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Vaccari et al . report that SIV vaccines formulated with two different adjuvants elicit distinct immune responses and effects on SIV acquisition in rhesus macaques. A recombinant vaccine containing Aventis Pasteur's canarypox vector (ALVAC)–HIV and gp120 alum decreased the risk of HIV acquisition in the RV144 vaccine trial. The substitution of alum with the more immunogenic MF59 adjuvant is under consideration for the next efficacy human trial. We found here that an ALVAC–simian immunodeficiency virus (SIV) and gp120 alum (ALVAC–SIV + gp120) equivalent vaccine, but not an ALVAC–SIV + gp120 MF59 vaccine, was efficacious in delaying the onset of SIV mac251 in rhesus macaques, despite the higher immunogenicity of the latter adjuvant. Vaccine efficacy was associated with alum-induced, but not with MF59-induced, envelope (Env)-dependent mucosal innate lymphoid cells (ILCs) that produce interleukin (IL)-17, as well as with 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.

Abstract Background. The RV144 ALVAC-HIV prime, AIDSVAX B/E boost afforded 60% efficacy against human immunodeficiency virus (HIV) acquisition at 1 year, waning to 31.2% after 3.5 years. We hypothesized that additional vaccinations might augment immune correlates of protection. Methods. In a randomized placebo-controlled double-blind study of 162 HIV-negative RV144 vaccine recipients, we evaluated 2 additional boosts, given 6–8 years since RV144 vaccination, for safety and immunogenicity, at weeks 0 and 24. Study groups 1–3 received ALVAC-HIV+AIDSVAX B/E, AIDSVAX B/E, and ALVAC-HIV, respectively, or placebo. Results. Vaccines were well tolerated. For groups 1 and 2, plasma immunoglobulin (Ig) G, IgA, and neutralizing antibody responses at week 2 were all significantly higher than 2 weeks after the last RV144 vaccination. IgG titers against glycoprotein (gp) 70V1V2 92TH023 increased 14-fold compared with 2 weeks after the last RV144 vaccination (14069 vs 999; P < .001). Groups 1 and 2 did not differ significantly from each other, whereas group 3 was similar to placebo recipients. Responses in groups 1 and 2 declined by week 24 but were boosted by the second vaccination, albeit at lower magnitude than for week 2. Conclusions. In RV144 vaccinees, AIDSVAX B/E with or without ALVAC-HIV 6–8 years after initial vaccination generated higher humoral responses than after RV144, but these responses were short-lived, and their magnitude did not increase with subsequent boost. Clinical Trials Registration. NCT01435135.

In this phase 1 human immunodeficiency virus vaccine trial of PENNVAX-G DNA, administered by Biojector 2000 or CELLECTRA electroporation device, boosted by modified vaccinia Ankara–Chiang Mai double recombinant, the vaccine was safe with similar immunogenicity observed between the DNA delivery arms. Abstract Background We report the first-in-human safety and immunogenicity evaluation of PENNVAX-G DNA/modified vaccinia Ankara–Chiang Mai double recombinant (MVA-CMDR) prime-boost human immuonodeficiency virus (HIV) vaccine, with intramuscular DNA delivery by either Biojector 2000 needle-free injection system (Biojector) or CELLECTRA electroporation device. Methods Healthy, HIV-uninfected adults were randomized to receive 4 mg of PENNVAX-G DNA delivered intramuscularly by Biojector or electroporation at baseline and week 4 followed by intramuscular injection of 108 plaque forming units of MVA-CMDR at weeks 12 and 24. The open-label part A was conducted in the United States, followed by a double-blind, placebo-controlled part B in East Africa. Solicited and unsolicited adverse events were recorded, and immune responses were measured. Results Eighty-eight of 100 enrolled participants completed all study injections, which were generally safe and well tolerated, with more immediate, but transient, pain in the electroporation group. Cellular responses were observed in 57% of vaccine recipients tested and were CD4 predominant. High rates of binding antibody responses to CRF01_AE antigens, including gp70 V1V2 scaffold, were observed. Neutralizing antibodies were detected in a peripheral blood mononuclear cell assay, and moderate antibody-dependent, cell-mediated cytotoxicity activity was demonstrated. Discussion The PVG/MVA-CMDR HIV-1 vaccine regimen is safe and immunogenic. Substantial differences in safety or immunogenicity between modes of DNA delivery were not observed. Clinical Trials Registration NCT01260727.

Background. The time to acquisition of simian immunodeficiency virus (SIV) infection following low-dose repeated rectal challenge correlated inversely with the number of transmitted/founder strains among macaques vaccinated with ALVAC-SIV/gp120 or gpl20 alone. We determined if the ability of postvaccination, prechallenge sera to enhance SIVmac251 transcytosis across epithelial cells was associated with transmitted/founder strain number. Methods. Transcytosis was carried out by exposing sera and SIVmac251 to the apical surface of human endometrial carcinoma (HEC-1A) cells at pH 6.0 and 12 hours later quantifying virus in fluid bathing the basolateral cell surface (maintained at pH 7.4). These conditions allow Fc neonatal receptor (FcRn)-dependent shuttling of virus across cells. Results. There was a strong correlation between the amount of virus transcytosed and number of transmitted variants (R = 0.86, P < .0001). We also found that 4 animals who remained uninfected after repeated rectal challenges had lower serum transcytosis activity than did 19 animals who subsequently became infected (P= .003). Using immunohistochemistry, we demonstrated FcRn on columnar epithelial cells facing the lumen of the macaque rectum. Conclusions. Vaccine-induced antibody capable of enhancing transcytosis in vitro via FcRn may play a role in determining transmitted/founder strain number and infection outcomes following in vivo challenge.

Background. The RV144 ALVAC-HIV prime, AIDSVAX B/E boost afforded 60% efficacy against human immunodeficiency virus (HIV) acquisition at 1 year, waning to 31.2% after 3.5 years. We hypothesized that additional vaccinations might augment immune correlates of protection. Methods. In a randomized placebo-controlled double-blind study of 162 HIV-negative RV144 vaccine recipients, we evaluated 2 additional boosts, given 6–8 years since RV144 vaccination, for safety and immunogenicity, at weeks 0 and 24. Study groups 1–3 received ALVAC-HIV+AIDSVAX B/E, AIDSVAX B/E, and ALVAC-HIV, respectively, or placebo. Results. Vaccines were well tolerated. For groups 1 and 2, plasma immunoglobulin (Ig) G, IgA, and neutralizing antibody responses at week 2 were all significantly higher than 2 weeks after the last RV144 vaccination. IgG titers against glycoprotein (gp) 70V1V2 92TH023 increased 14-fold compared with 2 weeks after the last RV144 vaccination (14069 vs 999; P < .001). Groups 1 and 2 did not differ significantly from each other, whereas group 3 was similar to placebo recipients. Responses in groups 1 and 2 declined by week 24 but were boosted by the second vaccination, albeit at lower magnitude than for week 2. Conclusions. In RV144 vaccinees, AIDSVAX B/E with or without ALVAC-HIV 6–8 years after initial vaccination generated higher humoral responses than after RV144, but these responses were short-lived, and their magnitude did not increase with subsequent boost. Clinical Trials Registration. NCT01435135

This corrects the article DOI: 10.1038/nm.4105

Nat. Med.; doi:10.1038/nm.4105; corrected online 16 June 2016 In the version of this article initially published online, an affiliation for Luca Schifanella was omitted and there was an error in the description of the phenotypic analyses of plasmablasts in the Online Methods. The error has been corrected for the print, PDF and HTML versions of this article.

A recombinant vaccine containing Aventis Pasteur's canarypox vector (ALVAC)-HIV and gp120 alum decreased the risk of HIV acquisition in the RV144 vaccine trial. The substitution of alum with the more immunogenic MF59 adjuvant is under consideration for the next efficacy human trial. We found here that an ALVAC-simian immunodeficiency virus (SIV) and gp120 alum (ALVAC-SIV + gp120) equivalent vaccine, but not an ALVAC-SIV + gp120 MF59 vaccine, was efficacious in delaying the onset of SIV sub(mac251) in rhesus macaques, despite the higher immunogenicity of the latter adjuvant. Vaccine efficacy was associated with alum-induced, but not with MF59-induced, envelope (Env)-dependent mucosal innate lymphoid cells (ILCs) that produce interleukin (IL)-17, as well as with 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.