Plasmodium falciparum Isolates in India Exhibit a Progressive Increase in Mutations Associated with Sulfadoxine-Pyrimethamine Resistance

Abstract

The combination of sulfadoxine-pyrimethamine (SP) is used as a second line of therapy for the treatment of uncomplicated chloroquine-resistant Plasmodium falciparum malaria. Resistance to SP arises due to certain point mutations in the genes for the dihydrofolate reductase (DHFR) and dihydropteroate synthetase (DHPS) enzymes of the parasite. We have analyzed these mutations in 312 field isolates of P. falciparum collected from different parts of India to assess the effects of drug pressure. The rate of mutation in the gene for DHFR was found to be higher than that in the gene for DHPS, although the latter had mutations in more alleles. There was a temporal rise in the number of isolates with double dhfr mutations and single dhps mutations, resulting in an increased total number of mutations in the loci for DHFR and DHPS combined over a 5-year period. During these 5 years, the number of isolates with drug-sensitive genotypes decreased and the number of isolates with drug-resistant genotypes (double DHFR mutations and a single DHPS mutation) increased significantly. The number of isolates with the triple mutations in each of the genes for the two enzymes (for a total of six mutations), however, remained very low, coinciding with the very low rate of SP treatment failure in the country. There was a regional bias in the mutation rate, as isolates from the northeastern region (the state of Assam) showed higher rates of mutation and more complex genotypes than isolates from the other regions. It was concluded that even though SP is prescribed as a second line of treatment in India, the mutations associated with SP resistance continue to be progressively increasing.Plasmodium falciparum is the most lethal of all human malaria parasites. This parasite causes epidemics in countries where malaria is endemic, resulting in large numbers of deaths. Widespread chloroquine resistance has forced many countries to use alternate drugs for the treatment of falciparum malaria, such as the combination of sulfadoxine and pyrimethamine (SP). However, the parasite can develop resistance to this drug combination as well through mutations in the genes for the enzymes involved in the folate biosynthesis pathway. Such mutations lead to the lowering of the drug binding affinity of the parasite enzymes (18,26,34,36,41). Resistance to pyrimethamine is attributed to mutations in the gene for the parasite enzyme dihydrofolate reductase (DHFR), whereas sulfadoxine resistance is associated with mutations in the gene for the parasite enzyme dihydropteroate synthetase (DHPS). The increased level of resistance has been found to be associated with increased numbers of mutations in the genes for these two enzymes. Multiple mutations in the genes for both enzymes result in SP treatment failure (39). Detection of these mutations in field isolates has been proposed as an alternate strategy for rapid screening for antifolate drug resistance (9,12,16,17,27,38).In India, chloroquine-resistant malaria was first reported in 1973, and since then resistance to ...

Monitoring antimalarial drug resistance in India via sentinel sites: outcomes and risk factors for treatment failure, 2009–2010

“…As seen in a previous study based on the same methodos, 9 the typing of dhps appeared to be relatively difficult; it was unsuccessful for 27.6% of the isolates for which typing was attempted. The prevalence of single or double dhps mutations among the isolates that were successfully Marked by the following, alone or in combination: danger signs for severe malaria on days 1, 2 or 3 in the presence of parasitaemia; parasitaemia level on day 2 higher than on day 0; parasitaemia level on day 3 more than 25% higher than on day 0; parasitaemia on day 3 plus fever.…”

“…8 Indian isolates of P. falciparum were also frequently found to carry mutations in the genes that code for the targets of sulfadoxine and pyrimethamine: dihydropteroate synthase (dhps) and dihydrofolate reductase (dhfr), respectively. 9 In 2005,…”

Prevalence of mutation and phenotypic expression associated with sulfadoxine-pyrimethamine resistance in Plasmodium falciparum and Plasmodium vivax

“…Primers PvDA (covering -75 to -55 bp upstream to the Pvdhfr-ts start codon), PvDB, PvDF and PvDr were designed from the known Pvdhfr-ts sequence of pyrimethamine-sensitive P. vivax isolate Ari/Pakistan (98123). DNA was extracted and subjected to Pcr amplification of a 720-bp fragment to the pfdhfr gene using the method described by Ahmad et al (2004). An aliquot of the primary amplicon was diluted and subjected to seminested Pcr using primer AMP1 (Plowe et al 1997) and DHFrr2 (5'-AcAgAAAtAAtttgAtActcA-3').…”

<i>In Vitro</i> Evaluation of the Antimalarial Activity of a Designed Novel Quinuclidine Derivative

“…Spectral analysis of the synthesized compound (C) confirmed the structure, which was then compared with the predicted structure 21 . Spectral data of Schiff base are as follows: (i) 1 After synthesis, docking study was performed between N-(pyridine-4-yl-methylene) quinuclidine-3-amine (C) and antimalarial target plasmepsin II using docking software Hex (version 5.0). The docking study exhibited high binding affinity with E value of -172.29 kcal mol -1 ( Figure 1 a and b).…”

“…It is widespread in all parts of India except in areas, which are not favourable for transmission and multiplication of malaria parasites [1][2][3][4][5][6] . Quinine, the oldest known antimalarial, led to the discovery of chloroquine, the most widely used antimalarial drug for almost more than half a century.…”