The influence of adjuvant on UreB protection against Helicobacter pylori through the diversity of CD4+ T-cell epitope repertoire

// Bin Li 1 , Hanmei Yuan 1 , Li Chen 2 , Heqiang Sun 1 , Jian Hu 3, 4 , Shanshan Wei 4 , Zhuo Zhao 1 , Quanming Zou 1 and Chao Wu 1 1 National Engineering Research Center of Immunological Products, Department of Microbiology and Biochemical Pharmacy, College of Pharmacy, Third Military Medical University, Chongqing, PR China 2 Department of Blood Transfusion, Xinqiao Hospital, Third Military Medical University, Chongqing, PR China 3 Department of Intensive Care Unit, Chengdu Military General Hospital, Chengdu, PR China 4 Department of Gastroenterology, Xinqiao Hospital, Third Military Medical University, Chongqing, PR China Correspondence to: Chao Wu, email: wuchao99261@163.com Quanming Zou, email: qmzou2007@163.com Keywords: adjuvants, vaccine, protection, immunodominant, epitopes Received: March 14, 2017     Accepted: June 20, 2017     Published: July 12, 2017 ABSTRACT Adjuvants are widely used to enhance the effects of vaccines against pathogen infections. Interestingly, different adjuvants and vaccination routes usually induce dissimilar immune responses, and can even have completely opposite effects. The mechanism remains unclear. In this study, urease B subunit (UreB), an antigen of Helicobacter pylori ( H. pylori ) that can induce protective immune responses, was used as a model to vaccinate mice. We investigated the effects of different adjuvants and routes on consequent T cell epitope-specific targeting and protection against H. pylori infection. Comparison of the protective effects of UreB, administered either subcutaneously ( sc ) or intranasally ( in ), with the adjuvants AddaVax ( sc ), Complete Freund’s adjuvant (CFA; sc ), or CpG oligonucleotide (CpG; sc or in ), indicated that only CFA ( sc ) and CpG ( in ) were protective. Protective vaccines induced T cells targeting epitopes that differed from that targeted by control vaccination. Subsequent peptide vaccination demonstrated that only two of the identified epitopes were protective: UreB 373–385 and UreB 317–329. Overall, we found that both adjuvant and vaccination route affected the T cell response repertoire to antigen epitopes. The data obtained in this study contribute to improved characterization of the relationship between adjuvants, routes of vaccination, and epitope-specific T cell response repertoires.