title: Immune response and protective efficacy of live attenuated Salmonella vaccine expressing antigens of Mycobacterium avium subsp. paratuberculosis against challenge in mice.
abstract: Mycobacterium avium subsp. paratuberculosis (MAP) causes chronic granulomatous enteritis in ruminants that leads to diarrhea and eventually death. Existing vaccines have proven useful in limiting disease progression but have not been effective in preventing infection. To address this problem we constructed an attenuated Salmonella (ΔyejE; ΔssaV) strain harboring a plasmid that expressed a fusion protein comprised of the Salmonella Type III secretion system (T3SS) effector SopE and MAP antigens (85A, 85B, SOD, 74F) and evaluated its potential as vaccine candidate against MAP infection in mice. Of various SopE-MAP fusion proteins analyzed, only SopE104-Ag85A C-terminal(202-347)-SOD N-terminal(1-72)-Ag85B C-terminal(173-330) and SopE104-74F(1-148+669-786)were successfully expressed and secreted into culture media as revealed by western blot analysis. Mice immunized with attenuated Salmonella (ΔyejE; ΔssaV) harboring the SopE104-Ag85A C-terminal(202-347)-SOD N-terminal(1-72)-Ag85B C-terminal(173-330) and SopE104-74F(1-148+669-786)plasmid generated a potent and long lasting Th1 response characterized by production of IFN-γ. The cytokine profile varied at various time points after immunization and challenge, which showed down regulation of Th2 cytokines (IL-4, IL-10) and up-regulation of proinflammatory cytokines (IL-12 and IL-17). Further, the immune response correlated with protection as revealed by reduced bacterial load and improved histopathology of spleen and liver, which showed fewer granulomas and lower numbers of acid-fast bacilli as compared to PBS controls. Interestingly, vaccination with antigens mixed with Ribi adjuvant (Agmix+Ribi) imparted better protection than the attenuated salmonella vectored vaccine. Thus, priming with a live recombinant Salmonella strain that secretes MAP antigens represents a promising approach that could lead to development of an efficacious and cost effective vaccine for Johne's disease.
authors.affiliation: Department of Population Medicine and Diagnostic Sciences, Department of Biomedical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853, USA.
authors.forename: Subhash
authors.initials: S
authors.lastname: Chandra
authors.forename: Syed M
authors.initials: SM
authors.lastname: Faisal
authors.forename: Jenn-Wei
authors.initials: JW
authors.lastname: Chen
authors.forename: Tsai-Tzu
authors.initials: TT
authors.lastname: Chen
authors.forename: Sean P
authors.initials: SP
authors.lastname: McDonough
authors.forename: Sen
authors.initials: S
authors.lastname: Liu
authors.forename: Maria A S
authors.initials: MA
authors.lastname: Moreira
authors.forename: Bruce L
authors.initials: BL
authors.lastname: Akey
authors.forename: Chao-Fu
authors.initials: CF
authors.lastname: Chang
authors.forename: Yung-Fu
authors.initials: YF
authors.lastname: Chang
mesh_terms: D000818:Animals; D000942:Antigens, Bacterial / Q000276:immunology*; D005260:Female; D051379:Mice; D008810:Mice, Inbred C57BL; D016927:Mycobacterium avium subsp. paratuberculosis / Q000276:immunology* / Q000472:pathogenicity*; D010283:Paratuberculosis / Q000276:immunology* / Q000517:prevention & control*; D014613:Vaccines, Attenuated / Q000276:immunology* / Q000627:therapeutic use*
chemical_list: D000942:Antigens, Bacterial; D014613:Vaccines, Attenuated