Giuseppe
Emeritus
[Source: Antimicrobial Agents and Chemotherapy, full text: (LINK). Abstract, edited.]
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Reduced artemisinin susceptibility of Plasmodium falciparum ring stages in western Cambodia
Benoit Witkowski 1,#, Nimol Khim 1, Pheaktra Chim 1, Saorin Kim 1, Sopheakvatey Ke 1, Nimol Kloeung 1, Sophy Chy 1, Socheat Duong 2, Rithea Leang 2, Pascal Ringwald 3, Arjen M. Dondorp 4, Rupam Tripura 4, Fran?oise Benoit-Vical 5, Antoine Berry 5, Olivier Gorgette 6, Fr?d?ric Ariey 6, Jean-Christophe Barale 6, Odile Mercereau-Puijalon 6 and Didier Menard 1,#
Author Affiliations: <SUP>1</SUP>Malaria Molecular Epidemiology Unit, Institut Pasteur in Cambodia, Phnom Penh, Cambodia; <SUP>2</SUP>National Center for Parasitology, Entomology and Malaria Control, Ministry of Health, Phnom Penh, Cambodia; <SUP>3</SUP>Global Malaria Programme, World Health Organization, Geneva, Switzerland; <SUP>4</SUP>Mahidol University, Bangkok, Thailand; <SUP>5</SUP>Toulouse University Hospital, Toulouse, France; <SUP>6</SUP>Institut Pasteur, Centre National de la Recherche Scientifique, Unit? de Recherche Associ?e 2581, Paris, France
ABSTRACT
The declining efficacy of artemisinin derivatives against Plasmodium falciparum in western Cambodia is a major concern. The knowledge gap in the understanding of the mechanisms involved hampers designing monitoring tools. Here, we culture-adapted twenty isolates from Pailin and Ratanakiri (artemisinin-resistant and -susceptible areas from western and eastern Cambodia, respectively) and studied their in vitro response to dihydroartemisinin. No significant difference was observed in the classical isotopic test between the two sets of isolates. However, a 6-hour pulse exposure to 700 nM dihydroartemisinin (Ring stage Survival Assay, RSA) revealed a clear-cut geographic dichotomy. The survival rate of exposed ring-stages was 17-fold higher in isolates from Pailin (median: 13.5%) compared to Ratanakiri (median: 0.8%), while exposed mature stages were equally and highly susceptible (0.6% and 0.7%, respectively). Ring-stages survived drug exposure by cell cycle arrest and resumed growth upon drug withdrawal. The reduced susceptibility to artemisinin in Pailin appears associated with an altered in vitro phenotype of ring-stages from Pailin in the RSA.
FOOTNOTES
#Corresponding authors. Dr Didier M?nard Malaria Molecular Epidemiology Unit, Institut Pasteur in Cambodia, Phnom Penh, Cambodia: Phone: +855 17 666 442. Fax: +855 23 725 606. Email: dmenard@pasteur-kh.org
#Dr Benoit Witkowski, Malaria Molecular Epidemiology Unit, Institut Pasteur in Cambodia, Phnom Penh, Cambodia: Phone: +855 23 426 009. Fax: +855 23 725 606. Email: bwitkowski@pasteur-kh.org
Copyright ? 2012, American Society for Microbiology. All Rights Reserved.
-Author Affiliations: <SUP>1</SUP>Malaria Molecular Epidemiology Unit, Institut Pasteur in Cambodia, Phnom Penh, Cambodia; <SUP>2</SUP>National Center for Parasitology, Entomology and Malaria Control, Ministry of Health, Phnom Penh, Cambodia; <SUP>3</SUP>Global Malaria Programme, World Health Organization, Geneva, Switzerland; <SUP>4</SUP>Mahidol University, Bangkok, Thailand; <SUP>5</SUP>Toulouse University Hospital, Toulouse, France; <SUP>6</SUP>Institut Pasteur, Centre National de la Recherche Scientifique, Unit? de Recherche Associ?e 2581, Paris, France
ABSTRACT
The declining efficacy of artemisinin derivatives against Plasmodium falciparum in western Cambodia is a major concern. The knowledge gap in the understanding of the mechanisms involved hampers designing monitoring tools. Here, we culture-adapted twenty isolates from Pailin and Ratanakiri (artemisinin-resistant and -susceptible areas from western and eastern Cambodia, respectively) and studied their in vitro response to dihydroartemisinin. No significant difference was observed in the classical isotopic test between the two sets of isolates. However, a 6-hour pulse exposure to 700 nM dihydroartemisinin (Ring stage Survival Assay, RSA) revealed a clear-cut geographic dichotomy. The survival rate of exposed ring-stages was 17-fold higher in isolates from Pailin (median: 13.5%) compared to Ratanakiri (median: 0.8%), while exposed mature stages were equally and highly susceptible (0.6% and 0.7%, respectively). Ring-stages survived drug exposure by cell cycle arrest and resumed growth upon drug withdrawal. The reduced susceptibility to artemisinin in Pailin appears associated with an altered in vitro phenotype of ring-stages from Pailin in the RSA.
FOOTNOTES
#Corresponding authors. Dr Didier M?nard Malaria Molecular Epidemiology Unit, Institut Pasteur in Cambodia, Phnom Penh, Cambodia: Phone: +855 17 666 442. Fax: +855 23 725 606. Email: dmenard@pasteur-kh.org
#Dr Benoit Witkowski, Malaria Molecular Epidemiology Unit, Institut Pasteur in Cambodia, Phnom Penh, Cambodia: Phone: +855 23 426 009. Fax: +855 23 725 606. Email: bwitkowski@pasteur-kh.org
Copyright ? 2012, American Society for Microbiology. All Rights Reserved.
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