Characterization of avian thymic hormone and chicken parvalbumin 3 target cells.

Avian thymic hormone (ATH) is a ß-parvalbumin produced by epithelial cells in the thymic cortex and in the eyes of chickens. Chicken parvalbumin 3 (CPV3) is a homologous protein produced in the thymus and in hair cells of the chicken ear. ATH circulates in the blood on a five-day cycle and stimulates cell-mediated immunity when administered to young chickens. We report the identification of target cells for ATH and CPV3 and the immunophenotype of target cells for ATH. Newly hatched chicks were injected intracoelomically with ATH and killed 5, 10, 15 or 20 min later. Naïve chickens also were killed at 1, 7 and 14 days of age. Various tissues were examined by EM for the presence of either ATH or CPV3 using colloidal gold labeling. Gold particles were initially present on plasma membranes of lymphocytes in T cell areas of spleen and cecal tonsils from the chicks injected with ATH, internalized within 10 min, and accumulated in nuclei by 20 min. Immunofluorescence staining also identified the presence of ATH in T cell areas of spleen and cecal tonsils. Target cells labeled for ATH were immunophenotyped by double labeling. They were positive for CD3, CD8 and the lymphocyte receptor TCR-1, a phenotype characteristic of cytotoxic γδ T cells. Some of the target cells in the spleen were TCR-3 positive. Targeting of lymphocytes by CPV3 indicated that it may also be an immunomodulating hormone.

Abundance of IFN-α and IFN-γ gene transcripts and absence of IL-2 transcripts in the blood of chickens vaccinated with live or inactivated NDV.

As immune responses to live and inactivated vaccines might differ, temporal responses of broiler chickens to vaccination were examined on the basis of the abundance in the circulating blood of gene transcripts of IFN-α, IFN-γ and IL-2, critical cytokines for immune responses. Blood samples were collected 6, 12 and 24 hours, and 7 and 14 days following vaccination with either live or inactivated Newcastle disease virus, La Sota strain, at 14 days of age, and the abundance of transcripts for each cytokine was assayed by real-time RT-PCR. Physiological saline and vaccine emulsion without viral antigen were administered to control groups for live and inactivated vaccine groups, respectively. The abundance of IFN-γ transcripts was elevated during the early times following vaccination and had reached baseline by the seventh day but the abundance of IFN-α transcripts remained elevated. Transcripts for neither IFN gene were detected in the control birds. The abundance of transcripts for each IFN was not different between the two vaccinated groups at any time. Transcripts for IL-2 were detected only in spleens from chicken embryos that had been inoculated with the live virus. The results show that cells stimulated to produce IFN-α and IFN-γ enter the circulating blood but those stimulated to produce IL-2 do not, or in very low number, and the IFN responses to both vaccines are the same.

Immunogenicity and safety of Queensland V4 and Ulster 2C strains of Newcastle disease virus given to maternally immune, newly hatched chickens by nebulization.

Commercial chickens with a high level of maternal antibodies for Newcastle disease were vaccinated when newly hatched with Queensland V4 or Ulster 2C Newcastle disease virus (NDV) strains by nebulization. The exposure time to a fine aerosol of vaccine produced with an ultrasonic nebulizer was 60 sec. The chickens were challenged oculonasally with virulent NDV strain Texas GB in weekly intervals up to the 49th day of life. Although protected for several weeks by maternal antibody, they were sufficiently protected thereafter by active immune response to the vaccines. Vaccinal reactions were not observed. Queensland V4 produced higher titers than Ulster 2C and provided better protection to challenge.

Avian thymic hormone treatment of peripheral blood mononuclear cells from young chicks stimulates acute graft-versus-host reaction in chicken embryos.

Avian thymic hormone (ATH) is a parvalbumin produced by epithelial cells in the thymic cortex of chickens and circulates in the blood on a 5-day cycle. It stimulates precocious development of cell-mediated immunity. The effect of partially purified extracts of thymus (TE) and purified ATH were tested for their effect on the acute graft-versus-host reaction (GVHR). Treatment of chicks for their first 3-days of life did not enhance the acute GVHR produced by their PBMC in 14-day-old embryos. PBMC from 3-day-old chicks were treated in vitro with TE, ATH, thymosin fraction 5 or thymosin alpha1 for 2 h and injected into 14-day-old embryos. Bone marrow cells and thymic lymphocytes were treated with TE. Only PBMC treated with TE or ATH produced an enhanced acute GVHR. Because ATH targets gammadelta T cells, the data implicate participation of donor gammadelta T cells in the acute GVHR.

Immunomodulation of chickens with the nonionic block polymer T150R1.

Chickens injected subcutaneously at one day of age with oil-in-water emulsions of the nonioinic block polymer T150R1 developed higher titres to sheep erythrocytes and killed Brucella abortus than did untreated chickens when they were immunised with the antigens one and two weeks later. The increase was IgM only. Cell-mediated immunity was not affected as measured by blastogenic responses. Morphometric analysis of tissue sections of bursae of Fabricius suggested the polymers were stimulating more rapid migration of B cells to peripheral organs.

Chicken anemia virus and infectious bursal disease virus interfere with transcription of chicken IFN-alpha and IFN-gamma mRNA.

Chicken anemia virus (CAV) and infectious bursal disease virus (IBDV) are the two most important viruses that cause immunosuppression in commercial chickens. Because inapparent, subclinical infections by these viruses cause immunosuppression, there is need for assessment of the immune status of chickens. Interference with induction of transcription for chicken interferon-alpha (ChIFN-alpha) and ChIFN-gamma was noted after subclinical infections with either CAV or IBDV. Because the immunosuppressive viruses of chickens may interfere with transcription for ChIFN-alpha and ChIFN-gamma, we propose using this interference to assess the immune status of chickens.