title: Active immunity and T-cell populations in pigs intraperitoneally inoculated with baculovirus-expressed transmissible gastroenteritis virus structural proteins.
abstract: The intraperitoneal inoculation of pigs with baculovirus-expressed transmissible gastroenteritis virus (TGEV) structural proteins (S, N, M) in conjunction with thermolabile Escherichia coli mutant toxin (LT-R192G) in incomplete Freund's adjuvant (IFA) was tested in an attempt to elicit active immunity to TGEV in gut-associated lymphoid tissues (GALT). Four groups of 63 (1-5-week-old) suckling, TGEV-seronegative pigs were used to assess the efficacy of the recombinant protein vaccine (group 3) in comparison with sham (group 1), commercial vaccine (group 2), and virulent TGEV Miller-strain-inoculated pigs (group 4). The TGEV-specific mucosal and systemic immune responses were measured after in vivo and in vitro stimulation with TGEV-antigens. The major T-cell subset distribution was analyzed in vivo and in vitro after stimulation of mononuclear cells with TGEV (from mesenteric lymph nodes of group 3 inoculated with TGEV-recombinant proteins). Induction of active immunity was assessed by challenge of pigs with virulent TGEV at 27 days of age. Baculovirus-expressed TGEV proteins coadministered with LT-R192G in IFA induced mesenteric lymph node immune responses associated with IgA-antibodies to TGEV and partial protection against TGEV-challenge. The high titers of serum IgG- and virus-neutralizing-antibodies to TGEV in group 3 pigs most likely reflected the dose of TGEV S-protein administered. At the day of TGEV-challenge, the in vitro stimulation of mononuclear cells from the mesenteric lymph nodes of group 3 pigs with inactivated TGEV resulted in an increase in double positive (CD4+CD8+), natural killer (CD2+CD4-CD8+dim) and cytotoxic (CD2+CD4-CD8+bright) T-cell phenotypes, accompanied by increased expression of interleukin-2 receptor and a decrease of the null (CD2-CD4-CD8-/SW6+) cell phenotype.
authors.affiliation: Food Animal Health Research Program, The Ohio State University, Ohio Agricultural Research and Development Center, Wooster 44691, USA.
authors.forename: K
authors.initials: K
authors.lastname: Sestak
authors.forename: R K
authors.initials: RK
authors.lastname: Meister
authors.forename: J R
authors.initials: JR
authors.lastname: Hayes
authors.forename: L
authors.initials: L
authors.lastname: Kim
authors.forename: P A
authors.initials: PA
authors.lastname: Lewis
authors.forename: G
authors.initials: G
authors.lastname: Myers
authors.forename: L J
authors.initials: LJ
authors.lastname: Saif
mesh_terms: D000818:Animals; D016367:Baculoviridae; D017934:Coronavirus / Q000276:immunology*; D005761:Gastroenteritis, Transmissible, of Swine / Q000517:prevention & control*; D005822:Genetic Vectors; D007110:Immunity, Active; D007274:Injections, Intraperitoneal; D018655:Lymphocyte Count; D013552:Swine; D013601:T-Lymphocytes / Q000166:cytology / Q000276:immunology*; D015678:Viral Structural Proteins / Q000276:immunology*
chemical_list: D015678:Viral Structural Proteins