Variability of non-structural proteins of equine arteritis virus during persistent infection of the stallion.

This study investigates the stability of certain non-structural proteins found in the equine arteritis virus (EAV) during a lengthy persistent infection in a stallion. The findings indicate varying degrees of genetic stability between these proteins, with nsp3 being the most stable with no observed amino acid substitutions.

Research Background and Methodology

• The study focuses on the equine arteritis virus (EAV), known to cause respiratory disease and other ailments in horses. Specifically, research scrutinizes the genetic stability of certain non-structural proteins (nsp1, nsp2, nsp3, nsp4) during a prolonged, persistent infection in a stallion of the Malopolska breed.
• Over the course of nearly seven years (from November 2004 to June 2011), 11 semen samples were collected from this persistently infected stallion.
• Researchers extracted the viral RNA from these semen samples and amplified it for analysis. They then sequenced the amplified RNA and compared the resulting sequences with those of other known strains of EAV.

Findings

• Upon analysis of the ORF1a sequence, which encodes the non-structural proteins under investigation, the researchers identified a total of 84 synonymous and 16 non-synonymous mutations.
• The nsp2 protein was found to be the most variable part of ORF1a, showing 13 non-synonymous substitutions.
• They found that the degree of amino acid identity between different isolates of the virus ranged from 98.91% to 100%.
• Meanwhile, very few non-synonymous mutations were found in the nsp1 (one substitution) and nsp4 (two substitutions) proteins.
• The most stable protein examined was nsp3. Researchers noted no amino acid substitutions in this protein throughout the entire observation period.

Implications

• The findings of this study provide important insights into the genetic stability of these non-structural proteins (nsp1, nsp2, nsp3, nsp4) of EAV during a persistent infection.
• Understanding the genetic stability and variation of these proteins can help elucidate the virus’s mechanisms of persistence, potentially aiding in the development of more effective treatment and control methods for EAV.