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Alphavirus replicon particles as candidate HIV vaccines.
Nancy L Davis1, Ande West, Elizabeth Reap
1Department of Microbiology and Immunology, University of North Carolina, Chapel Hill 27599, USA. joiner@med.unc.edu
IUBMB Life
|July 18, 2002
Summary
Venezuelan equine encephalitis virus (VEE) replicon particles (VRPs) show promise as vaccines. VRPs expressing SIV antigens induced neutralizing antibodies and CTLs in macaques, reducing viral loads after challenge.
Area of Science:
- Virology
- Immunology
- Vaccine Development
Background:
- Venezuelan equine encephalitis virus (VEE) replicon particles (VRPs) utilize self-replicating RNA for high-level immunogen expression.
- VEE biology enables expression in lymph nodes and induction of mucosal immunity.
- VRPs are engineered to express foreign genes, replacing viral structural proteins.
Purpose of the Study:
- To evaluate VRPs as a vaccine platform for infectious diseases.
- To assess the impact of VRP envelope glycoprotein mutations on immune responses.
- To test VRPs expressing SIV antigens in macaques and a VRP HIV vaccine candidate.
Main Methods:
- VRPs were constructed using VEE replicase and helper RNAs expressing foreign genes (GFP, HA, SIV antigens).
- Experiments involved immunizing mice and macaques with VRPs, followed by challenge studies.
- A candidate VRP HIV vaccine expressing Clade C Gag was manufactured for a Phase I trial.
Main Results:
- Mutations in VRP envelope glycoproteins influenced lymph node targeting and immune response efficiency in mice.
- VRPs expressing SIV antigens induced neutralizing antibodies and CTLs in macaques.
- Vaccinated macaques showed reduced viral loads and preserved CD4 counts after SIV challenge.
Conclusions:
- VRPs are a viable vaccine platform, demonstrating efficacy in preclinical models.
- Further development of VRP-based vaccines, including for HIV, is warranted.
- VRP technology holds potential for inducing robust and protective immune responses.