Some factors influencing the induction, maintenance and degree of maternally transmitted protective immunity to malaria ( Plasmodium berghei)

Abstract

A primary infection of the mother rat, induced at the time of mating, promoted a high level of immunity to P. berghei in the progeny. The level of protection diminished markedly when the interval between the time of infection and mating was 2 months or longer. However, some protective immunity was noted in the progeny whose mothers had been infected for as long a period as 9 months. When mothers who had been infected 2 and 4 months previously were rechallenged with infected erythrocytes at the time of mating an enhanced level of maternally derived protective immunity was present in the progeny. Infected and non-infected adult female rats were inoculated with a non-living P. berghei antigen and infected erythrocytes. The level of protective immunity conferred upon the progeny of these animals was compared. The ascending order of protection was as follows: in progeny from (1) non-infected mothers given non-living antigen at time of mating, (2) mothers infected 2 months prior to mating, (3) mothers given an infective inoculum 2 months prior to mating and inoculated with non-living antigen at time of mating, (4) mothers given an infective inoculum 2 months prior to mating and rechallenged with parasitized erythrocytes at time of mating.