| Summary: | <p>Abstract</p> <p>Background</p> <p>Appropriate monitoring of vector resistance to insecticides is an integral component of planning and evaluation of insecticide use in malaria control programmes. The malaria vectors <it>Anopheles gambiae s.s</it>. and <it>Anopheles arabiensis </it>have developed resistance to pyrethroid insecticides as a result of a mechanism conferring reduced nervous system sensitivity, better known as knockdown resistance (<it>kdr</it>). In <it>An. gambiae s.s</it>. and <it>An. arabiensis</it>, two different substitutions in the <it>para</it>-type sodium channel, a L1014F substitution common in West Africa and a L1014S replacement found in Kenya, are linked with <it>kdr</it>. Two different allele-specific polymerase chain reactions (AS-PCR) are needed to detect these known <it>kdr </it>mutations. However, these AS-PCR assays rely on a single nucleotide polymorphism mismatch, which can result in unreliable results.</p> <p>Methods</p> <p>Here, a new assay for the detection of knockdown resistance in <it>An. gambiae s.s</it>. and <it>An. arabiensis </it>based on Fluorescence Resonance Energy Transfer/Melt Curve analysis (FRET/MCA) is presented and compared with the existing assays.</p> <p>Results</p> <p>The new FRET/MCA method has the important advantage of detecting both <it>kdr </it>alleles in one assay. Moreover, results show that the FRET/MCA is more reliable and more sensitive than the existing AS-PCR assays and is able to detect new genotypes. By using this technique, the presence of the East African <it>kdr </it>mutation (L1014S) is shown for the first time in <it>An</it>. <it>arabiensis </it>specimens from Uganda. In addition, a new <it>kdr </it>genotype is reported in <it>An. gambiae s.s</it>. from Uganda, where four <it>An. gambiae </it><it>s.s.</it> mosquitoes possess both, the West (L1014F) and East (L1014S) African <it>kdr </it>allele, simultaneously.</p> <p>Conclusion</p> <p>The presence of both <it>kdr </it>mutations in the same geographical region shows the necessity of a reliable assay that enables to detect both mutations in one single assay. Hence, this new assay based on FRET/MCA will improve the screening of the <it>kdr </it>frequencies in <it>An. gambiae s.s</it>. and <it>An. arabiensis</it>.</p>
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