Conserved alleles in Plasmodium falciparum variant antigens: studies on existence and immunological response in individuals from an endemic area

Abstract

An important factor in the pathogenicity of the protozoan parasite Plasmodium falciparum, the causing agent of Malaria, is the presence and expression of highly polymorphic antigens encoded by the multigene families var rif and stevor. The extreme polymorfism of these genes in strains from different geographic locations around the world is in contrast to the observation of a number of conserved alleles in Amazonian isolates, similar to the previously described conserved var gene var2csa. In this project, we first evaluate if the apparently “conserved” alleles of var, rif and stevor genes indeed occur in the majority of Amazonian isolates and in a number of control samples from Gabon/Africa. In the following, recombinant proteins of the “conserved” alleles will be expressed and the humoral immune response against these antigens will be measured in imunoblots and Elisas. As controls, proteins from apparently “rare” variants are produced and the immune response measured in parallel. In order to estimate the importance of the response against these antigens, sera/plasma from individuals with different experience of malarial infection will be employed (primary infected individuals/symptomatic individuals/non-symptomatic individuals). The resulting data will add important information which will help to explain the conservation of these antigens and their corresponding genes.