Keywords
Abstract
The short history of creation of BCG vaccine as artificially created mutant of the virulent strain of M. bovis is stated. It is shown that the base of modification of BCG is a loss of numerous genetic factors of virulence owing to repeated passaging on an adverse medium. In particular, one of major factors of virulence of pathogenic micobacteria the specific region of difference of RD1 is absent at all sub- strains of BCG. Existent postvaccinal complications are explained by residual virulence of vaccine, also as well as special features of immunity of a human macroorganism. For the explanation of the residual virulence of vaccine the great importance has the discovery of L-transforma- tion of BCG in an organism of the vaccinated children (N.A. Shmelyov, I.R. Dorozhkova, H. S. Zemskova, 1976) which allows the long persistence of L-forms in lymph nodes, but under adverse conditions for a macroorgan- ism L-forms can reverse in cellular forms and cause post- vaccinal complications of various gravity.