Up- and downstream PCR analysis of 20 M. hominis isolates and vmp PCR. A, Top: Schematic illustration of the open reading frames (indicated by open arrows) of the vaa locus of M. hominis isolate 132. Bottom: The position relative to the open reading frames of the primers used (indicated by small arrows). B, Agarose gel electrophoresis of the PCR reactions obtained using vaa upstream primer sets (F1, R1), (F2, R1) and (F3, R1) on the 20 M. hominis isolates indicated above the bands. The size of the PCR products and primer set used are indicated to the left. C, D and E, PCR reactions observed using the vaa downstream primer sets (F4, R4), (F6, R3) and (F5, R2), respectively. The (F6, R3) primer set was derived from vmp-1 and the (F5, R2) primer set (green arrows) was derived from the vmp-2 and vmp-3 genes of isolates 4195 and 7488. Isolates categorized as having vmp-1, vmp-2 and vmp-3 genes are indicated with green, orange and magenta coloring of letters, respectively.