title: Non-immunogenicity of overlapping gag peptides pulsed on autologous cells after vaccination of HIV infected individuals.
abstract: BACKGROUND
  HIV Gag-specific CD4+ and CD8+ T-cell responses are important for HIV immune control. Pulsing overlapping Gag peptides on autologous lymphocytes (OPAL) has proven immunogenic and effective in reducing viral loads in multiple pigtail macaque studies, warranting clinical evaluation.
  
  
  METHODS
  We performed a phase I, single centre, placebo-controlled, double-blinded and dose-escalating study to evaluate the safety and preliminary immunogenicity of a novel therapeutic vaccine approach 'OPAL-HIV-Gag(c)'. This vaccine is comprised of 120 15mer peptides, overlapping by 11 amino acids, spanning the HIV Gag C clade sequence proteome, pulsed on white blood cells enriched from whole blood using a closed system, followed by intravenous reinfusion. Patients with undetectable HIV viral loads (<50 copies/ml plasma) on HAART received four administrations at week 0, 4, 8 and 12, and were followed up for 12 weeks post-treatment. Twenty-three people were enrolled in four groups: 12 mg (n = 6), 24 mg (n = 7), 48 mg (n = 2) or matching placebo (n = 8) with 18 immunologically evaluable. T-cell immunogenicity was assessed by IFNγ ELIspot and intracellular cytokine staining (ICS).
  
  
  RESULTS
  The OPAL-HIV-Gag(c) peptides were antigenic in vitro in 17/17 subjects. After vaccination with OPAL-HIV-Gag(c), 1/6 subjects at 12 mg and 1/6 subjects at 24 mg dose groups had a 2- and 3-fold increase in ELIspot magnitudes from baseline, respectively, of Gag-specific CD8+ T-cells at week 14, compared to 0/6 subjects in the placebo group. No Gag-specific CD4+ T-cell responses or overall change in Rev, Nef, Tat and CMV specific responses were detected. Marked, transient and self-limiting lymphopenia was observed immediately post-vaccination (4 hours) in OPAL-HIV-Gag(c) but not in placebo recipients, with median fall from 1.72 to 0.67 million lymphocytes/mL for active groups (P<0.001), compared to post-placebo from 1.70 to 1.56 lymphocytes/ml (P = 0.16).
  
  
  CONCLUSIONS
  Despite strong immunogenicity observed in several Macaca nemestrina studies using this approach, OPAL-HIV-Gag(c) was not significantly immunogenic in humans and improved methods of generating high-frequency Gag-specific T-cell responses are required.
  ClinicalTrials.gov, Registry number: NCT01123915, URL trial registry database: http://www.clinicaltrials.gov/ct2/results?term=OPAL-HIV-1001&Search=Search.
authors.affiliation: Department of Paediatrics, University of Oxford, Oxford, United Kingdom ; KwaZulu-Natal Research Institute for Tuberculosis and HIV (K-RITH), Nelson R Mandela School of Medicine, University of Kwazulu-Natal, Durban, KwaZulu-Natal, South Africa ; Department of International Health, Immunology and Microbiology, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Henrik N
authors.initials: HN
authors.lastname: Kløverpris
authors.forename: Akil
authors.initials: A
authors.lastname: Jackson
authors.forename: Amanda
authors.initials: A
authors.lastname: Handley
authors.forename: Peter
authors.initials: P
authors.lastname: Hayes
authors.forename: Jill
authors.initials: J
authors.lastname: Gilmour
authors.forename: Lynn
authors.initials: L
authors.lastname: Riddell
authors.forename: Fabian
authors.initials: F
authors.lastname: Chen
authors.forename: Mark
authors.initials: M
authors.lastname: Atkins
authors.forename: Marta
authors.initials: M
authors.lastname: Boffito
authors.forename: Bruce D
authors.initials: BD
authors.lastname: Walker
authors.forename: Jim
authors.initials: J
authors.lastname: Ackland
authors.forename: Mark
authors.initials: M
authors.lastname: Sullivan
authors.forename: Philip
authors.initials: P
authors.lastname: Goulder
mesh_terms: D016915:AIDS Vaccines / Q000276:immunology* / Q000627:therapeutic use*; D000293:Adolescent; D000328:Adult; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology; D005260:Female; D015658:HIV Infections / Q000276:immunology* / Q000517:prevention & control*; D006801:Humans; D007371:Interferon-gamma / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D055815:Young Adult
chemical_list: D016915:AIDS Vaccines; D007371:Interferon-gamma