Intranasal delivery of DNA IL-12 during mucosal DNA-Prime/MVA-Boost immunization schemes enhanced the cellular immune response against HIV-1 Env antigen

ANA MARÍA RODRIGUEZ; DANIELA MÓNACO; MARIANO ESTEBAN; HORACIO SALOMÓN; M.MAGDALENA GHERARDI

Amsterdam, Holanda.

Conferencia; AIDS Vaccine 2006; 2006

Background: As the major route of HIV transmission is through the exposure of mucosal surfaces to the virus, designing of mucosal immunization regimes aimed to induce mucosal immune responses is highly needed. Objectives: To analyze the mucosal action of IL-12 alone or in combination with the subunit B of cholera toxin (CTB), applied in DNA-prime/MVA-boost intranasal immunization (in) schemes. Different groups of Balb/c mice were immunized by intranasal route with a heterologous DNA prime-MVA boost regimen, in which both vectors express the HIV- Env subtype B protein. Some groups of mice received DNAIL-12 (50 ug) at priming, in the presence or not of 50 mg of CTB applied at prime and booster doses. Prime and boost doses were spaced by 14 days and 10 days after boosting, mice were sacrificed and the different samples obtained to evaluate the cellular immune response generated. Results: Groups of mice in which DNAIL-12 was co-inoculated with the DNAenv plasmid showed the highest specific cellular immune response in the spleen; evaluated as IFN-g  secreting cells assayed by ELISPOT, and cytokine levels after specific re-stimulation. This enhancement appears to be dose-dependent since in the group in which DNAIL-12 dose was of 100mg the response was four-fold higher than in control mice: (DNAenv-MVAenv), while the enhancement observed was two-fold superior when 50mg of DNAIL-12 was applied. The response generated in groups inoculated with either 50mg or 100mg was equivalent or even higher than that induced in mice co-inoculated with cholera toxin (CT) in both prime and booster doses.  Co-inoculation of CTB with DNAIL-12 generated a reduction, or a similar response, to that induced in its absence depending on the dose of DNAIL-12 administered. Significant responses at both genito-rectal and regional draining lymph nodes were detected in the group which received the higher IL-12 dose. When specific IL-2 secretion was also determined, significant responses were generated in animals co-inoculated with CT and in those in which received 100 mg of DNAIL-12. Conclusion: Mucosal DNAIL-12 administration resulted effective to improve the immunogenicity of DNA/MVA schemes after intranasal route. Further evaluation of both cellular and humoral immune responses at mucosal sites will be carried out. These results are of importance due to the need to improve mucosal vaccine strategies against HIV.