Carnauba wax nanoparticles enhance strong systemic and mucosal cellular and humoral immune responses to HIV-gp140 antigen

Induction of humoral responses to HIV at mucosal compartments without inflammation is important for vaccine design. We developed charged wax nanoparticles that efficiently adsorb protein antigens and are internalized by DC in the absence of inflammation. HIV-gp140-adsorbed nanoparticles induced stronger in vitro T-cell proliferation responses than antigen alone. Such responses were greatly enhanced when antigen was co-adsorbed with TLR ligands. Immunogenicity studies in mice showed that intradermal vaccination with HIV-gp140 antigen-adsorbed nanoparticles induced high levels of specific IgG. Importantly, intranasal immunization with HIV-gp140-adsorbed nanoparticles greatly enhanced serum and vaginal IgG and IgA responses. Our results show that HIV-gp140-carrying wax nanoparticles can induce strong cellular/humoral immune responses without inflammation and may be of potential use as effective mucosal adjuvants for HIV vaccine candidates

Modulating mucosal immune responses to HIV

Development of a successful vaccine against HIV is likely to require the induction of strong and long-lasting humoral immune responses at the mucosal portals of virus entry. One approach to achieve this is the direct immunisation of mucosal sites. However, there is a need for potent and safe adjuvants that work at mucosal surfaces. A number of cytokines have recently been identified that specifically activate B-cells including BAFF, APRIL and TSLP. The hypothesis of this thesis is that these cytokines will act as adjuvants to boost antibody responses to mucosally delivered HIV antigen. Following immunisation of mice, serum and vaginal samples were tested for gp140-specific IgA and IgG responses. Splenocytes were assessed for T-cell proliferation and gp140-specific IgA and IgG antibody secreting cells. Cytokine production by T-cells after in vitro stimulation with CN54gp140 peptides was also assessed. TSLP, but not APRIL or BAFF, induced strong immune responses after nasal " immunisation, comparable to those seen with cholera toxin. Responses were still detected 4 months after the last boost, indicating a long lasting response. TSLP also induced T -cell proliferative responses to gp 140 after nasal immunisation and induced a T H2 type immune response but without induction of an allergic response. Due to cost limitations on the mass production of protein for use as an adjuvant, it was also tested whether TSLP could be delivered in the form of a plasmid DNA adjuvant. These studies demonstrated limited efficacy. In conclusion, the study demonstrated that B-cell activating cytokine TSLP, but not BAFF and APRIL can work as a mucosal adjuvant. It is notable that there was no significant development of allergic responses following administration of TSLP. This is 4 , the first time that TSLP has been demonstrated to have a positive effect as a mucosal adjuvant, and specifically promoting mucosal and systemic responses to HIV gp140.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Modulating mucosal immune responses to HIV

Development of a successful vaccine against HIV is likely to require the induction of strong and long-lasting humoral immune responses at the mucosal portals of virus entry. One approach to achieve this is the direct immunisation of mucosal sites. However, there is a need for potent and safe adjuvants that work at mucosal surfaces. A number of cytokines have recently been identified that specifically activate B-cells including BAFF, APRIL and TSLP. The hypothesis of this thesis is that these cytokines will act as adjuvants to boost antibody responses to mucosally delivered HIV antigen. Following immunisation of mice, serum and vaginal samples were tested for gp140-specific IgA and IgG responses. Splenocytes were assessed for T-cell proliferation and gp140-specific IgA and IgG antibody secreting cells. Cytokine production by T-cells after in vitro stimulation with CN54gp140 peptides was also assessed. TSLP, but not APRIL or BAFF, induced strong immune responses after nasal " immunisation, comparable to those seen with cholera toxin. Responses were still detected 4 months after the last boost, indicating a long lasting response. TSLP also induced T -cell proliferative responses to gp 140 after nasal immunisation and induced a T H2 type immune response but without induction of an allergic response. Due to cost limitations on the mass production of protein for use as an adjuvant, it was also tested whether TSLP could be delivered in the form of a plasmid DNA adjuvant. These studies demonstrated limited efficacy. In conclusion, the study demonstrated that B-cell activating cytokine TSLP, but not BAFF and APRIL can work as a mucosal adjuvant. It is notable that there was no significant development of allergic responses following administration of TSLP. This is 4 , the first time that TSLP has been demonstrated to have a positive effect as a mucosal adjuvant, and specifically promoting mucosal and systemic responses to HIV gp140.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Glucopyranosyl Lipid Adjuvant (GLA), a Synthetic TLR4 agonist, promotes potent systemic and mucosal responses to intranasal immunization with HIVgp140.

Successful vaccine development against HIV will likely require the induction of strong, long-lasting humoral and cellular immune responses in both the systemic and mucosal compartments. Based on the known immunological linkage between the upper-respiratory and urogenital tracts, we explored the potential of nasal adjuvants to boost immunization for the induction of vaginal and systemic immune responses to gp140. Mice were immunized intranasally with HIV gp140 together with micellar and emulsion formulations of a synthetic TLR4 agonist, Glucopyranosyl Lipid Adjuvant (GLA) and responses were compared to R848, a TLR7/8 agonist, or chitosan, a non TLR adjuvant. GLA and chitosan but not R848 greatly enhanced serum immunoglobulin levels when compared to antigen alone. Both GLA and chitosan induced high IgG and IgA titers in nasal and vaginal lavage and feces. The high IgA and IgG titers in vaginal lavage were associated with high numbers of gp140-specific antibody secreting cells in the genital tract. Whilst both GLA and chitosan induced T cell responses to immunization, GLA induced a stronger Th17 response and chitosan induced a more Th2 skewed response. Our results show that GLA is a highly potent intranasal adjuvant greatly enhancing humoral and cellular immune responses, both systemically and mucosally

Non-human primate to human immunobridging demonstrates a protective effect of Ad26.ZEBOV, MVA-BN-Filo vaccine against Ebola

Abstract Without clinical efficacy data, vaccine protective effect may be extrapolated from animals to humans using an immunologic marker that correlates with protection in animals. This immunobridging approach was used for the two-dose Ebola vaccine regimen Ad26.ZEBOV, MVA-BN-Filo. Ebola virus (EBOV) glycoprotein binding antibody data obtained from 764 vaccinated healthy adults in five clinical studies (NCT02416453, NCT02564523, NCT02509494, NCT02543567, NCT02543268) were used to calculate mean predicted survival probability (with preplanned 95% confidence interval [CI]). We used a logistic regression model based on EBOV glycoprotein binding antibody responses in vaccinated non-human primates (NHPs) and NHP survival after EBOV challenge. While the protective effect of the vaccine regimen in humans can be inferred in this fashion, the extrapolated survival probability cannot be directly translated into vaccine efficacy. The primary immunobridging analysis evaluated the lower limit of the CI against predefined success criterion of 20% and passed with mean predicted survival probability of 53.4% (95% CI: 36.7–67.4)

GLA is a more potent mucosal adjuvant than R848 or chitosan.

<p>BALB/c mice were immunized i.n. three times at 3 week intervals with 10 µg gp140 and 10 µg GLA (▴), 10 µg R848 (○) or 100 µg chitosan (□) compared to antigen alone (▪). Serum (A, B), vaginal lavage (C, D), feces (E,F) were collected after each immunization and nasal lavage collected at d 63 only (G, H). gp140 specific IgG (A, C, E, G) and IgA (B, D, F, H) were measured by ELISA. Points represent mean of n = 10 mice ± SEM, *p<0.05, **p<0.01, ***p<0.001 comparing GLA and chitosan; #p<0.05, ##p<0.01, ###p<0.001 comparing GLA and R848.</p

Immune correlates analysis of the ENSEMBLE single Ad26.COV2.S dose vaccine efficacy clinical trial.

Measuring immune correlates of disease acquisition and protection in the context of a clinical trial is a prerequisite for improved vaccine design. We analysed binding and neutralizing antibody measurements 4 weeks post vaccination as correlates of risk of moderate to severe-critical COVID-19 through 83 d post vaccination in the phase 3, double-blind placebo-controlled phase of ENSEMBLE, an international randomized efficacy trial of a single dose of Ad26.COV2.S. We also evaluated correlates of protection in the trial cohort. Of the three antibody immune markers we measured, we found most support for 50% inhibitory dilution (ID50) neutralizing antibody titre as a correlate of risk and of protection. The outcome hazard ratio was 0.49 (95% confidence interval 0.29, 0.81; P = 0.006) per 10-fold increase in ID50; vaccine efficacy was 60% (43%, 72%) at non-quantifiable ID50 (&lt;2.7 IU50 ml-1) and increased to 89% (78%, 96%) at ID50 = 96.3 IU50 ml-1. Comparison of the vaccine efficacy by ID50 titre curves for ENSEMBLE-US, the COVE trial of the mRNA-1273 vaccine and the COV002-UK trial of the AZD1222 vaccine supported the ID50 titre as a correlate of protection across trials and vaccine types

Partnership for Research on Ebola VACcination (PREVAC): protocol of a randomized, double-blind, placebo-controlled phase 2 clinical trial evaluating three vaccine strategies against Ebola in healthy volunteers in four West African countries

International audienceAbstract Introduction The Ebola virus disease (EVD) outbreak in 2014–2016 in West Africa was the largest on record and provided an opportunity for large clinical trials and accelerated efforts to develop an effective and safe preventative vaccine. Multiple questions regarding the safety, immunogenicity, and efficacy of EVD vaccines remain unanswered. To address these gaps in the evidence base, the Partnership for Research on Ebola Vaccines (PREVAC) trial was designed. This paper describes the design, methods, and baseline results of the PREVAC trial and discusses challenges that led to different protocol amendments. Methods This is a randomized, double-blind, placebo-controlled phase 2 clinical trial of three vaccine strategies against the Ebola virus in healthy volunteers 1 year of age and above. The three vaccine strategies being studied are the rVSVΔG-ZEBOV-GP vaccine, with and without a booster dose at 56 days, and the Ad26.ZEBOV,MVA-FN-Filo vaccine regimen with Ad26.ZEBOV given as the first dose and the MVA-FN-Filo vaccination given 56 days later. There have been 4 versions of the protocol with those enrolled in Version 4.0 comprising the primary analysis cohort. The primary endpoint is based on the antibody titer against the Ebola virus surface glycoprotein measured 12 months following the final injection. Results From April 2017 to December 2018, a total of 5002 volunteers were screened and 4789 enrolled. Participants were enrolled at 6 sites in four countries (Guinea, Liberia, Sierra Leone, and Mali). Of the 4789 participants, 2560 (53%) were adults and 2229 (47%) were children. Those < 18 years of age included 549 (12%) aged 1 to 4 years, 750 (16%) 5 to 11 years, and 930 (19%) aged 12–17 years. At baseline, the median (25th, 75th percentile) antibody titer to Ebola virus glycoprotein for 1090 participants was 72 (50, 116) EU/mL. Discussion The PREVAC trial is evaluating—placebo-controlled—two promising Ebola candidate vaccines in advanced stages of development. The results will address unanswered questions related to short- and long-term safety and immunogenicity for three vaccine strategies in adults and children. Trial registration ClinicalTrials.gov NCT02876328 . Registered on 23 August 2016