ABSTRACT
OBJECTIVE: To perform genetic analysis of the ORF5 of equine arteritis virus (EAV) may provide new insights into the genetic evolution and origin of the Argentinean EAV sequences. METHODS: A total of 76 sequences were analyzed by neighbor joining (NJ), maximum parsimony and maximum likelihood algorithms. The analysis of the selective pressures was performed using the Tajima's test. RESULTS: The trees showed similar topologies. Two clades were identified: the first clade was formed by strains isolated mainly from a donkey, whereas the second clade presented four large groups from different geographic regions exclusively from Equus caballus. In this clade, we identified a group formed by South African and another one by South American and European sequences. In the latter, the monophyletic group was formed by seven Argentinean sequences. In the NJ tree, we identified a group formed by six Argentinean sequences. The Tajima's test showed a D value of 1.73663, indicating that the sequences analyzed follow a neutral evolution model. CONCLUSION: We concluded that the Argentinean sequences have a paraphyletic origin and that the fixation of point mutation might follow the neutral model evolution; however, we identified purifying pressures that may be involved in the differentiation of the EAV sequences.
Subject(s)
Arterivirus Infections/veterinary , Equartevirus/genetics , Equartevirus/isolation & purification , Horse Diseases/virology , Phylogeny , Algorithms , Animals , Argentina , Arterivirus Infections/virology , Base Sequence , Equartevirus/classification , Europe , Evolution, Molecular , Genetic Variation , Horses/virology , Male , Molecular Sequence Data , North America , Semen/virology , Sequence Alignment/veterinary , South AfricaABSTRACT
We report the nucleotide sequence and genetic diversity of four Equine Arteritis Virus (EAV) ORF 5 and 6 from Argentina isolates, obtained from asymptomatic virus-shedding stallions. Nucleic acid recovered from the isolates were amplified by RT-PCR and sequenced. Nucleotide and deduced amino acid sequences from the Argentine isolates were compared with 17 sequences available from the GenBank. Phylogenetic analysis revealed that the Argentine isolates grouped together in a definite cluster near European strains. Despite the greater genetic variability among ORF 5 from different isolates and strains of EAV, phylogenetic trees based on ORF 5 and 6 are similar. Both trees showed that virus sequences from America and Europe segregate into distinct clades based on sequence analysis of either ORF 5 or 6. This study constitutes the first characterization of Argentine EAV isolates.
