Polymorphisms in Pfmdr1, Pfcrt, and Pfnhe1Genes Are Associated with Reduced In VitroActivities of Quinine in Plasmodium falciparumIsolates from Western Kenya

Autor: Cheruiyot, Jelagat, Ingasia, Luicer A., Omondi, Angela A., Juma, Dennis W., Opot, Benjamin H., Ndegwa, Joseph M., Mativo, Joan, Cheruiyot, Agnes C., Yeda, Redemptah, Okudo, Charles, Muiruri, Peninah, Bidii, Ngalah S., Chebon, Lorna J., Angienda, Paul O., Eyase, Fredrick L., Johnson, Jacob D., Bulimo, Wallace D., Andagalu, Ben, Akala, Hoseah M., Kamau, Edwin
Zdroj: Antimicrobial Agents and Chemotherapy; April 2014, Vol. 58 Issue: 7 p3737-3743, 7p
Abstrakt: ABSTRACTIn combination with antibiotics, quinine is recommended as the second-line treatment for uncomplicated malaria, an alternative first-line treatment for severe malaria, and for treatment of malaria in the first trimester of pregnancy. Quinine has been shown to have frequent clinical failures, and yet the mechanisms of action and resistance have not been fully elucidated. However, resistance is linked to polymorphisms in multiple genes, including multidrug resistance 1 (Pfmdr1), the chloroquine resistance transporter (Pfcrt), and the sodium/hydrogen exchanger gene (Pfnhe1). Here, we investigated the association between in vitroquinine susceptibility and genetic polymorphisms in Pfmdr1codons 86 and 184, Pfcrtcodon 76, and Pfnhe1ms4760 in 88 field isolates from western Kenya. In vitroactivity was assessed based on the drug concentration that inhibited 50% of parasite growth (the IC50), and parasite genetic polymorphisms were determined from DNA sequencing. Data revealed there were significant associations between polymorphism in Pfmdr1-86Y, Pfmdr1-184F, or Pfcrt-76T and quinine susceptibility (P< 0.0001 for all three associations). Eighty-two percent of parasites resistant to quinine carried mutant alleles at these codons (Pfmdr1-86Y, Pfmdr1-184F, and Pfcrt-76T), whereas 74% of parasites susceptible to quinine carried the wild-type allele (Pfmdr1-N86, Pfmdr1-Y184, and Pfcrt-K76, respectively). In addition, quinine IC50values for parasites with Pfnhe1ms4760 3 DNNND repeats were significantly higher than for those with 1 or 2 repeats (P= 0.033 and P= 0.0043, respectively). Clinical efficacy studies are now required to confirm the validity of these markers and the importance of parasite genetic background.
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