Serotyping Plasmodium falciparum malaria with S-antigens

Abstract

The heat-stable proteins known as S-antigens which are associated with Plasmodium falciparum malarial infections in man show considerable serological diversity¹. Usually, different S-antigens appear in separate malarial episodes in individuals exposed to reinfection². The antigens have a worldwide distribution in endemic areas but the restricted number and characteristic specificity of S-antigens recovered from experimentally infected Aotus monkeys suggest that these antigens might provide suitable markers for serotyping isolates of P. falciparum³. Two kinds of evidence to support this idea are presented here. First, S-antigens which characterise an isolate of parasites are shown to retain their specificity over long periods of passage either in vivo or in vitro. Second, predictable mixtures of S-antigens can be recovered from cultures of P. falciparum after deliberately mixing isolates which each give rise to characteristic S-antigens.