Hart P D, Armstrong J A
Infect Immun. 1974 Oct;10(4):742-6. doi: 10.1128/iai.10.4.742-746.1974.
Strains H37Ra and H37Rv, attenuated and virulent variants, respectively, of the original human strain H37 of Mycobacterium tuberculosis, were used to infect cultures of mouse peritoneal macrophages. Bacterial viability of each strain was assessed over a 2-week period, and the cellular response to H37Ra during the first week was observed using electron microscopy. Prelabeling of secondary lysosomes with ferritin was used to facilitate the estimation of fusion of the lysosomes with phagosomes containing the bacteria. Streptomycin was excluded from the medium of cell cultures infected with H37Ra. The intracellular viability of strain H37Rv (in the presence of streptomycin) showed a lag during the first week after infection and then rose progressively to a mean figure seven times the starting level. In contrast, the viability of strain H37Ra declined, on the average, to one-fifth of the starting level during the first week; moreover, this decline occurred in the absence of antibiotics. In the second week a variable rise in the viable count took place, usually regaining the starting level. Electron microscopy of macrophages infected with H37Ra revealed a higher proportion of "damaged" bacteria 5 days after infection than at 1 day, in keeping with the decline in viability. Phagosomes containing these "damaged" (and presumed dead) organisms showed virtually universal fusion with prelabeled lysosomes. Phagosomes containing "intact" bacteria of this strain showed a prevalence of fusion varying from 38 to 56%, somewhat higher than the level previously reported for "intact" organisms of H37Rv. Nevertheless, the lysosome-phagosome fusion response to "intact" H37Ra was still far less extensive than that observed previously towards "intact" M. lepraemurium (around 90%). In conclusion, a difference between the macrophage lysosome-phagosome fusion response towards viable organisms of strain H37Ra and to the virulent strain H37Rv was observed, but was not pronounced, and the present findings are in keeping with the increasingly held view that H37Ra should be regarded as a low-virulence or attenuated strain rather than truly avirulent.
结核分枝杆菌原始人菌株H37的减毒株H37Ra和强毒株H37Rv，分别用于感染小鼠腹腔巨噬细胞培养物。在两周时间内评估各菌株的细菌活力，并在第一周使用电子显微镜观察对H37Ra的细胞反应。用铁蛋白对次级溶酶体进行预标记，以促进对溶酶体与含有细菌的吞噬体融合的估计。在感染H37Ra的细胞培养物培养基中不添加链霉素。H37Rv菌株（在链霉素存在下）的细胞内存活率在感染后的第一周出现滞后，然后逐渐上升至平均水平，是起始水平的七倍。相比之下，H37Ra菌株的活力在第一周平均下降至起始水平的五分之一；此外，这种下降是在没有抗生素的情况下发生的。在第二周，活菌数出现了不同程度的上升，通常恢复到起始水平。对感染H37Ra的巨噬细胞进行电子显微镜观察发现，感染5天后“受损”细菌的比例高于1天，这与活力下降一致。含有这些“受损”（推测已死亡）生物体的吞噬体几乎与预标记的溶酶体普遍融合。含有该菌株“完整”细菌的吞噬体显示融合发生率在38%至56%之间，略高于先前报道的H37Rv“完整”生物体的水平。然而，溶酶体-吞噬体对“完整”H37Ra的融合反应仍远不如先前观察到的对“完整”鼠麻风杆菌的反应广泛（约90%）。总之，观察到巨噬细胞溶酶体-吞噬体对H37Ra菌株活菌和强毒株H37Rv的融合反应存在差异，但不明显，目前的研究结果与越来越多人持有的观点一致——H37Ra应被视为低毒或减毒株，而非真正无毒株。
