title: Protective cellular responses elicited by vaccination with influenza nucleoprotein delivered by a live recombinant attenuated Salmonella vaccine.
abstract: Orally administered recombinant attenuated Salmonella vaccines (RASVs) elicit humoral and mucosal immune responses against the immunizing antigen. The challenge in developing an effective vaccine against a virus or an intracellular bacterium delivered by RASVs is to introduce the protective antigen inside the host cell cytoplasm for presentation to MHC-I molecules for an efficient cell mediated immune response. To target the influenza nucleoprotein (NP) into the host cell cytosol, we constructed a regulated delayed lysis in vivo RASV strain χ11246(pYA4858) encoding influenza NP with a chromosomal deletion of the sifA gene to enable it to escape from the endosome prior to lysis. Oral immunization of mice with χ11246(pYA4858) (SifA⁻) with 3 booster immunizations resulted in complete protection (100%) against a lethal influenza virus (rWSN) challenge (100 LD₅₀) compared to 25% survival of mice immunized with the isogenic χ11017(pYA4858) (SifA⁺) strain. Reducing the number of booster immunizations with χ11246(pYA4858) from 3 to 2 resulted in 66% survival of mice challenged with rWSN (100 LD₅₀). Immunization with χ11246(pYA4858) via different routes provided protection in 80% orally, 100% intranasally and 100% intraperitoneally immunized mice against rWSN (100 LD₅₀). A Th1 type immune response was elicited against influenza NP in all experiments. IFN-γ secreting NP₁₄₇₋₁₅₅ specific T cells were not found to be correlated with protection. The role of antigen-specific CD8⁺ T cells remains to be determined. To conclude, we showed that Salmonella can be designed to deliver antigen(s) to the host cell cytosol for presumably class I presentation for the induction of protective immune responses.
authors.affiliation: The Biodesign Institute, Center for Infectious Diseases and Vaccinology, Arizona State University, Tempe, AZ 85287-5401, USA.
authors.forename: Shamaila
authors.initials: S
authors.lastname: Ashraf
authors.forename: Wei
authors.initials: W
authors.lastname: Kong
authors.forename: Shifeng
authors.initials: S
authors.lastname: Wang
authors.forename: Jiseon
authors.initials: J
authors.lastname: Yang
authors.forename: Roy
authors.initials: R
authors.lastname: Curtiss
mesh_terms: D000818:Animals; D003600:Cytosol / Q000382:microbiology; D005260:Female; D015395:Histocompatibility Antigens Class I / Q000378:metabolism; D007117:Immunization, Secondary; D007252:Influenza Vaccines / Q000008:administration & dosage* / Q000276:immunology; D007371:Interferon-gamma / Q000096:biosynthesis; D051379:Mice; D008807:Mice, Inbred BALB C; D019590:Nucleocapsid Proteins; D009975:Orthomyxoviridae / Q000472:pathogenicity; D009976:Orthomyxoviridae Infections / Q000276:immunology* / Q000517:prevention & control / Q000821:virology; D016601:RNA-Binding Proteins / Q000235:genetics / Q000276:immunology*; D012486:Salmonella typhimurium / Q000235:genetics* / Q000472:pathogenicity; D013601:T-Lymphocytes / Q000276:immunology*; D014611:Vaccination; D014613:Vaccines, Attenuated / Q000008:administration & dosage* / Q000276:immunology; D014614:Vaccines, Synthetic / Q000008:administration & dosage* / Q000276:immunology; D014758:Viral Core Proteins / Q000235:genetics / Q000276:immunology*
chemical_list: D015395:Histocompatibility Antigens Class I; D007252:Influenza Vaccines; C048842:NP protein, Influenza A virus; D019590:Nucleocapsid Proteins; D016601:RNA-Binding Proteins; D014613:Vaccines, Attenuated; D014614:Vaccines, Synthetic; D014758:Viral Core Proteins; D007371:Interferon-gamma