Sensitivity of the LAMP assay and nested PCR method. LAMP and nested PCR assays were carried out using the DNA extracted from purified T. gondii tachyzoite (RH strain). (A) HeLa cell monolayer infected with T. gondii tachyzoites in DMEM supplemented with 2% fetal bovine serum. (B) Purified tachyzoites by Percoll density gradients centrifugation. (C) 529 bp-nested PCR reaction with T. gondii DNA. (D) B1-LAMP reaction with T. gondii DNA. (E) 529 bp- LAMP reaction with T. gondii DNA. Lanes 1 - 9 represent 6 ng, 600 pg, 60 pg, 6 pg, 600 fg, 60 fg, 6 fg, 0.6 fg and 0.06 fg of DNA, respectively; lane M represents a 2,000 bp DNA ladder; lane N represents a negative control.