USE OF A SEMI-NESTED PCR DIAGNOSIS TEST TO EVALUATE ANTIFOLATE RESISTANCE OF PLASMODIUM-FALCIPARUM ISOLATES

The antifols, inhibitors of the dihydrofolate reductase (DHFR), such a s pyrimethamine and proguanil, have been used against Plasmodium falci parum in the areas where chloroquine resistance is widespread. This us e has selected resistant strains in Southeast Asia and South America. The resistance is correlated with point mutations in precise positions of the DHFR gene. A reliable semi-nested PCR diagnosis test was estab lished and used to determine the genotypic features of 29 isolates of P. falciparum originating from Africa. The results obtained by the PCR technique were compared with those of the in vitro drug sensitivity t est. Some isolates were found to be polyclonal. Among the mutations te sted, only mutations on codon 108 which generate an asparagine induce a decrease in sensitivity to pyrimethamine and cycloguanil, whereas mu tation on codon 59 strengthens resistance to both antifols. No mutatio n on codon 16 or codon 164 was found. (C) 1995 Academic Press Limited