Limited polymorphism of the Kelch propeller domain in P. malariae and P. ovale isolates from Thailand

Artemisinin resistance in P. falciparum, the agent of severe malaria, is currently a major obstacle to malaria control in southeast Asia. The gene named "kelch13" has been associated with artemisinin resistance in P. falciparum The orthologue of the kelch gene in P. vivax has been identified and a small number of mutations found in previous studies. The kelch orthologues in the other two human malaria parasites, P. malariae and P. ovale, have not yet been studied. Therefore, in this study, the orthologous kelch genes in P. malariae, P. ovale wallikeri and P. ovale curtisi were isolated and analysed for the first time. The homology of kelch in P. malariae and P. ovale was 84.8% and 82.7%, respectively, when compared to P. falciparum Kelch polymorphisms were studied in 13 P. malariae and 5 P. ovale isolates from Thailand. There were 2 non-synonymous mutations found in these samples. One mutation was P533L, which was found in 1 of 13 P. malariae isolates, and the other was K137R, found in one isolate of P. ovale wallikeri (n=4). This could have resulted from artemisinin drug pressure, since P. falciparum co-infection is common.