Assessment of correlation between in vitro CD3+ T cell susceptibility to EAV infection and clinical outcome following experimental infection.

The research focuses on analysing the correlation between a horse’s susceptibility to Equine Arteritis Virus (EAV) infection in vitro and the severity of clinical signs when infected in vivo. It found that horses with a particular haplotype, associated with in vitro CD3(+) T cell resistance to EAV, showed significantly increased clinical signs of disease.

Study Objective and Methodology

• This research sought to explore whether the differences in resistance or susceptibility of a particular type of horse’s immune cells (CD3(+) T cells) to EAV relate to the outcome and severity of clinical signs exhibited by the infected horses. The focus was on the differences in in vitro (outside the body) infection susceptibility.
• Horses were classified into two separate groups based on their CD3(+) T cells’ in vitro susceptibility or resistance phenotype. This genetic phenotype was determined through testing the horses’ cells with the virulent Bucyrus strain (VBS) of EAV.

Experimental Procedure and Assessment

• Following classification, the horses were experimentally infected with a recombinant version of the VBS strain of EAV.
• The horses were then evaluated in terms of the presence and severity of clinical symptoms, duration of virus shedding (extent to which they spread the virus), and intensity of viral shedding.
• Additionally, the production of inflammation-inducing (proinflammatory) and immune response-modifying (immunomodulatory) chemical compounds (cytokines) was examined in the horses’ blood cells. This was done utilizing real-time quantitative Reverse Transcription Polymerase Chain Reaction (RT-PCR), a laboratory technique used to measure the amount of specific RNA (in this case, mRNA for cytokines).

Outcomes and Conclusion

• The results showed a significant difference between the groups of horses based on cytokine mRNA expression and the severity of illness. There was particularly strong evidence of heightened clinical signs in the horses identified as being CD3(+) T cell resistant in vitro.
• This is the first study that presents direct evidence of a correlation between differences in host genotype (specific genetic characteristics) and the severity of clinical signs, viral replication extent, and cytokine gene expression induced by the virulent strain of EAV.
• The findings suggest that the horse’s CD3(+) T cell resistance or susceptibility could predict severity of EAV clinical signs. This information may be relevant in developing more effective treatments and preventive strategies for EAV.