Determination of the genus specificity of PCR. (A) Analysis by agarose gel electrophoresis and ethidium bromide staining. (B) Southern blot and hybridization with a digoxigenin-11–dUTP-labeled probe. Lane 1, φX174 DNA cleaved with HaeIII as a molecular size marker, lane 2, L. infantum (106 organisms); lane 3, T. gondii (106 organisms); lane 4, T. gondii DNA (1 μg); lane 5, human DNA (1 μg); lane 6, T. cruzi (106 organisms); lane 7, P. vivax (0.3%); lane 8, P. ovale (0.1%); lane 9, P. malariae (1%); lane 10, pBR322 DNA cleaved with HaeIII as a molecular size marker; lane 11, P. falciparum (0.5%). Arrows at the right indicate the 291-bp PCR product.