Experimental Parasitology 99, 175–179 (2001) doi:10.1006/expr.2001.4646, available online at http://www.idealibrary.com on RESEARCH BRIEF Plasmodium vivax: Polymerase Chain Reaction Amplification Artifacts Limit the Suitability of pvgam1 as a Genetic Marker 1 Mallika Imwong,* Sasithon Pukrittakayamee,* Sornchai Looareesuwan,* Jean Poirriez,² Geoffrey Pasvol,‡ Nicholas J. White,* ,¶ and Georges Snounou§ ,2 *Faculty of Tropical Medicine, Mahidol University, 420/6 Rajvithi Road, Bangkok 10400, Thailand; ² Laboratoire de Biologie, Centre Hospitalier, 130 Avenue Louis Herbeaux, BP 6367, 59385 Dunkerque Ce ´dex 1, France; ‡Wellcome Centre for Clinical Tropical Medicine, Imperial College School of Medicine, Lister Unit, Northwick Park Hospital, Harrow, Middlesex HA1 3UJ, United Kingdom; §Unite ´ de Parasitologie Bio-Me ´dicale, Institut Pasteur, 25 & 28 Rue du Dr. Roux, 75724 Paris Cedex 15, France; and ¶ Center for Tropical Medicine, Nuffield Department of Clinical Medicine, John Radcliffe Hospital, Oxford, United Kingdom Imwong, M., Pukrittakayamee, S., Looareesuwan, S., Poirriez, J., in clinical and epidemiological studies. A similar ability to distinguish Pasvol, G., White, N. J., and Snounou, G. 2001. Plasmodium vivax: between different P. vivax populations would therefore be desirable. Polymerase chain reaction amplification artifacts limit the suitability Molecular studies of P. vivax have been restricted by the difficulties of pvgam1 as a genetic marker. Experimental Parasitology 99, in maintaining parasites in in vitro culture (Golenda et al. 1997). So 175–179.  2001 Elsevier Science (USA) far only four P. vivax genes of potential usefulness as specific genetic Index Descriptors and Abbreviations: deoxyribonucleic acid (DNA); markers have been identified. The P. vivax circumsporozoite protein genotyping; malaria; polymerase chain reaction (PCR); PCR artifact; gene ( pvcs) contains a size polymorphic repeated central domain (Arnot Plasmodium vivax; pvgam1. et al. 1985, 1990; Mann et al. 1994; Qari et al. 1992, 1994). The merozoite surface protein 1 gene ( pvmsp1) contains regions polymor- phic with respect to size and sequence (Cheng et al. 1993; Del Portillo et al. 1991; Pasay et al. 1995; Premawansa et al. 1993; Putaporntip et al. 1997). Samples from many different regions have been typed Plasmodium vivax is the most prevalent of the four human malaria successfully using these genes. The third marker, the gene coding for parasites. The morbidity from malaria in endemic areas of Central and the merozoite protein 3 ( pvmsp3) (Galinski et al. 1999), also appears South America, North Africa, the Middle East and the sub-Indian to be a practical genetic marker, since numerous variants were found continent results primarily from infections by this species. In Thailand in only 28 samples from Papua, New Guinea, by relatively simple as in other parts of Southeast Asia and in Oceania, the prevalence of restriction fragment length polymorphism (RFLP) analysis (Bruce et this parasite species rivals that of Plasmodium falciparum, and the al. 1999, 2000). The fourth gene, pvgam1, codes for a protein expressed emergence and spread of P. vivax parasites resistant to chloroquine during sexual stages (Snewin et al. 1995b). Analysis of a variable and to Fansidar in these regions, which mirrors ominously that of P. region of the gene suggested extensive size polymorphism when 4 falciparum, is of major concern. The availability of polymorphic ge- variants were observed in only 10 samples obtained from Sri Lankan netic markers for P. falciparum parasites has proven to be of great value patients (Snewin et al. 1995a). However no further studies of this gene have been reported since. In this study we present the results of an analysis of the pvgam1 1 The sequence data reported herein have been submitted to GenBank polymorphic region from 225 P. vivax samples from Thailand, India, and assigned Accession No. AF366060. Madagascar, and the Comoro Islands. The blood samples were obtained 2 To whom correspondence should be addressed. Fax: (+33) (1) 45 68 86 40. E-mail: snounou@pasteur.fr. on admission from patients attending the Hospital for Tropical Diseases 0014-4894/01 $35.00 175  2001 Elsevier Science (USA) All rights reserved.