VACCINATION AGAINST TUBERCULOSIS WITH NONLIVING VACCINES .3. VACCINATION OF GUINEA PIGS WITH FRACTIONS OF PHENOL-KILLED TUBERCLE BACILLI

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Abstract
The immunogenic activity of 2 fractions of phenol-killed, acetone-washed tubercle bacilli was investigated in guinea pigs, employing post-infection survival time as the criterion of efficacy. A crude methanol extract was found capable of bestowing, on occasion, a degree of enhanced resistance against subsequent infection with living, virulent tubercle bacilli. Vaccination with immunogenically effective quantities of the extract did not usually result in the development of tuberculin skin hypersensitivity. The degree of survival protection elicited by the extract was often lower than that given by living BCG, however, and could frequently not be demonstrated at all. Possible reasons for the sporadic nature of the immunogenic behavior of this preparation are discussed. In contrast, the immunogenic powers of residues of methanol extractions were found to be consistently of an order approaching that of the living BCG vaccine. The residues produced a low degree of tuberculin skin hypersensitivity. Combinations of immunogenically inactive preparations of methanol extract and quantities of their residues too small to elicit protection by themselves appeared to be synergistic. The future approach to the development of an effective and acceptable antituberculosis vaccine is discussed in the light of these findings and with regard to recent developments in the area of the immunologic nonspecificity of the effects initiated by microorganisms in the tissues of higher animals.