Scientific Publications

Saponin/MPLA Nanoparticles (SMNP) is a novel vaccine adjuvant that exhibited excellent safety and potency in a range of preclinical models. Successful scale-up manufacturing under current Good Manufacturing Practices (cGMP) is vital for advancing the clinical development of this promising new adjuvant. Here we report studies transitioning from small-scale formulation to the production of clinical trial material (CTM) in accordance with cGMP. By optimizing the process, a 100-fold scale increase was achieved through closed-system dilution and diafiltration, ensuring both sterility and process efficiency. Analytical characterization confirmed that the SMNP produced under cGMP conditions maintained consistent particle size, morphology, and polydispersity compared to preclinical batches. Hemolysis testing validated safety by assessing QS-21-related activity. Stability studies, conducted in accordance with ICH (International Council for Harmonisation) guidelines, demonstrated both chemical and colloidal integrity during prolonged refrigeration, while also identifying potential degradation risks at frozen or elevated temperatures. This research emphasizes critical factors for ensuring reproducibility, managing raw material variability, and developing scalable, aseptic processes. These results provide a foundation for advancing SMNP-based adjuvants into early-phase clinical trials and subsequent commercial production.

Uganda recently declared the end of its sixth Sudan virus (SUDV) outbreak; the prior outbreak having ended just two years earlier. Efficacious vaccines are licensed for protection against Ebola virus (EBOV), but there is no evidence that these afford clinical protection against other orthoebolaviruses. While EBOV has been extensively characterized in humans and animal models, the evidence base for SUDV is more limited due to the lower frequency of outbreaks and cases to date. It is therefore valuable to consider how, and to what extent, our knowledge and evidence base on EBOV can be leveraged to support the development of countermeasures against SUDV. This rapid review aims to examine and compare the existing evidence on the natural history of EBOV and SUDV in non-human primates (NHP). Overall, 24 studies (described in 25 articles) were identified for inclusion: 19 evaluated EBOV, four evaluated SUDV, and one evaluated both. Results confirm that EBOV and SUDV infection result in very similar disease in NHP, characterized by a severe systemic inflammatory response and disseminated intravascular coagulopathy, leading to tissue and organ damage and fluid loss. Clinical presentation and progression, clinical pathology observations, and characteristics of the host immune response were consistent across viruses. There is some indication that EBOV may result in slightly faster disease progression and marginally higher mortality than SUDV, though there is substantial overlap, and minor differences are also observed with different EBOV variants. While infection of rhesus and cynomolgus macaques with SUDV or EBOV are widely accepted models of human disease, an equivalent comparison of available human data would be valuable.

Anti-HIV envelope broadly neutralizing antibodies (bnAbs) are alternatives to conventional antiretrovirals with the potential to prevent and treat infection, reduce latent reservoirs, and/or mediate a functional cure. Clinical trials with “first-generation” bnAbs used alone or in combination show promising antiviral effects but also highlight that additional engineering of “enhanced” antibodies will be required for optimal clinical utility, while preserving or enhancing Current Good Manufacturing Practices (cGMP) manufacturing capability. Here, we report the engineering of an anti-CD4-binding site (CD4bs) bnAb, N49P9.3. Through a series of rational modifications, we produced a variant, N49P9.6-FR-LS, that demonstrates enhanced potency, superior antiviral activity in combination with other bnAbs, low polyreactivity, and longer circulating half-life. Additional engineering for manufacturing produced a final variant, eN49P9, with properties conducive to cGMP production. Overall, these efforts demonstrate the feasibility of developing enhanced anti-CD4bs bnAbs with greatly improved antiviral properties as well as potential translational value.

While broadly neutralizing antibodies (bnAbs) have been clinically shown to prevent HIV-1 acquisition, their relative effectiveness against regionally relevant HIV-1 forms is not clear. In the present study, we examined the extent of neutralization susceptibility of contemporary HIV-1 Indian clade C at a population level along with a head-to-head comparison with that from South Africa against a panel of clinically relevant best-in-class bnAbs. Env-pseudotyped viruses encoding HIV-1 India clade C env were found to be best neutralized by the V3 glycan-directed bnAbs (10-1074 and BG18) and select CD4 binding site (CD4bs)-directed bnAbs (VRC07, N6, and 1-18); however, they demonstrated significant resistance to V1/V2 apex-directed bnAbs. Interestingly, the magnitude of the neutralization sensitivity differed between contemporary India and South Africa clade C. Neutralization resistance to key bnAbs was observed to be associated with differences in residues on Env that form bnAb contact sites, gp120 loop lengths, and potential N-linked glycans. Notably, the second generation CD4bs bnAbs (VRC07, N6, 1-18) showed neutralization of VRC01- and 3BNC117-resistant viruses but with two- to sevenfold reduced potency compared to the VRC01-sensitive counterparts, likely due to the enrichment of resistance-associated residues observed in loop D. Predictive analysis indicated that the combination of BG18, N6, and PGDM1400 can provide over 95% neutralization coverage of contemporary India clade C at 1 µg/mL (IC80), an observation distinct from that observed with Africa clade C. Our study clearly highlights that both the complementarity of bnAb classes and the regionally relevant HIV-1 forms are important in achieving clinical effectiveness.IMPORTANCEWhile the development of vaccines to prevent HIV infection remains a global priority, their potential effectiveness is limited by the extraordinarily diversified circulating forms of HIV-1. The prospect of best-in-class broadly neutralizing antibodies (bnAbs) as a potential prevention option has been demonstrated in several studies, including the phase 2b Antibody-Mediated Prevention trials; however, to be broadly applicable, bnAbs will need to overcome the substantial variability of HIV env circulating globally, beyond the regions where efficacy trials are conducted. The present study highlights that the region-specific contemporary HIV-1 clade C viruses not only vary in their degree of susceptibility to the best-in-class clinically relevant bnAbs, but also are evolving at a population level to become increasingly resistant to the best-in-class bnAbs. Overall, the outcome of this study highlights the need for periodic assessment of sequence and neutralization profiles of the circulating regionally relevant HIV-1 forms toward prioritizing the bnAb combination suitable for effective intervention.

Background: Even within the context of antiretroviral treatment and prevention, an HIV-1 vaccine remains the best strategy for ending the HIV/AIDS epidemic. A vaccine is particularly needed in sub-Saharan Africa, where HIV-1 greatly affects people's lives and economy. Here, we aimed to assess the safety and immunogenicity of candidate T-cell vaccines in African populations. Methods: HIV-CORE 006 was a double-blind, randomised, placebo-controlled phase 1 trial conducted across four clinical research centres in Uganda, Kenya, and Zambia. Eligible participants were not pregnant, were living without HIV-1 or HIV-2, had a low likelihood of acquiring HIV-1, were aged 18-50 years, fully comprehended the purpose and details of this study as outlined in the participant information sheet, and passed an assessment of understanding before providing written informed consent. Participants were randomly assigned (9:2) to receive either a vaccine regimen or a placebo. The vaccine was administered as ChAdOx1.tHIVconsv1 (C1) followed by MVA.tHIVconsv3 (M3) and MVA.tHIVconsv4 (M4) in regimen C1-M3M4. The first primary outcome was the vaccines' safety assessment, assessed in all participants who received at least one vaccine or placebo dose. The second primary outcome evaluated the C1-M3M4 regimen's induction of HIVconsvX-specific T-cell responses by assessing the proportion of vaccine recipients who responded to the vaccination, assessed in all participants who received all doses of vaccine or placebo as per protocol. This study is registered with ClinicalTrials.gov, NCT04553016, and the Pan-African Clinical Trials Registry PACTR202006495409011, and is now closed. Findings: Between July 15, 2021, and Nov 2, 2022, 89 healthy adults living without HIV-1 were randomly assigned, with 88 receiving either the vaccine (n=72) or placebo (n=16). Of these 88 participants, 57 (65%) were male and 31 (35%) were female. The C1, M3, and M4 vaccine components were well tolerated and induced HIVconsvX-specific responses in 70 (99%) of the 71 participants who completed all vaccine doses. Vaccine-elicited T cells peaked at a median of 2310 (IQR 1080-4480) IFN-γ spot-forming units per 106 peripheral blood mononuclear cells and recognised a median of eight (five to ten) of ten peptide pools spanning the HIVconsvX immunogen. The total frequencies of elicited T cells decreased 4·6 times over a 40-week follow-up period compared with the peak responses. Upon antigenic re-exposure, T cells proliferated, exhibited multiple effector functions, and inhibited HIV-1 representatives from clades A, B, C, and D. Interpretation: Results from key sub-Saharan African populations supported the safety of the vaccine regimen previously shown in the first-in-human trial in the UK. The induction of T cells and their characteristics encourage vaccine integration into HIV-1 cure strategies, which could inform HIV-1 prevention efforts.

The development of germline-targeting vaccines represents a potentially transformative strategy to elicit broadly neutralizing antibodies (bnAbs) against HIV and other antigenically diverse pathogens. Here, we report on structural characterization of vaccine-elicited VRC01-class bnAb precursors in the IAVI G001 Phase 1 clinical trial with the eOD-GT8 60mer nanoparticle as immunogen. High-resolution X-ray structures of eOD-GT8 monomer complexed with Fabs of five VRC01-class bnAb precursors with >90% germline identity revealed a conserved mode of binding to the HIV CD4-binding site via IGHV1-2-encoded heavy chains, mirroring mature bnAb interactions. The light-chain V-gene diversity emulated VRC01 bnAbs and stabilized antigen engagement, while their conserved five-residue LCDR3 motifs prevented steric clashes. Notably, the VRC01-class bnAb precursors accommodated the N276 glycan, a key barrier in HIV Env recognition, through structural rearrangements in HCDR3 or LCDR1, despite its absence in the immunogen. Surface plasmon resonance analysis showed that 87% of elicited antibodies retained glycan binding capacity, albeit with reduced affinity. These findings validate the ability of eOD-GT8 60mer nanoparticles to prime VRC01-class bnAb precursors with native-like paratopes but with intrinsic glycan adaptability. Structural mimicry of mature bnAbs was observed even with limited somatic hypermutation, indicating that critical features are encoded in the germline repertoire. The structures highlight how germline-encoded features drive bnAb-like recognition at early stages. This work provides molecular evidence supporting germline targeting in humans and provides guidance for designing booster immunogens to shepherd affinity maturation toward broad neutralization.

A protective HIV vaccine will need to induce broadly neutralizing antibodies (bnAbs) in humans, but priming rare bnAb precursor B cells has been challenging. In a double-blinded, placebo-controlled phase 1 human clinical trial, the recombinant, germline-targeting envelope glycoprotein (Env) trimer BG505 SOSIP.v4.1-GT1.1, adjuvanted with AS01B, induced bnAb precursors of the VRC01-class at a high frequency in the majority of vaccine recipients. These bnAb precursors, which target the CD4 receptor binding site, had undergone somatic hypermutation characteristic of the VRC01-class. A subset of isolated VRC01-class monoclonal antibodies neutralized wild-type pseudoviruses and was structurally extremely similar to bnAb VRC01. These results further support germline-targeting approaches for human HIV vaccine design and demonstrate atomic-level manipulation of B cell responses with rational vaccine design.

A leading HIV vaccine strategy requires a priming immunogen to induce broadly neutralizing antibody (bnAb) precursors, followed by a series of heterologous boosters to elicit somatic hypermutation (SHM) and produce bnAbs. In two randomized, open-label phase 1 human clinical trials, IAVI G002 in the United States and IAVI G003 in Rwanda and South Africa (IAVI, International Aids Vaccine Initiative), we evaluated the safety and immunogenicity of mRNA-encoded nanoparticles as priming immunogens (both trials) and first-boosting immunogens (IAVI G002). The vaccines were generally safe and well tolerated, except that 18% of IAVI G002 participants experienced skin reactions. Priming induced bnAb precursors with substantial frequencies and SHM; heterologous boosting elicited increased SHM, affinity, and neutralization activity toward bnAb development; and elicited antibodies exhibited precise bnAb structural mimicry. The results establish clinical proof of concept that heterologous boosting can advance bnAb precursor maturation and demonstrate bnAb priming in Africa, where the HIV burden is highest.

Pre-exposure prophylaxis (PrEP) has proven to be a powerful tool in preventing HIV infection. There is limited information about the factors associated with willingness to use different PrEP modalities among adolescent girls and young women (AGYW) in Africa. We assessed willingness to use long-acting injectable PrEP (LAI-PrEP) among 14-24-year-old AGYW at high risk of HIV in Uganda, and associated factors determined using multivariable complementary log-log regression. Of the 285 participants, 69.8% of participants showed willingness to use LAI-PrEP despite only 3.9% having knowledge about it before enrolment. Report of recent transactional sex was high (92.6%). Participants that were divorced/separated (aOR = 1.74, 95% CI 1.03-2.92) and those with multiple sexual partners (aOR = 2.11, 95% CI 1.46-3.06) compared to those with one partner were more likely to be willing to use LAI-PrEP while those that were screened as heavy episodic drinkers (consuming 6 or more drinks on an occasion as per the AUDIT tool) were less likely to be willing to use LAI-PrEP (aOR = 0.61, 95% CI 0.42-0.87). LAI PrEP has shown efficacy in clinical trials; the product is approved for use by the Government of Uganda (MoH) and should be expedited for use by AGYW engaged in paid sex and those with multiple sexual partnerships. As it becomes available, we recommend PrEP education and counseling to increase awareness of LAI PrEP as an alternative HIV prevention method.

Highly effective antiretroviral-based HIV prevention plays an important role in ending the global HIV/AIDS epidemic. However, the sustainable control of the epidemic is hampered by unequal access to prevention options, including HIV testing, alongside with drug resistance and ongoing barriers to accessing sustainable HIV treatment. Therefore, an HIV vaccine, combined with effective prevention and treatment, remains an absolute necessity to control the epidemic. Yet, the recent discontinuation of four major vaccine efficacy studies is raising concerns about the future of HIV vaccine research and development globally, and particularly in the European region where funding for vaccine research and development has shrinked. This viewpoint emphasises that supporting HIV vaccine research and development at the European level remains crucial: it is not only necessary to control the epidemic, but it promotes innovation, strengthens health security, epidemic preparedness, and health sovereignty while contributing to the economies of European nations.

Background: Lassa fever (LF) is a zoonotic haemorrhagic disease caused by Lassa virus (LASV), which is endemic in West African countries. The multimammate rat is the main animal reservoir and its geographic range is expected to expand due to influences like climate change and land usage, and this will place larger parts of Africa at risk. We conducted preclinical development on a promising experimental vaccine that allowed its advancement into human trials. Methods: The LF vaccine is based on a vesicular stomatitis virus (VSV) vector in which the VSV glycoprotein (G) was replaced with the LASV glycoprotein complex (GPC). Earlier studies showed that this vaccine (VSVΔG-LASV-GPC) was efficacious in macaques, thus we regenerated VSVΔG-LASV-GPC using laboratory and documentation practices required to support vaccine manufacturing and human trials. The efficacy of the clinical vaccine candidate was assessed in cynomolgus macaques and more extensive immunologic analysis was performed than previously to investigate immune responses associated with protection. Findings: A single VSVΔG-LASV-GPC vaccination elicited innate, humoural and cellular immune responses, prevented development of substantial LASV viraemia, and protected animals from disease. Vaccinated macaques developed polyfunctional antibodies and serum was shown to neutralize virus expressing GPCs representative of geographically diverse LASV lineages. Interpretation: The VSVΔG-LASV-GPC clinical candidate elicited immunity that protected 10 of 10 vaccinated macaques from disease supporting its use in a clinical development program, which recently progressed to phase 2 clinical trials. Moreover, immunologic analysis showed that virus-neutralizing serum antibodies likely played a role in preventing LASV disease in vaccinated macaques.

High replicative capacity (RC) HIV-1 strains are associated with elevated viral loads and faster disease progression in the absence of antiretroviral therapy. Understanding the mechanisms by which high RC strains adversely affect the host is essential for developing novel anti-HIV interventions. This study investigates cellular metabolism, cytokine induction, and cell-to-cell spread as potential mechanisms differentiating clinical outcomes between low and high RC strains of HIV-1. We constructed chimeric viruses containing patient-derived gag-proteases from HIV-1 subtypes B and C in the NL4-3 backbone. Viral RC was determined using a green fluorescent protein (GFP)-reporter T-cell line assay and cytokine production in T-cells was assessed using Luminex. Virus cell-to-cell spread efficiency was measured through flow cytometry-based detection of p24, while nutrient uptake assays and mitotracker dye detection served as surrogate markers for T-cell metabolism and mitochondrial function. Chimeric subtype C viruses exhibited significantly lower RC compared to subtype B viruses (P = 0.0008). Cytokine profiling revealed distinct cytokine signatures associated with low RC subtype C viruses. Viral RC negatively correlated with tumor necrosis factor alpha (TNF-α), IL-8, and IL-13 induction, while it positively correlated with platelet-derived growth factor (PDGF-bb), IL-7, monocyte chemoattractant protein-1 (MCP-1), fibroblast growth factor (FGF)-basic levels, viral spread efficiency (P = 0.008, r = 0.5), and cellular glucose uptake (P = 0.02, r = 0.5). Conversely, RC was negatively correlated with glutamine levels (P = 0.001, r = −0.7), indicating a link between RC and nutrient utilization. Furthermore, mitochondrial depolarization was elevated in subtype B infections when compared to subtype C infections (P = 0.0008). These findings indicate that high RC strains exert distinct cellular effects that may influence HIV-1 pathogenesis, highlighting the need to develop novel therapeutic strategies.

Background Lassa fever, caused by Lassa virus, is a severe disease, endemic in Western Africa, for which no vaccines or therapeutics are yet approved. Understanding the immune responses elicited by candidate vaccines is key for approval, including characterisation of antibody epitopes recognised and capacity for neutralisation. Methods Here we used negative-stain electron microscopy polyclonal antibody epitope mapping (EMPEM), in-vitro pseudovirus neutralisation assays, and biophysical antibody competition assays to uncover components of polyclonal antibody responses elicited in nonhuman primates 26 days after receipt of a single immunisation with a fully protective, recombinant, replication-competent vesicular stomatitis virus-based vaccine bearing the Lassa virus glycoprotein GPC. Findings Although the vaccinee sera are overall poorly-neutralising, we do directly visualise, within the polyclonal pool, antibodies targeting epitopes on GPC that are consistent with neutralisation, as well as competition with known neutralising mAbs. Nearly every animal, for example, produced antibodies that compete with mAbs against GP1-A and GPC-A neutralising epitopes. The most abundant classes of antibodies, however, are directed against interior interfaces of GPC, while other antibodies recognise post-fusion GPC epitopes not consistent with neutralisation. Interpretation It may be that some individual antibodies in the pool are neutralising, but that the abundance of non-neutralising epitopes reduces potency as measured at the polyclonal level. The finding, however, neutralisation-consistent sites and competition with known neutralising antibodies are important steps in vaccine design toward eliciting more potent neutralisation