Genetic diversity of equine arteritis virus strains among permanently infected stallions in stallion depots in Poland

摘要

The purpose of the study was to analyse the genetic diversity of Polish EAV isolates. Genetic variability can lead to increased virulence of isolates and to significant changes in EAV antigen properties influencing the results of laboratory testing. Studies on genetic modifications of viral genomes as well as on the phylogenetic affinity of strains have facilitated the investigation of viral evolution. Phylogenetic analysis was performed on 32 isolates that were isolated from the semen of asymptomatic virus-shedding stallions originating from 8 national studs. These isolates were compared with 15 reference EAV strains commonly used in phylogenesis. On the basis of the nucleotide sequence analysis of ORF5 gene encoding GP5 glycoprotein it was shown that Polish EAV isolates belonged to two subgroups and demonstrated the closest relationship to the European strains. None of these strains had any relationship to the first Polish strain Wroclaw-2 isolated in 1976. The homology of ORF5 nucleotide and predicted GP5 amino-acid sequences of Polish isolates attained a level of 81.2-99.0% and 90.1-99.4% respectively. Analyzing the genetic diversity of ORF5 facilitated the conducting of retrospective epizootic investigations.