giangaspero
M
M
Dipartimento di Medicina Veterinaria, Università degli studi, Milan, Italy.
Harasawa
R
R