HIV vaccines: a brief overview

Heterologous DNA Prime/Protein Boost Immunization Targeting Nef-Tat Fusion Antigen Induces Potent T-cell Activity and in vitro Anti-SCR HIV-1 Effects

BACKGROUND

Heterologous combinations in vaccine design are an effective approach to promote T cell activity and antiviral effects. The goal of this study was to compare the homologous and heterologous regimens targeting the Nef-Tat fusion antigen to develop a human immunodeficiency virus-1 (HIV-1) therapeutic vaccine candidate.

METHODS

At first, the DNA and protein constructs harboring HIV-1 Nef and the first exon of Tat as linked form (pcDNA-nef-tat and Nef-Tat protein) were prepared in large scale and high purity. The generation of the Nef-Tat protein was performed in the E. coli expression system using an IPTG inducer. Then, we evaluated and compared immune responses of homologous DNA prime/ DNA boost, homologous protein prime/ protein boost, and heterologous DNA prime/protein boost regimens in BALB/c mice. Finally, the ability of mice splenocytes to secret cytokines after exposure to single-cycle replicable (SCR) HIV-1 was compared between immunized and control groups in vitro.

RESULTS

The nef-tat gene was successfully subcloned in eukaryotic pcDNA3.1 (-) and prokaryotic pET-24a (+) expression vectors. The recombinant Nef-Tat protein was generated in the E. coli Rosetta strain under optimized conditions as a clear band of ~ 35 kDa detected on SDS-PAGE. Moreover, transfection of pcDNA-nef-tat into HEK-293T cells was successfully performed using Lipofectamine 2000, as confirmed by western blotting. The immunization studies showed that heterologous DNA prime/protein boost regimen could significantly elicit the highest levels of Ig- G2a, IFN-γ, and Granzyme B in mice as compared to homologous DNA/DNA and protein/protein regimens. Moreover, the secretion of IFN-γ was higher in DNA/protein regimens than in DNA/DNA and protein/protein regimens after exposure of mice splenocytes to SCR HIV-1 in vitro.

CONCLUSION

The chimeric HIV-1 Nef-Tat antigen was highly immunogenic, especially when applied in a heterologous prime/ boost regimen. This regimen could direct immune response toward cellular immunity (Th1 and CTL activity) and increase IFN-γ secretion after virus exposure.

Novel Antiretroviral Therapeutic Strategies for HIV

When the first cases of HIV infection appeared in the 1980s, AIDS was a deadly disease without any therapeutic alternatives. Currently, there is still no cure for most cases mainly due to the multiple tissues that act as a reservoir for this virus besides the high viral mutagenesis that leads to an antiretroviral drug resistance. Throughout the years, multiple drugs with specific mechanisms of action on distinct targets have been approved. In this review, the most recent phase III clinical studies and other research therapies as advanced antiretroviral nanodelivery systems will be here discussed. Although the combined antiretroviral therapy is effective in reducing viral loading to undetectable levels, it also presents some disadvantages, such as usual side effects, high frequency of administration, and the possibility of drug resistance. Therefore, several new drugs, delivery systems, and vaccines have been tested in pre-clinical and clinical trials. Regarding drug delivery, an attempt to change the route of administration of some conventional antiretrovirals has proven to be successful and surpassed some issues related to patient compliance. Nanotechnology has brought a new approach to overcoming certain obstacles of formulation design including drug solubility and biodistribution. Overall, the encapsulation of antiretroviral drugs into nanosystems has shown improved drug release and pharmacokinetic profile.

Comparison of the efficacy of HIV-1 Nef-Tat-Gp160-p24 polyepitope vaccine candidate with Nef protein in different immunization strategies

OBJECTIVES

One of the promising strategies for effective HIV-1 vaccine design involves finding the polyepitope immunogens using T cell epitopes.

METHODS

Herein, an HIV-1 polyepitope construct (i.e., Nef-Tat-Gp160-P24) comprising of several epitopes from Nef, Tat, Gp160, and P24 proteins was designed. To improve its immunogenicity in BALB/c mice, cell-penetrating peptides (HR9 & MPG for DNA delivery, and LDP-NLS & CyLoP-1 for protein transfer), Montanide adjuvant, and heterologous DNA prime/polypeptide boost strategy were used. To compare the immunogenicity, Nef was utilized as a vaccine candidate. The levels of total IgG and its subclasses, cytokines, and Granzyme B were assessed using ELISA.

RESULTS

Immunological studies showed that heterologous prime-boost regimens for both antigens could considerably augment the levels of IgG2a, IgG2b, IFN-γ, and Granzyme B directed toward Th1 and CTL immune responses in comparison with homologous prime-boost strategies. The levels of IFN-γ, IL-10, total IgG, IgG1, and IgG2b were drastically higher in groups immunized with Nef-Tat-Gp160-P24 in heterologous prime-boost regimens than those in groups immunized with Nef.

CONCLUSIONS

The use of the Nef-Tat-Gp160-P24 polyepitope immunogen in heterologous prime-boost strategy could generate the mixture of Th1 and Th2 responses directed further toward Th1 response as a hopeful method for improvement of HIV-1 vaccine.

Forecasting future HIV infection cases: evidence from Indonesia

Countries throughout the world, including Indonesia, are facing a complex problem with regards to HIV infection incidences and its prevalence. This is despite some local governments in some provinces of Indonesia working together with the Social Ministry of Indonesia to eradicate prostitution. There are high numbers of HIV sub-types in Indonesia such as HIV-1 (CRF01_AE and B). The forecast was conducted with the Autoregressive Integrated Moving Average model. The ARMA (1,1) was observed to be the best model for forecasting the number of HIV patients in Indonesia. This forecasting has been done since March 2019. Based on its dynamic forecasting with ARMA (1,1), this study proved the number of HIV-positive patients, from 2019 to 2030, had increased from 22,679 to 36,255, by almost 37% within 12 years. Indonesia is facing a growing trend in the number of new HIV cases, until 2030 which caused by stopped their follow-up treatments or they have ceased in consuming the Antiretroviral drugs even though the Indonesian government was provided national health insurance which covers the Antiretroviral drug and a limited number of health-care services providing the Antiretroviral therapy. Therefore, investigations focusing on estimate the number of HIV patients in Indonesia is an important finding. The information can be used as a resource for policy and decision making for plans and programs.

Combination of Mechanical and Chemical Methods Improves Gene Delivery in Cell-based HIV Vaccines

OBJECTIVE

Novel vaccination approaches are required to control human immunodeficiency virus (HIV) infections. The membrane proximal external region (MPER) of Env gp41 subunit and the V3/glycans of Env gp120 subunit were known as potential antigenic targets for anti-HIV-1 vaccines. In this study, we prepared the modified dendritic cells (DCs) and mesenchymal stem cells (MSCs) with HIV-1 MPER-V3 gene using mechanical and chemical approaches.

METHODS

At first, MPER-V3 fusion DNA delivery was optimized in dendritic cells (DCs) and mesenchymal stem cells (MSCs) using three mechanical (i.e., uniaxial cyclic stretch, equiaxial cyclic stretch and shear stress bioreactors), and two chemical (i.e., TurboFect or Lipofectamine) methods. Next, the modified DCs and MSCs with MPER-V3 antigen were compared to induce immune responses in vivo.

RESULTS

Our data showed that the combination of equiaxial cyclic stretch loading and lipofectamine twice with 48 h intervals increased the efficiency of transfection about 60.21 ± 1.05 % and 65.06 ± 0.09 % for MSCs and DCs, respectively. Moreover, DCs and MSCs transfected with MPER-V3 DNA in heterologous DC or MSC prime/ peptide boost immunizations induced high levels of IgG2a, IgG2b, IFN-γ and IL-10 directed toward Th1 responses as well as an increased level of Granzyme B. Indeed, the modified MSCs and DCs with MPER-V3 DNA could significantly enhance the MPER/V3-specific T-cell responses compared to MPER/V3 peptide immunization.

CONCLUSIONS

These findings showed that the modified MSC-based immunization could elicit effective immune responses against HIV antigen similar to the modified DC-based immunization.

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.

M918: A Novel Cell Penetrating Peptide for Effective Delivery of HIV-1 Nef and Hsp20-Nef Proteins into Eukaryotic Cell Lines

BACKGROUND

HIV-1 Nef protein is a possible attractive target in the development of therapeutic HIV vaccines including protein-based vaccines. The most important disadvantage of protein-based vaccines is their low immunogenicity which can be improved by heat shock proteins (Hsps) as an immunomodulator, and cell-penetrating peptides (CPPs) as a carrier.

METHODS

In this study, the HIV-1 Nef and Hsp20-Nef proteins were generated in E.coli expression system for delivery into the HEK-293T mammalian cell line using a novel cell-penetrating peptide, M918, in a non-covalent fashion. The size, zeta potential and morphology of the peptide/protein complexes were studied by scanning electron microscopy (SEM) and Zeta sizer. The efficiency of Nef and Hsp20-Nef transfection using M918 was evaluated by western blotting in HEK-293T cell line.

RESULTS

The SEM data confirmed the formation of discrete nanoparticles with a diameter of approximately 200-250 nm and 50-80 nm for M918/Nef and M918/Hsp20-Nef, respectively. The dominant band of ~ 27 kDa and ~ 47 kDa was detected in the transfected cells with the Nef/ M918 and Hsp20-Nef/ M918 nanoparticles at a molar ratio of 1:20 using anti-HIV-1 Nef monoclonal antibody. These bands were not detected in the un-transfected and transfected cells with Nef or Hsp20- Nef protein alone indicating that M918 could increase the penetration of Nef and Hsp20-Nef proteins into the cells.

CONCLUSION

These data suggest that M918 CPP can be used to enter HIV-1 Nef and Hsp20-Nef proteins inside mammalian cells efficiently as a promising approach in HIV-1 vaccine development.

Gene and protein delivery using four cell penetrating peptides for HIV-1 vaccine development

Cell penetrating peptides (CPPs) can potently transport therapeutic molecules to target cells for treatment of a variety of diseases. Thus, their use is critical to improve therapeutic vaccines. Histidine-rich nona-arginine (HR9) and primary amphipathic peptide (MPG) showed the ability to transfer DNA into the cells. Moreover, the peptide derived from the C-terminal of the tumor suppressor protein p14ARF (M918) and arginine-rich peptide (penetratin) were utilized to deliver polypeptides and proteins into the living cells. In this study, the immunostimulatory properties of HIV-1 Nef DNA and protein constructs were evaluated using small heat shock protein 20 (sHsp20) and Freund's emulsion as an adjuvant, and four CPPs (HR9, MPG, M918, and penetratin) as a gene or protein carrier in BALB/c mice. Our data indicated that the HR9/DNA, MPG/DNA, M918/protein, and penetratin/protein complexes formed the stable nanoparticles that were effectively delivered in HEK-293T cell line at certain ratios. Moreover, a heterologous Hsp20-Nef DNA + MPG prime/rHsp20-Nef protein+M918 boost regimen significantly elicited higher levels of IgG2a, IgG2b, IFN-gamma, and Granzyme B directed toward Th1 responses in a long period (3 months) after the last immunization compared to other groups. Furthermore, the effective role of Hsp20 was detected as a natural adjuvant in enhancing immune responses against HIV-1 Nef antigen. These findings demonstrated that the simultaneous use of M918 and MPG CPPs as protein and gene carriers improves HIV-1 Nef-specific B- and T-cell immune responses as a promising approach for development of HIV-1 monovalent vaccine.

Vaginal Lactobacilli Induce Differentiation of Monocytic Precursors Toward Langerhans-like Cells: in Vitro Evidence

Lactobacilli have immunomodulatory mechanisms that affect the host cell immune system, leading to inhibition of HIV-1 transmission. Thus, lactobacilli as mucosal delivery vehicles for developing HIV-1 vaccines have attracted interest in recent years. Herein, we investigated the immunomodulatory effects of six strains of Lactobacillus naturally isolated from vaginal samples, including Lactobacillus crispatus (L. crispatus), L. fermentum, L. jensenii, L. gasseri, L. delbrueckii and L. johnsonii, on differentiation of monocytic precursors. L. crispatus, L. fermentum and L. delbrueckii could drive human monocytic cell line THP-1 cells to differentiate into dendritic-like cells according to the morphology. Moreover, L. crispatus increased costimulatory molecules including CD40, CD80 and CD86, and Langerhans cell specific C-type lectin receptors CD207, while L. fermentum decreased these molecules in THP-1 cells. Furthermore, L. crispatus promoted the differentiation of THP-1 cells with specific markers, phagocytic features, cytokine production ability and reduced the expression of receptors for HIV-1 entry of Langerhans cells. However, in the presence of L. fermentum, THP-1 cells did not show the above alterations. Moreover, similar effects of L. crispatus and L. fermentum were observed in CD14⁺ monocytes. These data suggested that L. crispatus facilitates the differentiation of monocytic precursors toward Langerhans-like cells in vitro. We further identified the cell wall components of Lactobacillus and found that peptidoglycans (PGNs), rather than bacteriocins, S-layer protein and lipoteichoic acid, were key contributors to the induction of CD207 expression. However, PGNs originating from Bacillus subtilis, E. coli JM109 and E. coli DH5α did not elevate CD207 expression, indicating that only PGN derived from Lactobacillus could enhance CD207 expression. Finally, the recognized receptors of L. crispatus (such as TLR2 and TLR6) and the upstream transcription factors (PU.1, TAL1, TIF1γ, and POLR2A) of CD207 were examined, and the expression of these molecules was enhanced in THP-1 cells following L. crispatus treatment. Thus, this study offers powerful evidence that vaginal lactobacilli modulate monocytic precursor differentiation into Langerhans-like cells probably via activating the TLR2/6-TFs-CD207 axis. These data provide clues for further investigation of the original occurrence, development and differentiation of Langerhans cells from monocytes.

Mucosal antibody responses to vaccines targeting SIV protease cleavage sites or full-length Gag and Env proteins in Mauritian cynomolgus macaques

HIV mutates rapidly and infects CD4⁺ T cells, especially when they are activated. A vaccine targeting conserved, essential viral elements while limiting CD4⁺ T cell activation could be effective. Learning from natural immunity observed in a group of highly HIV-1 exposed seronegative Kenyan female sex workers, we are testing a novel candidate HIV vaccine targeting the 12 viral protease cleavage sites (PCSs) (the PCS vaccine), in comparison with a vaccine targeting full-length Gag and Env (the Gag/Env vaccine) in a Mauritian cynomolgus macaque/SIV model. In this study we evaluated these vaccines for induction of mucosal antibodies to SIV immunogens at the female genital tract. Bio-Plex and Western blot analyses of cervicovaginal lavage samples showed that both the PCS and Gag/Env vaccines can elicit mucosal IgG antibody responses to SIV immunogens. Significantly higher increase of anti-PCS antibodies was induced by the PCS vaccine than by the Gag/Env vaccine (p<0.0001). The effect of the mucosal antibody responses in protection from repeated low dose pathogenic SIVmac251 challenges is being evaluated.

Promise and problems associated with the use of recombinant AAV for the delivery of anti-HIV antibodies

Attempts to elicit antibodies with potent neutralizing activity against a broad range of human immunodeficiency virus (HIV) isolates have so far proven unsuccessful. Long-term delivery of monoclonal antibodies (mAbs) with such activity is a creative alternative that circumvents the need for an immune response and has the potential for creating a long-lasting sterilizing barrier against HIV. This approach is made possible by an incredible array of potent broadly neutralizing antibodies (bnAbs) that have been identified over the last several years. Recombinant adeno-associated virus (rAAV) vectors are ideally suited for long-term delivery for a variety of reasons. The only products made from rAAV are derived from the transgenes that are put into it; as long as those products are not viewed as foreign, expression from muscle tissue may continue for decades. Thus, use of rAAV to achieve long-term delivery of anti-HIV mAbs with potent neutralizing activity against a broad range of HIV-1 isolates is emerging as a promising concept for the prevention or treatment of HIV-1 infection in humans. Experiments in mice and monkeys that have demonstrated protective efficacy against AIDS virus infection have raised hopes for the promise of this approach. However, all published experiments in monkeys have encountered unwanted immune responses to the AAV-delivered antibody, and these immune responses appear to limit the levels of delivered antibody that can be achieved. In this review, we highlight the promise of rAAV-mediated antibody delivery for the prevention or treatment of HIV infection in humans, but we also discuss the obstacles that will need to be understood and solved in order for the promise of this approach to be realized.

Microbicide vaginal rings: Technological challenges and clinical development

Vaginal rings (VRs) are flexible, torus-shaped, polymeric devices designed to sustain delivery of pharmaceutical drugs to the vagina for clinical benefit. Following first report in a 1970 patent application, several steroid-releasing VR products have since been marketed for use in hormone replacement therapy and contraception. Since 2002, there has been growing interest in the use of VR technology for delivery of drugs that can reduce the risk of sexual acquisition of human immunodeficiency virus type 1 (HIV-1), the causative agent of acquired immunodeficiency syndrome (AIDS). Although no vaginally-administered product has yet been approved for HIV reduction/prevention, extensive research efforts are continuing and a number of VR devices offering sustained release of so-called 'HIV microbicide' compounds are currently being evaluated in late-stage clinical studies. This review article provides an overview of the published scientific literature within this important field of research, focusing primarily on articles published within peer-reviewed journal publications. Many important aspects of microbicide-releasing VR technology are discussed, with a particular emphasis on the technological, manufacturing and clinical challenges that have emerged in recent years.

Current Advances in Virus-Like Particles as a Vaccination Approach against HIV Infection

HIV-1 virus-like particles (VLPs) are promising vaccine candidates against HIV-1 infection. They are capable of preserving the native conformation of HIV-1 antigens and priming CD4+ and CD8+ T cell responses efficiently via cross presentation by both major histocompatibility complex (MHC) class I and II molecules. Progress has been achieved in the preclinical research of HIV-1 VLPs as prophylactic vaccines that induce broadly neutralizing antibodies and potent T cell responses. Moreover, the progress in HIV-1 dendritic cells (DC)-based immunotherapy provides us with a new vision for HIV-1 vaccine development. In this review, we describe updates from the past 5 years on the development of HIV-1 VLPs as a vaccine candidate and on the combined use of HIV particles with HIV-1 DC-based immunotherapy as efficient prophylactic and therapeutic vaccination strategies.

Exploring the Potential Health Impact and Cost-Effectiveness of AIDS Vaccine within a Comprehensive HIV/AIDS Response in Low- and Middle-Income Countries

BACKGROUND

The Investment Framework Enhanced (IFE) proposed in 2013 by the Joint United Nations Programme on HIV/AIDS (UNAIDS) explored how maximizing existing interventions and adding emerging prevention options, including a vaccine, could further reduce new HIV infections and AIDS-related deaths in low- and middle-income countries (LMICs). This article describes additional modeling which looks more closely at the potential health impact and cost-effectiveness of AIDS vaccination in LMICs as part of UNAIDS IFE.

METHODS

An epidemiological model was used to explore the potential impact of AIDS vaccination in LMICs in combination with other interventions through 2070. Assumptions were based on perspectives from research, vaccination and public health experts, as well as observations from other HIV/AIDS interventions and vaccination programs. Sensitivity analyses varied vaccine efficacy, duration of protection, coverage, and cost.

RESULTS

If UNAIDS IFE goals were fully achieved, new annual HIV infections in LMICs would decline from 2.0 million in 2014 to 550,000 in 2070. A 70% efficacious vaccine introduced in 2027 with three doses, strong uptake and five years of protection would reduce annual new infections by 44% over the first decade, by 65% the first 25 years and by 78% to 122,000 in 2070. Vaccine impact would be much greater if the assumptions in UNAIDS IFE were not fully achieved. An AIDS vaccine would be cost-effective within a wide range of scenarios.

INTERPRETATION

Even a modestly effective vaccine could contribute strongly to a sustainable response to HIV/AIDS and be cost-effective, even with optimistic assumptions about other interventions. Higher efficacy would provide even greater impact and cost-effectiveness, and would support broader access. Vaccine efficacy and cost per regimen are critical in achieving cost-effectiveness, with cost per regimen being particularly critical in low-income countries and at lower efficacy levels.

Development of a novel AIDS vaccine: the HIV-1 transactivator of transcription protein vaccine

INTRODUCTION

Classical approaches aimed at targeting the HIV-1 envelope as well as other structural viral proteins have largely failed. The HIV-1 transactivator of transcription (Tat) is a key HIV virulence factor, which plays pivotal roles in virus gene expression, replication, transmission and disease progression. Notably, anti-Tat Abs are uncommon in natural infection and, when present, correlate with the asymptomatic state and lead to lower or no disease progression. Hence, targeting Tat represents a pathogenesis-driven intervention.

AREAS COVERED

Here, we review the rationale and the translational development of a therapeutic vaccine targeting the Tat protein. Preclinical and Phase I studies, Phase II trials with Tat in anti-Tat Ab-negative, virologically suppressed highly active antiretroviral therapy-treated subjects in Italy and South Africa were conducted. The results indicate that Tat-induced immune responses are necessary to restore immune homeostasis, to block the replenishment and to reduce the size of the viral reservoir. Additionally, they may help in establishing key parameters for highly active antiretroviral therapy intensification and a functional cure.

EXPERT OPINION

We propose the therapeutic setting as the most feasible to speed up the testing and comparison of preventative vaccine candidates, as the distinction lies in the use of the vaccine in uninfected versus infected subjects and not in the vaccine formulation.

Intranasal and oral vaccination with protein-based antigens: advantages, challenges and formulation strategies

Most pathogens initiate their infections at the human mucosal surface. Therefore, mucosal vaccination, especially through oral or intranasal administration routes, is highly desired for infectious diseases. Meanwhile, protein-based antigens provide a safer alternative to the whole pathogen or DNA based ones in vaccine development. However, the unique biopharmaceutical hurdles that intranasally or orally delivered protein vaccines need to overcome before they reach the sites of targeting, the relatively low immunogenicity, as well as the low stability of the protein antigens, require thoughtful and fine-tuned mucosal vaccine formulations, including the selection of immunostimulants, the identification of the suitable vaccine delivery system, and the determination of the exact composition and manufacturing conditions. This review aims to provide an up-to-date survey of the protein antigen-based vaccine formulation development, including the usage of immunostimulants and the optimization of vaccine delivery systems for intranasal and oral administrations.

Challenges in HIV Vaccine Research for Treatment and Prevention

Many attempts have been made or are ongoing for HIV prevention and HIV cure. Many successes are in the list, particularly for HIV drugs, recently proposed also for prevention. However, no eradication of infection has been achieved so far with any drug. Further, a residual immune dysregulation associated to chronic immune activation and incomplete restoration of B and T cell subsets, together with HIV DNA persistence in reservoirs, are still unmet needs of the highly active antiretroviral therapy, causing novel “non-AIDS related” diseases that account for a higher risk of death even in virologically suppressed patients. These “ART unmet needs” represent a problem, which is expected to increase by ART roll out. Further, in countries such as South Africa, where six millions of individuals are infected, ART appears unable to contain the epidemics. Regretfully, all the attempts at developing a preventative vaccine have been largely disappointing. However, recent therapeutic immunization strategies have opened new avenues for HIV treatment, which might be exploitable also for preventative vaccine approaches. For example, immunization strategies aimed at targeting key viral products responsible of virus transmission, activation, and maintenance of virus reservoirs may intensify drug efficacy and lead to a functional cure providing new perspectives also for prevention and future virus eradication strategies. However, this approach imposes new challenges to the scientific community, vaccine developers, and regulatory bodies, such as the identification of novel immunological and virological biomarkers to assess efficacy end-points, taking advantage from the natural history of infection and exploiting lessons from former trials. This review will focus first on recent advancement of therapeutic strategies, then on the progresses made in preventative approaches, discussing concepts, and problems for the way ahead for the development of vaccines for HIV treatment and prevention.