The effect of lymphocytic choriomeningitis virus-induced suppression of the delayed-type hypersensitivity reaction on virus clearance and pathogenicity

In the murine lymphocytic choriomeningitis virus (LCMV) infection T effector cell populations are essential in the development of fatal disease following intracerebral (i.c.) inoculation [5, 6] as well as in the clearance of virus after an extracerebral infection [4] which generally takes a subclinical course. By increasing the virus dose from 102 (low-dose) to 104 LDso (high-dose) the fatal i.c. LCMV infection is changed into a clinically inapparent one, and at the same time a selective delayed-type hypersensitivity (DTH) unresponsiveness is induced, while the cytotoxic T cell response remains essentially unchanged. Furthermore, high-dose mice infected by the i.c. or the intravenous (i.v.) route contain large amounts of virus late after the infection as compared to i.v. infected low-dose mice [7]. We have investigated the effect of the DTH reactivity/ unresponsiveness on viral pathogenicity and virus clearance.