Biased distribution of msp1 and msp2 allelic variants in Plasmodium falciparum populations in Thailand

• Published in: Transactions of the Royal Society of Tropical Medicine and Hygiene Vol. 93; no. 4; pp. 369 - 374
• Main Authors: Snounou, Georges, Zhu, Xinping, Siripoon, Napaporn, Jarra, William, Thaithong, Sodsri, Brown, K.Neil, Viriyakosol, Suganya
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Oxford Elsevier Ltd 01-07-1999; Royal Society of Tropical Medicine and Hygiene; Elsevier
• Subjects: Animals; Antigens, Protozoan - genetics; Bias; Biological and medical sciences; Cross-Sectional Studies; epidemiology; Gene Frequency; glurp; Human protozoal diseases; Humans; Infectious diseases; Malaria; Malaria, Falciparum - epidemiology; Malaria, Falciparum - genetics; Medical sciences; Merozoite Surface Protein 1 - genetics; msp1; msp2; Parasitic diseases; Plasmodium falciparum; Plasmodium falciparum - genetics; polymerase chain reaction; Polymerase Chain Reaction - methods; population genetics; Protozoal diseases; Protozoan Proteins - genetics; Sensitivity and Specificity; Thailand; Thailand - epidemiology; Tropical medicine; Thailand; Asia; glurp; Plasmodium falciparum; epidemiology; population genetics; msp1; msp2; Thailand; polymerase chain reaction; Human; Protozoa; Apicomplexa; Protozoal disease; Malaria; Genetic variant; Parasitosis; Epidemiology; Infection; Polymerase chain reaction; Allele; Distribution; Genetics; Population
• ISSN: 0035-9203; 1878-3503
• DOI: 10.1016/S0035-9203(99)90120-7

Plasmodium falciparum isolates were obtained from Thai patients attending a malaria clinic on the Thai-Kampuchean border over 4 cross-sectional surveys carried out at 3-monthly intervals. The genetic structure of the parasite populations was determined by nested polymerase chain reaction (PCR) amplification of polymorphic regions of 3
P. falciparum antigen genes:
msp1,
msp2 and
glurp. Although a high degree of diversity characterized these isolates, the overall population structure of the parasites associated with patent malaria infections was observed to remain relatively stable over time. The highest degree of polymorphism was observed with
msp2, and the mean number of lines per infection (multiplicity of infection) calculated with this marker was higher than that obtained using
msp1 or
glurp alone, or combined. Infections with ⩾ 2 parasite lines were seen in 76% of the samples, and were proportionally more numerous at the start and end of the rainy season. Two interesting exceptions to the random distribution were observed and involved 2 allelic variants which in one case were found dissociated (
msp1 MAD20-family) and in the other were associated (
msp2 FC27-family). The epidemiological significance of these types of data is discussed.