Chemokine Adjuvanted Electroporated-DNA Vaccine Induces Substantial Protection from Simian Immunodeficiency Virus Vaginal Challenge

There have been encouraging results for the development of an effective HIV vaccine. However, many questions remain regarding the quality of immune responses and the role of mucosal antibodies. We addressed some of these issues by using a simian immunodeficiency virus (SIV) DNA vaccine adjuvanted with plasmid-expressed mucosal chemokines combined with an intravaginal SIV challenge in rhesus macaque (RhM) model. We previously reported on the ability of CCR9 and CCR10 ligand (L) adjuvants to enhance mucosal and systemic IgA and IgG in small animals. In this study, RhMs were intramuscularly immunized five times with either DNA or DNA plus chemokine adjuvant delivered by electroporation followed by challenge with SIVsmE660. Sixty-eight percent of all vaccinated animals (P=0.0016) remained either uninfected or had aborted infection compared to only 14% in the vaccine naïve group. The highest protection was observed in the CCR10L chemokines group, where 6 of 9 animals had aborted infection and two remained uninfected, leading to 89% protection (P=0.0003). The induction of mucosal SIV-specific antibodies and neutralization titers correlated with trends in protection. These results indicate the need to further investigate the contribution of chemokine adjuvants to modulate immune responses and the role of mucosal antibodies in SIV/HIV protection.