Search Results (85)

Human immunodeficiency virus (HIV) infection remains a major challenge in global health. In recent years, vaccines have emerged as an important tool for the treatment and prevention of HIV-related complications. This review article addresses the evolving landscape of vaccines for people living with HIV (PLWH), evaluating current vaccination strategies for standard vaccines and travel vaccines in PLWH compared to the general population and offering a summary of the current recommended vaccines. It evaluates studies for vaccine effectiveness and safety and discusses methods to improve vaccination rates among PLWH. Systematic research was carried out using keywords. We address the current state of knowledge and highlight areas for future research and development. Full article

Background: Human immunodeficiency virus (HIV) remains a global health challenge despite significant advancements in antiretroviral therapy and prevention strategies. Developing a safe and effective vaccine that protects people worldwide has been a major goal, yet the genetic variability and rapid mutation rate of the virus continue to pose substantial challenges. Methods: In this review paper, we aim to provide a comprehensive review of previous vaccine candidates and the progress made in HIV vaccine clinical trials, spanning from the late 1990s to 2025. PubMed and ClinicalTrials.gov were searched for English-language Phase 1–3 HIV vaccine trials published from 1990 to March 2025. After de-duplication, titles/abstracts and then full texts were screened; trial phase, regimen, immunogenicity, efficacy, and correlates were extracted into a structured spreadsheet. Owing to platform heterogeneity, findings were synthesized narratively and arranged chronologically to trace the evolution of vaccine strategies. Results: Early vaccine trials demonstrated that a protein subunit vaccine failed to protect against infection, revealing the complexity of HIV evasion strategies and shifting the focus to a comprehensive immune response, including both antibody and T-cell responses. Trials evaluating the role of viral vectors in generating cell-mediated immunity were also insufficient, and suggested that targeting T cell response alone was not enough. In 2009, the RV144 trial made a breakthrough by showing partial protection against HIV infection and providing the first indication of efficacy. This partial success influenced subsequent trials, prompting researchers to further explore the complex immune response required for protection and consider combinations of vaccine technologies to achieve robust, long-lasting immunity. Conclusion: Despite setbacks, decades of rigorous efforts have provided significant contributions to HIV vaccine discovery and development, offering hope for preventing and protecting against HIV infection. The field remains active by continuing to advance our understanding of the virus, refining vaccine strategies, and employing novel technologies. Full article

Background/Objectives: This study aimed to explore how HTLV-2 infection affects the production of broadly neutralizing antibodies (bNAbs) in persons with HIV-1 (PWH) and to assess the impact of boosted protease inhibitors (PIs). Methods: We evaluated broadly neutralizing antibody (bNAb) activity in 65 PWH, which included 27 who were also co-infected with HTLV-2. All participants were former injection drug users with HCV antibodies and were receiving suppressive antiretroviral therapy (ART). Neutralizing activity was assessed against six recombinant HIV-1 viruses that represent five different subtypes. B cell subsets were also analyzed. Results: HTLV-2 co-infection and the lack of ritonavir-boosted protease inhibitors (r-PIs) were both independently associated with higher neutralization scores (p = 0.017 and p = 0.005, respectively). Among those not on r-PIs, individuals co-infected with HTLV-2 showed significantly higher neutralization scores (p = 0.027) and a broader neutralization breadth (83.4% vs. 48.5%, p = 0.015) compared to those infected only with HIV-1. Additionally, HTLV-2 co-infected individuals had more resting memory B cells (p = 0.001) and fewer activated memory B cells (p = 0.017) than the HIV-1 mono-infected individuals. In our multivariate analysis, only HTLV-2 co-infection remained independently associated with neutralization scores (p = 0.027). Elite neutralizers (with a breadth score of ≥10) had more naive B cells and fewer resting memory B cells compared to those with weaker neutralization in both groups. Conclusions: Co-infection with HTLV-2 enhances bNAb production in PWH on suppressive ART and, in particular, in the absence of r-PI regimens. The prominent neutralizing activity corresponded with B cell subset distributions. The results suggest the complexity regarding the interaction between viral co-infections, antiretroviral regimens, and humoral immune compartments and may inform further H1V-1 pathogenesis inquiries or the appropriate design of a vaccine. Full article

During 2022, AIDS claimed a life every minute and about 9.2 million HIV-infected people were not on treatment. In addition, a person living with HIV is estimated to be 20–30 times more susceptible to developing active tuberculosis. Every year, 130,000 infants are newly infected, with vertical transmission being the main cause of pediatric HIV infection. Thus, the development of an effective, safe, and accessible vaccine for neonates and/or adults is an urgent need to prevent or control HIV infection or progression to AIDS. An effective HIV vaccine should induce long-lasting mucosal immunity, broadly neutralizing antibodies, innate immunity, and robust stimulation of CD4+ and CD8+ T-cell responses. Recombinant BCG is a promising live-attenuated bacterial vaccine vector because of its capacity to stimulate T-cell immunity. As a slow-growing microorganism, it provides prolonged low-level antigenic exposure upon infecting macrophages and APCs, potentially stimulating both effector and memory T-cell responses. BCG is considered safe and is currently administered to 80% of infants in countries where it is part of the national immunization program. Additionally, BCG offers several benefits as a live vaccine vehicle since it is cost-effective, easy to mass-produce, and heat stable. It is also well-suited for newborns, as maternal antibodies do not interfere with its efficacy. Furthermore, BCG has a strong safety profile, having been administered to over three billion people as a TB vaccine. In this review, we provide an extensive summary of the literature relating to immunogenicity studies in animal models performed since 2011. Moreover, we provide a comprehensive analysis of the key factors influencing the design of recombinant BCG as a live vaccine vehicle: (i) expression vectors; (ii) selection of HIV immunogen; (iii) promoters to regulate gene expression; (iv) BCG strain and BCG codon optimization; (v) genetic plasmid stability; (vi) influence of preexisting immunity, route, and dose immunization; and (vii) safety profile. Full article

Background/Objectives: The development of an effective HIV vaccine has faced persistent challenges, as evidenced by the recent discontinuation of the Mosaico phase 3 trial. This study aims to critically examine the obstacles encountered in HIV vaccine development, with a focus on the Mosaico trial, which tested the Ad26.Mos4.HIV vaccine among 3,900 participants across multiple countries. We also explore emerging vaccine technologies and their potential in overcoming these challenges, while reflecting on lessons from previous trials to inform future strategies. Methods: We reviewed the Mosaico trial’s approach, which involved testing the efficacy of the Ad26.Mos4.HIV vaccine. We compared the outcomes of the Mosaico trial with other major HIV vaccine trials, including HVTN 702, Imbokodo, and RV144. We explored the limitations of the immune responses elicited by the Mosaico vaccine. The review focused on the generation of broadly neutralizing antibodies (bNAbs) and the challenges related to antigenic diversity and B-cell engagement. Emerging vaccine technologies, such as virus-like particles (VLPs), nanoparticles, SOSIP trimers, and mRNA platforms, were also analysed for their scalability, immune durability, and potential to advance HIV vaccine development. Results: The Mosaico trial was discontinued due to insufficient efficacy in reducing HIV acquisition, primarily due to the inability of the vaccine to induce bNAbs, which are crucial for targeting the diverse HIV-1 strains. A major challenge was the inadequate engagement of germline B-cell precursors, compounded by the antigenic diversity of the virus. The analysis showed that emerging vaccine platforms, such as VLPs, nanoparticles, SOSIP trimers, and mRNA-based approaches, hold promise but present challenges related to scalability and the durability of immune responses. The role of T cells and adjuvants in enhancing vaccine efficacy was also highlighted as critical for integrating both humoral and cellular immunity. Conclusions: The Mosaico trial, as well as other major HIV vaccine trials, underscores the need for a multi-pronged approach that incorporates both antibody and T-cell responses to tackle the complexities of HIV-1. Future efforts in HIV vaccine development must focus on inducing bNAbs, generating robust T-cell responses, and utilizing scalable vaccine platforms. The integration of artificial intelligence (AI) into vaccine design offers new opportunities to optimize immunogenic targets, which could significantly improve the potential for durable and broad immune protection. The development of a successful HIV vaccine by 2030 is achievable but relies on leverage on advanced technologies including artificial intelligence, innovation and insights from past trial data. Full article

Background: The RV144 trial in Thailand is the only HIV-1 vaccine efficacy trial to date to demonstrate any efficacy. Genetic signatures suggested that antibodies targeting the variable loop 2 (V2) of the HIV-1 envelope played an important protective role. The ALVAC prime and protein boost follow-up trial in southern Africa (HVTN702) failed to show any efficacy. One hypothesis for this is the greater diversity of subtype C viruses in southern Africa relative to CRF01_AE in Thailand. Methods: Here, we determined whether an ALVAC prime with computationally selected gp120 boost immunogens maximizing coverage of diversity of subtype C viruses in the variable V1 and V2 regions (V1V2) improved the protection of non-human primates (NHPs) from a heterologous subtype C SHIV challenge compared to more traditional regimens. Results: An ALVAC prime with Trivalent subtype C gp120 boosts resulted in statistically significant protection from repeated intrarectal SHIV challenges compared to the control. Evaluation of the immunogenicity of each vaccine regimen at the time of challenge demonstrated that different gp120 combination boosts elicited similar high magnitudes of gp120 and breadth of V1V2-binding antibodies, as well as strong Fc-mediated immune responses. Low-to-no neutralization of the challenge virus was detected. A Cox proportional hazard analysis of five pre-selected immune parameters at the time of challenge identified ADCC against the challenge envelope as a correlate of protection. Systems serology analysis revealed that immune responses elicited by the different vaccine regimens were distinct and identified further correlates of resistance to infection. Conclusions: Computationally designed vaccines with maximized subtype C V1V2 coverage mediated protection of NHPs from a heterologous Tier-2 subtype C SHIV challenge. Full article

The development of an effective HIV-1 vaccine remains a formidable challenge in biomedical research. Despite significant advancements in our understanding of HIV biology and pathogenesis, progress has been impeded by factors such as the virus's genetic diversity, high mutation rates, and its ability to establish latent reservoirs. Recent innovative approaches, including mosaic vaccines and mRNA technology to induce broadly neutralizing antibodies, have shown promise. However, the efficacy of these vaccines has been modest, with the best results achieving approximately 30% effectiveness. Ongoing research emphasizes the necessity of a multifaceted strategy to overcome these obstacles and achieve a breakthrough in HIV-1 vaccine development. This review summarizes current approaches utilized to further understand HIV-1 biology and to create a global vaccine. We discuss the impact of these approaches on vaccine development for other diseases, including COVID-19, influenza, and Zika virus. Additionally, we highlight the specific limitations faced with each approach and present the methods researchers employ to overcome these challenges. These innovative techniques, which have demonstrated preclinical and clinical success, have advanced the field closer to the ultimate goal of developing a global HIV-1 vaccine. Leveraging these advancements will enable significant strides in combating HIV-1 and other infectious diseases, ultimately improving global health outcomes. Full article

Background: HIV-1 envelope (Env) variable loops 1 and 2 (V1V2) directed non-neutralizing antibodies were a correlate of decreased transmission risk in the RV144 vaccine trial. Thus, the elicitation and breadth of antibody responses against the V1V2 of HIV-1 Env are important considerations for HIV-1 vaccine candidates. The V1V2 region’s highly variable nature and the extensive diversity of subtype C HIV-1 Envelopes (Envs) make the V1V2 response breadth a high priority for HIV-1 vaccine regimens aiming for V1V2-mediated protection in Southern Africa. Here, we determined whether the breadth of the anti-V1V2 vaccine response can be broadened by including HIV-1 Env strains computationally designed to enhance the coverage of subtype C V1V2 sequence diversity. Methods: Three subtype C Env strains were selected to maximize antibody binding coverage while complementing subtype C vaccine gp120s that were given in human clinical trials in South Africa, as well as to improve epitope accessibility. Humoral immunogenicity of a novel trivalent gp120 vaccine immunogen, a bivalent gp120 boost already in clinical trials (1086C and TV1), and a pentavalent (all five gp120s combined) were evaluated in a preclinical immunization study in guinea pigs. The pentavalent combination was further evaluated with alum versus glucopyranosyl lipid adjuvants formulated in squalene-in-water emulsion (GLA-SE) adjuvants in non-human primates. The breadth of the anti-V1V2 response was assessed using an array of cross-subtype variable loops 1&2 (V1V2) scaffold proteins and linear V2 peptides. Results: The breadth of the IgG response against V1V2 antigens of the trivalent and pentavalent groups was comparable, and both were greater than the breadth of the bivalent group. Linear epitope mapping showed that two linear epitopes in V2 were targeted by the vaccinated animals: the V2 hotspot focused at ¹⁶⁹K that potentially correlated with decreased HIV-1 risk in RV144 and the V2.2 site (¹⁷⁹LDV/I¹⁸¹) that is part of the integrin α4β7 binding site. The bivalent vaccine elicited a significantly higher magnitude of binding to the V2 hotspot compared to the trivalent vaccine whereas the trivalent vaccine elicited significantly higher binding to the V2.2 epitope compared to the bivalent vaccine, while the pentavalent recognized both regions. Conclusions: These results demonstrate that the three new computationally selected subtype C Envs successfully complemented 1086C and TV1 for broader V1V2 antibody responses, and, in concert with adjuvants that stimulate V1V2 responses, can be considered as part of a rationale immunogen design to improve V1V2 IgG coverage in future vaccine trials in South Africa. Full article

Background: Elite-neutralizer-derived HIV-1 envelopes (Envs), which induce broadly neutralizing antibodies (bnAbs), can inform HIV-1 vaccine design by serving as templates for bnAb-eliciting vaccines. Since single Env-based immunizations are insufficient to induce bnAb responses, sequential regimens using multivalent immunogens or Env cocktails hold greater promise. This underscores the need to develop stable Env trimers from diverse HIV-1 strains, particularly clade-C, which accounts for 50% of global infections and over 90% in India and South Africa. While various platforms exist to stabilize soluble Env trimers for use as antigenic baits and vaccines, stabilizing clade C trimers remains challenging. Methods: We stabilized an HIV-1 clade C trimer based on an Env isolated from a pediatric elite neutralizer (AIIMS_329) using multiple platforms, including SOSIP.v8.2, ferritin nanoparticles (NPs) and I53-50 two-component NPs, followed by characterization of their biophysical, antigenic, and immunogenic properties. Results: The stabilized 329 Envs showed binding to multiple HIV-1 bnAbs, with negligible binding to non-neutralizing antibodies. Negative-stain electron microscopy confirmed the native-like conformation of the Envs. Multimerization of 329 SOSIP.v8.2 on ferritin and two-component I53-50 NPs improved the affinity to HIV-1 bnAbs and showed higher immunogenicity in rabbits. Conclusions: The soluble 329 Env protein could serve as an antigenic bait, and multimeric 329 NP Envs are potential vaccine candidates. Full article

Background: The development of a protective vaccine is critical for conclusively ending the human immunodeficiency virus (HIV) epidemic. Methods: We constructed nucleotide-modified mRNA vaccines expressing HIV-1 Env and Gag proteins. Env–gag virus-like particles (VLPs) were generated through co-transfection with env and gag mRNA vaccines. BALB/c mice were immunized with env mRNA, env–gag VLP mRNA, env plasmid DNA vaccine, or lipid nanoparticle (LNP) controls. HIV Env-specific binding and neutralizing antibodies in mouse sera were assessed via enzyme-linked immunosorbent assay (ELISA) and pseudovirus-based neutralization assays, respectively. Env-specific cellular immune responses in mouse splenocytes were evaluated using an Enzyme-linked immunosorbent assay (ELISpot) and in vivo cytotoxic T cell-killing assays. Results: The Env-specific humoral and cellular immune responses elicited by HIV-1 env mRNA and env–gag VLP mRNA vaccine were stronger than those induced by the DNA vaccine. Specific immune responses induced by the env mRNA vaccine were significantly stronger in the high-dose group than in the low-dose group. Immunization with co-formulated env and gag mRNAs elicited superior cellular immune responses compared to env mRNA alone. Conclusions: These findings suggest that the env–gag VLP mRNA platform holds significant promise for HIV-1 vaccine development. Full article

Background/Objectives: The impact of virion maturation on neutralizing antibody responses in HIV treatment is not fully understood. This study examines whether antiretroviral regimens (ART) with boosted protease inhibitors (b-PI), which increase exposure to immature virions, affect neutralization capacity compared to Non-b-PI regimens. Methods: Neutralization activity was assessed in 45 HIV-infected individuals on b-PI regimens and 56 on Non-b-PI regimens, adjusting for factors like infection duration, ART initiation, and immune markers. Individuals on b-PI regimens had significantly lower neutralization scores [mean: 6.1, 95% Confidence Interval (CI): 5.3–6.9] than those on Non-b-PI regimens (mean: 8.9, 95% CI: 8.0–9.9; p < 0.0001). This difference was not explained by infection duration or CD4+ counts. CD4+/CD8+ ratios were positively associated with neutralization, while b-PI use was negatively associated. A regression model indicated that b-PI use significantly predicted lower neutralization scores (beta = −0.30, p = 0.049). Conclusions: These findings suggest that exposure to immature virions via b-PI use reduces neutralizing antibody responses, highlighting the importance of virion maturation in antibody induction. ART regimens promoting exposure to mature virions may enhance neutralization, with potential implications for HIV vaccine design. Further research is needed to explore implications for HIV vaccine design, especially using virus-like particles. Full article

HIV-1 has an antisense gene overlapping env that encodes the ASP protein. ASP functions are still unknown, but it has been associated with gp120 in the viral envelope and membrane of infected cells, making it a potential target for immune response. Despite this, immune response patterns against ASP are poorly described and can be influenced by the high genetic variability of the env gene. To explore this, we analyzed 100k HIV-1 ASP sequences from the Los Alamos HIV sequence database using phylogenetic, Shannon entropy (Hs), and logo tools to study ASP variability in worldwide and Brazilian sequences from the most prevalent HIV-1 subtypes in Brazil (B, C, and F1). Data obtained in silico guided the design and synthesis of 15-mer overlapping peptides through spot synthesis on cellulose membranes. Peptide arrays were screened to assess IgG and IgM responses in pooled plasma samples from HIV controllers and individuals with acute or recent HIV infection. Excluding regions with low alignment accuracy, several sites with higher variability (Hs > 1.5) were identified among the datasets (25 for worldwide sequences, 20 for Brazilian sequences). Among sites with Hs < 1.5, sequence logos allowed the identification of 23 other sites with subtype-specific signatures. Altogether, amino acid variations with frequencies > 20% in the 48 variable sites identified were included in 92 peptides, divided into 15 sets, representing near full-length ASP. During the immune screening, the strongest responses were observed in three sets, one in the middle and one at the C-terminus of the protein. While some sets presented variations potentially associated with epitope displacement between IgG and IgM targets and subtype-specific signatures appeared to impact the level of response for some peptides, signals of cross-reactivity were observed for some sets despite the presence of B/C/F1 signatures. Our data provides a map of ASP regions preferentially targeted by IgG and IgM responses. Despite B/C/F1 subtype signatures in ASP, the amino acid variation in some areas preferentially targeted by IgM and IgG did not negatively impact the response against regions with higher immunogenicity. Full article

Arenavirus-based vectors are being investigated as therapeutic vaccine candidates with the potential to elicit robust CD8 T-cell responses. We compared the immunogenicity of replicating (artPICV and artLCMV) and non-replicating (rPICV and rLCMV) arenavirus-based vectors expressing simian immunodeficiency virus (SIV) Gag and Envelope (Env) immunogens in treatment-naïve non-human primates. Heterologous regimens with non-replicating and replicating vectors elicited more robust SIV IFN-γ responses than a homologous regimen, and replicating vectors elicited significantly higher cellular immunogenicity than non-replicating vectors. The heterologous regimen elicited high anti-Env antibody titers when administered intravenously, with replicating vectors inducing significantly higher titers than non-replicating vectors. Intramuscular immunization resulted in more durable antibody responses than intravenous immunization for both vector platforms, with no difference between the replicating and non-replicating vectors. Overall, both replicating and non-replicating arenavirus vectors generated robust T- and B-cell-mediated immunity to SIV antigens in treatment-naïve non-human primates, supporting further evaluation of these vectors in a clinical setting for HIV therapy. Full article

The mechanisms underlying unsatisfactory immune reconstitution in HIV-1 positive patients under ART have not been fully elucidated, even after years of investigation. Thus, this study aimed to assess the correlation between age and thymic production profile, and its influence on inadequate immunological recovery. Here, 44 ART-treated patients with undetectable plasma HIV-1 load (<40 copies/mL) were classified as 31 immunological responders (IR) and 13 immunological non-responders (INR), according to their CD4+ T-cell count after 18 months of ART. The thymic function was assessed by identifying recent thymic emigrants (RTEs) CD4+ T cells (CD4+/CD45RA+CD31+) in PBMCs using flow cytometry. Clinical data were also analyzed from medical records. The INR group showed a higher age at ART initiation (41 ± 3.0) compared to the IR (33.7 ± 2.1) group (p = 0.041). Evaluating RTE CD4+ T-cells, we observed a lower percentage in the INR group (19.5 ± 6.3) compared to the IR group (29.9 ± 11.5) (p = 0.012). There was a strong negative correlation between age at ART initiation and RTE CD4+ T-cells in INRs (r = −0.784, p = 0.004). Our study has highlighted the thymic insufficiency and aging-related immunosenescence with unsatisfactory immunological recovery during ART in HIV-1 positive patients. Full article

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. Full article