Glycoprotein such as neuraminidase is an enzyme occurring in some viruses and bacteria. It is characterized by a series of specific biochemical, enzymatic and immunological properties. The observed prevalence of chronic virus infections as well as liver diseases, glomerulonephritis, conjunctive tissue diseases and other autoaggressive illnesses which occur in their course have become the reason for experimental studies in which according to established patterns enzymatically active and inactive neuraminidase was administered to rabbits in a prolonged way.