[Incorporation of influenza virus antigens into the envelope of the avian oncornavirus].

The mixture of influenza virus and pseudotype of Rous sarcoma virus--RSV (PAB-A) grown in chick embryos or cell culture of chick fibroblasts produces a progeny which can be partially neutralized by a heterologous immune serum. The fraction of viral particles, the transformation activity of which is susceptible to suppression by both homologous anti-RSV (PAB-A) and heterologous serum, immune to influenza virus, amounts to approximately 20%. After passivation, these particles lose this property which suggests a non-genetical character of the phenomenon. Hence, dual infection results in phenotypic mixing and formation of particles with nucleoproteid of RSV (PAS-A) which contain antigens of avian sarcoma and influenza viruses in their envelopes.