Relation Between the Loss of Acid-Fastness due to the UV Irradiation and the Virulence of Tubercle Bacilli

As reported in the previous paper tubercle bacilli are deprived of their acid-fast stainability completely by the UV irradiation for a certain time period. Obviously longer time period of UV irradiation is required for the complete loss of acid-fastness in the virulent type strains than in the a- or low-virulent ones. This fact seems to suggesst the difference in the cell wall structure between these two types of tubercle bacilli and is likely to enable us to attribute the virulence of tubercle bacilli primarily to the proper cell wall structure. Based on the results obtasned a very simple method to distinguish, even roughly, these two types of strain by the staining of smears was devised. Further, the relation between the virulence and the cell wall structure of tubercle bacilli was discussed.