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Volume 9 Supplement 2

AIDS Vaccine 2012

Potency of an HIV-SAM™ vaccine in a heterologous prime-boost vaccination regimen


Recombinant alphavirus replicon particles (VRP), carrying self-amplifying RNA, protects rhesus macaques against SHIVSF162P4 challenge when used in prime-boost regimen.


Novartis has developed a synthetic self-amplifying mRNA (SAM™) vaccine platform that avoids limitations of cell culture production and employs synthetic non-viral vaccine delivery systems.


We evaluated systemic and mucosal immune responses in mice and rabbits using the SAM™ platform expressing HIV-1 gp140 (HIV-SAM™ vaccine) prime, protein/MF59 vaccine boost regimen for both HIV-1 Clade B and C Env antigens. In mice, the primed Env-specific IgG response to 1 µg of the HIV-SAM™ vaccine was comparable to a 10 µg dose of an identically formulated DNA vaccine, 10(7) IU of VRP, and 10 µg protein/MF59 vaccines. The HIV-SAM™ vaccine primed response could be boosted robustly by a protein/MF59 vaccine and resulted in a balanced IgG1, IgG2a subclass response, similar to that seen with the VRP vaccine, but unlike the dominant IgG1 response to protein/MF59 only vaccinations. Both Env-specific CD4+ and CD8+ T-cell responses were detectable after two HIV-SAM™ vaccinations. A TH1 type (IFNγ+, IL-5-) profile was demonstrable for the HIV-SAM™ vaccine primed, protein boosted CD4+ T-cell response, similar to that seen with the DNA or VRP primed protein boosted responses, in contrast to a TH2 type (IFNγlow, IL-5+) response seen with protein/MF59 vaccination. In rabbits, priming with the 25 or 50 µg of the formulated HIV-SAM™ vaccine induced robust and avid Env-binding IgG and HIV neutralizing antibodies that were superior to 500 µg of an unformulated DNA vaccine and comparable to VRP and protein/MF59 vaccines. In addition, protein/MF59 boostable Env-specific vaginal wash Ig was consistently demonstrable in both mice and rabbits immunized with the HIV-SAM™.


Together, these results suggest that HIV-SAM™ vaccine is potent and versatile and offers potential as a novel immune priming strategy. NIAID-NIH Grant 5P01AI066287.

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This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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Banerjee, K., Cu, Y., Sun, Y. et al. Potency of an HIV-SAM™ vaccine in a heterologous prime-boost vaccination regimen. Retrovirology 9 (Suppl 2), P312 (2012).

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  • Vaccine Delivery System
  • Boost Regimen
  • Vaginal Wash
  • Cell Culture Production
  • Replicon Particle