RESUMEN
Mycobacterium bovis is the causative agent of bovine tuberculosis and belongs to the Mycobacterium tuberculosis complex. M. bovis usually carries only one or a few copies of the insertion sequence IS6110 in its genome. The aim of this study was evaluation of copy number of IS6110 in M. bovis isolates by restriction fragment length polymorphism [RFLP] method. In this experimental study, 25 lymph node specimens of tuberculin-positive cattle were collected and cultured by standard methods, afterward genomic DNA was extracted by chloroform-isoamyl alcohol. Genetic studies were conducted by Pvull and DNA hybridization with IS6110. Two isolates displayed more than of 4 copies of IS6110 by RFLP [IS6110-RFLP] method. The results of this study are unique and specific in Iran but reported in the world rarely. Therefore the new strains of M. bovis imported to Iran from other countries of the world