Genomic context and homology of the PE_PGRS17 and PE_PGRS18 genes. Genetic map showing the genomic context of the PE_PGRS17 (Rv0978c) and PE_PGRS18 (Rv0980c) genes within the genome of M. tuberculosis H37Rv. (B) Schematic representation of the homology shared between the PE_PGRS17 and PE_PGRS18 nucleotide sequences. Note the sequence relatedness with the PE_PGRS 45 (Rv2615c). MAR: major alignable coding region.