Temporal expression of liver-stage malaria antigens shapes vaccine efficacy

Vaccine-induced cytotoxic T cells can prevent malaria by killing parasite-infected hepatocytes during the liver stage. While several antigenic targets have been identified, little consideration has been given to their temporal expression. Here, we identified SERA1 of Plasmodium berghei as a late liver-stage target in rodent malaria and further showed that the classic vaccine antigen thrombospondin-related adhesion protein (TRAP) is only an early target. While vaccination with either antigen alone was modestly protective, combining these antigens enabled killing over the entire liver-stage, greatly improving efficacy. Given the relatively long liver-stage in human malaria, our findings imply TRAP-dependent vaccines likely utilize only a small proportion of the available liver-stage to eradicate parasites. Our findings further indicate that considerations of temporal coverage when selecting vaccine antigens will improve efficacy.