Enhanced efficacy of a DNA vaccine based in Semiliki virus vectors expressing the complete glycoprotein G (G) of Vesicular Stomatitis Virus (VSV) in priming cellular and humoral immune responses in mice

LORENA OGAS, OLGA FRANCO, EDUARDO SCODELLER, ALEJANDRA CAPOZZO, PABLO GRIGERA.

Viña del Mar. Chile.

Congreso; 9th Latin American Congress of Immunology; 2009

We studied the  immunogenicity of plasmid DNA vaccines based in Semliki Forest virus-based replicative vectors (pSFV) compared to a conventional cytomegalovirus promoter-driven DNA vector (pCDNA), both expressing  the complete VSV-G or a deleted version (dG) respectively. Following an heterologous prime-boost immunization schedule, groups of 5 BALB/c female (6-8 week old) received 2 doses (i.m.,2 weeks apart) of 100ug of pSFV or pCMV (i.m.) expressing VSV-G, and were boosted 14 days later with 0.1ug of inactivated VSV. Animals primed with pSFV-G elicited the highest titers of specific antibodies with balanced IgG1-IgG2a levels, significantly higher those vaccinated with pSFV expressing dG.  Low humoral responses where found in mice vaccinated with conventional pCMV vectors. All immunization-schemes elicited IFN-g responses enhanced by an unspecific stimulation by pSFV. The results presented in this work show that genetic immunization with VSV-G using the platform of SFV induces a remarkable immune response, much more than the expected for a standard DNA vaccine. These results can be explained based on the particularity of this system to induce the formation in vivo of viral particles after injection of DNA.