Cell mediated immunity in equine herpesvirus type 1 infection I. In vitro lymphocyte blastogenesis and serum neutralization antibody in normal parturient and aborting mares.

The research investigates the impact of equine herpesvirus type 1 on the immune responses in horses, specifically on lymphocyte activity and serum antibody levels. It finds that immune responses vary between horses from different farms and there is no clear correlation between serum neutralizing antibody levels and lymphocyte stimulation.

Investigation of Equine Herpesvirus Type 1

The study concentrates on the effects of equine herpesvirus type 1, a virus responsible for a range of diseases in horses. Researchers studied the immune responses in 19 pregnant mares from three different farms. These responses were observed during the termination of their pregnancies, either through normal foaling or viral abortion likely due to the equine herpesvirus type 1 infection.

• The immune response under investigation was the blastogenic transformation of peripheral blood mononuclear cells – essentially, the proliferation of certain types of white blood cells in response to the infection.
• Researchers also inspected antibody levels in a process known as serum neutralization, where the capability of certain antibodies to neutralize the herpesvirus in the blood was measured.

Results and Findings

Results varied based on the farm of origin for the mares, indicating potential environmental influences on immune response.

• For mares from Farm 1 and 2, which had viral abortions, the stimulation indexes of lymphocytes varied from 2.1 to 10.8. This indicates a response to the viral infection. However, there was no significant difference in lymphocyte activity between mares that had normal births and those that had viral abortions.
• Interestingly, from one mare, the virus was isolated from mononuclear cells two months post-abortion. Her lymphocyte stimulation index was not significantly different compared to other mares on the farm indicating the virus might persist in the organism without drastically influencing immune response.
• The stimulation index ranged from 1.6 to 2.9 for mares from the third farm, which did not experience any viral abortions nor had any history of it.
• Most mares had low serum neutralization antibody levels, between 1/4 and 1/20, albeit some had higher levels.
• Notably, the study found no direct correlation between the extent of serum neutralizing antibody and lymphocyte stimulation indices, suggesting these two immune reactions might operate independently in response to the virus.

In conclusion, the study provides nuanced insights into the heterogeneous immunological responses induced by equine herpesvirus type 1 in horses, potentially driven by environmental factors, without identifying clear patterns in antibody and cellular responses.