Apparent Reciprocal Exchange of Characters between the Mel and NWS Strains of Influenza A Virus in the Brain of One-day Old Mice

EVIDENCE has accumulated in the work of Burnet and his colleagues 1,2 that some form of genetic interchange takes place between two strains of influenza virus that have been inoculated into a susceptible host in adequate amounts. However, information about the interaction between the non-neurotropic, Mel , and the neurotropic, NWS , strains of influenza A , which was among the first to be described 1 , remained deficient in some important respects.