Pyrimethamine was first introduced for the treatment of malaria in Asia and Africa during the early 1980s, replacing chloroquine, and has become the first line of drugs in many countries. In recent years, development of pyrimethamine resistance in Plasmodium vivax has become a barrier to effective malaria control strategies. Here, we describe the use of meta-barcoded deep amplicon sequencing technology to assess the evolutionary origin of pyrimethamine resistance by analysing the flanking region of dihydrofolate reductase (dhfr) locus.
WR99210, a former antimalarial drug candidate now widely used for the selection of Plasmodium transfectants, selectively targets the parasite dihydrofolate reductase thymidine synthase bifunctional enzyme (DHFR-TS) but not human DHFR, which is not fused with TS. Accordingly, WR99210 and plasmids expressing human dhfr have become valued tools for the genetic modification of parasites in the laboratory.
In a bid to come up with effective compounds as inhibitors in antimalarial treatment, we built a library containing about 2,000 traditional Chinese medicine(TCM)-derived compounds retrieved from TCM Data-base@Taiwan. The active sites of both the wild type and mutant Plasmodium falciparum dihydrofolate reductase (pfDHFR) were explored using computational tools. pfDHFR, one of the prime drug targets in the prevention of malaria infection induced by the female anopheles mosquito has continued to coffer resistance to drugs (antifolates) due to mutation in some of the key amino acid residues crucial for its inhibition.