RESTRICTION-FRAGMENT-LENGTH-POLYMORPHISM OF MYCOBACTERIUM-TUBERCULOSIS STRAINS FROM VARIOUS REGIONS OF INDIA, USING DIRECT REPEAT PROBE

Intraspecies differentiation was studied on 68 M. tuberculosis strains obtained from 6 states of India by restriction fragment length polymo rphism (RFLP) using a direct repeat probe (DR probe) hybridised with A lu I digest of DNA. Most strains showed polymorphism based patterns th at comprised between 2 to 7 bands and were grouped into 26 RFLP types. Of the 11 strains tested from Amritsar, 8 were RFLP type 5; the remai ning 3 were of type 11 and were exclusively confined to this region. T he strains from other regions were more heterogeneous. We confirm that DR-associated RFLP can be an excellent tool for the differentiation o f M. tuberculosis strains. Depending on their geographical origin, the se strains can be differentiated to a large extent by DR fingerprintin g.