Analysis of immunogenicity of different protein groups from malaria parasite Plasmodium falciparum.

It was observed that pressure of host immune system leads to diversifying selection (which can be measured in terms of pN/pS ratio). In this research we checked whether Plasmodium falciparum proteins containing experimentally evident epitopes from the IEDB database are subject to diversifying selection. We also investigated which life stage of this parasite and which proteins are subject to the strongest immune pressure. To answer these questions we used information about experimentally evident epitopes from P. falciparum, that interact with human immune system and sequences of different isolates of P. falciparum obtained from PlasmoDB. We confirmed the expectations that proteins containing IEDB epitopes are subject to stronger diversifying selection which is evidenced by higher pN/pS ratio. A stage characterized by the highest average pN/pS ratio is that of the sporozoite. The greatest fraction of putative antigens is also present at this stage. We also found that the sporozoite stage is particularly interesting for further analysis as it potentially contains the highest number of unidentified epitopes.