Polymorphisms of the pfmdr1 but not the pfnhe-1 gene is associated with in vitro quinine sensitivity in Thai isolates of Plasmodium falciparum

• Published in: Malaria Journal
• Main Authors: Poyomtip Teera, Suwandittakul Nantana, Sitthichot Narumon, Khositnithikul Rommanee, Tan-ariya Peerapan, Mungthin Mathirut
• Format: Article in Journal/Newspaper
• Language: English
• Published: BMC 2012
• Subjects: Arctic medicine. Tropical medicine; RC955-962; Infectious and parasitic diseases; RC109-216; Arctic
• Online Access: https://doi.org/10.1186/1475-2875-11-7; https://doaj.org/article/90372e0cd25f44fdafec77193ae72dd7

Abstract Background The emergence of Plasmodium falciparum resistance to most currently used anti-malarial drugs is a major problem in malaria control along the Thai-Myanmar and Thai-Cambodia borders. Quinine (QN) with tetracycline/doxycycline has been used as the second-line treatment for uncomplicated falciparum malaria. In addition, QN monotherapy has been the first-line treatment for falciparum malaria in pregnant women. However, reduced in vitro and in vivo responses to QN have been reported. To date, a few genetic markers for QN resistance have been proposed including Plasmodium falciparum chloroquine resistance transporter ( pfcrt ), P. falciparum multidrug resistance 1 ( pfmdr1 ), and P. falciparum Na + /H + exchanger ( pfnhe-1 ). This study was to investigate the role of the pfmdr1 and pfnhe-1 gene on in vitro QN sensitivity in Thai isolates of P. falciparum . Methods Eighty-five Thai isolates of P. falciparum from the Thai-Myanmar and Thai-Cambodia borders from 2003-2008 were determined for in vitro QN sensitivity using radioisotopic assay. Polymorphisms of the pfmdr1 and pfnhe-1 gene were determined by PCR-RFLP and sequence analysis. Associations between the in vitro QN sensitivity and the polymorphisms of the pfmdr1 and pfnhe-1 gene were evaluated. Results The mean QN IC 50 was 202.8 nM (range 25.7-654.4 nM). Only four isolates were QN resistant when the IC 50 of >500 nM was used as the cut-off point. Significant associations were found between the pfmdr1 mutations at codons N86Y and N1042D and in vitro QN sensitivity. However, no associations with the number of DNNND, DDNNNDNHNDD, and NHNDNHNNDDD repeats in the microsatellite ms4760 of the pfnhe-1 gene were identified. Conclusion Data from the present study put doubt regarding the pfnhe-1 gene as to whether it could be used as the suitable marker for QN resistance in Thailand. In contrast, it confirms the influence of the pfmdr1 gene on in vitro QN sensitivity.