Effect of Westphal Lipid A on Viral Activities in Mice and Hamsters

Abstract

Westphal''s lipid A assayed in mice and hamsters enhanced non-specific host resistance against the activities of viruses such as was demonstrated earlier for bacterial endo-toxins and for other materials of microbial origin. Lipid A, given intracerebrally into mice, suppressed neurotoxicity of concentrated influenza A virus and reduced the activities of neurotropic influenza (NWS) and herpes simplex viruses as measured by survival and by survival time. Given subcutaneously, it was active against influenza. A virus and, following intraperitoneal injection, was active against encephalomyocarditis virus but showed slight if any activity against measles in hamsters or neurotropic (NWS) influenza virus in mice. It was inactive against Lansing type II poliovirus and Coxsackie B3 virus when given intracerebrally and intraperitoneally, respectively. Greatest activity was in the suppression of pneumonia virus of mice (PVM), even when administered up to 72 hours following viral infection. The lipid A did not appear to suppress proliferation of neurotropic NWS influenza virus even though it did reduce the clinical consequence of such infection at low virus dose. Lipid A is discussed against the background of other host resistance factors.