Comparative analysis of ORF5 nucleotide sequences and amino acid sequences of the GP5 protein of equine arteritis virus (EAV) detected in the semen of stallions from Eastern Poland.

The research focuses on analyzing the differences in nucleotide sequences of a gene fragment (ORF5) and the corresponding amino acid sequences of a protein (GP5) of the equine arteritis virus (EAV) found in the semen of infected stallions from Eastern Poland.

Study Scope

• This comparative study involved analyzing the ORF5 gene fragment nucleotide sequences and the GP5 protein amino acid sequences. The sequences observed in this study come from the equine arteritis virus (EAV) strains found in semen samples from infected stallions located in Eastern Poland.
• The research looked at samples from 41 stallions, all of whom had blood serum which tested positive for antigens specific to EAV.
• Out of these, the EAV genetic material was found in samples from 5 horses, with one horse showing a persistent presence of viral RNA throughout the 4-year span of the study.

Findings

• The researchers found that the similarity between the ORF5 nucleotide sequences of EAV from their own studies ranged between 90.7% and 99%.
• When compared with a sequence of an isolate of the PL1 virus (found in Polish horses earlier), the similarity ranged between 76.6% and 83%.
• The analysis of the primary structure of the capsid glycoprotein, encoded by the studied section of ORF5, revealed that amino acid substitution happens most frequently in region V1 of GP5, particularly between positions 61 and 121.

Phylogenetic Analysis

• By conducting a phylogenetic analysis comparing their own isolates with sequences of viruses isolated from horses in the USA, Europe, and New Zealand (available in the gene bank), the team was able to determine that the majority of detected strains of the virus can be classified into the European group.
• The protoplast (origins) of this European group of EAV is traced back to Austrian strain of EAV.