The immune responses to antigenic variants of Babesia bigemina in the bovine.

Four Babesia bigemina stabilates were used to determine the immune response of cattle to acute and chronic blood- and tick-borne infections. Thirty-two intact calves were divided into 16 groups of two and each calf was inoculated with infective B bigemina erythrocytic stabilates. Twenty-eight days later they were challanged with homologous and heterologous stabilates, and monitored for an additional 20 days. The hosts' apparently reduced response to homologous challenge but marked immune response to heterologous challenge indicated antigenic differences between the isolates and confirmed the conclusions reached by examination of the serological data.