Low prevalence of dihydro folate reductase (dhfr) and dihydropteroate synthase (dhps) quadruple and quintuple mutant alleles associated with SP resistance in Plasmodium vivax isolates of West Bengal, India.

Background: Emergence of chloroquine resistant Plasmodium vivax is a serious obstacle towards malaria control in India. This study elucidates the temporal pattern of antifolate [sulfadoxine-pyrimethamine (SP)] resistance in P. vivax infection by means of genetic polymorphisms, especially analysing the single nucleotide polymorphisms of dihydrofolate reductase (pvdhfr) and dihydropteroate synthase (pvdhps) gene among the field isolates of urban Kolkata Municipal Corporation and rural Purulia region of West Bengal, India.

Methods: Blood samples were collected from 99 microscopically diagnosed P. vivax patients (52 from Kolkata Municipal Corporation and 47 from Purulia). Parasitic DNA was extracted followed by polymerase chain reaction and sequencing of different codons of pvdhfr gene (15, 33, 50, 57, 58, 61, 64, 117, and 173 codons) and pvdhps gene (373, 380, 382, 383, 384, 512, 553, 585, and 601 codons) were performed to identify the mutations.

Results: Prevalence of double mutant dhfr A15P33N50F57 R 58 T61V64 N 117 I173 allele (53.85 %) was observed in Kolkata Municipal Corporation (KMC) whereas in Purulia, wild dhfr A15P33N50F57S58T61V64S117I173 allele was predominated (48.94 %). In pvdhps gene a significant number of isolates (17.31 %) in KMC contained the double mutant S373E380S382 G 383 P384K512 G 553 V585M601 allele. pvdhfr and pvdhps combination haplotype revealed the emergence of quadruple (13.46 %) and quintuple (3.84 %) mutant allele in KMC, which might result in poor clinical response against antifolate drugs.

Conclusion: The study reveals that P. vivax parasites in rural Purulia may still be susceptible to SP but additional caution should be taken for treatment of vivax malaria in KMC to limit the blooming of quadruple and quintuple mutant allele in the remainder of the West Bengal, India.