Simultaneous replacement of consecutive ech1 and ech2 genes by a MS/GW construct pDEST/ ech -Hyg-GAPDH. A) Diagram of ech1, ech2 and Hyg-GAPDH-IR genomic loci in WT and ech+/-/Hyg parasites. B) PCR genotyping analysis of: no template control (water); ech+/-/Hyg (ech+/-) and WT CL (WT). See additional file 3: Table S5 for nucleotide sequences of primers. C) Southern blot analysis of two clones (2 and 4) of ech+/-/Hyg. Left panel, gDNA digested with BanI and hybridized with Hyg CDS; right panel, gDNA digested with EcoRI and hybridized with labeled ech1 CDS. Diagrams not to scale. Numbers are sizes (bp) of expected products.