Samaddar Sourabh, Grewal Rajdeep Kaur, Sinha Saptarshi, Ghosh Shrestha, Roy Soumen, Das Gupta Sujoy K
Department of Microbiology, Centenary Campus, Bose Institute, Kolkata, West Bengal, India.
Main Campus, Bose Institute, Kolkata, West Bengal, India.
Appl Environ Microbiol. 2015 Oct 16;82(1):124-33. doi: 10.1128/AEM.02700-15. Print 2016 Jan 1.
Mycobacteriophages infect mycobacteria, resulting in their death. Therefore, the possibility of using them as therapeutic agents against the deadly mycobacterial disease tuberculosis (TB) is of great interest. To obtain better insight into the dynamics of mycobacterial inactivation by mycobacteriophages, this study was initiated using mycobacteriophage D29 and Mycobacterium smegmatis as the phage-host system. Here, we implemented a goal-oriented iterative cycle of experiments on one hand and mathematical modeling combined with Monte Carlo simulations on the other. This integrative approach lends valuable insight into the detailed kinetics of bacterium-phage interactions. We measured time-dependent changes in host viability during the growth of phage D29 in M. smegmatis at different multiplicities of infection (MOI). The predictions emerging out of theoretical analyses were further examined using biochemical and cell biological assays. In a phage-host interaction system where multiple rounds of infection are allowed to take place, cell counts drop more rapidly than expected if cell lysis is considered the only mechanism for cell death. The phenomenon could be explained by considering a secondary factor for cell death in addition to lysis. Further investigations reveal that phage infection leads to the increased production of superoxide radicals, which appears to be the secondary factor. Therefore, mycobacteriophage D29 can function as an effective antimycobacterial agent, the killing potential of which may be amplified through secondary mechanisms.
分枝杆菌噬菌体感染分枝杆菌，导致其死亡。因此，将它们用作治疗致命分枝杆菌病结核病（TB）的治疗剂的可能性备受关注。为了更深入地了解分枝杆菌噬菌体使分枝杆菌失活的动力学，本研究以分枝杆菌噬菌体D29和耻垢分枝杆菌作为噬菌体-宿主系统展开。在此，我们一方面实施了目标导向的迭代实验循环，另一方面进行了结合蒙特卡罗模拟的数学建模。这种综合方法为细菌-噬菌体相互作用的详细动力学提供了有价值的见解。我们在不同感染复数（MOI）下，测量了噬菌体D29在耻垢分枝杆菌中生长期间宿主活力随时间的变化。利用生化和细胞生物学检测进一步检验了理论分析得出的预测结果。在一个允许发生多轮感染的噬菌体-宿主相互作用系统中，如果仅将细胞裂解视为细胞死亡的唯一机制，细胞计数下降的速度会比预期更快。除了裂解之外，考虑细胞死亡的第二个因素可以解释这一现象。进一步研究表明，噬菌体感染会导致超氧自由基的产生增加，这似乎就是第二个因素。因此，分枝杆菌噬菌体D29可以作为一种有效的抗分枝杆菌剂，其杀伤潜力可能通过次要机制得到增强。
