Regional Poultry Research Laboratory Lines Research Articles

Major Histocompatibility (B) Complex-Associated Differences in the Delayed Wattle Reaction to Staphylococcal Antigen

The influence of the major histocompatibility (B) complex on the delayed wattle reaction (DWR) to Staphylococcus aureus was studied in 109 segregants (B2/B2, B2/B5, and B5/B5) of a fourth generation cross between inbred Regional Poultry Research Laboratory lines 61 and 151. Chickens were sensitized at 6 weeks of age with S. aureus antigen. One week later, DWR was evaluated by injecting the right wattle with S. aureus antigen. Thickness measurements were taken 4, 24, 48, 72, and 96 hr after injection. A quadratic equation model was used for each bird to calculate maximum wattle thickness, hour of maximum response, and rate of response development and decline. In males, the maximum wattle thickness in response to S. aureus antigen was significantly greater in B2/B5 heterozygotes (1.77 ± .07 mm) than in either homozygote, B2/B2 (1.36 ± .13 mm) or B5/B5 (1.39 ± .08 mm). Heterozygous males reached maximum response sooner and recovered more quickly than homozygous males but these differences were not statistically significant. In females, response developed later than in males but no B complex effect was detected in either rate of development or maximum response.

Tests of association of immunoglobulin allotype genes and viral oncogenesis in chickens.

Chickens from Regional Poultry Research Laboratory (RPRL) inbred line 6(3) are resistant to virally-induced Marek's disease (MD) and lymphoid leukosis (LL) and are relatively strong regressors of virally-induced Rous sarcomas. In contrast, RPRL line 100 chickens are highly susceptible to MD and LL and are weaker regressors of Rous sarcomas than line 6(3). RPRL lines 100 and 6(3) differ for alleles at the IgG-1 (G-1) allotype locus, but have identical IgM-1 (M-1) allotype alleles. To test the possible association of the G-1 locus with variations in resistance to virally-induced tumors, homozygous and heterozygous genotypes among F3 crosses were infected. F3 chickens with different G-1 types were comparable in their resistance to MD tumors following inoculation with the JM strain of the MD virus, and for their ability to regress Rous sarcoma tumors induced by the Rous sarcoma virus (RSV) RAV-1. However, following RAV-1 virus infection a smaller proportion of G-1a/G-1aF3 or F4 birds developed LL tumors than G-1a/G-1e and G-1e/G-1e birds. Genes determining immunoglobulin heavy chains were therefore associated with a recessive resistance to B-cell lymphomagenesis in chickens.

A Non-MHC Genetic Influence on Response to Rous Sarcoma Virus-Induced Tumors in Chickens

Avian-leukosis-free females from Regional Poultry Research Laboratory (RPRL) inbred lines 6(1) and 7(2) were inseminated with pooled semen from RPRL line 15I5 males. The progeny resulting from the two crosses 15I5 X 6(1) and 15I5 X 7(2) were of the B2/B15 major histocompatibility complex (MHC) genotype, the B2 haplotypes from lines 6(1) and 7(2) being indistinguishable. When challenged with Rous sarcoma virus (RSV) at 6 weeks of age, 30 out of 31 progeny of cross 15I5 X 6(1) developed tumors that rapidly regressed, whereas 26 of 29 progeny of cross 15I5 X 7(2) died with progressive tumor growth. On the other hand, 15 of 18 B2/B15 segregants from the three-way cross (15I5 X 6(3]F1 X 7(2), identical in source to the MHC of the (15I5 X 7(2]F1 progressors, were characterized by tumor regression. Thus influences associated with non-MHC background genes from lines 6(1), 6(3), and 7(2) appeared to be critical to host response to RSV-induced sarcomas. Similar findings suggesting a strong non-MHC influence on anti-sarcoma response were obtained using 107 F2 and 77 backcross progeny of RPRL line 100 and noninbred University of New Hampshire (UNH) line 105. The B2 haplotype of line 100 was associated with tumor regression when combined with the line 105 background and with tumor progression when expressed on the line 100 background. Suppression of the anti-tumor response associated with line 100 appeared to be fairly generalized, since a poor response to tumor was observed regardless of which of three subgroups of RSV was used to induce tumor.

Independent segregation of ev 10 and ev 11, genetic loci for spontaneous production of endogenous avian retroviruses

F 1 males produced by crossing Regional Poultry Research Laboratory line 15I 4 that carries endogenous viral ( ev) genes 1, 6, and 10 and a partially defined gene, ev 11, with line 15 B that carries ev 1 and 7 were backerossed to line 15 B females. The DNA of 72 progeny embryos was digested by BamHI and Kpn and hybridization of resulting fragments with 32P-labeled viral RNA showed that ev 6, 10, and 11 were autosomal genes and not closely linked, and confirmed that ev 7 was sex linked. ev 10 and 11 were consistently associated with complete virus production, confirming that the newly defined ev 11 codes for a complete endogenous retrovirus.

Ontogeny and Line Differences in the Mitogenic Response of Chicken Lymphocytes

Ontogeny of mitogen response was studied using Regional Poultry Research Laboratory lines 6 and 7 and Cornell lines JM-N and -P chickens over a 30-week experimental period. Purified lymphocyte assay and sequential monitoring with whole-blood assay show lines 6 and N to be low responders compared to lines 7 and P, respectively. The difference in phytohemagglutinin (PHA) response between lines 6 and 7 increased with age, whereas that between lines N and P remained consistent for all ages. An association seems to exist between the low PHA responsiveness of lines 6 and N and resistance to Marek's disease (MD), a lymphoproliferative disease caused by MD virus in susceptible chickens. The fact that lines 6 and 7 have the same B2 -haplotype but differ in PHA response seems to substantiate the evidence by others that the genetic control of PHA response is not linked to the Ea-B locus of the MHC complex. This does not preclude, however, the possibility that the response of lines N and P is MHC-linked.

Skin-Graft Histocompatibility Within Regional Poultry Research Laboratory Inbred Chicken Lines

Skin grafts were exchanged between specific-pathogen-free chicks within the Regional Poultry Research Laboratory (RPRL) inbred lines that are characterized for retrovirus susceptibility and immunogenetic traits. Lines 61 and 63 were histocompatible whereas lines 15I4 and 15I5 were nearly histocompatible. The RPRL Line 72 is only histocompatible within families at present, and line 100 has considerable heterogeneity for minor histoantigens. Reaseheath Line C (RH-C) has been established at the RPRL and is histocompatible. Numerous males in lines 61, 63, 15I4, and RH-C are able to reject female grafts containing the female-specific histoantigen. Two Ea-B-alleles in 15I4 previously detected by blood-typing determined rapid skin graft rejection.

Independent segregation of ev 2 and ev 10, genetic loci for spontaneous production of endogenous avian retroviruses

F 1 males produced by mating two independently derived inbred lines of chickens (Regional Poultry Research Laboratory lines 7 2 and 151,) that spontaneously produce subgroup E retrovirus were mated to females from a line negative for subgroup E virus production. Approximately 80% of the progeny embryos produced a subgroup E virus. This result supports the hypothesis that two or more dominant genes at different loci can each control virus production. Analysis of the DNA of progeny embryos by digestion with restriction endonucleases Sst I and Bam HI and hybridization of the resulting fragments with 32P-labeled viral RNA showed that subgroup E virus production was associated with two and possibly three structural gene loci. The previously identified locus ev 2 from line 7 2 and a newly defined locus ev 10 from line 151 4 were clearly associated with virus production. Another new locus ev 11, found in 151 4, was tentatively identified and associated with virus production.

Low Incidence of Lymphoid Tumors in Chickens Continuously Producing Endogenous Virus

A flock of 258 male and 243 female chickens of a cross of Regional Poultry Research Laboratory lines 15B and 7(2) were kept in a filtered-air positive-pressure house and observed for tumors from 100 to more than 729 days of age. These birds produced high titers of a subgroup E endogenous virus from the middle of the embryonic incubation period through the end of the experiment. No neoplasms were observed in the males. The females had two neoplasms indistinguishable from lymphoid leukosis and three other neoplasms not involving lymphoid cells. No evidence was found of infection with exogenous lymphoid leukosis viruses, Marek's disease virus, reticuloendotheliosis virus, or adenovirus (isolated on the isolation farm). Inoculation of another sample of this cross with a lymphoid leukosis virus of subgroup A resulted in 88% mortality with neoplasms (mostly lymphoid leukosis) by 167 days of age. The conclusion is that high levels of spontaneously produced endogenous virus do not induce high levels of neoplasms in chickens susceptible to lymphoid leukosis.

Endogenous virus expression in chicken lines maintained at the Regional Poultry Research Laboratory

Lines of chickens maintained at the Regional Poultry Research Laboratory (RPRL) and free of exogenous lymphoid leukosis virus (LLV) infection were assayed for expression of endogenous LLV. Embryos were assayed for the expression of infectious subgroup E LLVs, particulate RNA-directed DNA polymerase, antigens which could serve as envelope antigens for the envelope defective Bryan Rous sarcoma virus (chf), and the group-specific antigens of the leukosis-sarcoma virus group (gs). RPRL inbred lines 6 1, 6 3, 7 2, 100, and 15 B were similar in endogenous virus expression to the previously characterized Beltsville Agricultural Research Center inbred lines 6, 7 2, 100, and 15. The expression of endogenous LLV was characterized for the first time in three sublines of RPRL line 15 chickens. Line 15 1, was gs + chf +; line 15I 4, gs − chf +; and line 15I 5, gs − chf +. Some 15 1, and 15I 5 embryos produced infectious subgroup E, but all 15I 4 embryos produced infectious subgroup E virus. Two RPRL noninbred lines were also characterized Line P was segregating for subgroup E virus production and the gs + chf + phenotype. Line N was segregating for subgroup E virus production, the gs + chf + and gs − chf + phenotypes.

Genetic Nature of Regression of Rous sarcoma Virus-Induced Tumors in Crosses of Regional Poultry Research Laboratory Lines 6 and 72 ,

Regional Poultry Research Laboratory (RPRL) inbred lines 61, 63, and 72 and F1, F2, and reciprocal backcross progenies of these lines were used to investigate host-gene effects upon the regression of Rous sarcoma virus (RSV)-induced tumors. Lines 61 and 63 were susceptible to subgroup A and C lymphoid leukosis (LL) viruses and line 72 was resistant to subgroup A but was segregating for susceptibility to subgroup C LL virus. Viruses of RSV subgroups A and C were used. Lines 61, 63, and 72 were homozygous for shared blood group alleles B2, C5, L1, and r.The incidence of tumor regression was higher in line 63 than in 72, and in reciprocal F1 crosses of these lines was of the same order of magnitude as in line 63. Progeny from F1, generation parents mated to line 63 had a higher frequency of regression than offspring from F1 generation parents mated to line 72. The frequency of regression in F2 generation offspring was intermediate between the two backcrosses.The data suggest that either a locus (or loci) other than L and B has a role in Rous tumor regression in this species or the immune response region of the B blood group-major histocompatibility complex differs in the two lines even though the serological and/or graft vs. host regions have not been shown to differ.

The role of the tvb locus in genetic resistance to RSV(RAV-0)

Genetic susceptibility to RSV(RAV-0), an avian sarcoma virus belonging to subgroup E. has been studied in two sets of inbred chicken lines. Data from the Reaseheath lines suggested that a recessive gene, independent of susceptibility to subgroup B, controlled resistance to subgroup E virus. This gene was assumed to be a new tve locus. Studies of the Regional Poultry Research Laboratory (RPRL) lines suggested that a recessive gene for resistance was located at the tvb locus and thus genetically linked to resistance to subgroup B virus. Crosses and backcrosses of Reaseheath and RPRL lines were assayed for susceptibility to RSV(RAV-0) and RSV(RAV-2) on the chorioallantoic membrane. The data completely support the hypothesis that a single locus controls recessive resistance to subgroup B and E viruses. Therefore, there was no evidence for an independent tve locus.

Further Observations concerning Rous Virus Neutralizing Antibodies and Neoplasia. I. In Farm Flocks

CCORDING to Winton,10 Rous virus neutralizing antibodies (RVNA) have been observed by Duran-Reynals in the sera of chickens from the Regional Poultry Research Laboratory (RPL) with lymphomatosis. Forty-five percent of the sera from RPL Line 9 chicks hatched in Iowa were found to contain RVNA, while the parent stock experienced 41 percent lymphomatosis.6 Kenzy and Neuzil7 found RVNA in more than 60 percent of the sera from farm flocks in Iowa with 30 to 50 percent