title: Killed Bacillus subtilis spores as a mucosal adjuvant for an H5N1 vaccine.
abstract: Heat killed spores of the Gram-positive bacterium Bacillus subtilis have been evaluated as a vaccine delivery system with mucosal adjuvant properties for influenza. Killed spores were able to bind H5N1 virions (NIBRG-14; clade 1) and, when intra-nasally administered to mice, resulting immune responses, both humoral and cell mediated, were enhanced compared to immunization with the virion alone. Levels of both systemic IgG and mucosal sIgA specific to the virion were elevated. Levels of IgG2a (a Th(1) antibody type) were strongly enhanced when the virion was co-administered with killed spores. Cytokine induction in stimulated splenocytes was also apparent indicating balanced T(h)1 and T(h)2 responses. Evidence of cross-neutralization of clade 2.2 viruses was shown. In a challenge experiment mice dosed two times with spores adsorbed with just 20 ng HA (hemagglutinin) of inactivated NIBRG-14 were fully protected against challenge with 20 LD(50) of H5N2 virus. Interestingly, partial protection (60%) was observed in animals dosed only with killed spores. Mice dosed only with killed spores were shown to be fully protected against H5N2 (5 LD(50)) infection indicating that innate immunity and its stimulation by spores may play an important role in protection. Supporting this killed spores were (i) shown to stimulate TLR-mediated expression of NF-κB, and (ii) able to recruit NK cells into lungs and induce maturation of DCs. This work demonstrates the potential and underlying mechanism for the use of bacterial spores as an adjuvant for H5N1 vaccination.
authors.affiliation: Laboratory Science Division, International Vaccine Institute, Seoul 151-818, Republic of Korea.
authors.forename: Manki
authors.initials: M
authors.lastname: Song
authors.forename: Huynh A
authors.initials: HA
authors.lastname: Hong
authors.forename: Jen-Min
authors.initials: JM
authors.lastname: Huang
authors.forename: Claire
authors.initials: C
authors.lastname: Colenutt
authors.forename: Dinh Duy
authors.initials: DD
authors.lastname: Khang
authors.forename: Thi Van Anh
authors.initials: TV
authors.lastname: Nguyen
authors.forename: Sung-Moo
authors.initials: SM
authors.lastname: Park
authors.forename: Byoung-Shik
authors.initials: BS
authors.lastname: Shim
authors.forename: Ho Hyun
authors.initials: HH
authors.lastname: Song
authors.forename: In Su
authors.initials: IS
authors.lastname: Cheon
authors.forename: Ji Eun
authors.initials: JE
authors.lastname: Jang
authors.forename: Jung-ah
authors.initials: JA
authors.lastname: Choi
authors.forename: Young Ki
authors.initials: YK
authors.lastname: Choi
authors.forename: Konrad
authors.initials: K
authors.lastname: Stadler
authors.forename: Simon M
authors.initials: SM
authors.lastname: Cutting
mesh_terms: D000276:Adjuvants, Immunologic / Q000008:administration & dosage*; D000281:Administration, Intranasal; D000818:Animals; D057134:Antibodies, Neutralizing / Q000097:blood; D000914:Antibodies, Viral / Q000032:analysis / Q000097:blood; D001412:Bacillus subtilis / Q000276:immunology*; D003429:Cross Reactions; D016207:Cytokines / Q000096:biosynthesis; D004195:Disease Models, Animal; D005260:Female; D018928:Immunity, Mucosal; D007070:Immunoglobulin A / Q000032:analysis; D007074:Immunoglobulin G / Q000097:blood; D053124:Influenza A Virus, H5N1 Subtype / Q000276:immunology*; D053125:Influenza A Virus, H5N2 Subtype / Q000276:immunology / Q000472:pathogenicity; D007252:Influenza Vaccines / Q000008:administration & dosage / Q000276:immunology*; D007963:Leukocytes, Mononuclear / Q000276:immunology; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D009976:Orthomyxoviridae Infections / Q000517:prevention & control; D013154:Spleen / Q000276:immunology; D013171:Spores, Bacterial / Q000276:immunology*; D016019:Survival Analysis
chemical_list: D000276:Adjuvants, Immunologic; D057134:Antibodies, Neutralizing; D000914:Antibodies, Viral; D016207:Cytokines; D007070:Immunoglobulin A; D007074:Immunoglobulin G; D007252:Influenza Vaccines