title: Pentamers not found in the universal proteome can enhance antigen specific immune responses and adjuvant vaccines.
abstract: Certain short peptides do not occur in humans and are rare or non-existent in the universal proteome. Antigens that contain rare amino acid sequences are in general highly immunogenic and may activate different arms of the immune system. We first generated a list of rare, semi-common, and common 5-mer peptides using bioinformatics tools to analyze the UniProtKB database. Experimental observations indicated that rare and semi-common 5-mers generated stronger cellular responses in comparison with common-occurring sequences. We hypothesized that the biological process responsible for this enhanced immunogenicity could be used to positively modulate immune responses with potential application for vaccine development. Initially, twelve rare 5-mers, 9-mers, and 13-mers were incorporated in frame at the end of an H5N1 hemagglutinin (HA) antigen and expressed from a DNA vaccine. The presence of some 5-mer peptides induced improved immune responses. Adding one 5-mer peptide exogenously also offered improved clinical outcome and/or survival against a lethal H5N1 or H1N1 influenza virus challenge in BALB/c mice and ferrets, respectively. Interestingly, enhanced anti-HBsAg antibody production by up to 25-fold in combination with a commercial Hepatitis B vaccine (Engerix-B, GSK) was also observed in BALB/c mice. Mechanistically, NK cell activation and dependency was observed with enhancing peptides ex vivo and in NK-depleted mice. Overall, the data suggest that rare or non-existent oligopeptides can be developed as immunomodulators and supports the further evaluation of some 5-mer peptides as potential vaccine adjuvants.
authors.affiliation: Special Pathogens Program, National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, Canada.
authors.forename: Ami
authors.initials: A
authors.lastname: Patel
authors.forename: Jessica C
authors.initials: JC
authors.lastname: Dong
authors.forename: Brett
authors.initials: B
authors.lastname: Trost
authors.forename: Jason S
authors.initials: JS
authors.lastname: Richardson
authors.forename: Sarah
authors.initials: S
authors.lastname: Tohme
authors.forename: Shawn
authors.initials: S
authors.lastname: Babiuk
authors.forename: Anthony
authors.initials: A
authors.lastname: Kusalik
authors.forename: Sam K P
authors.initials: SK
authors.lastname: Kung
authors.forename: Gary P
authors.initials: GP
authors.lastname: Kobinger
mesh_terms: D000818:Animals; D005289:Ferrets; D017325:Hepatitis B Vaccines / Q000276:immunology; D000949:Histocompatibility Antigens Class II / Q000276:immunology*; D007252:Influenza Vaccines / Q000276:immunology; D007694:Killer Cells, Natural / Q000276:immunology*; D051379:Mice; D008807:Mice, Inbred BALB C; D020543:Proteome / Q000276:immunology*
chemical_list: D017325:Hepatitis B Vaccines; D000949:Histocompatibility Antigens Class II; D007252:Influenza Vaccines; D020543:Proteome