Using a unique vaccine antigen matched and single HIV Clade C approach we have assessed the immunogenicity of a DNApoxvirus-protein
strategy in mice and rabbits, administering MVA and protein immunizations either sequentially or
simultaneously and in the presence of a novel TLR4 adjuvant, GLA-AF. Mice were vaccinated with combinations of HIV env/
gag-pol-nef plasmid DNA followed by MVA-C (HIV env/gag-pol-nef) with HIV CN54gp140 protein (+/2GLA-AF adjuvant) and
either co-administered in different muscles of the same animal with MVA-C or given sequentially at 3-week intervals. The
DNA prime established a population of B cells that were able to mount a statistically significant anamnestic response to the
boost vaccines. The greatest antigen-specific antibody response was observed in animals that received all vaccine
components. Moreover, a high proportion of the total mucosal IgG (20 – 50%) present in the vaginal vault of these
vaccinated animals was vaccine antigen-specific. The potent elicitation of antigen-specific immune responses to this vaccine
modality was also confirmed in rabbits. Importantly, co-administration of MVA-C with the GLA-AF adjuvanted HIV
CN54gp140 protein significantly augmented the antigen-specific T cell responses to the Gag antigen, a transgene product
expressed by the MVA-C vector in a separate quadriceps muscle. We have demonstrated that co-administration of MVA and
GLA-AF adjuvanted HIV CN54gp140 protein was equally effective in the generation of humoral responses as a sequential
vaccination modality thus shortening and simplifying the immunization schedule. In addition, a significant further benefit of
the condensed vaccination regime was that T cell responses to proteins expressed by the MVA-C were potently enhanced,
an effect that was likely due to enhanced immunostimulation in the presence of systemic GLA-AF.