Which bacterial strain si used ot develop BCG vaccine?

The BCG (Bacillus Calmette-Guérin) vaccine is developed using a live attenuated strain of Mycobacterium bovis. This strain is derived from Mycobacterium bovis, which is closely related to Mycobacterium tuberculosis, the bacterium that causes tuberculosis (TB). The strain used in the BCG vaccine has been weakened through prolonged culture, making it less virulent but still capable of stimulating an immune response.