Comparación de diferentes sondas de DNA para la detección de Plasmodium falciparum

Abstract

Probes pRepHind, Rep 20, p242B-1, pPF-14, clone 26 and 34 were compared for their ability to detect P. falciparum in field conditions. Ninety four clinical samples from patients living in the malaria endemic area of Tumaco (Pacific Coast) plus 88 from Villavicencio (Eastern Plains) were tested in "dot-blot" hibridization experiments. Probes Rep 20, p242B 1- 1, pRepHind and pPF-14 detected up to 17 pg of purified P. falciparum DNA, while clone 26 and clone 34 detected up to 425 pg DNA. Probes pPF-14, p242B 1- 1, pRepHind and Rep 20 exhibited comparable detecttion levels of parasites in infected blood samples. Sensitivity declined from 75-94% in subjects with parasitemias higher tan 10.000 par./ul to 15-42% in subjects with parasitemias lower than 100 par.100 par./ul  PPF- 14 and p242B 1- 1 showed the highest sensitivity, while clone 26 and 34 presented significantly lower sensitivities. Al1 probes showed to be highly specific. Detection levels are dependent on specimen treatment. Treatment consisting of serum removal, Triton X- 100 lysis, Proteinase K digestion, Phenol and Chloroform extractions followed by Ethanol precipitation yielded 100% sensitivity for specimens with parasite density higher than 1.000 par./ul.