Antigenic Competition in HIV Preventive Vaccines
Condition: HIV Infections
MeSH terms: HIV Infections
Study type: Interventional
Phase: Phase 1

Summary: 
      HIV vaccines are designed to create an immune response to certain components of the HIV virus
      called peptides. Previous research indicates that one peptide, called Gag, may be
      particularly important for stimulating an immune response to HIV. Many vaccines being studied
      combine multiple peptides, but including other peptides may weaken the body's response to
      Gag. This study will test whether a vaccine that targets Gag and another peptide called Env
      is better than a vaccine without Env at causing an immune response to Gag.
    

Detailed description: 
      HIV vaccines are designed to create an immune response to certain parts of the HIV virus
      called peptides. Researchers believe that eliciting a response to a peptide called Gag is
      particularly important. Most HIV vaccines in current clinical trials combine multiple
      peptides, but including these other peptides may cause antigenic competition. Antigenic
      competition occurs when the body's immune system reaction to one part of a vaccine weakens or
      inhibits the response to another part of the vaccine. Specifically, this study is concerned
      that having too many other peptides in a vaccine might weaken the specific immune response to
      Gag. This study will test whether a vaccine which only includes the peptides Gag and Pol
      elicits a stronger immune response to Gag and Pol than a vaccine that also includes the
      peptides Env A, B, and C.

      Participation in this study will last 6 months. The number of study visits will vary by study
      site. Participants will be randomly assigned to receive injections of one of two vaccines in
      their upper arm. One group of participants will receive rAd5 gag/pol, which contains only the
      Gag and Pol peptides, while the other group of participants will receive rAd5 gag/pol Env
      A/B/C, which contains the Gag, Pol, and Env A, B, and C peptides. For 3 days after injection,
      participants will need to record their temperature and any side effects, and they will be
      contacted by study staff 7 days after the injection for follow-up monitoring.

      During study visits, participants will complete the following assessments: an HIV test; a
      physical exam; collection of blood samples; a pregnancy test; and an interview about health,
      medications, HIV risk behaviors, and experiences with the study.

      Participants will be contacted by study staff once a year for 5 years after the vaccination
      for follow-up health and safety monitoring.
    

Intervention name(s): rAd5 Gag-Pol Env A/B/C; rAd5 Gag-Pol
Intervention type(s): Biological; Biological
Intervention description(s): 1×10^10 particle units (PU) rAd5 Gag-Pol, Env A/B/C (3:1:1:1 mixture) delivered via intramuscular injection; 5×10^9 PU rAd5 Gag-Pol delivered via intramuscular injection
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Double (Participant, Care Provider)
Primary purpose: Prevention
Keywords: HIV Preventive Vaccine; HIV Seronegativity