Summary
Forty-three
strains of classical swine fever (hog cholera) virus (CSFV) from
outbreaks in pigs in Europe, Asia and America, two strains from
commercial CSFV modified live vaccines and a strain isolated from
a diseased lamb from Spain were subjected to analyses of nucleotide
sequence variations in the 5
terminal region of the genome. These isolates were divided into
three clusters, namely: CSFV-1, CSFV-2, and CSFV-3, based on palindromic
nucleotide substitutions in the 5
untranslated region (UTR). The homology degree, according to nucleotide
base pairing variation in the secondary palindromic structure of
the three variable loci V1, V2 and V3, was 60% in the CSFV species,
with a mean divergence value of 6.19 base pairs (bp). relatedness
within genotypes ranged from 71.11% to 100%, with mean divergence
values from 5.5 to 0.73 base pairs. Subgenotypes showed a divergence
ranging from 1 to 9 base pairs within the genotype. Genotype CSFV-1
revealed 15 base pair combinations with 13 divergent base pairs,
resulting in 4 subgenotypes with 6 variants in subgenotype
CSFV-1.1, including the reference strain Brescia and 6 variants
in subgenotype CSFV-1.2, including the Alfort reference strain.
Subgenotypes CSFV-1.3 and CSFV-1.4 comprised one and two variants,
respectively. Genotype CSFV-2 was represented by the Spanish ovine
isolate 5440/99 and the genotype CSFV-3 included the Japanese strains
Okinawa/86 and Kanagawa/74. CSFV genotypes revealed a strong relationship
with Border disease virus strains, showing relatively low divergence
values when compared to other pestivirus species. Evaluation of
nucleotide base pair divergence among genotypes and expression of
evolutionary changes in the CSFV species led to the construction
of a phylogenetic tree based on secondary structure.
Keywords
Classical
swine fever, Genotypes, Hog cholera, Nucleotide, Palindromic nucleotide
substitution, Pestivirus.
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