title: Embryonic infection with the endogenous avian leukosis virus Rous-associated virus-0 alters responses to exogenous avian leukosis virus infection.
abstract: We inoculated susceptible chicken embryos with the endogenous avian leukosis virus Rous-associated virus-0 (RAV-0) on day 6 of incubation. At 1 week after hatching, RAV-0-infected and control chickens were inoculated with either RAV-1 or RAV-2, exogenous viruses belonging to subgroups A and B, respectively. The chickens injected with RAV-0 as embryos remained viremic with exogenous virus longer and either failed to develop type-specific humoral immunity to exogenous virus or developed it later than the control chickens not inoculated with RAV-0. The RAV-0-injected chickens also developed neoplasms at a much higher frequency than did the control chickens. We suggest that the lower immune responses of the RAV-0-injected chickens were due to an immunological tolerance to envelope group-specific glycoproteins shared among endogenous and exogenous viruses.
mesh_terms: D000818:Animals; D000914:Antibodies, Viral / Q000276:immunology; D001353:Avian Leukosis / Q000235:genetics* / Q000276:immunology / Q000382:microbiology; D001354:Avian Leukosis Virus / Q000235:genetics*; D002642:Chick Embryo / Q000382:microbiology*; D005786:Gene Expression Regulation; D005814:Genes, Viral; D006023:Glycoproteins / Q000276:immunology; D009374:Neoplasms, Experimental / Q000235:genetics / Q000382:microbiology; D009500:Neutralization Tests
chemical_list: D000914:Antibodies, Viral; D006023:Glycoproteins