Lessons for general vaccinology research from attempts to develop an HIV vaccine

Tracing the recent updates on vaccination approaches and significant adjuvants being developed against HIV

INTRODUCTION

Human Immunodeficiency Virus type 1 (HIV1); the causative agent of Acquired Immunodeficiency Syndrome (AIDS), has been a major target of the scientific community to develop an anti-viral therapy. Some successful discoveries have been made during the last two decades in the form of availability of antiviral therapy in endemic regions. Nevertheless, a total cure and safety vaccine has not yet been designed to eradicate HIV from the world.

AREAS COVERED

The purpose of this comprehensive study is to compile recent data regarding therapeutic interventions against HIV and to determine future research needs in this field. A systematic research strategy has been used to gather data from recent, most advanced published electronic sources. Literature based results show that experiments at the invitro level and animal models are continuously in research annals and are providing hope for human trials.

EXPERT OPINION

There is still a gap and more work is needed in the direction of modern drug and vaccination designs. Moreover coordination is necessary among researchers, educationists, public health workers, and the general community to communicate and coordinate the repercussions associated with the deadly disease. It is important for taking timely measures regarding mitigation and adaptation with HIV in future.

Chimeric Human Papillomavirus-16 Virus-like Particles Presenting P18I10 and T20 Peptides from HIV-1 Envelope Induce HPV16 and HIV-1-Specific Humoral and T Cell-Mediated Immunity in BALB/c Mice

In this study, the HIV-1 P18I10 CTL peptide derived from the V3 loop of HIV-1 gp120 and the T20 anti-fusion peptide of HIV-1 gp41 were inserted into the HPV16 L1 capsid protein to construct chimeric HPV:HIV (L1:P18I10 and L1:T20) VLPs by using the mammalian cell expression system. The HPV:HIV VLPs were purified by chromatography. We demonstrated that the insertion of P18I10 or T20 peptides into the DE loop of HPV16 L1 capsid proteins did not affect in vitro stability, self-assembly and morphology of chimeric HPV:HIV VLPs. Importantly, it did not interfere either with the HIV-1 antibody reactivity targeting sequential and conformational P18I10 and T20 peptides presented on chimeric HPV:HIV VLPs or with the induction of HPV16 L1-specific antibodies in vivo. We observed that chimeric L1:P18I10/L1:T20 VLPs vaccines could induce HPV16- but weak HIV-1-specific antibody responses and elicited HPV16- and HIV-1-specific T-cell responses in BALB/c mice. Moreover, could be a potential booster to increase HIV-specific cellular responses in the heterologous immunization after priming with rBCG.HIVA vaccine. This research work would contribute a step towards the development of the novel chimeric HPV:HIV VLP-based vaccine platform for controlling HPV16 and HIV-1 infection, which is urgently needed in developing and industrialized countries.

Intersecting Pandemics of HIV and SARS-CoV-2: Commentary on the Special Issue

PURPOSE OF REVIEW

This editorial introduces this special Global Health Section on the interface of the HIV/AIDS and COVID-19 pandemics.

RECENT FINDINGS

Authors of articles in this special issue take on a variety of topics that capture how the acute COVID-19 pandemic affected global efforts towards HIV control, and how co-infection, stigma, and social determinants of disease have affected populations on multiple continents. Two historic pandemics -- HIV/AIDS and COVID-19 -- have affected the world in our lifetimes at a level reminiscent of the 1918-1919 H1N1 influenza pandemic. We have much to learn from both experiences to optimize pandemic disease control, prevention, and management.

Vaccine targeting SIVmac251 protease cleavage sites protects macaques against vaginal infection

After over 3 decades of research, an effective anti-HIV vaccine remains elusive. The recently halted HVTN702 clinical trial not only further stresses the challenge to develop an effective HIV vaccine but also emphasizes that unconventional and novel vaccine strategies are urgently needed. Here, we report that a vaccine focusing the immune response on the sequences surrounding the 12 viral protease cleavage sites (PCSs) provided greater than 80% protection to Mauritian cynomolgus macaques against repeated intravaginal SIVmac251 challenges. The PCS-specific T cell responses correlated with vaccine efficacy. The PCS vaccine did not induce immune activation or inflammation known to be associated with increased susceptibility to HIV infection. Machine learning analyses revealed that the immune microenvironment generated by the PCS vaccine was predictive of vaccine efficacy. Our study demonstrates, for the first time to our knowledge, that a vaccine which targets only viral maturation, but lacks full-length Env and Gag immunogens, can prevent intravaginal infection in a stringent macaque/SIV challenge model. Targeting HIV maturation thus offers a potentially novel approach to developing an effective HIV vaccine.

HIV Vaccine Development: 35 Years of Experimenting in the Funding of Biomedical Research

Funding vaccine development research is more complicated than simply putting out an announcement of funds available. The funders must decide whether product development can be accomplished by purely applied research, or whether more fundamental knowledge is needed before product development can be started. If additional basic knowledge is needed, identifying the specific area of the knowledge gap can be a challenge. Additionally, when there appears to be a clear path of applied research sometimes obstacles are encountered that require a return to more basic work. After deciding on the work to be done, funders must attract the scientists with the broad range of needed skills to cover all the stages of development. Collaborations must be promoted and alliances with other funders and industry must be developed. Funders use multiple tools and strategies to accomplish these tasks with varying success.

Immunotherapy targeting the Streptococcus pyogenes M protein or streptolysin O to treat or prevent influenza A superinfection

Viral infections complicated by a bacterial infection are typically referred to as coinfections or superinfections. Streptococcus pyogenes, the group A streptococcus (GAS), is not the most common bacteria associated with influenza A virus (IAV) superinfections but did cause significant mortality during the 2009 influenza pandemic even though all isolates are susceptible to penicillin. One approach to improve the outcome of these infections is to use passive immunization targeting GAS. To test this idea, we assessed the efficacy of passive immunotherapy using antisera against either the streptococcal M protein or streptolysin O (SLO) in a murine model of IAV-GAS superinfection. Prophylactic treatment of mice with antiserum to either SLO or the M protein decreased morbidity compared to mice treated with non-immune sera; however, neither significantly decreased mortality. Therapeutic use of antisera to SLO decreased morbidity compared to mice treated with non-immune sera but neither antisera significantly reduced mortality. Overall, the results suggest that further development of antibodies targeting the M protein or SLO may be a useful adjunct in the treatment of invasive GAS diseases, including IAV-GAS superinfections, which may be particularly important during influenza pandemics.

T cell-based strategies for HIV-1 vaccines

Despite 30 years of effort, we do not have an effective HIV-1 vaccine. Over the past decade, the HIV-1 vaccine field has shifted emphasis toward antibody-based vaccine strategies, following a lack of efficacy in CD8+ T-cell-based vaccine trials. Several lines of evidence, however, suggest that improved CD8+ T-cell-directed strategies could benefit an HIV-1 vaccine. First, T-cell responses often correlate with good outcomes in non-human primate (NHP) challenge models. Second, subgroup studies of two no-efficacy human clinical vaccine trials found associations between CD8+ T-cell responses and protective effects. Finally, improved strategies can increase the breadth and potency of CD8+ T-cell responses, direct them toward preferred epitopes (that are highly conserved and/or associated with viral control), or both. Optimized CD8+ T-cell vaccine strategies are promising in both prophylactic and therapeutic settings. This commentary briefly outlines some encouraging findings from T-cell vaccine studies, and then directly compares key features of some T-cell vaccine candidates currently in the clinical pipeline.

Updated Studies on the Development of HIV Therapeutic Vaccine

BACKGROUND

Among the various types of pharmaceuticals, vaccines have a special place. However, in the case of HIV, nearly after 40 years of its discovery, an effective vaccine still is not available. The reason lies in several facts mainly the variability and smartness of HIV as well as the complexity of the interaction between HIV and immune responses. A robust, effective, and longterm immunity is undoubtedly what a successful preventive vaccine should induce in order to prevent the infection of HIV. Failure of human trials to this end has led to the idea of developing therapeutic vaccines with the purpose of curing already infected patients by boosting their immune responses against the virus. Nevertheless, the exceptional ability of the virus to escape the immune system based on the genetically diverse envelope and variable protein products have made it difficult to achieve an efficient therapeutic vaccine.

OBJECTIVE

We aimed at studying and comparing different approaches to HIV therapeutic vaccines.

METHODS

In this review, we summarized the human trials undergoing on HIV therapeutic vaccination which are registered in the U.S. clinical trial database (clinicaltrials.gov). These attempts are divided into different tables, according to the type of formulation and application in order to classify and compare their results.

RESULT/CONCLUSION

Among several methods applied in studied clinical trials which are mainly divided into DNA, Protein, Peptide, Viral vectors, and Dendritic cell-based vaccines, protein vaccine strategy is based on Tat protein-induced anti-Tat Abs in 79% HIV patients. However, the studies need to be continued to achieve a durable efficient immune response against HIV-1.

CD8+ T cells in HIV control, cure and prevention

HIV infection can be effectively treated by lifelong administration of combination antiretroviral therapy, but an effective vaccine will likely be required to end the HIV epidemic. Although the majority of current vaccine strategies focus on the induction of neutralizing antibodies, there is substantial evidence that cellular immunity mediated by CD8⁺ T cells can sustain long-term disease-free and transmission-free HIV control and may be harnessed to induce both therapeutic and preventive antiviral effects. In this Review, we discuss the increasing evidence derived from individuals who spontaneously control infection without antiretroviral therapy as well as preclinical immunization studies that provide a clear rationale for renewed efforts to develop a CD8⁺ T cell-based HIV vaccine in conjunction with B cell vaccine efforts. Further, we outline the remaining challenges in translating these findings into viable HIV prevention, treatment and cure strategies.

Recently, antibody-mediated control of HIV infection has received considerable attention. Here, the authors discuss the importance of CD8⁺ T cells in HIV infection and suggest that efforts to develop vaccines that target these cells in conjunction with B cells should be renewed.

Effect of diversity in gp41 membrane proximal external region of primary HIV-1 Indian subtype C sequences on interaction with broadly neutralizing antibodies 4E10 and 10E8

Human Immunodeficiency Virus-1 Clade C (HIV-1C) dominates the AIDS epidemic in India, afflicting 2.1 million individuals within the country and more than 15 million people worldwide. Membrane proximal external region (MPER) is an attractive target for broadly neutralizing antibody (bNAb) based therapies. However, information on MPER sequence diversity from India is meagre due to limited sampling of primary viral sequences. In the present study, we examined the variation in MPER of HIV-1C from 24 individuals in Mumbai, India by high throughput sequencing of uncultured viral sequences. Deep sequencing of MPER (662-683; HXB2 envelope amino acid numbering) allowed quantification of intra-individual variation up to 65% at positions 662, 665, 668, 674 and 677 within this region. These variable positions included contact sites targeted by bNAbs 2F5, Z13e1, 4E10 as well as 10E8. Both major and minor epitope variants i.e. 'haplotypes' were generated for each sample dataset. A total of 23, 34 and 25 unique epitope haplotypes could be identified for bNAbs 2F5, Z13e1 and 4E10/10E8 respectively. Further analysis of 4E10 and 10E8 epitopes from our dataset and meta-analysis of previously reported HIV-1 sequences from India revealed 26 epitopes (7 India-specific), heretofore untested for neutralization sensitivity. Peptide-Ab docking predicted 13 of these to be non-binding to 10E8. ELISA, Surface Plasmon Resonance and peptide inhibition of HIV-1 neutralization assays were then performed which validated predicted weak/non-binding interactions for peptides corresponding to six of these epitopes. These results highlight the under-representation of 10E8 non-binding HIV-1C MPER sequences from India. Our study thus underscores the need for increased surveillance of primary circulating envelope sequences for development of efficacious bNAb-based interventions in India.

Induction of Broad and Polyfunctional HIV-1-Specific T Cell Responses by the Multiepitopic Protein TMEP-B Vectored by MVA Virus

A human immunodeficiency virus (HIV)/acquired immune deficiency syndrome (AIDS) vaccine able to induce long-lasting immunity remains a major challenge. We previously designed a T cell multiepitopic immunogen including protective conserved epitopes from HIV-1 Gag, Pol and Nef proteins (TMEP-B), that induced potent HIV-1-specific CD8 T cells when vectored by DNA and combined with the vaccine candidate modified vaccinia virus Ankara (MVA)-B. Here, we described the vectorization of TMEP-B in MVA (MVA-TMEP) and evaluated the T cell immunogenicity profile elicited in mice when administered in homologous (MVA/MVA) or heterologous (DNA/MVA) prime/boost vector regimens or using homologous or heterologous inserts. The heterologous vector regimen was superior to the homologous protocol in inducing T cell responses. DNA-TMEP-primed animals boosted with MVA-TMEP or MVA-B exhibited the highest magnitudes of HIV-1-specific CD8, CD4 and T follicular helper (Tfh) cells, with MVA-TMEP significantly expanding Gag-specific CD8 T cell responses. In the homologous vector regimen, all groups exhibited similar HIV-1-specific CD8 and CD4 T cell responses, but both MVA-B/MVA-B and MVA-TMEP/MVA-TMEP combinations elicited higher Gag-Pol-Nef (GPN)-specific CD8 T cell responses compared to MVA-TMEP/MVA-B. Our results revealed an enhanced induction of HIV-1-specific T cell responses by TMEP-B when vectored in both DNA and MVA, and supported their use in combined prime/boost strategies for HIV-1 prevention and/or therapy.