Genetic detection of Plasmodium falciparum with Chelex-extracted DNA from thin blood smears / 中华传染病杂志

ABSTRACT

Objective To investigate the feasibility of Chelex DNA extraction from thin blood smears for genetic analysis, and to develop smear-based nested polymerase chain reaction (PCR) of the 18S RNA of Plasrnodium falciparum. Methods Chelex-100 which was chelating ion exchange resin was used to extract DNA from Giemsa-stained or unstained thin blood smears of different concentrations of Plasmodium falciparum. With the extracted DNA as the template, 18S RNA gene was amplified by nested PCR to test the susceptibility of Chelex method. Results Positive band of 205bp appeared in nested PCR with DNA extracted from Giemsa-stained or unstained thin blood smears of patient with falciparum malaria. Using the Chelex method, the detection limits of the smear-based nested PCR were 1.5 × 101 parasite/μL blood for Giemsa-stained and 1.5×10-1 parasite/μL blood for unstained thin blood smears. Conclusions Chelex DNA extraction is a simple and efficient method for extracting trace amount of DNA from thin blood smear. The smear-based nested PCR developed in this study is feasible to identify the gene from reserved thin blood smears and will provide a new approach for clinical diagnosis and study of molecular epidemiology.