Haemopoietic defects in mice infected with lymphocytic choriomeningitis virus. 1. The enhanced x-ray sensitivity of virus infected mice.

Abstract

Seemingly paradoxical observations were made with mice exposed to infections with the LCM virus and treatment with X‐rays. The X‐irradiation could afford a beneficial effect upon the cource of the viral infection or cause a serious aggravation. The beneficial effect was associated with X‐ray treatment given prior to the inoculation of virus. This pre‐irradiation effectively prevented an antiviral immune response and protected mice against lethal intracerebral challenges with the virus. However, doses of X‐rays which were sublethal for normal mice provoked a lethal disease when given to mice previously inoculated with the virus. Fatal outcomes were observed with persistent, tolerant virus carriers and with i. p. infected adult mice, that is, in cases of normally inapparent LCM virus infections. The X‐ray induced deaths were apparently not related to any enhanced growth of the virus in the irradiated mice. Clinical findings and reconstitution experiments strongly indicated that the striking increase in the sensitivity to X‐rays was caused by a haemopoietic defect in the LCM virus infected mice. The nature of this haemopoietic disorder is not readily explained. Thus several observations made it unlikely that the LCM virus had any direct damaging effect upon the haemopoietic cells. Moreover, the findings with the persistent, tolerant virus carriers provided evidence against any immunopathological basis of the disorder.