Project description:Concerns about impending failure of artemisinin compounds (ART) have grown with global use of ART-based combination therapy (ACT) against malaria. WHO has defined Plasmodium falciparum resistance to ART as prolonged parasite clearance half-life in vivo (t1/2) plus the presence of certain K13 Kelch-propeller substitutions, e.g. C580Y. Recrudescences and fever clearance times after ART monotherapy, however, have not correlated well with these criteria. We have crossed K13 C580 wild-type and 580Y-mutant parasites for ART studies in Aotus. Artesunate treated C580- but not 580Y-infections recrudesced requiring retreatment, and K13 type had little or no effect on t1/2. These results challenge K13 and t1/2 variations as markers of increased resistance to ART per se and emphasize the need for effective partner drugs in ACTs.
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:Non-human primates belonging to the Aotus genus have been shown to be excellent experimental models for evaluating drugs and vaccine candidates against malaria and other human diseases. The immune system of this animal model must be characterised to assess whether the results obtained here can be extrapolated to humans. Class I and II major histocompatibility complex (MHC) proteins are amongst the most important molecules involved in response to pathogens; in spite of this, the techniques available for genotyping these molecules are usually expensive and/or time-consuming. Previous studies have reported MHC-DRB class II gene typing by microsatellite in Old World primates and humans, showing that such technique provides a fast, reliable and effective alternative to the commonly used ones. Based on this information, a microsatellite present in MHC-DRB intron 2 and its evolutionary patterns were identified in two Aotus species (A. vociferans and A. nancymaae), as well as its potential for genotyping class II MHC-DRB in these primates.
Project description:The goal of this study is to identify P. vivax genes whose expression is dependent on the intact spleen in experimental infections in Aotus monkeys.