Variations in palpal ornamentation of Anopheles fluviatilis species T and U (Diptera: Culicidae) and their taxonomic consequence

64-68Anopheles fluviatilis sensu lato James is a highly efficient malaria vector in Indian subcontinent and Iran which is comprised of at least four sibling species provisionally designated as species S, T, U and V. An important morphological characteristic for differentiation of this species complex from other closely related anopheline species complex, the Minimus Complex, is the ratio of length of subapical pale band to dark band intervening apical and subapical pale bands on the maxillary palps of female mosquito. Here, we report variation in the subapical pale band in An. fluviatilis, especially in species U, to the extent that palps of some specimens resemble members of Minimus Complex, inferring that palpal ornamentation may not be reliable characteristics for identification of An. fluviatilis. Taxonomic consequence of such variation is discussed

Knockdown resistance (kdr)-like mutations in the voltage-gated sodium channel of a malaria vector Anopheles stephensi and PCR assays for their detection

<p>Abstract</p> <p>Background</p> <p>Knockdown resistance (<it>kdr</it>) in insects, resulting from mutation(s) in the voltage-gated sodium channel (vgsc) gene is one of the mechanisms of resistance against DDT and pyrethroid-group of insecticides. The most common mutation(s) associated with knockdown resistance in insects, including anophelines, has been reported to be present at residue Leu1014 in the IIS6 transmembrane segment of the vgsc gene. This study reports the presence of two alternative <it>kdr</it>-like mutations, L1014S and L1014F, at this residue in a major malaria vector <it>Anopheles stephensi </it>and describes new PCR assays for their detection.</p> <p>Methods</p> <p>Part of the vgsc (IIS4-S5 linker-to-IIS6 transmembrane segment) of <it>An. stephensi </it>collected from Alwar (Rajasthan, India) was PCR-amplified from genomic DNA, sequenced and analysed for the presence of deduced amino acid substitution(s).</p> <p>Results</p> <p>Analysis of DNA sequences revealed the presence of two alternative non-synonymous point mutations at L1014 residue in the IIS6 transmembrane segment of vgsc, i.e., T>C mutation on the second position and A>T mutation on the third position of the codon, leading to Leu (TTA)-to-Ser (TCA) and -Phe (TTT) amino acid substitutions, respectively. Polymerase chain reaction (PCR) assays were developed for identification of each of these two point mutations. Genotyping of <it>An. stephensi </it>mosquitoes from Alwar by PCR assays revealed the presence of both mutations, with a high frequency of L1014S. The PCR assays developed for detection of the <it>kdr </it>mutations were specific as confirmed by DNA sequencing of PCR-genotyped samples.</p> <p>Conclusions</p> <p>Two alternative <it>kdr-</it>like mutations, L1014S and L1014F, were detected in <it>An. stephensi </it>with a high allelic frequency of L1014S. The occurrence of L1014S is being reported for the first time in <it>An. stephensi</it>. Two specific PCR assays were developed for detection of two <it>kdr</it>-like mutations in <it>An. stephensi</it>.</p

Polymorphism in drug resistance genes dihydrofolate reductase and dihydropteroate synthase in Plasmodium falciparum in some states of India

Abstract Background Sulfadoxine-pyrimethamine (SP) combination drug is currently being used in India for the treatment of Plasmodium falciparum as partner drug in artemisinin-based combination therapy (ACT). Resistance to sulfadoxine and pyrimethamine in P. falciparum is linked with mutations in dihydropteroate synthase (pfdhps) and dihydrofolate reductase (pfdhfr) genes respectively. This study was undertaken to estimate the prevalence of such mutations in pfdhfr and pfdhps genes in four states of India. Methods Plasmodium falciparum isolates were collected from two states of India with high malaria incidence i.e., Jharkhand and Odisha and two states with low malaria incidence i.e., Andhra Pradesh and Uttar Pradesh between years 2006 to 2012. Part of sulfadoxine-pyrimethamine (SP) drug resistance genes, pfdhfr and pfdhps were PCR-amplified, sequenced and analyzed. Results A total of 217 confirmed P. falciparum isolates were sequenced for both Pfdhfr and pfdhps gene. Two pfdhfr mutations 59R and 108N were most common mutations prevalent in all localities in 77 % of isolates. Additionally, I164L was found in Odisha and Jharkhand only (4/70 and 8/84, respectively). Another mutation 51I was found in Odisha only (3/70). The pfdhps mutations 436A, 437G, 540E and 581G were found in Jharkhand and Odisha only in 13, 26, 14 and 13 % isolates respectively, and was absent in Uttar Pradesh and Andhra Pradesh. Combined together for pfdhps and pfdhfr locus, triple, quadruple, quintuple and sextuple mutations were present in Jharkhand and Odisha while absent in Uttar Pradesh and Andhra Pradesh. Conclusion While only double mutants of pfdhfr was present in low transmission area (Uttar Pradesh and Andhra Pradesh) with total absence of pfdhps mutants, up to sextuple mutations were present in high transmission areas (Odisha and Jharkhand) for both the genes combined. Presence of multiple mutations in pfdhfr and pfdhps genes linked to SP resistance in high transmission area may lead to fixation of multiple mutations in presence of high drug pressure and high recombination rate

Additional file 2: Table S2. of Polymorphism in drug resistance genes dihydrofolate reductase and dihydropteroate synthase in Plasmodium falciparum in some states of India

Spatial and temporal distribution of P. falciparum dhps point mutations among Indian isolates. (DOC 54 kb

Additional file 1: Table S1. of Polymorphism in drug resistance genes dihydrofolate reductase and dihydropteroate synthase in Plasmodium falciparum in some states of India

Spatial and temporal distribution of P. falciparum dhfr point mutations among Indian isolates. (DOC 57 kb