The Effect of Induced Isohemagglutinin on the Course of Blood-Induced Plasmodium Lophurae Infections in Chickens

Abstract

Summary Experiments were designed to evaluate the importance of induced isohemagglutinin on blood induced Plasmodium lophurae infections. Prior injection with homologous whole blood caused a striking reduction in mean peak parasitemia presumably due to the induced isohemagglutinin. The low level infections which did occur in birds with induced isohemagglutinin appeared to run a normal course. It was suspected that free merozoites in the blood inoculum might be responsible for the low level infections in experimental birds. However, washing the erythrocytes of the inoculum did not reduce the magnitude or course of the low level infections. Prior injection with washed homologus erythrocytes was also strikingly effective in inducing isohemagglutinin and reducing the expected parasitemia. However, a comparison of the effects of prior injection of homologous infected and homologous noninfected whole blood showed that isohemagglutinin is not solely responsible for resistance to homologous superinfection. Apparently specific plasmodial antibody is essential for absolute resistance to homologous superinfection since there is an abrupt termination in the course of challenging infections.