Plasmodium falciparum isolates from Angola show the StctVMNT haplotype in the pfcrt gene

Abstract

BackgroundEffective treatment remains a mainstay of malaria control, but it is unfortunately strongly compromised by drug resistance, particularly in Plasmodium falciparum, the most important human malaria parasite. Although P. falciparum chemoresistance is well recognized all over the world, limited data are available on the distribution and prevalence of pfcrt and pfmdr1 haplotypes that mediate resistance to commonly used drugs and that show distinct geographic differences.MethodsPlasmodium falciparum-infected blood samples collected in 2007 at four municipalities of Luanda, Angola, were genotyped using PCR and direct DNA sequencing. Single nucleotide polymorphisms in the P. falciparum pfcrt and pfmdr1 genes were assessed and haplotype prevalences were determined.Results and DiscussionThe most prevalent pfcrt haplotype was StctVMNT (representing amino acids at codons 72-76). This result was unexpected, since the StctVMNT haplotype has previously been seen mainly in parasites from South America and India. The CVIET, CVMNT and CVINT drug-resistance haplotypes were also found, and one previously undescribed haplotype (CVMDT) was detected. Regarding pfmdr1, the most prevalent haplotype was YEYSNVD (representing amino acids at codons 86, 130, 184, 1034, 1042, 1109 and 1246). Wild haplotypes for pfcrt and pfmdr1 were uncommon; 3% of field isolates harbored wild type pfcrt (CVMNK), whereas 21% had wild type pfmdr1 (NEYSNVD). The observed predominance of the StctVMNT haplotype in Angola could be a result of frequent travel between Brazil and Angola citizens in the context of selective pressure of heavy CQ use.ConclusionsThe high prevalence of the pfcrt SVMNT haplotype and the pfmdr1 86Y mutation confirm high-level chloroquine resistance and might suggest reduced efficacy of amodiaquine in Angola. Further studies must be encouraged to examine the in vitro sensitivity of pfcrt SVMNT parasites to artesunate and amodiaquine for better conclusive data.

Various pfcrt and pfmdr1 Genotypes of Plasmodium falciparum Cocirculate with P. malariae, P. ovale spp., and P. vivax in Northern Angola

“…Surprisingly, this haplotype, which is usually found in South America and parts of Asia, was detected in adult samples from Luanda in 2007 (15). Despite the proximity of Luanda to our study site, we have not found this haplotype among our samples, suggesting that AQ would still be effective in this area.…”

“…The different pfcrt mutant haplotypes have a consistent geographical distribution: the CQR haplotype CVIET is predominant in southeast Asia and Africa, whereas the AQ-resistant (AQR) haplotype SagtVMNT is predominant in Asia and South America, and StctVMNT, from South America, is very rare in Africa (16).The wild-type haplotype CVMNK is widespread (6,16,29,38). A recent study reported the presence of the StctVMNT haplotype of pfcrt in Angola, but this has not yet been verified by others (15,37). Polymorphisms in the parasite protein Pgh-1, encoded by pfmdr1, are thought to modulate resistance to drugs such as quinine, mefloquine, halofantrine, artemisinin, lumefantrine, CQ, and AQ (1,21,32,38).…”

Different Patterns of pfcrt and pfmdr1 Polymorphisms in P. falciparum Isolates from Nigeria and Brazil: The Potential Role of Antimalarial Drug Selection Pressure

“…8,21,22 Our single nucleotide polymorphisms findings in isolates from Brazil and Nigeria provide additional evidence supporting the association of SVMNT and CVIET haplotypes respectively with P. falciparum isolates of South American and African origin. However, recent studies from Africa, notably in Tanzania, 3 Angola, 17 and Ghana 22 have reported the presence of SVMNT pfcrt haplotype in parasites from these various areas. Although it has been proposed that human migration and the strong commercial relationship between Brazil and Angola could have allowed for the import of the SVMNT haplotype from Brazil to Angola, 17 the same haplotype was found in parasites from Tanzania, 3 a country without strong commercial relationship with South America.…”

“…However, recent studies from Africa, notably in Tanzania, 3 Angola, 17 and Ghana 22 have reported the presence of SVMNT pfcrt haplotype in parasites from these various areas. Although it has been proposed that human migration and the strong commercial relationship between Brazil and Angola could have allowed for the import of the SVMNT haplotype from Brazil to Angola, 17 the same haplotype was found in parasites from Tanzania, 3 a country without strong commercial relationship with South America. AQ has been suggested, as the driver of the selection of the SVMNT haplotype in Tanzania.…”

“…3,14 The PCR product were purified through the Wizard SV Gel and PCR Clean-Up System kit (Promega, Southampton, UK) and sequenced directly on an ABI PRISM 3100-Avant Genetic Analyzer with Big Dye Terminator v3.1 Cycle Sequencing kit (Applied Biosystems, Foster City, CA). 17 Sequence analysis was performed using FinchTV (Geospiza Inc., Seattle, WA) for sequence chromatogram visualization and the mutations were localized using Mutation Surveyor (SoftGenetics LLC, State College, PA). The 3D7 sequence was used as reference and was obtained from PlasmoDB (http://plasmodb.org/plasmo/).…”