Genetic diversity of Plasmodium falciparum field samples from an isolated Colombian village.

Abstract

Colombian field isolates of Plasmodium falciparum were analyzed for genetic diversity. Fifty-three samples were collected as thick smears from patients living in Panguí, an isolated area with low migration. While the samples were being collected, Panguí was experiencing an epidemic outbreak of malaria. The samples were typified using nested polymerase chain reaction (PCR) amplification of block 2 of the merozoite surface protein 1 (MSP1) gene and nested PCR with mutation-specific primers for position 108 of the dihydrofolate reductase enzyme gene. The results for the circulating population of parasites in Panguí show low diversity-four allelic forms-using MSP1 as a marker, a fact that contrasts with data reported for certain Asian and African zones. A high percentage of mixed infections was observed, as was high complexity of the infection. No differential distributions were found for any allelic type.

Restricted Genetic Diversity of Plasmodium Falciparum Major Merozoite Surface Protein 1 in Isolates From Colombia

“…In a second study carried out in Chocó (northwest Colombia) in 1997, all three MSP-1 block 2 allelic types were detected although MAD20 was the predominant allele and K1 was the least frequent. 15 In studies carried out during 2000-2001 in the Turbo and Zaragoza municipalities of northwestern and northeastern Colombia, respectively, 100% of P. falciparum samples contained only the MAD20 block 2 allelic type, similar to our studies in Buenaventura. 23 The latter study and our study, which were both carried out at approximately the same time, suggest that current P. falciparum populations may have become more homogeneous in several regions of Colombia.…”

“…The average temperature is 26°C (78.8°F). 11,13,15 Plasmodium falciparum isolates. Blood samples positive for P. falciparum were collected from symptomatic patients (patients with fever and headache) who attended the Program for Tropical Diseases and Immunology Institute in Buenaventura after consent was provided to Malaria Vaccine and Drug Development Center health personnel.…”

Genotipificación de los genes msp1 (bloque 2) y dhfr (codón108) de Plasmodium falciparum en muestras de campo recolectadas en cuatro localidades endémicas de Colombia.

“…Para definir el alotipo presente se realizó PCR anidada utilizando los iniciadores OK1 y OK2 para el alotipo K1, OK3 y OK4 para el alotipo MAD20 y OK5 y OK6 para el alotipo RO33 (cuadro1), usando las mismas condiciones de la PCR universal. Como control positivo se utilizó ADN de las cepas de referencia Haiti135 (para el alotipo K1), FCB1 (para el alotipo MAD20) y 7G8 (para el alotipo RO33) (19 Gen msp1: los iniciadores se usaron para amplificar el bloque 2 del gen msp1 y establecer la presencia de los alelos K1, MAD20 y RO33. Inicialmente se hizo un primer PCR para amplificar el bloque 2 del gen msp-1 usando los iniciadores OK11 y OK12.…”

“…Amplicón: producto que amplifican los iniciadores. Como control positivo se utilizó ADN de las cepas de referencia 3D7 (para el alotipo S108), FCB1 (para el alotipo T108) y T4 (para el alotipo N108) (19,26).…”

“…Estudios previos realizados en Colombia sobre la diversidad genética de P. falciparum mostraron que las poblaciones de parásitos eran genética-mente homogéneas al interior de cada región geográfica estudiada, aunque había algunas diferencias en la distribución entre regiones (17)(18)(19)(20). En el presente trabajo se analizó la diversidad genética de las poblaciones de P. falciparum circulantes en cuatro zonas endémicas de malaria en Colombia y la variabilidad de la población de parásitos durante el tiempo de la infección malárica, utilizando como marcadores moleculares la región polimórfica del bloque 2 del gen msp1 y el codón 108 del gen dhfr.…”