Meyers, Paul A.

Abstract With a leukocyte blastogenesis assay and 3 M KCl extracts of chicken cells infected or infected and transformed by various avian tumor viruses (ATV), the time course of development of cellular reactivity in RSV tumor-bearing chickens to antigens expressed on these cell types was examined. Leukocyte reactivity to mitogens in RSV-injected birds was also investigated. Similarly, humoral responses to ATV-antigens and virus-induced antigens were assessed over time, by measuring the development of antiviral neutralizing antibody, as well as antibody to cell surface antigens on various cell types, by means of an isotopic antiglobulin test (IAT). There were no differences in phytohemmaglutinin responsiveness between the leukocytes of RSV-injected birds and control birds, but responses to pokeweed mitogen were sometimes elevated in RSV-injected animals. Cellular immunity to 3 M KCl extracts, principally to those extracts containing structural components of the virus envelope, developed between 3 and 5 weeks post-injection, during tumor growth and regression, and then declined, although the immune response could be restimulated by virus rechallenge. For the most part, responses to nonvirion tumor-specific surface antigen (TSSA) was weak except after RSV rechallenge. Humoral reactivity as measured by IAT also seemed to correlate well with the presence of virus envelope antigens (VEA) on infected indicator cells and appeared before antiviral neutralizing antibody. The data indicated that, at least during the primary response, major immune reactivity in RSV-injected birds appeared to be directed against VEA and that TSSA appeared to be most immunogenic when VEA was also present.

Abstract In a reexamination of congenital infection of chickens with ALV, one of the classical models of immunologic tolerance, we were unable to demonstrate that there was any evidence suggesting humoral immune reactivity to the infecting virus. In ALV-F42 congenitally infected birds that have a persistent viremia and no neutralizing antibody detectable by conventional means, we could find no evidence of host IgG deposits in the kidneys, nor any suggestion of renal pathology or damage. In addition, attempts to precipitate any putative circulating infections virus-antibody complexes by treatment with a highly specific anti-globulin were negative nor were there titer differences in the viremic plasmas of bursectomized birds compared to nonbursectomized birds, indicating that the chickens were not making either a masked neutralizing or a nonneutralizing antibody response to the infecting virus. The evidence presented indicates that congenital infection of chickens with ALV does, at least at the humoral level, result in a state of immunologic tolerance to the infecting agent.

Abstract Normal chickens and chickens congenitally infected with an avian leukosis virus (ALV) of antigenic subgroup A were challenged with strains of Rous sarcoma virus (RSV) of two different antigenic subgroups (B and C) and tumor induction and growth as well as humoral antibody to viral envelope antigen (VEA) and tumor-specific surface antigen (TSSA) were measured. There was no effect of congenital ALV infection on RSV tumor incidence or latent period but the growth rate and size of the tumors were much higher in congenitally infected birds as compared to controls. Whereas most tumors in the RSV-challenged normal birds regressed, tumors in ALV-infected birds grew progressively. There were no striking differences in the number of birds in either group in the incidence of anti-TSSA or anti-VEA antibodies nor did the presence of either type of antibody reflect the tumor status of the host.

Abstract Using highly sensitive and quantitative radioimmunoassay procedures we have measured the effects of different concentrations of three commonly used detergents, SDS, DOC, and Triton X-100, on antibody-antigen reactions. Triton X-100 had a relatively mild effect on primary antigen-antibody bindings, the precipitin reaction, and a double antibody RIA as evidenced by only an 8 to 10% inhibition of binding or precipitation. These results were not detergent concentration dependent, as Triton concentrations ranging from 5 to 0.1% had virtually no differential effects. Sodium deoxycholate (DOC) had a more profound effect on both primary antigen-antibody binding and the precipitin reaction than did Triton X-100, and its effects, unlike those of Triton X-100, were concentration dependent. There was a direct relationship between concentration of DOC and degree of inhibition of both primary binding and immune precipitation especially in antigen excess. Sodium dodecylsulfate (SDS), at concentrations 10- to 100-fold less than either Triton X-100 or DOC, had profound inhibitory effects on primary antigen-antibody binding, the precipitin reaction, and a double antibody radioimmunoassay. Generally, at concentrations greater than 0.01% SDS, almost all immunochemical reactivity is destroyed.

Abstract Significantly elevated (2- to 5-fold higher than controls) serum levels of IgG were found in chickens congenitally infected with F42 strain of avian leukosis (ALV-F42), a subgroup A avian leukosis virus (ALV). A further increase in IgG levels in congentially infected birds was found to be induced by injection of influenza virus in complete Freund's adjuvant (CFA). Serum immunoglobulin M (IgM) levels were not significantly elevated in ALV congenitally infected chickens except in those animals that had been injected with influenza virus in CFA. Hypergammaglobulinemia in ALV infected birds resulted only after congenital infection and not after infection of immunologically competent birds. Therefore this phenonemen appeared to have striking parallels with other persistent or chronic viral infections that have been previously described in mammals.