Differences in the multiplication at elevated temperature of influenza virus recombinants pathogenic and nonpathogenic for chicken

Abstract

Evidence is presented that the body temperature of chickens at 41° selects virus recombinants with a genome constellation necessary for pathogenicity in chickens. It could be shown that recombinants of influenza A viruses pathogenic for chicken grow equally well at 37 and 41° whereas the nonpathogenic recombinants have a significantly lower growth rate at 41°. Hybridization studies with recombinants derived from fowl plague virus and A/turkey/England/63 revealed that at 41° such isolates are selected which possess all the genes coding for the polymerase complex from one wild type parent virus. Furthermore, only pathogenic recombinants showed an increase in plaque size when the incubation temperature was shifted from 37 to 41°. The behavior of virus recombinants at elevated temperature therefore is a useful marker for rapid in vitro selection of pathogenic or nonpathogenic recombinants.