Previously, priming rhesus macaques with Adenovirus type 5 host range mutant-recombinants

Previously, priming rhesus macaques with Adenovirus type 5 host range mutant-recombinants encoding Tat and Env and boosting with Tat and Env protein in MPL-SE controlled chronic viremia by 4 logs following homologous intravenous SHIV89. for protective PCDH9 efficacy. prime/Tat protein boosting regimen conferred no protection at all (Demberg et al., 2007). In comparison with a multigenic regimen (incorporating Env, Gag, Nef and Tat immunogens) which reduced chronic viremia only 3 logs, the better chronic phase protection resulting from the Tat/Env regimen was associated with higher binding titers to Tat and Env and better antibody-dependent cellular cytotoxicity (ADCC) mediating antibodies (Florese et al., MGCD0103 2009). This result is in agreement with several other studies in non-human primate models of SIV and SHIV infection, in which vaccine-elicited high avidity antibodies mediating ADCC as well as antibody-dependent cell-mediated viral inhibition (ADCVI) are correlated with partial protection and control of viremia (Gomez-Roman et al., 2005; Hidajat et al., 2009; Xiao et al., 2010). Moreover, it is believed that the 30% protection achieved in the recent clinical vaccine trial in Thailand (RV144) (Rerks-Ngarm et al., 2009) was conferred at least in part by ADCC- mediating antibodies. Ninety-nine percent of vaccinees exhibited binding antibodies to gp120 and 2/3 of them had detectable ADCC titers to gp120-coated target cells (Haynes et al., 2011). The design of our previous Tat/Env study lacked an envelope only vaccine group, so we could not distinguish the contribution to protective efficacy of Env versus Tat. Moreover, the dual tropic SHIV89.6p challenge was homologous to the immunogens. Here we have addressed these issues, MGCD0103 and report our findings from a study comparing immunogenicity and protective efficacy of a Tat plus Env immunization regimen to Tat only and Env only regimens followed by a heterologous R5 tropic SHIV1157ipd3N4 challenge. Results Cytokines/chemokines induced by Ad-recombinant vaccination To determine if Tat expressed by Ad5hr-HIVtat could potentially modulate immune responses, we examined MGCD0103 induction by Ad-recombinant priming of cytokines and chemokines, representative of both innate and adaptive acute immune responses, in PBMC and bronchoalveolar lavage (BAL) cells. In PBMC, 2 weeks after the first Ad immunization, only MIP-1 was consistently up-regulated more than 2-fold in all groups including the control group which received Ad empty vector (Fig. 1A). MIP-1 and IL-15 were not up-regulated in any group. Up-regulation of the remaining cytokines/chemokines across the 4 groups was sporadic. Three days following the second Ad immunization, only IFN- and MIP-1 were consistently up-regulated more than 2-fold in all groups (Fig. 1B). By 8 days after the second Ad, only IFN- exhibited greater than 2-fold up-regulation in all but the controls (Fig. 1C). Fig. 1 Real time PCR evaluation of cytokine and chemokine responses after Ad priming in PBMC and BAL BAL cells were examined as representative of a mucosal effector site. Two weeks after the first Ad immunization (intra-nasal) they showed cytokine/chemokine levels higher than those observed in PBMC after the first Ad prime (Fig. 1D). TNF-, IL-10, MIP-1 and IL-8 were consistently up-regulated more than 2-fold in all 4 macaque groups, as were IFN- and MIP-1 in all but the controls. Rantes was only up-regulated in the Env immunization group. As with the PBMC, significant differences between responses by the Ad-recombinants compared to the Ad empty vector were not obtained. Two weeks after the second Ad immunization (intratracheal) we observed stronger responses in the lung compared to responses following the first Ad administration (Fig. 1E), likely reflecting improved targeting of Ad-recombinants to the upper respiratory tract. All cytokines/chemokines measured were up-regulated more than 2-fold. Overall, data in both PBMC and BAL showed no evidence of modulation of cytokine/chemokine responses by the inserted genes in the Ad recombinants. Rather, results obtained were in response to the vector itself. Cellular responses In the previous Tat/Env study, vaccine-elicited cellular immune responses were.