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

Blastic transformation of peripheral blood mononuclear cells and serum neutralization antibody levels for equine herpesivurs type 1 were measured in 19 mares from three farms at the time of termination of their pregnancy by normal foaling or viral abortion. The stimulation indexes of lymphocytes obtained from the mares from two farms (Farm 1 and 2) which had virus abortions, ranged from 2.1 to 10.8. But there was no significant difference in stimulation index levels between the aborting and normal foaling mares on these two farms. Equine herpesvirus type 1 was isolated from the mononuclear cells of one mare (No. 5) about two months after she aborted. The stimulation index of lymphocytes from that mare was not significantly different from that of other mares on these farms. Stimulation index of lymphocytes from the mares on one farm (Farm 3) where there was no virus abortion or previous history of virus abortion but were exposed to virus antigen from vaccination, ranged from 1.6 to 2.9. The serum neutralization antibody levels were low in most mares ranging from 1/4 to 1/20 and in three mares these were higher. There was no direct correlation between the levels of serum neutralization antibody and stimulation index of lymphocytes from the mares on these farms.