Immunomodulatory effects of cytokines in turkeys and the role of cytokines in the pathogenesis of infectious diseases
[Thesis]
S. Rautenschlein
J. M. Sharman
University of Minnesota
1998
230-230 p.
Ph.D.
University of Minnesota
1998
The imiquimod S-28828 induced high serum levels of type I IFN in turkeys after oral administration. Spleen, bone marrow and peripheral blood leukocytes produced IFN following in vitro stimulation with S-28828. High dose treatment of turkeys with S-28828 enhanced the mortality rate of Escherichia coli (E. coli)-infected birds and impaired bacterial clearance from the liver. S-28828 reduced the incidence of HEV-induced gross and histopathologic lesions and inhibited HEV-replication in the spleen. In ovo vaccination with recombinant FPV vaccines did not influence hatchability, survival rate, performance, or weight gain in turkeys. SPF-turkeys vaccinated in ovo with the FPV-NDV-type II IFN construct were significantly (usdP < 0.05usd) better protected against NDV challenge than birds vaccinated with FPV-NDV or FPV-NDV-type I IFN constructs. Turkeys vaccinated with the FPV-NDV-type II IFN construct had anti-NDV antibodies at eleven days post vaccination (PV); one week earlier than the turkeys vaccinated with FPV-NDV or FPV-NDV-type I IFN. Virulent HEV increased apoptotic rates in the spleen at 3 and 4 days post infection (PI). At 2, 3 and 4 days PI, spleen cells from HEV-infected turkeys cultured ex vivo released interleukin 6-like factor (IL-6). At 3 days PI, spleen cells from infected birds also produced tumor necrosis like factor (TNF) and nitric oxide inducing factors (NOIF) after ex vivo stimulation with concanavalin A. Tissue culture attenuated HEV (HEVp30) and marble spleen disease virus (MSDV) were used for simultaneous vaccination with NDV Hitchner B1 (NDV-B1). Birds vaccinated with HEVp30 + NDV-B1 or MSDV + NDV-B1 had enhanced pathological lesions and an increased apoptotic rate in splenocytes (usdP < 0.05usd) in comparison with single agent inoculated groups. Simultaneously vaccinated turkeys had fewer HEV-infected splenocytes at 4 days PV than the birds given HEVp30 or MSDV alone. At 14 days PV, the anti-HEV antibody response was lower and anti-NDV antibody response was higher in dually vaccinated turkeys than in the birds that received single vaccines. Splenocytes from NDV-B1-vaccinated turkeys produced nitric oxide (NO) after stimulation in vitro with lipopolysaccharide (LPS) while HEVp30- or MSDV-vaccinated turkeys did not produce NO following similar stimulation.