Centrifuged mucosal samples (diluted 1:10) were passed over the chip surface at a flow rate of 30 l/min for 3 min, followed by a 5-min dissociation period

Centrifuged mucosal samples (diluted 1:10) were passed over the chip surface at a flow rate of 30 l/min for 3 min, followed by a 5-min dissociation period. mucosal IgG to the gp120 variable region 2 (V2) and the expression of 12 genes, ten of which are part of the RAS pathway. The association between RAS activation and vaccine efficacy was also observed in an independent efficacious SIV-vaccine approach. Whether RAS activation, mucosal ILCs and antibodies to V2 are also important hallmarks of HIV-vaccine efficacy in humans will require further studies. The RV144 HIV-vaccine trial, which used ALVACCHIV and AIDSVAX HIV gp120, clade B and E proteins formulated in alum, resulted in limited but significant (= 0.04) protection from HIV acquisition1. Serum IgG antibodies against Env variable region 1 (V1) and V2 were inversely correlated with the risk of HIV-1 infection2, and sieve analysis demonstrated genetic markers of immunologic pressure at positions 169 and 181 of V2 (ref. 3). Monomeric serum IgA to HIV-Env was positively correlated with the risk of HIV-1 acquisition and inhibited IgG-mediated, antibody-dependent cell cytotoxicity (ADCC)2, 4. The correlate analyses pointed to the importance of antibodies for protection, which suggests that changing the formulation of the gp120 antigen to include a more immunogenic adjuvant could improve vaccine efficacy. Alum is a T helper (Th) cell 2Cinducing adjuvant, whereas the oil-in-water emulsion MF59 adjuvant elicits Th1 and Th2 responses and affects antibody isotypes in an antigen-dependent manner5. Importantly, MF59 has been proposed as the adjuvant of choice for the next set of ALVAC + gp120 vaccine trials in humans, which will be conducted in South Africa (http://vaccineenterprise.org/content/P5Partnership). Prior macaque studies demonstrated that the administration of ALVACCSIV, either alone or in combination with Presapogenin CP4 gp120, induced protection against SIVmac251 acquisition, depending on the dosage of challenge6C8. Here we tested whether we could recapitulate the protection observed in RV144 by using the ALVAC + gp120 alumCSIV vaccine in macaques, and we took advantage of the similar vaccine efficacy conferred by this model to identify systemic and mucosal correlates of risk of SIVmac251 acquisition. Finally, we tested whether the MF59 adjuvant improves the efficacy of this vaccine regimen. Surprisingly, we observed no vaccine efficacy, despite the ability of MF59 to induce Rabbit polyclonal to AP3 higher immune responses than alum. The reduced risk of virus acquisition in the alum-vaccine group was associated with the induction of mucosal ILCs and mucosal antibodies to V2 that were correlated with the expression of ten of 12 genes that constitute part of the RAS pathway. Further studies will be required to assess whether these results in macaques can be extended to HIV vaccines for humans. RESULTS Alum but not MF59 reduced the risk of SIVmac251 acquisition 54 rhesus macaques were assigned to two vaccine arms that controlled for the major histocompatibility complex (MHC)-I alleles present, age, weight and gender. All macaques were primed twice, at week 0 and week 4, with ALVACCSIV, and received two boosters, one each at week 12 and week 24, Presapogenin CP4 with ALVACCSIV together with the gD-g p120 M766 and gD-gp120 CG7V formulated either in Presapogenin CP4 alum (= 27) or MF-59 (= 27). We used two gp120 Presapogenin CP4 proteins that differ in their amino acid sequence to emulate RV144 that used the gp120 clades E and B (ref. 1) (Fig. 1a). Of note, because MF59 is dose sparing, the amount of gp120 in the boosters was halved for the latter group (alum, 200 g; MF59, 100 g). An additional 47 unvaccinated macaquesof those, 24 concurrent and 23 historicalwere used as controls that matched vaccinated animals (weight, gender and MHC-I alleles; Supplementary Fig. 1aCF). Our study was powered to compare the relative vaccine efficacy in vaccinated macaques with placebo controls, but not to compare vaccine efficacy between the two regimens. We challenged animals intrarectally weekly with ten repeated low doses of SIVmac251, starting 4 weeks after the final immunization. The time Presapogenin CP4 of challenge was chosen to model early exposure after vaccination, given that high-risk volunteers in HIV-vaccine trials may be exposed to the virus soon after vaccination. Vaccination with ALVACCSIV + gp120 alum reduced the risk of SIVmac251 acquisition relative to unvaccinated controls (logCrank test; = 0.020), showing an estimated vaccine efficacy of 44% at each challenge (Fig. 1b). By contrast, the ALVACCSIV + gp120 MF59 vaccine regimen did not reduce the risk of infection (logCrank test, = 0.562; Fig. 1c). Whether the outcome would differ with a later challenge will require further experimentation. Quantitation of mucosal Ki67+CD4+ cells and circulating CD4+ T cells that expressed the activation markers Ki67.

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