An immunochemical demonstration of a pregnancy-specific protein in the horse and its use in the serological detection of early pregnancy

Abstract

Summary. Two-dimensional crossed immunoelectrophoresis of sera from pregnant and non-pregnant horses, using antisera developed against early pregnant mare serum, revealed the presence of two immunologically related proteins one of which appeared to be specific to the pregnant state. This pregnancy-specific protein had \g=b\2-electrophoretic mobility and was first detectable at Day 6 after successful mating with a stallion. The second protein had \g=g\2-electrophoretic mobility and was present in sera from pregnant and non-pregnant horses. The proteins were termed \g=b\2-horse pregnancy protein and \g=g\2-horse protein respectively. The latter appeared to be immunologically related to the former in that the precipitin lines of the 2 proteins showed continuity. Samples from 16 mares mated with a stallion were investigated for the \g=b\2-protein during the first 3 weeks after mating. Of the 11 successful matings, confirmed by ultrasonic scanning at 90 days or by a successful outcome, 10 mares showed the presence of the protein. In all of 14 non-pregnant sera taken from mares not recently mated, the protein was not detec-