Recent studies have shown that the HIV elite controllers have elevated numbers of high avidity polyfunctional cytotoxic HIV Gag-specific CD8+ T-cells in the mucosae compare to the HIV progressors [11], [12] and [13]. HIV transmits mostly via the genital tract or rectal mucosa and the first CD4 T cell depletion occurs in the gut mucosae [14]. It is now established that HIV is a disease of the mucosae, thus a mucosal vaccine approach may prove more useful in preventing and controlling HIV infection [15] and [16]. Unfortunately, due to the complexities

associated with delivery, safety and evaluation of vaccines efficacy in the mucosae, no mucosal HIV vaccine strategy has yet entered clinical development. Belyakov and PR-171 nmr co-workers have demonstrated that the intra-rectal immunisation induces local mucosal compartmentalisation of CTL of high “functional avidity” and protection of gastrointestinal CD4+ T cells from SHIV viral depletion in rhesus macaques compared to systemic delivery [17] and [18]. Consistent to their finding we have also found that i.m. rDNA/i.n. rFPV can induce

improved protection in macaques [19]. Since then in our laboratory we have studied the immune outcomes induced following mucosal and systemic heterologous prime-boost vaccination of antigenically distinct poxvirus vectors, Avipoxvirus Bleomycin research buy fowlpox virus (FPV)-HIVgag/pol prime followed by an attenuated Orthopoxvirus vaccinia virus (VV)-HIVgag/pol booster vaccination [20]. These studies have shown that according to the route of vaccine delivery the quality or avidity of HIV-specific CD8 T cells can be vastly different and specifically, IL-13 and IL-4 have an inhibitory influence upon the development of high avidity CD8+ T cell responses. Our data has demonstrated that (i) mucosal vaccination

the can induce high avidity HIV-specific CD8+ T cells with reduced IL-4/IL-13 activity and better protective efficacy [21], (ii) IL-13 in the cell milieu has a direct negative impact upon CD8+ T cell avidity [22] and (iii) direct neutralisation of endogenous IL-13 activity using a high affinity cytokine receptor, IL-13Rα2 adjuvanted HIV vaccines delivered intranasal/intramuscular strategy can induce high avidity systemic and mucosal HIV-gag specific CD8+ T cell responses, with enhanced cytokine/chemokine expression and greater protective efficacy [23]. Surprisingly, transient inhibition of IL-13 activity at the site of immunisation in wild-type mice generated similar CD8+ T cell responses in regards to avidity and anti-viral protection as IL-13−/− gene knockout mice immunised with control vaccines [23]. Cytokines IL-4 and IL-13 share sequence similarity, cell surface receptor subunits, intracellular signalling and relatively similar functional effects on cells.