Persistent virus infections in studies of the immune response.

Some recent studies on immune phenomena in persistent virus infections, employing non-cytolytic viruses, are reviewed. This includes the refutation of a possible inheritance of tolerance and some aspects of drug-induced tolerance to persistent viruses, with its consequences for possible treatment of virus-induced immunopathological diseases. The biological peculiarities of viruses involved in persistent or chronic infections are discussed with respect to the balance between the immune system and the infectious agent.