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%
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.