Lethal role of interferon in lymphocytic choriomeningitis virus-induced encephalitis.

After intracerebral inoculation of adult C3H mice, the 'docile' strain of lymphocytic choriomeningitis (LCM) virus multiplied to high titre in several visceral organs. Although the virus content of lung, liver, spleen and brain was high, these mice did not die but became long-term carriers of the virus. Injection of mice with the same dose of the 'aggressive' strain of LCM virus resulted in much lower virus titres in these organs; nevertheless, 100% of the mice died within 7 to 9 days. The results presented here show that mice infected with the 'aggressive' virus do not die if treated with anti-interferon globulin. Under these conditions the titres of 'aggressive' virus were as high in the different organs as in mice injected with the 'docile' virus. These results are consistent with the hypothesis that inhibition of LCM virus multiplication in various organs by interferon results in a lethal disease. The possible mechanisms underlying this seemingly paradoxical phenomenon are discussed.