Molecular epidemiology of Plasmodium vivax anti-folate resistance in India

Abstract

BackgroundSulphadoxine and pyrimethamine are anti-folate drugs that show synergistic anti-malarial effect. Point mutations in dihydrofolate reductase (dhfr) and dihydropteorate synthatase (dhps) cause anti-folate drug resistance phenotype in human malaria parasites. This study presents pattern of point mutations in dhfr/dhps genes among Indian sub-continent.MethodsMicroscopically diagnosed one hundred Plasmodium vivax field isolates were collected from five widely separated geographical regions of India. Dhfr and dhps genes were PCR amplified and sequenced. Previously published mutations data were collected and analyzed using Chi square test to identify geographical cluster of mutant/wild type genotypes.ResultsSequence analysis revealed single (S58R), double (S58R/S117N) and quadruple (F57L/S58R/T61M/S117T/) point mutations at dhfr and single (A383G) to double (A383G/A553G) mutations at dhps in P. vivax field isolates. In addition, three new mutations were also observed at dhfr. Both, dhfr and dhps genes revealed tandem repeat variations in field isolates. Dhps revealed very low mutation frequency (14.0%) compared to dhfr (50.70%). Comparative analysis revealed a progressive increase in frequency of quadruple mutant dhfr genotype (p < 0.001) within five years in north-eastern state (Kamrup, Assam). Frequency of dhfr genotypes revealed three distinct geographical clusters of wild (northern India), double mutant (southern India), and quadruple mutant (north-eastern and island regions of India) on the Indian sub-continent.ConclusionStudy suggests that SP may be susceptible to P. vivax in India, except Andaman and north-eastern state. The distinction of geographical regions with sensitive and resistant parasite phenotypes would be highly useful for designing and administering national anti-malarial drug policy.

Prevalence of Polymorphisms in Antifolate Drug Resistance Molecular Marker Genes pvdhfr and pvdhps in Clinical Isolates of Plasmodium vivax from Kolkata, India

“…A high risk of therapeutic failure of SP is significantly associated with the quadruple mutant allele L 57 R 58 M 61 T 11 (17,28). No triple or quadruple mutation in pvdhfr was detected in the parasite population prevailing in the study area, which is unlike the findings made by other investigators from India (19,21,22).…”

“…In the present study, we observed both the mutations in 40% of the isolates. But we did not find mutations at codons I13L, F57L, T61M, P33L, S93H, S117T, I172V, and I173L which have been reported from different parts of the country by various workers (19)(20)(21)(22). It has been hypothesized that the S117N mutation is the first step in the drug resistance selection process, and S117T has been strongly associated with SP resistance (30) in areas with extensive use of SP (31,32), but the mutation was not found in the present study.…”

“…We reported a high prevalence of quadruple and quintuple mutations in the pfdhfr-pfdhps genes in field isolates of P. falciparum from the same state (34) where SP was introduced for the treatment of chloroquine-resistant falciparum malaria in 2002, but no such data are available from urban Kolkata. The types and rates of multiple mutations of the pvdhfrpvdhps genotypes are lower than those found in other parts of the country (21,22). The results suggest that the P. vivax parasites in urban Kolkata may still be susceptible to SP.…”

“…The prevalence of pvdhfr and pvdhps mutations has been studied in many regions in Southeast Asia, including Indonesia, Papua New Guinea, Sri Lanka, and Pakistan; but such information from India is scarce (19)(20)(21)(22), and no data are available from this part of the country.…”

Point Mutations, Their Transition Rates and Involvements in Human and Animal Disorders

“…Although the mechanisms by which malaria parasites develop resistance to drugs are unclear, current knowledge suggests that a main mechanism of resistance is the alteration of target enzymes by point mutation. Mutations in dihydrofolate reductase (dhfr) and dihydropteorate synthatase (dhps) cause anti-folate resistance in human malaria parasites against drugs sulphadoxine and pyrimethamin with synergystic anti-malarial effect (Prajapati et al, 2011). A constant monitoring is necessary to keep information about newly emerging drug resistance in Plasmodium, e.g.…”