falciparum; using msp2 PCR, 97/388 www.selleckchem.com/products/dorsomorphin-2hcl.html individuals were found positive, giving a prevalence rate of 25% P. falciparum malaria. RFLP analysis was successfully conducted on 80 samples. The msp2 PCR fragment revealed 56 (70%) single infections, 18 (22.5%) double infections, five (6.25%) triple infections and one (1.25%) quadruple infection. The mean multiplicity of infection (MOI; mean number of co-infecting parasite clones) in P. falciparum positive samples was 1.39. Ten PCR reactions were performed for the five genes associated with drug resistance. Of the 97 P. falciparum positive samples analysed, 21 (21.6%) showed poor amplification for the majority of the PCR reactions (> 5 poor PCR results out of 10) and had thus to be excluded. The 76 (78.4%) remaining samples were used for genotyping by microarray.
Sixteen unclear microarray typing outcomes were confirmed by sequencing of the corresponding gene fragments (Macrogen Inc., Korea). Overall, the analysed population showed to be very homogenous (Figure (Figure2).2). Two different haplotypes were observed for the two CQ resistance-associated genes. With 70% of the patients having a single infection and the unambiguous DNA microarray signals, it was considered that co-infecting clones had the same pattern of SNPs. The most dominant haplotype showed mutations at positions pfmdr1 N86Y and pfcrt C72 S, N75D/E, K76T, A220 S, N326 D, and I356L, and was observed in 98.4% (61/62) of the population. The second haplotype was observed in one sample only (1.6%) and differed from the first one by having one additional mutation at position N1042 D in pfmdr1.
Other SNPs related to CQ resistance were all wild-type. Figure 2 Observed haplotypes of SNPs related to resistance to CQ, SP and artemisinin derivatives. A haplotype is defined by the combination of mutations in genes related to drug resistance. Grey indicates mutations and white indicates wild-type. Two different … For the genes involved in SP resistance, mutations were fixed at positions C59R and S108N in pfdhfr. Other SNPs in pfdhfr and pfdhps were all wild-type. No mutation was detected in pfATPase6. Discussion The outcome of CQ+SP against falciparum malaria was investigated at a clinic located close to Honiara in the SI. At the same time, the presence of resistance-associated SNPs in P. falciparum was assessed in the surrounding asymptomatic community, screened by a cross-sectional survey.
The resistance-associated SNPs observed in the sample set are in line with previous findings from other malaria areas worldwide. Regarding SP resistance, all samples presented two fixed mutations at positions C59R and S108N in pfdhfr and none in pfdhps. The importance of cumulative mutations conferring SP resistance has been described; in particular the combination Cilengitide of the SNPs pfdhfr S108N, N51I, C59R and pfdhps A437G, K540E [9,28] being correlated with anti-folate treatment failure.