Abstract:

Objective To investigate the potential of mycobacteriophage TM4 in resuscitating dormant cells of M.tuberculosis. Methods Dormant cells of M.tuberculosis were induced by prolonged closed culture of log-phase M.tuberculosis at 37 ℃, which were proven through drug sensitivity test and electron microscope. M.tuberculosis colony count and electron microscope were used to detect whether the dormant cells of M.tuberculosis had been resuscitated by TM4. Results Dormant cells of M.tuberculosis were obtained successfully by closed culture for 180 d at 37 ℃. The amount of M.tuberculosis at the bottom of the tube in Rpf E group was more than that of the other groups through naked eye after culturing 3 d at 37 ℃. While the amount of M.tuberculosis at the bottom in TM4 group did not increased obviously until culturing for 8 d. M.tuberculosis was still non-culturable in the three groups after culturing 1 d. Along with further culture, part of M.tuberculosis turned culturable, the concentration of resuscitated M.tuberculosis in control, TM4, and Rpf E groups was 0, 0.7×10², and 2×10⁴ CFU/mL, respectively after culturing 6 d. The concentration of resuscitated M.tuberculosis in control, TM4, and Rpf E groups increased to 3.4×10, 1.68×10⁷, and 2.1×10⁹ CFU/mL, respectively after culturing 14 d. Various shapes of M.tuberculosis for culturing 17 d in the three groups were watched through electron microscope. There were lots of thin-wall M.tuberculosis, a few dormant cells of M.tuberculosis with thick wall, and cell pieces in TM4 group; whereas the field of view of Rpf E group was filled with plentiful thin-wall M.tuberculosis; as we excepted, a lot of thick-wall M.tuberculosis and a few thin wall M.tuberculosis were observed in control group. Conclusion Mycobacteriophage TM4 can resuscitate dormant cells of M.tuberculosis.

Key words: bacteriophage TM4, dormant cells of M.tuberculosis, resuscitation, tuberculosis