[Immune response during the course of chronic experimental rabies]

The immune response was studied in the time course in comparison with virus titers in the brain in chronic course of the disease in random-bred and BALB/c mice infected intracerebrally with street rabies virus, the Yak strain. The virus-neutralizing antibodies were first found in the blood by the end of the incubation period and in the brain tissue at 7-8 days of the disease. Then their titers increased as the disease progressed reaching maximum (in the blood 1:97,313, in the brain 1:63,090) by 42-55 days. From the moment of virus-neutralizing antibody detection in the brain tissue virus titres decreased progressively with the period of the disease and increasing antibody concentrations in the brain tissue. By 42-55 days of the disease virus titres did not exceed 1.0 lg LD50/0.03 ml. Similar virus titer--antibody concentration in brain tissue dependence was observed in experiments in rats and rabbits. Very high antibody titers in the blood and brain tissue had no effect on the progredient course of the disease and fatal outcome. The study allowed the diagnostic criteria of chronic infection to be determined as well as its differences from the acute and abortive forms of rabies.