A study of Enzyme variation and chloroquine sensitivity of plasmodium falciparum in Vitro

Blood sampler- from children with malaria, were used to set up iri_ vitro cultures of Plasmodium falciparam using fresh human serum to enrich the culture medium. A number of investigation:-; airafid at improving the i_n vitro cultivation t e c h n i q u e ware carried out. Changing culture; medium two times every 24 hours instead of once had n positive effect on the final parasitemia level. Any e f f e c t of extra glucose on parasite growth was not obvious within the two asexual cycles period considered. A number of human sera treated at 56 58 C for 30-45 minutes to Qestrojr complement resulted in a parasitemia twice that obtained with ordinary sera. A further observation on change of so rum was made on a continuous culture which had been maintained in two different human sera for the first 37 days in vitro. The cultures where serum was changed displayed a marked reduction in parasitemia though this was only temporary. However, when heat treated seruir was used no decrease in parasitemia was apparent. S tarch-ge 1-e loc trophoreses ol dirf^r-^nt isolates of P. ralcj^parum fron Zambia revealed enzyme " •=> n i 3 t-j o n in r-i nr o.c" phosphate isornerase ( G P I ) , 6-phospho gluconate denydrogenase ( 6 - P G D ) , and adenosine dean/inase ( A D A ) . Parasite lactato d-.ihydrogens.se (L DH) and peptidase-E (PEP-E) showed no v a r i a t i o n . /- rere enzyme form, 5-PGD-2, was observed at a frequency of 80% but a standard is required to c o n f i rm the e n z y ;-ie typ n , Five different isnlatos of F. fai_c_i.p:aj^urR wci'-e subjected to different low c ore tivt r-at i ons of chloroquina ijri vitro,. Their grovrth was s r c c o s r fully inliibi to d by this drug and they were classifiad as b::ing sensitive. Parasite growth was narkedly reduced after 48 hours of drug administration and completely inhibited by 72 hours although for the last 2U hours culture was in drug-free medium