title: Mimotopes selected by biopanning with high-titer HIV-neutralizing antibodies in plasma from Chinese slow progressors.
abstract: OBJECTIVE
  One approach to identifying HIV-1 vaccine candidates is to dissect the natural antiviral immune response in treatment-naïve individuals infected for over ten years, considered slow progressor patients (SPs). It is suspected that SP plasma has strongly neutralizing antibodies (NAb) targeting specific HIV viral epitopes.
  
  
  METHODS
  NAbs levels of 11 HIV-1-infected SPs were detected by PBMC-based neutralization assays. To investigate SP NAb epitope, this study used a biopanning approach to obtain mimotopes of HIV-1 that were recognized by SP plasma NAbs. IgG was purified from high-titer NAb SP plasma, and used as the ligand for three rounds of biopanning to select HIV-specific mimotopes from a phage-displayed random peptide library. Double-antibody sandwich ELISA, competitive inhibition assays, and peptide sequence analysis were used to evaluate the characteristics of phage-borne mimotopes.
  
  
  RESULTS
  SPs had significantly more plasma neutralizing activity than typical progressors (TPs) (p=0.04). P2 and P9 plasma, which have highest-titer HIV-NAb, were selected as ligands for biopanning. After three rounds of biopanning, 48 phage clones were obtained, of which 22 clones were consistent with requirement, binding with HIV-1 positive plasma and unbinding with HIV-1 negative plasma. Compared with linear HIV-1 protein sequence and HIV-1 protein structure files, only 12 clones were possible linear mimotopes of NAbs. In addition, the C40 clone located in gp41 CHR was found to be a neutralizing epitope, which could inhibit pooled HIV-1 positive plasma reaction.
  
  
  CONCLUSIONS
  Biopanning of serum IgG can yield mimotopes of HIV-1-related antigen epitopes. This methodology provides a basis for exploration into HIV-1-related antigen-antibody interactions and furthers NAb immunotherapy and vaccine design.
authors.affiliation: Key Laboratory of Immunology of AIDS, Ministry of Health, The First Affiliated Hospital, China Medical University, Shenyang, Liaoning, China.
authors.forename: Xiaoli
authors.initials: X
authors.lastname: Zhang
authors.forename: Xiaoxu
authors.initials: X
authors.lastname: Han
authors.forename: Di
authors.initials: D
authors.lastname: Dai
authors.forename: Mingjia
authors.initials: M
authors.lastname: Bao
authors.forename: Zining
authors.initials: Z
authors.lastname: Zhang
authors.forename: Min
authors.initials: M
authors.lastname: Zhang
authors.forename: Tristan
authors.initials: T
authors.lastname: Bice
authors.forename: Min
authors.initials: M
authors.lastname: Zhao
authors.forename: Yaming
authors.initials: Y
authors.lastname: Cao
authors.forename: Hong
authors.initials: H
authors.lastname: Shang
mesh_terms: D057134:Antibodies, Neutralizing / Q000276:immunology*; D002681:China; D003429:Cross Reactions; D004797:Enzyme-Linked Immunosorbent Assay; D000939:Epitopes / Q000276:immunology*; D015483:HIV Antibodies / Q000276:immunology*; D015699:HIV Envelope Protein gp120 / Q000276:immunology; D015700:HIV Envelope Protein gp41 / Q000276:immunology; D015658:HIV Infections / Q000276:immunology*; D015497:HIV-1 / Q000276:immunology*; D006801:Humans; D019151:Peptide Library
chemical_list: D057134:Antibodies, Neutralizing; D000939:Epitopes; D015483:HIV Antibodies; D015699:HIV Envelope Protein gp120; D015700:HIV Envelope Protein gp41; D019151:Peptide Library