Vaccination with ALVAC and AIDSVAX to prevent HIV-1 infection in Thailand

Novel Oral Adjuvant to Enhance Cytotoxic Memory-Like NK Cell Responses in an HIV Vaccine Platform

Antibody-dependent cell-mediated cytotoxicity, mediated by natural killer (NK) cells and antibodies, emerged as a secondary correlate of protection in the RV144 HIV vaccine clinical trial, the only vaccine thus far demonstrating some efficacy in human. Therefore, leveraging NK cells with enhanced cytotoxic effector responses may bolster vaccine induced protection against HIV. Here, we investigated the effect of orally administering indole-3-carbinol (I3C), an aryl hydrocarbon receptor (AHR) agonist, as an adjuvant to an RV144-like vaccine platform in a mouse model. We demonstrate the expansion of KLRG1-expressing NK cells induced by the vaccine together with I3C. This NK cell subset exhibited enhanced vaccine antigen-specific cytotoxic memory-like features. Our study underscores the potential of incorporating I3C as an oral adjuvant to HIV vaccine platforms to enhance antigen-specific (memory-like) cytotoxicity of NK cells against HIV-infected cells. This approach may contribute to enhancing the protective efficacy of HIV preventive vaccines against HIV acquisition.

Vaccine induction of heterologous HIV-1-neutralizing antibody B cell lineages in humans

A critical roadblock to HIV vaccine development is the inability to induce B cell lineages of broadly neutralizing antibodies (bnAbs) in humans. In people living with HIV-1, bnAbs take years to develop. The HVTN 133 clinical trial studied a peptide/liposome immunogen targeting B cell lineages of HIV-1 envelope (Env) membrane-proximal external region (MPER) bnAbs (NCT03934541). Here, we report MPER peptide-liposome induction of polyclonal HIV-1 B cell lineages of mature bnAbs and their precursors, the most potent of which neutralized 15% of global tier 2 HIV-1 strains and 35% of clade B strains with lineage initiation after the second immunization. Neutralization was enhanced by vaccine selection of improbable mutations that increased antibody binding to gp41 and lipids. This study demonstrates proof of concept for rapid vaccine induction of human B cell lineages with heterologous neutralizing activity and selection of antibody improbable mutations and outlines a path for successful HIV-1 vaccine development.

Contemporary HIV-1 consensus Env with AI-assisted redesigned hypervariable loops promote antibody binding

An effective HIV-1 vaccine must elicit broadly neutralizing antibodies (bnAbs) against highly diverse Envelope glycoproteins (Env). Since Env with the longest hypervariable (HV) loops is more resistant to the cognate bnAbs than Env with shorter HV loops, we redesigned hypervariable loops for updated Env consensus sequences of subtypes B and C and CRF01_AE. Using modeling with AlphaFold2, we reduced the length of V1, V2, and V5 HV loops while maintaining the integrity of the Env structure and glycan shield, and modified the V4 HV loop. Spacers are designed to limit strain-specific targeting. All updated Env are infectious as pseudoviruses. Preliminary structural characterization suggests that the modified HV loops have a limited impact on Env's conformation. Binding assays show improved binding to modified subtype B and CRF01_AE Env but not to subtype C Env. Neutralization assays show increases in sensitivity to bnAbs, although not always consistently across clades. Strikingly, the HV loop modification renders the resistant CRF01_AE Env sensitive to 10-1074 despite the absence of a glycan at N332.

Opportunities and challenges for T cell-based influenza vaccines

Vaccination remains our main defence against influenza, which causes substantial annual mortality and poses a serious pandemic threat. Influenza virus evades immunity by rapidly changing its surface antigens but, even when the vaccine is well matched to the current circulating virus strains, influenza vaccines are not as effective as many other vaccines. Influenza vaccine development has traditionally focused on the induction of protective antibodies, but there is mounting evidence that T cell responses are also protective against influenza. Thus, future vaccines designed to promote both broad T cell effector functions and antibodies may provide enhanced protection. As we discuss, such vaccines present several challenges that require new strategic and economic considerations. Vaccine-induced T cells relevant to protection may reside in the lungs or lymphoid tissues, requiring more invasive assays to assess the immunogenicity of vaccine candidates. T cell functions may contain and resolve infection rather than completely prevent infection and early illness, requiring vaccine effectiveness to be assessed based on the prevention of severe disease and death rather than symptomatic infection. It can be complex and costly to measure T cell responses and infrequent clinical outcomes, and thus innovations in clinical trial design are needed for economic reasons. Nevertheless, the goal of more effective influenza vaccines justifies renewed and intensive efforts.

Safety and immunogenicity of a polyvalent DNA-protein HIV vaccine with matched Env immunogens delivered as a prime-boost regimen or coadministered in HIV-uninfected adults in the USA (HVTN 124): a phase 1, placebo-controlled, double-blind randomised controlled trial

BACKGROUND

An effective HIV vaccine will most likely need to have potent immunogenicity and broad cross-subtype coverage. The aim of the HIV Vaccine Trials Network (HVTN) 124 was to evaluate safety and immunogenicity of a unique polyvalent DNA-protein HIV vaccine with matching envelope (Env) immunogens.

METHODS

HVTN 124 was a randomised, phase 1, placebo-controlled, double-blind study, including participants who were HIV seronegative and aged 18-50 years at low risk for infection. The DNA vaccine comprised five plasmids: four copies expressing Env gp120 (clades A, B, C, and AE) and one gag p55 (clade C). The protein vaccine included four DNA vaccine-matched GLA-SE-adjuvanted recombinant gp120 proteins. Participants were enrolled across six clinical sites in the USA and were randomly assigned to placebo or one of two vaccine groups (ie, prime-boost or coadministration) in a 5:1 ratio in part A and a 7:1 ratio in part B. Vaccines were delivered via intramuscular needle injection. The primary outcomes were safety and tolerability, assessed via frequency, severity, and attributability of local and systemic reactogenicity and adverse events, laboratory safety measures, and early discontinuations. Part A evaluated safety. Part B evaluated safety and immunogenicity of two regimens: DNA prime (administered at months 0, 1, and 3) with protein boost (months 6 and 8), and DNA-protein coadministration (months 0, 1, 3, 6, and 8). All randomly assigned participants who received at least one dose were included in the safety analysis. The study is registered with ClinicalTrials.gov (NCT03409276) and is closed to new participants.

FINDINGS

Between April 19, 2018 and Feb 13, 2019, 60 participants (12 in part A [five men and seven women] and 48 in part B [21 men and 27 women]) were enrolled. All 60 participants received at least one dose, and 14 did not complete follow-up (six of 21 in the prime-boost group and eight of 21 in the coadminstration group). 11 clinical adverse events deemed by investigators as study-related occurred in seven of 48 participants in part B (eight of 21 in the prime-boost group and three of 21 in the coadministration group). Local reactogenicity in the vaccine groups was common, but the frequency and severity of reactogenicity signs or symptoms did not differ between the prime-boost and coadministration groups (eg, 20 [95%] of 21 in the prime-boost group vs 21 [100%] of 21 in the coadministration group had either local pain or tenderness of any severity [p=1·00], and seven [33%] vs nine [43%] had either erythema or induration [p=0·97]), nor did laboratory safety measures. There were no delayed-type hypersensitivity reactions or vasculitis or any severe clinical adverse events related to vaccination. The most frequently reported systemic reactogenicity symptoms in the active vaccine groups were malaise or fatigue (five [50%] of ten in part A and 17 [81%] of 21 in the prime-boost group vs 15 [71%] of 21 in the coadministration group in part B), headache (five [50%] and 18 [86%] vs 12 [57%]), and myalgia (four [40%] and 13 [62%] vs ten [48%]), mostly of mild or moderate severity.

INTERPRETATION

Both vaccine regimens were safe, warranting evaluation in larger trials.

FUNDING

US National Institutes of Health and US National Institute of Allergy and Infectious Diseases.

Broadly neutralizing antibodies for HIV prevention: a comprehensive review and future perspectives

SUMMARYThe human immunodeficiency virus (HIV) epidemic remains a formidable global health concern, with 39 million people living with the virus and 1.3 million new infections reported in 2022. Despite anti-retroviral therapy's effectiveness in pre-exposure prophylaxis, its global adoption is limited. Broadly neutralizing antibodies (bNAbs) offer an alternative strategy for HIV prevention through passive immunization. Historically, passive immunization has been efficacious in the treatment of various diseases ranging from oncology to infectious diseases. Early clinical trials suggest bNAbs are safe, tolerable, and capable of reducing HIV RNA levels. Although challenges such as bNAb resistance have been noted in phase I trials, ongoing research aims to assess the additive or synergistic benefits of combining multiple bNAbs. Researchers are exploring bispecific and trispecific antibodies, and fragment crystallizable region modifications to augment antibody efficacy and half-life. Moreover, the potential of other antibody isotypes like IgG3 and IgA is under investigation. While promising, the application of bNAbs faces economic and logistical barriers. High manufacturing costs, particularly in resource-limited settings, and logistical challenges like cold-chain requirements pose obstacles. Preliminary studies suggest cost-effectiveness, although this is contingent on various factors like efficacy and distribution. Technological advancements and strategic partnerships may mitigate some challenges, but issues like molecular aggregation remain. The World Health Organization has provided preferred product characteristics for bNAbs, focusing on optimizing their efficacy, safety, and accessibility. The integration of bNAbs in HIV prophylaxis necessitates a multi-faceted approach, considering economic, logistical, and scientific variables. This review comprehensively covers the historical context, current advancements, and future avenues of bNAbs in HIV prevention.

A remarkable genetic shift in a transmitted/founder virus broadens antibody responses against HIV-1

A productive HIV-1 infection in humans is often established by transmission and propagation of a single transmitted/founder (T/F) virus, which then evolves into a complex mixture of variants during the lifetime of infection. An effective HIV-1 vaccine should elicit broad immune responses in order to block the entry of diverse T/F viruses. Currently, no such vaccine exists. An in-depth study of escape variants emerging under host immune pressure during very early stages of infection might provide insights into such a HIV-1 vaccine design. Here, in a rare longitudinal study involving HIV-1 infected individuals just days after infection in the absence of antiretroviral therapy, we discovered a remarkable genetic shift that resulted in near complete disappearance of the original T/F virus and appearance of a variant with H173Y mutation in the variable V2 domain of the HIV-1 envelope protein. This coincided with the disappearance of the first wave of strictly H173-specific antibodies and emergence of a second wave of Y173-specific antibodies with increased breadth. Structural analyses indicated conformational dynamism of the envelope protein which likely allowed selection of escape variants with a conformational switch in the V2 domain from an α-helix (H173) to a β-strand (Y173) and induction of broadly reactive antibody responses. This differential breadth due to a single mutational change was also recapitulated in a mouse model. Rationally designed combinatorial libraries containing 54 conformational variants of V2 domain around position 173 further demonstrated increased breadth of antibody responses elicited to diverse HIV-1 envelope proteins. These results offer new insights into designing broadly effective HIV-1 vaccines.

CoPoP liposomes displaying stabilized clade C HIV-1 Env elicit tier 2 multiclade neutralization in rabbits

One of the strategies towards an effective HIV-1 vaccine is to elicit broadly neutralizing antibody responses that target the high HIV-1 Env diversity. Here, we present an HIV-1 vaccine candidate that consists of cobalt porphyrin-phospholipid (CoPoP) liposomes decorated with repaired and stabilized clade C HIV-1 Env trimers in a prefusion conformation. These particles exhibit high HIV-1 Env trimer decoration, serum stability and bind broadly neutralizing antibodies. Three sequential immunizations of female rabbits with CoPoP liposomes displaying a different clade C HIV-1 gp140 trimer at each dosing generate high HIV-1 Env-specific antibody responses. Additionally, serum neutralization is detectable against 18 of 20 multiclade tier 2 HIV-1 strains. Furthermore, the peak antibody titers induced by CoPoP liposomes can be recalled by subsequent heterologous immunization with Ad26-encoded membrane-bound stabilized Env antigens. Hence, a CoPoP liposome-based HIV-1 vaccine that can generate cross-clade neutralizing antibody immunity could potentially be a component of an efficacious HIV-1 vaccine.

The Question of HIV Vaccine: Why Is a Solution Not Yet Available?

Ever since its discovery, human immunodeficiency virus type 1 (HIV-1) infection has remained a significant public health concern. The number of HIV-1 seropositive individuals currently stands at 40.1 million, yet definitive treatment for the virus is still unavailable on the market. Vaccination has proven to be a potent tool in combating infectious diseases, as evidenced by its success against other pathogens. However, despite ongoing efforts and research, the unique viral characteristics have prevented the development of an effective anti-HIV-1 vaccine. In this review, we aim to provide an historical overview of the various approaches attempted to create an effective anti-HIV-1 vaccine. Our objective is to explore the reasons why specific methods have failed to induce a protective immune response and to analyze the different modalities of immunogen presentation. This trial is registered with NCT05414786, NCT05471076, NCT04224701, and NCT01937455.

Perceptions and Acceptance of a Prophylactic Vaccine for Human Immunodeficiency Virus (HIV): A Qualitative Study

BACKGROUND

Despite advances in human immunodeficiency virus (HIV) prevention methods, such as the advent of pre-exposure prophylaxis (PrEP), the number of people with newly acquired HIV remains high, particularly in at-risk groups. A prophylactic HIV vaccine could contribute to reduced disease prevalence and future transmission and address limitations of existing options, such as suboptimal long-term adherence to PrEPs.

METHODS

This qualitative study aimed to capture perceptions towards and acceptance of prophylactic HIV vaccination in three adult populations in the United States: the general population, 'at-risk' individuals (e.g. men who have sex with men, transgender individuals, gender-nonconforming individuals, and individuals in a sexual relationship with a person living with HIV), and parents/caregivers of children aged 9-17 years. Interviews were conducted with 55 participants to explore key drivers and barriers to HIV vaccine uptake, and a conceptual model was developed.

RESULTS

The sample was diverse; participants were 51% female, aged 20-57 years (mean 37 years), 33% with high school diploma as highest education level, and identified as White (42%), Black or African American (35%), of Hispanic, Latino, or Spanish origin (22%), or other races/ethnicities (8%) [groupings are not mutually exclusive]. Perceptions were influenced by individual, interpersonal, community, institutional, and structural factors. Overall, 98% of participants thought vaccination would be beneficial in preventing HIV. Key considerations/barriers included perceived susceptibility, i.e. whether participants felt there was a risk of contracting HIV (discussed by 90%); the clinical profile of the vaccine (e.g. the adverse effect profile [98%], and vaccine efficacy [85%], cost [73%] and administration schedule [88%]); and concerns around potential vaccine-induced seropositivity (VISP; 62%). Stigma was not found to be an important barrier, with a general view that vaccination status was personal. Participants in the 'at-risk' group were the most likely to accept an HIV vaccine (70%). Unique concerns in the subgroups included how a potential vaccine's clinical profile compared with PrEP, voiced by those receiving/considering PrEP, and considerations of children's views on the topic, voiced by parents/caregivers.

CONCLUSIONS

Understanding these factors could help develop HIV vaccine research strategies and contribute toward public health messaging to support future HIV vaccination programs.

Impact of Recombinant VSV-HIV Prime, DNA-Boost Vaccine Candidates on Immunogenicity and Viremia on SHIV-Infected Rhesus Macaques

Currently, no effective vaccine to prevent human immunodeficiency virus (HIV) infection is available, and various platforms are being examined. The vesicular stomatitis virus (VSV) vaccine vehicle can induce robust humoral and cell-mediated immune responses, making it a suitable candidate for the development of an HIV vaccine. Here, we analyze the protective immunological impacts of recombinant VSV vaccine vectors that express chimeric HIV Envelope proteins (Env) in rhesus macaques. To improve the immunogenicity of these VSV-HIV Env vaccine candidates, we generated chimeric Envs containing the transmembrane and cytoplasmic tail of the simian immunodeficiency virus (SIV), which increases surface Env on the particle. Additionally, the Ebola virus glycoprotein was added to the VSV-HIV vaccine particles to divert tropism from CD4 T cells and enhance their replications both in vitro and in vivo. Animals were boosted with DNA constructs that encoded matching antigens. Vaccinated animals developed non-neutralizing antibody responses against both the HIV Env and the Ebola virus glycoprotein (EBOV GP) as well as systemic memory T-cell activation. However, these responses were not associated with observable protection against simian-HIV (SHIV) infection following repeated high-dose intra-rectal SHIV SF162p3 challenges.

HIV-1 Gag, Pol, and Env diversified with limited adaptation since the 1980s

Knowledge of HIV-1 global sequence diversity is critical for developing an effective prophylactic against HIV-1 infection. We developed the Hervé platform to analyze and visualize trends in HIV-1 diversification. Using Hervé, we analyzed 4,830 Env, 4,407 Gag, and 3,002 Pol publicly available independent sequences corresponding to subtypes A1, A6, B, C, D, F1, and G and circulating recombinant forms (CRFs) 01_AE, 02_AG, and 07_BC; sequences were sampled between 1980 and 2020 from 82 countries. HIV-1 diversified with a median of 1.82 amino acid substitutions per year in Env, 0.297 in Gag, and 0.779 in Pol. Yet, Env subtype B diversification plateaued post-2000. Pairwise diversity within subtypes and CRFs increased by 41.82% (range = 24.85%-54.41%) in Env, 56.93% (15.38%-89.16%) in Gag, and 46.12% (11.70%-70.57%) in Pol. Consensus sequences based on sequences sampled in each decade remained relatively stable over time. Similarly, at antibody epitope sites, only 0-8 residues that were minority variants became consensus over time in any subtype/CRF and only one known drug resistance mutation site differed from the reference (subtype G). The apparent contradiction between the fast diversification of HIV-1 and its limited adaptation illustrates that HIV-1 evolution is not directional and its consensus is at the intersection of millions of within-host selective processes occurring in a star-like manner. While a consensus sequence is a better representation of HIV-1 diversity than any individual sequence, consensus sequences have progressively become more distant from the circulating sequences they represent.

IMPORTANCE

Global surveillance of HIV-1 sequences is critical for designing relevant prophylactic and therapeutic interventions to infection. We designed an open-source platform, Hervé, for analyzing and visualizing the diversification dynamics of HIV-1 protein sequences. We characterized the evolution of over 12,000 HIV-1 Env, Gag, and Pol protein sequences from 1980-2020 and found that, despite a steady increase in intra-subtype and circulating recombinant form diversity, the most frequent residue at each site, i.e., the consensus, has varied only moderately.

Safety and immunogenicity of a subtype C ALVAC-HIV (vCP2438) vaccine prime plus bivalent subtype C gp120 vaccine boost adjuvanted with MF59 or alum in healthy adults without HIV (HVTN 107): A phase 1/2a randomized trial

BACKGROUND

Adjuvants are widely used to enhance and/or direct vaccine-induced immune responses yet rarely evaluated head-to-head. Our trial directly compared immune responses elicited by MF59 versus alum adjuvants in the RV144-like HIV vaccine regimen modified for the Southern African region. The RV144 trial of a recombinant canarypox vaccine vector expressing HIV env subtype B (ALVAC-HIV) prime followed by ALVAC-HIV plus a bivalent gp120 protein vaccine boost adjuvanted with alum is the only trial to have shown modest HIV vaccine efficacy. Data generated after RV144 suggested that use of MF59 adjuvant might allow lower protein doses to be used while maintaining robust immune responses. We evaluated safety and immunogenicity of an HIV recombinant canarypox vaccine vector expressing HIV env subtype C (ALVAC-HIV) prime followed by ALVAC-HIV plus a bivalent gp120 protein vaccine boost (gp120) adjuvanted with alum (ALVAC-HIV+gp120/alum) or MF59 (ALVAC-HIV+gp120/MF59) or unadjuvanted (ALVAC-HIV+gp120/no-adjuvant) and a regimen where ALVAC-HIV+gp120 adjuvanted with MF59 was used for the prime and boost (ALVAC-HIV+gp120/MF59 coadministration).

METHODS AND FINDINGS

Between June 19, 2017 and June 14, 2018, 132 healthy adults without HIV in South Africa, Zimbabwe, and Mozambique were randomized to receive intramuscularly: (1) 2 priming doses of ALVAC-HIV (months 0 and 1) followed by 3 booster doses of ALVAC-HIV+gp120/MF59 (months 3, 6, and 12), n = 36; (2) 2 priming doses of ALVAC-HIV (months 0 and 1) followed by 3 booster doses of ALVAC-HIV+gp120/alum (months 3, 6, and 12), n = 36; (3) 4 doses of ALVAC-HIV+gp120/MF59 coadministered (months 0, 1, 6, and 12), n = 36; or (4) 2 priming doses of ALVAC-HIV (months 0 and 1) followed by 3 booster doses of ALVAC-HIV+gp120/no adjuvant (months 3, 6, and 12), n = 24. Primary outcomes were safety and occurrence and mean fluorescence intensity (MFI) of vaccine-induced gp120-specific IgG and IgA binding antibodies at month 6.5. All vaccinations were safe and well-tolerated; increased alanine aminotransferase was the most frequent related adverse event, occurring in 2 (1.5%) participants (1 severe, 1 mild). At month 6.5, vaccine-specific gp120 IgG binding antibodies were detected in 100% of vaccinees for all 4 vaccine groups. No significant differences were seen in the occurrence and net MFI of vaccine-specific IgA responses between the ALVAC-HIV+gp120/MF59-prime-boost and ALVAC-HIV+gp120/alum-prime-boost groups or between the ALVAC-HIV+gp120/MF59-prime-boost and ALVAC-HIV+gp120/MF59 coadministration groups. Limitations were the relatively small sample size per group and lack of evaluation of higher gp120 doses.

CONCLUSIONS

Although MF59 was expected to enhance immune responses, alum induced similar responses to MF59, suggesting that the choice between these adjuvants may not be critical for the ALVAC+gp120 regimen.

TRIAL REGISTRATION

HVTN 107 was registered with the South African National Clinical Trials Registry (DOH-27-0715-4894) and ClinicalTrials.gov (NCT03284710).

Exploring HIV Vaccine Progress in the Pre-Clinical and Clinical Setting: From History to Future Prospects

The human immunodeficiency virus (HIV) continues to pose a significant global health challenge, with millions of people affected and new cases emerging each year. While various treatment and prevention methods exist, including antiretroviral therapy and non-vaccine approaches, developing an effective vaccine remains the most crucial and cost-effective solution to combating the HIV epidemic. Despite significant advancements in HIV research, the HIV vaccine field has faced numerous challenges, and only one clinical trial has demonstrated a modest level of efficacy. This review delves into the history of HIV vaccines and the current efforts in HIV prevention, emphasizing pre-clinical vaccine development using the non-human primate model (NHP) of HIV infection. NHP models offer valuable insights into potential preventive strategies for combating HIV, and they play a vital role in informing and guiding the development of novel vaccine candidates before they can proceed to human clinical trials.

Innate immune cell activation after HIV-1 vaccine administration is associated with increased antibody production

The RV144 Thai phase III clinical trial's canarypox-protein HIV vaccine regimen showed modest efficacy in reducing infection. We therefore sought to determine the effects of vaccine administration on innate cell activation and subsequent associations with vaccine-induced immune responses. RV306 was a randomized, double-blind clinical trial in HIV-uninfected Thai adults that tested delayed boosting following the RV144 regimen. PBMC collected from RV306 participants prior to and 3 days after the last boost were used to investigate innate immune cell activation. Our analysis showed an increase in CD38+ mucosal associated invariant T (MAIT) cells, CD38+ invariant natural killer T (iNKT) cells, CD38+ γδ T cells, CD38+, CD69+ and HLA-DR+ NK cells 3 days after vaccine administration. An increase in CD14-CD16+ non-classical monocytes and CD14+CD16+ intermediate monocytes accompanied by a decrease in CD14+CD16- classical monocytes was also associated with vaccine administration. Inclusion of ALVAC-HIV in the boost did not further increase MAIT, iNKT, γδ T, and NK cell activation or increase the proportion of non-classical monocytes. Additionally, NK cell activation 3 days after vaccination was positively associated with antibody titers of HIV Env-specific total IgG and IgG1. Vδ1 T cell activation 3 days after vaccine administration was associated with HIV Env-specific IgG3 titers. Finally, we observed trending associations between MAIT cell activation and Env-specific IgG3 titers and between NK cell activation and TH023 pseudovirus neutralization titers. Our study identifies a potential role for innate cells, specifically NK, MAIT, and γδ T cells, in promoting antibody responses following HIV-1 vaccine administration.

HIV epidemiology, prevention, treatment, and implementation strategies for public health

The global HIV response has made tremendous progress but is entering a new phase with additional challenges. Scientific innovations have led to multiple safe, effective, and durable options for treatment and prevention, and long-acting formulations for 2-monthly and 6-monthly dosing are becoming available with even longer dosing intervals possible on the horizon. The scientific agenda for HIV cure and remission strategies is moving forward but faces uncertain thresholds for success and acceptability. Nonetheless, innovations in prevention and treatment have often failed to reach large segments of the global population (eg, key and marginalised populations), and these major disparities in access and uptake at multiple levels have caused progress to fall short of their potential to affect public health. Moving forward, sharper epidemiologic tools based on longitudinal, person-centred data are needed to more accurately characterise remaining gaps and guide continued progress against the HIV epidemic. We should also increase prioritisation of strategies that address socio-behavioural challenges and can lead to effective and equitable implementation of existing interventions with high levels of quality that better match individual needs. We review HIV epidemiologic trends; advances in HIV prevention, treatment, and care delivery; and discuss emerging challenges for ending the HIV epidemic over the next decade that are relevant for general practitioners and others involved in HIV care.

Prophylactic HIV-1 vaccine trials: past, present, and future

An effective HIV-1 vaccine is a global health priority but has remained elusive for more than 40 years. Key scientific hurdles that have hampered vaccine development are the unprecedented genetic variability of the virus, the rapid establishment of persistent viral latency, and the challenges associated with induction of broadly neutralising antibodies. Clinical trials have been instrumental in evaluating scientific concepts and testing vaccine strategies. This Review discusses lessons learned from clinical trials of HIV-1 vaccines, current technologies that are being explored, and future considerations in the development of a safe and effective HIV-1 vaccine.

Contralateral second dose improves antibody responses to a 2-dose mRNA vaccination regimen

BACKGROUNDVaccination is typically administered without regard to site of prior vaccination, but this factor may substantially affect downstream immune responses.METHODSWe assessed serological responses to initial COVID-19 vaccination in baseline seronegative adults who received second-dose boosters in the ipsilateral or contralateral arm relative to initial vaccination. We measured serum SARS-CoV-2 spike-specific Ig, receptor-binding domain-specific (RBD-specific) IgG, SARS-CoV-2 nucleocapsid-specific IgG, and neutralizing antibody titers against SARS-CoV-2.D614G (early strain) and SARS-CoV-2.B.1.1.529 (Omicron) at approximately 0.6, 8, and 14 months after boosting.RESULTSIn 947 individuals, contralateral boosting was associated with higher spike-specific serum Ig, and this effect increased over time, from a 1.1-fold to a 1.4-fold increase by 14 months (P < 0.001). A similar pattern was seen for RBD-specific IgG. Among 54 pairs matched for age, sex, and relevant time intervals, arm groups had similar antibody levels at study visit 2 (W2), but contralateral boosting resulted in significantly higher binding and neutralizing antibody titers at W3 and W4, with progressive increase over time, ranging from 1.3-fold (total Ig, P = 0.007) to 4.0-fold (pseudovirus neutralization to B.1.1.529, P < 0.001).CONCLUSIONSIn previously unexposed adults receiving an initial vaccine series with the BNT162b2 mRNA COVID-19 vaccine, contralateral boosting substantially increases antibody magnitude and breadth at times beyond 3 weeks after vaccination. This effect should be considered during arm selection in the context of multidose vaccine regimens.FUNDINGM.J. Murdock Charitable Trust, OHSU Foundation, NIH.

The Interrelationship between HIV Infection and COVID-19: A Review of the Literature

The Corona Virus Disease 2019 (COVID-19) pandemic resulting from the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has led to significant morbidity and mortality in patients and put a strain on healthcare systems worldwide. The clinical characteristics and results of COVID-19 in immunosuppressed patients, such as people living with human immunodeficiency virus (PLWH), considered at higher risk of severe disease, are not well-characterized. Accumulated evidence indicates that COVID-19 and the human immunodeficiency virus (HIV) can interact in various ways. This review explored the similarities and differences in virology between SARS-CoV-2 and HIV, the effect of the COVID-19 vaccine on PLWH, the impact of the COVID-19 pandemic on PLWH care and prevention, and the influence of HIV-related factors on COVID-19. Discovering the potential link between HIV and COVID-19 may provide a novel way to avoid the factors of HIV and SARS-CoV-2 co-infection and advance future research.

Potent antibody-dependent cellular cytotoxicity of a V2-specific antibody is not sufficient for protection of macaques against SIV challenge

Fc-mediated antibody effector functions, such as antibody-dependent cellular cytotoxicity (ADCC), can contribute to the containment HIV-1 replication but whether such activities are sufficient for protection is unclear. We previously identified an antibody to the variable 2 (V2) apex of the HIV-1 Env trimer (PGT145) that potently directs the lysis of SIV-infected cells by NK cells but poorly neutralizes SIV infectivity. To determine if ADCC is sufficient for protection, separate groups of six rhesus macaques were treated with PGT145 or a control antibody (DEN3) by intravenous infusion followed five days later by intrarectal challenge with SIVmac239. Despite high concentrations of PGT145 and potent ADCC activity in plasma on the day of challenge, all animals became infected and viral loads did not differ between the PGT145- and DEN3-treated animals. To determine if PGT145 can protect against a neutralization-sensitive virus, two additional groups of six macaques were treated with PGT145 and DEN3 and challenged with an SIVmac239 variant with a single amino acid change in Env (K180S) that increases PGT145 binding and renders the virus susceptible to neutralization by this antibody. Although there was no difference in virus acquisition, peak and chronic phase viral loads were significantly lower and time to peak viremia was significantly delayed in the PGT145-treated animals compared to the DEN3-treated control animals. Env changes were also selected in the PGT145-treated animals that confer resistance to both neutralization and ADCC. These results show that ADCC is not sufficient for protection by this V2-specific antibody. However, protection may be achieved by increasing the affinity of antibody binding to Env above the threshold required for neutralization.

Nanoparticles and Antiviral Vaccines

Viruses have threatened human lives for decades, causing both chronic and acute infections accompanied by mild to severe symptoms. During the long journey of confrontation, humans have developed intricate immune systems to combat viral infections. In parallel, vaccines are invented and administrated to induce strong protective immunity while generating few adverse effects. With advancements in biochemistry and biophysics, different kinds of vaccines in versatile forms have been utilized to prevent virus infections, although the safety and effectiveness of these vaccines are diverse from each other. In this review, we first listed and described major pathogenic viruses and their pandemics that emerged in the past two centuries. Furthermore, we summarized the distinctive characteristics of different antiviral vaccines and adjuvants. Subsequently, in the main body, we reviewed recent advances of nanoparticles in the development of next-generation vaccines against influenza viruses, coronaviruses, HIV, hepatitis viruses, and many others. Specifically, we described applications of self-assembling protein polymers, virus-like particles, nano-carriers, and nano-adjuvants in antiviral vaccines. We also discussed the therapeutic potential of nanoparticles in developing safe and effective mucosal vaccines. Nanoparticle techniques could be promising platforms for developing broad-spectrum, preventive, or therapeutic antiviral vaccines.

High monoclonal neutralization titers reduced breakthrough HIV-1 viral loads in the Antibody Mediated Prevention trials

The Antibody Mediated Prevention (AMP) trials (NCT02716675 and NCT02568215) demonstrated that passive administration of the broadly neutralizing monoclonal antibody VRC01 could prevent some HIV-1 acquisition events. Here, we use mathematical modeling in a post hoc analysis to demonstrate that VRC01 influenced viral loads in AMP participants who acquired HIV. Instantaneous inhibitory potential (IIP), which integrates VRC01 serum concentration and VRC01 sensitivity of acquired viruses in terms of both IC50 and IC80, follows a dose-response relationship with first positive viral load (p = 0.03), which is particularly strong above a threshold of IIP = 1.6 (r = -0.6, p = 2e-4). Mathematical modeling reveals that VRC01 activity predicted from in vitro IC80s and serum VRC01 concentrations overestimates in vivo neutralization by 600-fold (95% CI: 300-1200). The trained model projects that even if future therapeutic HIV trials of combination monoclonal antibodies do not always prevent acquisition, reductions in viremia and reservoir size could be expected.

Rhesus macaques show increased resistance to repeated SHIV intrarectal exposure following a heterologous regimen of rVSV vector vaccine expressing HIV antigen

Despite the human immunodeficiency virus (HIV) pandemic continuing worldwide for 40 years, no vaccine to combat the disease has been licenced for use in at risk populations. Here, we describe a novel recombinant vesicular stomatitis virus (rVSV) vector vaccine expressing modified HIV envelope glycoproteins and Ebola virus glycoprotein. Three heterologous immunizations successfully prevented infection by a different clade SHIV in 60% of non-human primates (NHPs). No trend was observed between resistance and antibody interactions. Resistance to infection was associated with high proportions of central memory T-cell CD69 and CD154 marker upregulation, increased IL-2 production, and a reduced IFN-γ response, offering insight into correlates of protection.

Key considerations for the development of novel mRNA candidate vaccines in LMICs: A WHO/MPP mRNA Technology Transfer Programme meeting report

The WHO/MPP mRNA Technology Transfer Programme, initiated in 2021, focuses on establishing mRNA vaccine manufacturing capacity in LMICs. On 17-21 April 2023, Programme partners were convened to review technology transfer progress, discuss sustainability aspects and promote mRNA product development for diseases relevant to LMICs. To help guide product development, this report introduces key considerations for for understanding the likelihood of technical and regulatory success and of policy development and procurement for mRNA vaccines to be developed and manufactured in LMICs. The report underscores the potential for LMICs to establish sustainable mRNA R&D pipelines.

Conjugation of HIV-1 envelope to hepatitis B surface antigen alters vaccine responses in rhesus macaques

An effective HIV-1 vaccine remains a critical unmet need for ending the AIDS epidemic. Vaccine trials conducted to date have suggested the need to increase the durability and functionality of vaccine-elicited antibodies to improve efficacy. We hypothesized that a conjugate vaccine based on the learned response to immunization with hepatitis B virus could be utilized to expand T cell help and improve antibody production against HIV-1. To test this, we developed an innovative conjugate vaccine regimen that used a modified vaccinia virus Ankara (MVA) co-expressing HIV-1 envelope (Env) and the hepatitis B virus surface antigen (HBsAg) as a prime, followed by two Env-HBsAg conjugate protein boosts. We compared the immunogenicity of this conjugate regimen to matched HIV-1 Env-only vaccines in two groups of 5 juvenile rhesus macaques previously immunized with hepatitis B vaccines in infancy. We found expansion of both HIV-1 and HBsAg-specific circulating T follicular helper cells and elevated serum levels of CXCL13, a marker for germinal center activity, after boosting with HBsAg-Env conjugate antigens in comparison to Env alone. The conjugate vaccine elicited higher levels of antibodies binding to select HIV Env antigens, but we did not observe significant improvement in antibody functionality, durability, maturation, or B cell clonal expansion. These data suggests that conjugate vaccination can engage both HIV-1 Env and HBsAg specific T cell help and modify antibody responses at early time points, but more research is needed to understand how to leverage this strategy to improve the durability and efficacy of next-generation HIV vaccines.

Potency and durability of T and B cell immune responses after homologous and heterologous vector delivery of a trimer-stabilized, membrane-displayed HIV-1 clade ConC Env protein

Introduction

The generation of an HIV-1 vaccine able to induce long-lasting protective immunity remains a main challenge. Here, we aimed to modify next-generation soluble, prefusion-stabilized, close-to-native, glycan-engineered clade C gp140 envelope (Env) trimers (sC23v4 KIKO and ConCv5 KIKO) for optimal display on the cell surface following homologous or heterologous vector delivery.

Methods

A combination of the following modifications scored best regarding the preservation of closed, native-like Env trimer conformation and antigenicity when using a panel of selected broadly neutralizing (bnAb) and non-neutralizing (nnAb) monoclonal antibodies for flow cytometry: i) replacing the natural cleavage site with a native flexible linker and introducing a single amino acid substitution to prevent CD4 binding (*), ii) fusing a heterologous VSV-G-derived transmembrane moiety to the gp140 C-terminus, and iii) deleting six residues proximal to the membrane.

Results

When delivering membrane-tethered sC23v4 KIKO* and ConCv5 KIKO* via DNA, VSV-GP, and NYVAC vectors, the two native-like Env trimers provide differential antigenicity profiles. Whereas such patterns were largely consistent among the different vectors for either Env trimer, the membrane-tethered ConCv5 KIKO* trimer adopted a more closed and native-like structure than sC23v4 KIKO*. In immunized mice, VSV-GP and NYVAC vectors expressing the membrane-tethered ConCv5 KIKO* administered in prime/boost combination were the most effective regimens for the priming of Env-specific CD4 T cells among all tested combinations. The subsequent booster administration of trimeric ConCv5 KIKO* Env protein preserved the T cell activation levels between groups. The evaluation of the HIV-1-specific humoral responses induced in the different immunization groups after protein boosts showed that the various prime/boost protocols elicited broad and potent antibody responses, preferentially of a Th1-associated IgG2a subclass, and that the obtained antibody levels remained high at the memory phase.

Discussion

In summary, we provide a feasible strategy to display multiple copies of native-like Env trimers on the cell surface, which translates into efficient priming of sustained CD4+ T cell responses after vector delivery as well as broad, potent, and sustained antibody responses following booster immunizations with the homologous, prefusion-stabilized, close-to-native ConCv5 KIKO* gp140 Env trimer.

HIV-1 protective epitope-specific CD8+ T cells in HIV-1-exposed seronegative individuals

Although previous studies have reported HIV-1-specific T cell responses in HIV-1-exposed seronegative (HESN) individuals, there has been no detailed analysis of these T cells against HIV-1 infection. We investigated HIV-1-specific CD8+ T cell responses in 200 Japanese HESN men who have sex with men (MSM). T cell responses to 143 well-characterized HIV-1 epitope peptides were analyzed by intracellular cytokine staining assay consisting of 3-week cultures of PBMCs stimulated with peptides. HLA-B∗51:01-restricted Pol TI8-specific and HLA-A∗02:06-restricted Pol SV9-specific CD8+ T cells were identified in two and one individuals, respectively, whereas CD8+ T cells specific for other HLA-A∗02:06-restricted or HLA-B∗51:01 epitopes were not present in these individuals. These epitope-specific T cells recognized HIV-1-infected cells. Because these two epitopes were previously reported to be protective in HIV-1-infected individuals, these protective epitope-specific T cells might suppress HIV-1 replication in HESN-MSM individuals. The present study suggests the contribution of protective epitope-specific T cells to protection against HIV-1 infection.

Immunogenic arenavirus vector SIV vaccine reduces setpoint viral load in SIV-challenged rhesus monkeys

HIV affects more than 38 million people worldwide. Although HIV can be effectively treated by lifelong combination antiretroviral therapy, only a handful of patients have been cured. Therapeutic vaccines that induce robust de novo immune responses targeting HIV proteins and latent reservoirs will likely be integral for functional HIV cure. Our study shows that immunization of naïve rhesus macaques with arenavirus-derived vaccine vectors encoding simian immunodeficiency virus (SIVSME543 Gag, Env, and Pol) immunogens is safe, immunogenic, and efficacious. Immunization induced robust SIV-specific CD8+ and CD4+ T-cell responses with expanded cellular breadth, polyfunctionality, and Env-binding antibodies with antibody-dependent cellular cytotoxicity. Vaccinated animals had significant reductions in median SIV viral load (1.45-log10 copies/mL) after SIVMAC251 challenge compared with placebo. Peak viral control correlated with the breadth of Gag-specific T cells and tier 1 neutralizing antibodies. These results support clinical investigation of arenavirus-based vectors as a central component of therapeutic vaccination for HIV cure.

Generating and measuring effective vaccine-elicited HIV-specific CD8 + T cell responses

PURPOSE OF REVIEW

There is growing consensus that eliciting CD8 + T cells in addition to antibodies may be required for an effective HIV vaccine for both prevention and cure. Here, we review key qualities of vaccine-elicited CD8 + T cells as well as major CD8 + T cell-based delivery platforms used in recent HIV vaccine clinical trials.

RECENT FINDINGS

Much progress has been made in improving HIV immunogen design and delivery platforms to optimize CD8 + T cell responses. With regards to viral vectors, recent trials have tested newer chimp and human adenovirus vectors as well as a CMV vector. DNA vaccine immunogenicity has been increased by delivering the vaccines by electroporation and together with adjuvants as well as administering them as part of a heterologous regimen. In preclinical models, self-amplifying RNA vaccines can generate durable tissue-based CD8 + T cells. While it may be beneficial for HIV vaccines to recapitulate the functional and phenotypic features of HIV-specific CD8 + T cells isolated from elite controllers, most of these features are not routinely measured in HIV vaccine clinical trials.

SUMMARY

Identifying a vaccine capable of generating durable T cell responses that target mutationally vulnerable epitopes and that can rapidly intercept infecting or rebounding virus remains a challenge for HIV. Comprehensive assessment of HIV vaccine-elicited CD8 + T cells, as well as comparisons between different vaccine platforms, will be critical to advance our understanding of how to design better CD8 + T cell-based vaccines for HIV.

Prevention strategies for sexually transmitted infections, HIV, and viral hepatitis in Europe

The current prevention efforts for STIs, HIV and viral hepatitis in the WHO European Region, especially in the Central and Eastern subregions, are hindered by healthcare disparities, data gaps, and limited resources. In this comprehensive narrative review, we aim to highlight both achievements and persisting challenges while also exploring new developments that could significantly impact the prevention of these infections in the near future. While pre-exposure prophylaxis (PrEP) for HIV has been broadly approved and implemented in 38 out of 53 countries in the region, challenges remain, including cost, limited licensing, and incomplete adherence. We explore innovative approaches like on-demand PrEP, long-acting injectable cabotegravir, and intravaginal rings that have shown promising results, alongside the use of six-monthly lenacapavir, the outcomes of which are pending. Additionally, the potential of doxycycline post-exposure prophylaxis has been discussed, revealing efficacy in reducing chlamydia and syphilis risk, but effectiveness against gonorrhoea being contingent on tetracycline resistance rates, and the need of further data to determine potential resistance development in other bacteria and its impact on the gut microbiome. We examine successful vaccination campaigns against HBV and HPV, the ongoing development of vaccines for chlamydia, syphilis, herpesvirus, and gonorrhoea, and challenges in HIV vaccine research, including lines of research with significant potential like sequential immunization, T-cell responses, and mRNA technology. This review underscores the research endeavors that pave the way for a more resilient and robust approach to combating STIs, HIV, and viral hepatitis in the region.

Discovery medicine - the HVTN's iterative approach to developing an HIV-1 broadly neutralizing vaccine

PURPOSE OF REVIEW

In the past two decades, there has been an explosion in the discovery of HIV-1 broadly neutralizing antibodies (bnAbs) and associated vaccine strategies to induce them. This abundance of approaches necessitates a system that accurately and expeditiously identifies the most promising regimens. We herein briefly review the background science of bnAbs, provide a description of the first round of phase 1 discovery medicine studies, and suggest an approach to integrate these into a comprehensive HIV-1-neutralizing vaccine.

RECENT FINDINGS

With recent preclinical success including induction of early stage bnAbs in mouse knockin models and rhesus macaques, successful priming of VRC01-class bnAbs with eOD-GT8 in a recent study in humans, and proof-of-concept that intravenous infusion of VRC01 prevents sexual transmission of virus in humans, the stage is set for a broad and comprehensive bnAb vaccine program. Leveraging significant advances in protein nanoparticle science, mRNA technology, adjuvant development, and B-cell and antibody analyses, the HVTN has reconfigured its HIV-1 vaccine strategy by developing the Discovery Medicine Program to test promising vaccine candidates targeting six key epitopes.

SUMMARY

The HVTN Discovery Medicine program is testing multiple HIV-1-neutralizing vaccine candidates.

Mosaic HIV-1 vaccination induces anti-viral CD8+ T cell functionality in the phase 1/2a clinical trial APPROACH

IMPORTANCE

The functionality of CD8+ T cells against human immunodeficiency virus-1 (HIV-1) antigens is indicative of HIV-progression in both animal models and people living with HIV. It is, therefore, of interest to assess CD8+ T cell responses in a prophylactic vaccination setting, as this may be an important component of the immune system that inhibits HIV-1 replication. T cell responses induced by the adenovirus serotype 26 (Ad26) mosaic vaccine regimen were assessed previously by IFN-γ ELISpot and flow cytometric assays, yet these assays only measure cytokine production but not the capacity of CD8+ T cells to inhibit replication of HIV-1. In this study, we demonstrate direct anti-viral function of the clinical Ad26 mosaic vaccine regimen through ex vivo inhibition of replication of diverse clades of HIV-1 isolates in the participant's own CD4+ T cells.

Cytotoxic CD4+ T cells in chronic viral infections and cancer

CD4+ T cells play an important role in immune responses against pathogens and cancer cells. Although their main task is to provide help to other effector immune cells, a growing number of infections and cancer entities have been described in which CD4+ T cells exhibit direct effector functions against infected or transformed cells. The most important cell type in this context are cytotoxic CD4+ T cells (CD4+ CTL). In infectious diseases anti-viral CD4+ CTL are mainly found in chronic viral infections. Here, they often compensate for incomplete or exhausted CD8+ CTL responses. The induction of CD4+ CTL is counter-regulated by Tregs, most likely because they can be dangerous inducers of immunopathology. In viral infections, CD4+ CTL often kill via the Fas/FasL pathway, but they can also facilitate the exocytosis pathway of killing. Thus, they are very important effectors to keep persistent virus in check and guarantee host survival. In contrast to viral infections CD4+ CTL attracted attention as direct anti-tumor effectors in solid cancers only recently. Anti-tumor CD4+ CTL are defined by the expression of cytolytic markers and have been detected within the lymphocyte infiltrates of different human cancers. They kill tumor cells in an antigen-specific MHC class II-restricted manner not only by cytolysis but also by release of IFNγ. Thus, CD4+ CTL are interesting tools for cure approaches in chronic viral infections and cancer, but their potential to induce immunopathology has to be carefully taken into consideration.

NK cell subsets and dysfunction during viral infection: a new avenue for therapeutics?

In the setting of viral challenge, natural killer (NK) cells play an important role as an early immune responder against infection. During this response, significant changes in the NK cell population occur, particularly in terms of their frequency, location, and subtype prevalence. In this review, changes in the NK cell repertoire associated with several pathogenic viral infections are summarized, with a particular focus placed on changes that contribute to NK cell dysregulation in these settings. This dysregulation, in turn, can contribute to host pathology either by causing NK cells to be hyperresponsive or hyporesponsive. Hyperresponsive NK cells mediate significant host cell death and contribute to generating a hyperinflammatory environment. Hyporesponsive NK cell populations shift toward exhaustion and often fail to limit viral pathogenesis, possibly enabling viral persistence. Several emerging therapeutic approaches aimed at addressing NK cell dysregulation have arisen in the last three decades in the setting of cancer and may prove to hold promise in treating viral diseases. However, the application of such therapeutics to treat viral infections remains critically underexplored. This review briefly explores several therapeutic approaches, including the administration of TGF-β inhibitors, immune checkpoint inhibitors, adoptive NK cell therapies, CAR NK cells, and NK cell engagers among other therapeutics.

Safety and immunogenicity of a recombinant oligomeric gp145 subtype C Env protein (gp145 C.6980) HIV vaccine candidate in healthy, HIV-1-uninfected adult participants in the US

BACKGROUND

An approach to a preventive HIV vaccine is induction of effective broadly neutralizing antibodies (bnAbs) and effector binding antibodies (bAbs). Preclinical studies suggest that trimeric envelope (Env) proteins may elicit nAbs, which led to the development of the recombinant gp145 subtype C Env protein (gp145 C.6980) immunogen. HVTN 122 was a Phase 1 trial that evaluated the safety, tolerability, and immunogenicity of gp145 C.6980 in adults.

METHODS

Healthy, HIV-1 seronegative adults received three intramuscular injections of gp145 C.6980 with aluminum hydroxide (alum) at months 0, 2, and 6 at either 300 mcg (high dose, n = 25) or 100 mcg (low dose, n = 15), or placebo/saline (placebo, n = 5). Participants were followed for 12 months.

RESULTS

Forty-five participants were enrolled. High and low doses of the study protein were well-tolerated, with mild or moderate reactogenicity commonly reported. Only one adverse event (mild injection site pruritis) in one participant (low dose) was considered product-related; there were no dose-limiting toxicities. High and low dose recipients demonstrated robust bAb responses to vaccine-matched consensus gp140 Env and subtype-matched gp120 Env proteins two weeks post-last vaccination (response rates >90 %), while no responses were detected to a heterologous subtype-matched V1V2 antigen. No significant differences were seen between high and low dose groups. Participants in both experimental arms demonstrated nAb response rates of 76.5 % to a tier 1 virus (MW9635.26), but no responses to tier 2 isolates. Env-specific CD4 + T-cell responses were elicited in 36.4 % of vaccine recipients, without significant differences between groups; no participants demonstrated CD8 + T-cell responses.

CONCLUSIONS

Three doses of novel subtype C gp145 Env protein with alum were safe and well-tolerated. Participants demonstrated bAb, Env-specific CD4 + T-cell, and tier 1 nAb responses, but the regimen failed to induce tier 2 or heterologous nAb responses.

CLINICAL TRIALS REGISTRATION

NCT03382418.

Particulate antigens administrated by intranasal and intravaginal routes in a prime-boost strategy improve HIV-specific TFH generation, high-quality antibodies and long-lasting mucosal immunity

Mucosal surfaces serve as the primary entry points for pathogens such as SARS- CoV-2 coronavirus or HIV in the human body. Mucosal vaccination plays a crucial role to successfully induce long-lasting systemic and local immune responses to confer sterilizing immunity. However, antigen formulations and delivery methods must be properly selected since they are decisive for the quality and the magnitude of the elicited immune responses in mucosa. We investigated the significance of using particulate antigen forms for mucosal vaccination by comparing VLP- or protein- based vaccines in a mouse model. Based on a mucosal prime-boost immunization protocol combining (i) HIV- pseudotyped recombinant VLPs (HIV-VLPs) and (ii) plasmid DNA encoding HIV- VLPs (pVLPs), we demonstrated that combination of intranasal primes and intravaginal boosts is optimal to elicit both humoral and cellular memory responses in mucosa. Interestingly, our results show that in contrast to proteins, particulate antigens induce high-quality humoral responses characterized by a high breadth, long-term neutralizing activity and cross-clade reactivity, accompanying with high T follicular helper cell (TFH) response. These results underscore the potential of a VLP-based vaccine in effectively instigating long-lasting, HIV-specific immunity and point out the specific role of particulate antigen form in driving high-quality mucosal immune responses.

High throughput analysis of B cell dynamics and neutralizing antibody development during immunization with a novel clade C HIV-1 envelope

A protective HIV-1 vaccine has been hampered by a limited understanding of how B cells acquire neutralizing activity. Our previous vaccines expressing two different HIV-1 envelopes elicited robust antigen specific serum IgG titers in 20 rhesus macaques; yet serum from only two animals neutralized the autologous virus. Here, we used high throughput immunoglobulin receptor and single cell RNA sequencing to characterize the overall expansion, recall, and maturation of antigen specific B cells longitudinally over 90 weeks. Diversification and expansion of many B cell clonotypes occurred broadly in the absence of serum neutralization. However, in one animal that developed neutralization, two neutralizing B cell clonotypes arose from the same immunoglobulin germline and were tracked longitudinally. Early antibody variants with high identity to germline neutralized the autologous virus while later variants acquired somatic hypermutation and increased neutralization potency. The early engagement of precursors capable of neutralization with little to no SHM followed by prolonged affinity maturation allowed the two neutralizing lineages to successfully persist despite many other antigen specific B cells. The findings provide new insight into B cells responding to HIV-1 envelope during heterologous prime and boost immunization in rhesus macaques and the development of selected autologous neutralizing antibody lineages.

Prevention, treatment and cure of HIV infection

The development of antiretroviral therapy for the prevention and treatment of HIV infection has been marked by a series of remarkable successes. However, the efforts to develop a vaccine have largely failed, and efforts to discover a cure are only now beginning to gain traction. In this Review, we describe recent progress on all fronts - pre-exposure prophylaxis, vaccines, treatment and cure - and we discuss the unmet needs, both current and in the coming years. We describe the emerging arsenal of drugs, biologics and strategies that will hopefully address these needs. Although HIV research has largely been siloed in the past, this is changing, as the emerging research agenda is marked by multiple cross-discipline synergies and collaborations. As the limitations of antiretroviral drugs as a means to truly end the epidemic are becoming more apparent, there is a great need for continued efforts to develop an effective preventative vaccine and a scalable cure, both of which remain formidable challenges.

Oncoviruses: How do they hijack their host and current treatment regimes

Viruses have the ability to modulate the cellular machinery of their host to ensure their survival. While humans encounter numerous viruses daily, only a select few can lead to disease progression. Some of these viruses can amplify cancer-related traits, particularly when coupled with factors like immunosuppression and co-carcinogens. The global burden of cancer development resulting from viral infections is approximately 12%, and it arises as an unfortunate consequence of persistent infections that cause chronic inflammation, genomic instability from viral genome integration, and dysregulation of tumor suppressor genes and host oncogenes involved in normal cell growth. This review provides an in-depth discussion of oncoviruses and their strategies for hijacking the host's cellular machinery to induce cancer. It delves into how viral oncogenes drive tumorigenesis by targeting key cell signaling pathways. Additionally, the review discusses current therapeutic approaches that have been approved or are undergoing clinical trials to combat malignancies induced by oncoviruses. Understanding the intricate interactions between viruses and host cells can lead to the development of more effective treatments for virus-induced cancers.

HIV infection

The AIDS epidemic has been a global public health issue for more than 40 years and has resulted in ~40 million deaths. AIDS is caused by the retrovirus, HIV-1, which is transmitted via body fluids and secretions. After infection, the virus invades host cells by attaching to CD4 receptors and thereafter one of two major chemokine coreceptors, CCR5 or CXCR4, destroying the host cell, most often a T lymphocyte, as it replicates. If unchecked this can lead to an immune-deficient state and demise over a period of ~2-10 years. The discovery and global roll-out of rapid diagnostics and effective antiretroviral therapy led to a large reduction in mortality and morbidity and to an expanding group of individuals requiring lifelong viral suppressive therapy. Viral suppression eliminates sexual transmission of the virus and greatly improves health outcomes. HIV infection, although still stigmatized, is now a chronic and manageable condition. Ultimate epidemic control will require prevention and treatment to be made available, affordable and accessible for all. Furthermore, the focus should be heavily oriented towards long-term well-being, care for multimorbidity and good quality of life. Intense research efforts continue for therapeutic and/or preventive vaccines, novel immunotherapies and a cure.

Enhancement of Neutralization Responses through Sequential Immunization of Stable Env Trimers Based on Consensus Sequences from Select Time Points by Mimicking Natural Infection

HIV-1 vaccines have been challenging to develop, partly due to the high level of genetic variation in its genome. Thus, a vaccine that can induce cross-reactive neutralization activities will be needed. Studies on the co-evolution of antibodies and viruses indicate that mimicking the natural infection is likely to induce broadly neutralizing antibodies (bnAbs). We generated the consensus Env sequence for each time point in subject CH505, who developed broad neutralization activities, and selected five critical time points before broad neutralization was detected. These consensus sequences were designed to express stable Env trimers. Priming with the transmitted/founder Env timer and sequential boosting with these consensus Env trimers from different time points induced broader and more potent neutralizing activities than the BG505 Env trimer in guinea pigs. Analysis of the neutralization profiles showed that sequential immunization of Env trimers favored nAbs with gp120/gp41 interface specificity while the BG505 Env trimer favored nAbs with V2 specificity. The unique features such as consensus sequences, stable Env trimers and the sequential immunization to mimic natural infection likely has allowed the induction of improved neutralization responses.

Recent advances in poor HIV immune reconstitution: what will the future look like?

Combination antiretroviral therapy has demonstrated proved effectiveness in suppressing viral replication and significantly recovering CD4+ T cell count in HIV type-1 (HIV-1)-infected patients, contributing to a dramatic reduction in AIDS morbidity and mortality. However, the factors affecting immune reconstitution are extremely complex. Demographic factors, co-infection, baseline CD4 cell level, abnormal immune activation, and cytokine dysregulation may all affect immune reconstitution. According to report, 10-40% of HIV-1-infected patients fail to restore the normalization of CD4+ T cell count and function. They are referred to as immunological non-responders (INRs) who fail to achieve complete immune reconstitution and have a higher mortality rate and higher risk of developing other non-AIDS diseases compared with those who achieve complete immune reconstitution. Heretofore, the mechanisms underlying incomplete immune reconstitution in HIV remain elusive, and INRs are not effectively treated or mitigated. This review discusses the recent progress of mechanisms and factors responsible for incomplete immune reconstitution in AIDS and summarizes the corresponding therapeutic strategies according to different mechanisms to improve the individual therapy.

Advances in HIV therapeutics and cure strategies: findings obtained through non-human primate studies

Human immunodeficiency virus (HIV), the main contributor of the ongoing AIDS epidemic, remains one of the most challenging and complex viruses to target and eradicate due to frequent genome mutation and immune evasion. Despite the development of potent antiretroviral therapies, HIV remains an incurable infection as the virus persists in latent reservoirs throughout the body. To innovate a safe and effective cure strategy for HIV in humans, animal models are needed to better understand viral proliferation, disease progression, and therapeutic response. Nonhuman primates infected with simian immunodeficiency virus (SIV) provide an ideal model to study HIV infection and pathogenesis as they are closely related to humans genetically and express phenotypically similar immune systems. Examining the clinical outcomes of novel treatment strategies within nonhuman primates facilitates our understanding of HIV latency and advances the development of a true cure to HIV.

Additional boosting to the RV144 vaccine regimen increased Fc-mediated effector function magnitude but not durability

OBJECTIVES

The RV144 vaccine trial resulted in a decreased risk of HIV acquisition that was associated with a nonneutralizing antibody response. The objective of this study was to determine the impact of an additional boost to the RV144 vaccine regimen on antibody effector function and durability.

DESIGN

RV306 was a randomized, double-blind late boosting of the RV144 prime-boost regimen in HIV-uninfected Thai adults (NCT01931358). This analysis included study participants who received the RV144 vaccine regimen and received no additional boost (group 1) or were boosted with ALVAC-HIV and AIDSVAX (group 2) or only AIDSVAX alone (group 3) 24 weeks after completing the RV144 series.

METHODS

Plasma samples from RV306 study participants were used to measure antibody-dependent cellular phagocytosis (ADCP), antibody-dependent neutrophil phagocytosis (ADNP), antibody-dependent complement deposition (ADCD), antibody-dependent cellular cytotoxicity (ADCC), trogocystosis, and gp120-specifc IgG subclasses.

RESULTS

Additional boosting increased the magnitude of all Fc-mediated effector functions 2 weeks following the additional boost compared with 2 weeks after completing the RV144 regimen. However, only trogocytosis remained higher 24-26 weeks after the last vaccination for the study participants receiving an additional boost compared with those that did not receive an additional boost. The additional boost increased IgG1 and IgG4 but decreased IgG3 gp-120 specific antibodies compared with 2 weeks after completing the RV144 regimen.

CONCLUSION

Additional boosting of RV144 improved the magnitude but not the durability of some Fc-mediated effector functions that were associated with vaccine efficacy, with trogocytosis being the most durable.

Statistical and machine learning methods for immunoprofiling based on single-cell data

Immunoprofiling has become a crucial tool for understanding the complex interactions between the immune system and diseases or interventions, such as therapies and vaccinations. Immune response biomarkers are critical for understanding those relationships and potentially developing personalized intervention strategies. Single-cell data have emerged as a promising source for identifying immune response biomarkers. In this review, we discuss the current state-of-the-art methods for immunoprofiling, including those for reducing the dimensionality of high-dimensional single-cell data and methods for clustering, classification, and prediction. We also draw attention to recent developments in data integration.

Short Carbon Nanotube-Based Delivery of mRNA for HIV-1 Vaccines

Developing a safe and effective preventive for HIV-1 remains the hope for controlling the global AIDS epidemic. Recently, mRNA vaccines have emerged as a promising alternative to conventional vaccine approaches, primarily due to their rapid development and potential for low-cost manufacture. Despite the advantages of mRNA vaccines, challenges remain, especially due to the adverse effects of the delivery vehicle and low delivery efficiency. As a result, Luna Labs is developing a short carbon nanotube-based delivery platform (NanoVac) that can co-deliver mRNA and HIV-1 glycoproteins to the immune system efficiently with negligible toxicity. Surface chemistries of NanoVac were optimized to guide antigen/mRNA loading density and presentation. Multiple formulations were engineered for compatibility with both intramuscular and intranasal administration. NanoVac candidates demonstrated immunogenicity in rabbits and generated human-derived humoral and cellular responses in humanized mice (HIS). Briefly, 33% of the HIV-1-infected HIS mice vaccinated with NanoVac-mRNA was cleared of virus infection by 8-weeks post-infection. Finally, NanoVac stabilized the loaded mRNA against degradation under refrigeration for at least three months, reducing the cold chain burden for vaccine deployment.

Polyfunctional antibodies: a path towards precision vaccines for vulnerable populations

Vaccine efficacy determined within the controlled environment of a clinical trial is usually substantially greater than real-world vaccine effectiveness. Typically, this results from reduced protection of immunologically vulnerable populations, such as children, elderly individuals and people with chronic comorbidities. Consequently, these high-risk groups are frequently recommended tailored immunisation schedules to boost responses. In addition, diverse groups of healthy adults may also be variably protected by the same vaccine regimen. Current population-based vaccination strategies that consider basic clinical parameters offer a glimpse into what may be achievable if more nuanced aspects of the immune response are considered in vaccine design. To date, vaccine development has been largely empirical. However, next-generation approaches require more rational strategies. We foresee a generation of precision vaccines that consider the mechanistic basis of vaccine response variations associated with both immunogenetic and baseline health differences. Recent efforts have highlighted the importance of balanced and diverse extra-neutralising antibody functions for vaccine-induced protection. However, in immunologically vulnerable populations, significant modulation of polyfunctional antibody responses that mediate both neutralisation and effector functions has been observed. Here, we review the current understanding of key genetic and inflammatory modulators of antibody polyfunctionality that affect vaccination outcomes and consider how this knowledge may be harnessed to tailor vaccine design for improved public health.

The Mechanism of bnAb Production and Its Application in Mutable Virus Broad-Spectrum Vaccines: Inspiration from HIV-1 Broad Neutralization Research

Elite controllers among HIV-1-infected individuals have demonstrated a stronger ability to control the viral load in their bodies. Scientists have isolated antibodies with strong neutralizing ability from these individuals, which can neutralize HIV-1 variations; these are known as broadly neutralizing antibodies. The nucleic acid of some viruses will constantly mutate during replication (such as SARS-CoV-2), which will reduce the protective ability of the corresponding vaccines. The immune escape caused by this mutation is the most severe challenge faced by humans in the battle against the virus. Therefore, developing broad-spectrum vaccines that can induce broadly neutralizing antibodies against various viruses and their mutated strains is the best way to combat virus mutations. Exploring the mechanism by which the human immune system produces broadly neutralizing antibodies and its induction strategies is crucial in the design process of broad-spectrum vaccines.

Highly attenuated poxvirus-based vaccines against emerging viral diseases

Although one member of the poxvirus family, variola virus, has caused one of the most devastating human infections worldwide, smallpox, the knowledge gained over the last 30 years on the molecular, virological and immunological mechanisms of these viruses has allowed the use of members of this family as vectors for the generation of recombinant vaccines against numerous pathogens. In this review, we cover different aspects of the history and biology of poxviruses with emphasis on their application as vaccines, from first- to fourth-generation, against smallpox, monkeypox, emerging viral diseases highlighted by the World Health Organization (COVID-19, Crimean-Congo haemorrhagic fever, Ebola and Marburg virus diseases, Lassa fever, Middle East respiratory syndrome and severe acute respiratory syndrome, Nipah and other henipaviral diseases, Rift Valley fever and Zika), as well as against one of the most concerning prevalent virus, the Human Immunodeficiency Virus, the causative agent of AcquiredImmunodeficiency Syndrome. We discuss the implications in human health of the 2022 monkeypox epidemic affecting many countries, and the rapid prophylactic and therapeutic measures adopted to control virus dissemination within the human population. We also describe the preclinical and clinical evaluation of the Modified Vaccinia virus Ankara and New York vaccinia virus poxviral strains expressing heterologous antigens from the viral diseases listed above. Finally, we report different approaches to improve the immunogenicity and efficacy of poxvirus-based vaccine candidates, such as deletion of immunomodulatory genes, insertion of host-range genes and enhanced transcription of foreign genes through modified viral promoters. Some future prospects are also highlighted.