Studies on Nonspecific Acquired Resistance to Viral Toxicity in Mice.

Abstract

Prior intravenous injection of Escherichia coli endotoxin or influenza virus protected mice against subsequent challenge with the homologous agent. Prior intravenous injection of endotoxin protected mice against subsequent inoculation of toxic quantities of influenza virus, while previous injection of influenza virus failed to protect mice against challenge with endotoxin administered by the same route. Prior intracerebral injection of minute quantities of endotoxin, as well as sublethal quantities of influenza virus, exerted a protective effect in mice challenged 24 hours later with toxic quantities of the virus by the same route. Endotoxin failed to protect mice against infection with the neurotropic strain (NWS) of influenza virus or against the neuropathic effect of dilute Newcastle disease virus (RO strain). It is suggested that the mechanisms of viral interference and acquired resistance to viral toxicity are different.