[Cathepsin D activity in splenocytes in relation to Shigella virulence in an experiment]

The overtime study of changes in the activity of cathepsin D, a lysosomal enzyme, in the splenocytes of CBA mice after their infection with virulent and avirulent Shigella strains of the same origin and with the same antigenic structure has been made. As the result of two months of observations, changes in the activity of this enzyme in the cytoplasmic and lysosomal cell fractions have been found to occur in phases. The activity of cathepsin D has been shown to depend on the virulence of Shigella strains used for inoculation. Virulent Shigella strains induce the pronounced and prolonged activation of the enzyme in the lysosomes, as well as in the cytoplasm. The latter phenomenon is probably indicative of the pathological labilization of the lysosomal membranes, induced by the virulent culture. Avirulent Shigella strains induce only the transient activity of the enzyme in the lysosomes without any essential changes in the permeability of their membranes. These data point to the possibility of differentiating virulent and avirulent Shigella strains by the determination of the enzymatic activity of splenocytes in infected animals.