Time course of in vitro maturation of intra-erythrocytic malaria parasite: a comparison between Plasmodium falciparum and Plasmodium knowlesi

The schizont maturation assay for in vitro drug sensitivity tests has been a standard method employed in the global baseline assessment and monitoring of drug response in Plasmodium falciparum. This test is limited in its application to synchronous plasmodial infections because it evaluates the effect of drug on the maturation of parasite especially from ring to schizont stage and therefore synchronized P. falciparum cultures are required. On the other hand, P. knowlesi, a simian malaria parasite has a unique 24-h periodicity and maintains high natural synchronicity in monkeys. The present report presents the results of a comparative study on the course of in vitro maturation of sorbitol synchronized P. falciparum and naturally synchronous P. knowlesi. Ring stage parasites were incubated in RPMI medium supplemented with 10-15 percent pooled homologous serum in flat-bottomed 96-well micro plates using a candle jar at 37°C. The results suggest that the ideal time for harvesting the micro-assay plates for in vitro drug sensitivity test for sorbitol-synchronized P. falciparum and naturally synchronous P. knowlesi are from 26 to 30 h and from 22 to 25 h, respectively. The advantages of using P. knowlesi in chemotherapeutic studies are discussed

Biting behaviour of Armigeres subalbatus (Coquillett) with reference to host selection and landing.

Armigeres subalbatus (Coquillett), a vicious crepuscular biter, has been selected to study the biting behaviour with reference to factors affecting landing and host selection in the laboratory. The mosquito showed a higher attractancy to relatively warmer skin of human hands. There was also a significant attraction towards the artificially warmed hands than the normal ones, and the mosquitoes avoided the artificially cooled hands. Therefore, host temperature is a factor which influences the attraction and subsequent landings of A. subalbatus. When the mosquitoes were offered animal hosts, the order of host preference by these mosquitoes was hen > rabbit > guinea pig, both in single and two-host combinations thus, showing their preference to avian host.