Neutralization of pseudotypes of vesicular stomatitis virus by sera from avian retrovirus-infected hosts.

We investigated the capacity of lymphocytes and sera from chickens bearing tumors induced by avian sarcoma viruses (ASV) to interact with phenotypically mixed particles of vesicular stomatitis virus (VSV) and ASV. Immune chicken sera were able to specifically neutralize such VSV pseudotypes. This ability could be absorbed out, however, on purified preparations of avian retroviruses, suggesting that reactivity was primarily against avian retrovirus enveloped components. Supernatant fluids containing phenotypically mixed particles were unable to stimulate division of lymphocytes of tumor-bearing hosts, an ability possessed by culture fluids containing native ASV particles. Polyacrylamide gel analysis was unable to resolve any distinct pseudotype protein, which was not present in either of the parental virus types. Treatment with crude preparations of ultraviolet (UV)-irradiated VSV pseudotype material did not afford immunity against subsequent challenge with live ASV.