A simple alkali lysis method for Plasmodium falciparum DNA extraction from filter paper blood samples

A fast, simple, easy, efficient, and inexpensive method for DNA extraction from malaria parasites collected on filter paper would be very useful for molecular surveillance. The quality and quantity of DNA are critical to molecular diagnosis and analysis. Here, we developed a simple alkali lysis method for DNA extraction from blood samples on filter paper. The results showed that 10-50 mM NaOH and deionized water all effectively isolated parasite DNA at higher parasitemia, as witnessed by successful PCR amplification, while at a parasitemia of 0.01%, the 10 mM NaOH lysis condition generated the best results. Furthermore, DNA extracted by this method was successfully used to amplify a fragment of > 2000 bp. This method successfully extracted DNA from 1 mu l of blood at a parasitemia as low as 0.0001% (equivalent to 5 parasites /mu l). The DNA isolated by the 10 mM NaOH lysis method was stable to yield PCR products after storage at 4 degrees C or -20 degrees C for 12 months. These results indicate that this alkali lysis method is simple, effective, sensitive, and inexpensive for isolating stable Plasmo-dium DNA from dried blood spots on filter paper.