The Resistance of A2G Mice to Myxoviruses

Abstract

Summary Inbred A2G mice were found to be more resistant than other laboratory mice with respect to the following viral infections: neurotropic influenza A virus given intracerebrally (strains NWS, WSNF and Neuro-Kunz) and intranasally (strains NWS and WSNF); pneumotropic influenza A virus given intranasally (strains Swine, WS and PR8); and Sendai parainfluenza 1 virus given intranasally. Two mouse-adapted strains of Asian influenza (A/Singapore/1/57) were the only myxoviruses studied to which there was no difference in susceptibility between A2G and control animals. Not many more virus particles were required to initiate neuro-infection in A2G mice as compared to control mice. Virus titers reached in the brains after inoculation of neurotropic influenza virus were 100 times lower in A2G mice; similarly, 100 times less virus was recovered from lungs of A2G mice inoculated with Lee influenza B virus of low mouse virulence. No differences were found in the susceptibility to the toxic action of influenza A virus between A2G and control animals. After comparable inocula of influenza A virus given intranasally, A2G mice developed lower levels of hemagglutination-inhibiting and complement-fixing antibodies than did surviving controls. A2G and control mice proved equally susceptible to the following viruses: Yellow Fever 17 D, West Nile, EMC, Polio type 2 (mouse-adapted), Herpes simplex and ECHO type 9.