Localization of a dominantly expressed plasmodium berghei bir gen

Abstract

Malaria is a major burden both to the economy and the health of the population in the tropics. In Kenya four species of Plasmodium occur, P. falciparum, P. ovale, P. vivax and P. malaria, but Plasmodium falciparum accounts for 98% of all the cases. P. falciparum is able to cause cerebral malaria through cytoadhesion, mediated by variant surface antigens, Plasmodium falciparum Erythrocyte Membrane Protein 1, (PfEMP l), which are encoded by the var genes. Plasmodium berghei causes malaria in rodents. In this study P. berghei, ANKA strain which causes experimental cerebral malaria (ECM) was studied. Antigenic variation in malaria parasites is achieved by the expressed antigens being switched frequently. In P. falciparum the process is mediated by PfEMPl proteins, which are encoded by the var genes. The var genes are located at !he subtelomeric regions. A large multi gene superfamily, called the Plasmodium interspersed repeats (pir) which has striking similarities to the var genes were found in other Plasmodium species and the coding sequence of these genes are also located at the subtelomeric regions of the chromosomes. This family consists of the, vir genes in P. vivax, kir genes in P. knowlesi, cir genes in P. chabaudi, yir genes in P. yoelii and bir multigene family in P. berghei. The aim of the study was to localize a dominantly expressed bir gene, called BIRdom 1, and study its localization in infected red blood cells using IFA. In a study by Maier et al they identified a dominant member of the bir gene, BIRdoml, and that is the gene chosen for the study. In this study the BIRdom 1 gene was inserted into a vector and tagged with c-myc, so that the localization of the BIRdom 1 protein could easily be detected by immunoflourescence studies. Additionally it was used to investigate the protein expression of BIRdom 1 by western blot. The insertion of the gene was successful and staining of the protein with the antibodies, mouse anti-cmyc and Alexa fluor anti mouse antibodies. The IFA showed a cytosolic expression of the BIRdom l protein in blood stages. The uninfected red blood cells used as the control did not show any fluorescence. This showed that the expression of the BIR protein was cytosolic, however we do not rule out that the gene could also be expressed on the surface and more experiments are needed. This study was carried out at the University of Heidelberg, School of Medicine, Department of Infectious Diseases, Parasitology, under the Group of Dr. Steffen Borrmann.