The PE grouping assay (PEGAssay) pattern. Representation of the hybridization pattern results obtained using PEGAssay on selected members of the M. tuberculosis complex and other mycobacteria (M. canettii and M. smegmatis). Lanes 17 and 18 correspond to PE_PGRS17 and PE_PGRS18, respectively. MTBC strains producing a single reacting dot with PE_PGRS 17 (presence of the 12/40 polymorphism in PE_PGRS17 but not in PE_PGRS18) are referred to as "+/-" and belong to the PGRS type 1 group (PGRST1). Isolates whose PEGAssay pattern produces two reacting dots (presence of the 12/40 polymorphism in both PE_PGRS17 and PE_PGRS18 genes) are referred to as "+/+" and belong to the PGRS type 2 genotype (PGRST2). Finally, isolates whose PEGAssay produces no hybridization signal (absence of the 12/40 polymorphism from both PE_PGRS genes) are referred to as "-/-" and belong to the PGRS type 3 genotypic group (PGRST3). Note that M. smegmatis strain mc2 155, which lacks both PE_PGRS17 and PE_PGRS18 whole genes, produces no hybridization signal.