Thick-smear Plasmodium falciparum antigen from in vitro cultures for the indirect fluorescent antibody test

An important prerequisite for serological studies is the availability of specific antigens with which a high, consistently reproducible degree of test sensitivity can be obtained. In the present study, thick films of P. falciparum antigen were made from in vitro cultures in order to evaluate this antigen in terms of the sensitivity and reproducibility of the indirect fluorescent antibody test, as compared with an antigen prepared from washed infected erythrocytes of Aotus trivirgatus monkeys. The test was performed in 132 serum samples from 4 different sources. The results showed that the sensitivity and reproducibility of the two antigens compared well. No binding of donors' antibody to antigen was noticed within the 24-hour period of in vitroculture.