Antigenic analysis of Plasmodium yoelii liver stages by fluorescence antibody assays

Little is known about the immune response against liver stage antigens which were first described for Plasmodium falciparum. In order to provide a basis for experimental studies, we analysed antigenically the liver stages of Plasmodium yoelii using sera of restricted specificity. Several distinct fluorescence patterns could be described in maturing liver forms. One pattern was identified as corresponding to antigens specific to the liver phase which are also species specific. Another pattern corresponds to sporozoite surface antigens which were predominant in liver trophozoites. Trophozoite-like liver forms were detected at least 7 days after the injection of irradiated sporozoites suggesting that parasites may persist and contribute to the immunity induced by this procedure.