Differential Expression of var Gene Groups Is Associated with Morbidity Caused by Plasmodium falciparum Infection in Tanzanian Children

Thevar gene family ofPlasmodium falciparum encodes the variant surface antigenPlasmodium falciparum erythrocyte membrane protein 1 (PfEMP1). PfEMP1 is considered an important pathogenicity factor inP. falciparum infection because it mediates cytoadherence to host cell endothelial receptors.var genes can be grouped into three major groups, A, B, and C, and the conservedvar genes,var1-4 , according to sequence similarities in coding and noncoding upstream regions. Using real-time quantitative PCR in a study conducted in Tanzania, thevar transcript abundances of the differentvar gene groups were compared among patients with severe, uncomplicated, and asymptomatic malaria. Transcripts ofvar group A and B genes were more abundant in patients with severe malaria than in patients with uncomplicated malaria. In general, the transcript abundances ofvar group A and B genes were higher for children with clinical malaria than for children with asymptomatic infections. Thevar group C andvar1 -like transcript abundances were similar between the three sample groups. A transcript abundance pattern similar to that forvar group A was observed forvar2csa andvar3 -like genes. These results suggest that substantial and systematic differences invar gene expression exist between different clinical presentations.