Project description:Unlike in Asia and Latin America, Plasmodium vivax infections were rare in Sub-Saharan Africa due to the absence of the Duffy blood group antigen (Duffy Antigen), the only known erythrocyte receptor for the P. vivax merozoite invasion ligand, Duffy Binding Protein 1 (DBP1). However, P. vivax infections have been documented in Duffy-negative individuals throughout Africa, suggesting that P. vivax may use ligands other than DBP1 to invade Duffy-negative erythrocytes through other receptors. To identify potential P. vivax ligands, we compared parasite gene expression in Saimiri and Aotus monkey erythrocytes infected with P. vivax Salvador I (Sal I). DBP1 binds Aotus but does not bind to Saimiri erythrocytes, and thus P. vivax Sal I must invade Saimiri erythrocytes independently of DBP1. Comparing RNA sequencing (RNAseq) data for late stage infections in Saimiri and Aotus erythrocytes when invasion ligands are expressed, we identified genes that belong to tryptophan-rich antigen and MSP3 families that were more abundantly expressed in Saimiri infections as compared to Aotus infections. These genes may encode potential ligands responsible for P. vivax infections of Duffy-negative Africans.
Project description:The purpose of this reasearch is to identify and evaluate the global gene expression of Plasmodium knowlesi blood-stage parasites and specifically compare the gene expression profiles of samples derived from ex vivo versus long-term in vitro cultures. For ex vivo samples, a rhesus monkey was infected with P. knowlesi to obtain ring iRBCs to establish a short-term culture to immediately collect ex vivo derived time points every 4 hours in the course of the parasite’s 24-hour life cycle. For in vivo samples, they were generated from the same clone in the ex vivo culture adapted to long-term in vitro culture and were collected every 4 hours in the course of the parasite's 24-hour life cycle. Two replicate experiments(Aa and Ha) were developed from in vitro cultures. Samples labeled with Cy5 were hybridized against a reference RNA pool labeled with Cy3, consisting of equal amounts of P. knowlesi RNA from each time point.