Abstract: Objective  To develop BCG reference system to evaluate protective efficacy of new tuberculosis vaccine in China.  Methods  The guinea pigs were immunized by subcutaneous injection with 1/10 human dose (0.005 mg/0.2 ml) of BCG strains (D ₂ PB 302), and the saline was used as the control. A total of 4 experiments were performed respectively. Each guinea pig was infected by subcutaneous injection with 0.5 ml of Mtb suspension (200 to 2000 CFU/ml) at 5 weeks (testⅠand test Ⅱ), 28 weeks (test Ⅲ), and 60 weeks (test Ⅳ) after immunization, respectively. The guinea pigs were sacrificed 6 weeks after the infection. The pathological changes of livers, spleens and lungs of the guinea pigs were observed. The spleens were taken, homogenized and then cultured. Mtb colonies in the spleens were enumerated and the results were expressed as logarithm values. Results The lesion indexes of livers, spleens and lungs in test Ⅰ, Ⅱ, Ⅲ, Ⅳ were (10.0±3.8), (6.7±2.1), (10.0±4.5), and (14.4±4.8), respectively, significantly lower than those in the control groups［(46.9±4.8),  t=－0.63,  P<0.01; (36.3±6.0),  t=－4.63,  P<0.01; (57.5±6.2),  t=－6.24,  P<0.01; (56.9±5.0),  t=－6.16,  P<0.01, respectively］. Mtb colonies in the spleens in test Ⅰ, Ⅱ, Ⅲ, Ⅳ were lg (0.49±0.49), lg (0.38±0.38),  lg (2.16±0.93), and lg (1.46±0.69), respectively, significantly lower than those in the control groups［lg (5.41±0.18), t=－9.43, P<0.01; lg (5.11±0.19),  t=－11.22,  P<0.01; lg (5.44±0.27),  t=－3.39,  P<0.05; lg (5.43±0.20),  t=－5.55, P<0.01, respectively］. Conclusion  BCG reference system used to evaluate protective efficacy of new tuberculosis vaccine is reliable and stable. The BCG used in our country exhibits excellent protective efficacy.

Key words: BCG vaccine, Treatment outcome,  , Disease models, animal, Evaluation studies