Persistent LCM virus infection in the mouse. Immunity and tolerance.

The initiation of persistent infections with the Traub strain of the LCM virus is dependent not only on the number of immunocompetent cells present in the infected animals but probably also on the fact that the virus depresses the development of the bone marrow cells and causes a pronounced immunosuppression at the T cell level. By analysing the events leading to the termination of the virus carrier state by adoptive immunization, it was clearly demonstrated that the cellular immunity provoked was solely responsible for the virus elimination. Furthermore, helper T cells were shown to be necessary for the production of antibodies, which also occurs in adoptively immunized mice. In view of this finding, further experiments were performed, which strongly indicated that neither LCM-primed B cells nor LCM-primed helper T cells are present in mice that are persistent virus carriers. Similarly, neither cellular immunity to the LCM virus nor the presence of enhancing factors or suppressor cells could be detected. It is concluded that C(3)H mice that are persistent virus carriers have developed a humoral as well as a cellular immunological tolerance to the LCM virus.