Line Probe Assay (LPA) for rifampicin resistance in tuberculosis targets mutations primarily in which region of the rpoB gene?

• A N-terminal sigma factor binding domain
• B C-terminal zinc-binding domain
• C Catalytic aspartate residues of the active site
• D 81-base-pair rifampicin resistance-determining region (RRDR) ✓

Explanation

Over 95% of rifampicin-resistant M. tuberculosis strains carry mutations in the 81-bp RRDR of the rpoB gene (codons 507–533, corresponding to E. coli numbering 516–533). The LPA (e.g., GenoType MTBDRplus) uses reverse hybridization with wild-type and mutation probes covering this region; failure to hybridize to wild-type probes or hybridization to mutation probes indicates resistance. This region encodes part of the RNA polymerase beta subunit where rifampicin binds.

Reference: Ananthanarayan & Paniker's Textbook of Microbiology, 11th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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