Incorporation of CD40 ligand into SHIV virus-like particles (VLP) enhances SHIV-VLP-induced dendritic cell activation and boosts immune responses against HIV

Combination of S1-N-Terminal and S1-C-Terminal Domain Antigens Targeting Double Receptor-Binding Domains Bolsters Protective Immunity of a Nanoparticle Vaccine against Porcine Epidemic Diarrhea Virus

Variants of coronavirus porcine epidemic diarrhea virus (PEDV) frequently emerge, causing an incomplete match between the vaccine and variant strains, which affects vaccine efficacy. Designing vaccines with rapidly replaceable antigens and high efficacy is a promising strategy for the prevention of infection with PEDV variant strains. In our study, three different types of self-assembled nanoparticles (nps) targeting receptor-binding N-terminal domain (NTD) and C-terminal domain (CTD) of S1 protein, named NTDnps, CTDnps, and NTD/CTDnps, were constructed and evaluated as vaccine candidates against PEDV. NTDnps and CTDnps vaccines mediated significantly higher neutralizing antibody (NAb) titers than NTD and CTD recombinant proteins in mice. The NTD/CTDnps in varying ratios elicited significantly higher NAb titers when compared with NTDnps and CTDnps alone. The NTD/CTDnps (3:1) elicited NAb with titers up to 92.92% of those induced by the commercial vaccine. Piglets immunized with NTD/CTDnps (3:1) achieved a passive immune protection rate of 83.33% of that induced by the commercial vaccine. NTD/CTDnps (3:1) enhanced the capacity of mononuclear macrophages and dendritic cells to take up and present antigens by activating major histocompatibility complex I and II molecules to stimulate humoral and cellular immunity. These data reveal that a combination of S1-NTD and S1-CTD antigens targeting double receptor-binding domains strengthens the protective immunity of nanoparticle vaccines against PEDV. Our findings will provide a promising vaccine candidate against PEDV.

Sublingual Immunization with Chimeric C1q/CD40 Ligand/HIV Virus-like Particles Induces Strong Mucosal Immune Responses against HIV

Development of a vaccine that can elicit robust HIV specific antibody responses in the mucosal compartments is desired for effective prevention of HIV via sexual transmission. However, the current mucosal vaccines have either poor immunogenicity when administered orally or invite safety concerns when administered intranasally. Sublingual immunization has received more attention in recent years based on its efficiency in inducing systemic and mucosal immune responses in both mucosal and extra-mucosal tissues. To facilitate the transport of the immunogen across the sub-mucosal epithelial barrier, we found that CD91, the receptor of C1q, is prevalently expressed in the sublingual mucosal lining, and thus, a modified chimeric C1q surface conjugated CD40L/HIV VLP was generated. The ability of this chimeric C1q/CD40L/HIV VLP to bind, cross the epithelial layer, access and activate the sub-mucosal layer dendritic cells (DCs), and ultimately induce enhanced mucosal and systemic immune responses against HIV is evaluated in this study. We found that C1q/CD40L/HIV VLPs have enhanced binding, increased transport across the epithelial layer, and upregulate DC activation markers as compared to CD40L/HIV VLPs alone. Mice immunized with C1q/CD40L/HIV VLPs by sublingual administration showed higher levels of IgA salivary antibodies against both HIV Gag and Env than mice immunized with CD40L/HIV VLPs. Moreover, sublingual immunization with C1q/CD40L/HIV VLPs induced more Env- and Gag-specific IFN-γ producing T cells than the CD40L/HIV VLPs group. Interestingly, C1q/CD40L/HIV VLP immunization can also induce more mucosal homing T cells than that in CD40L/HIV VLP group. Our data suggest that incorporation of C1q to CD40L/HIV VLPs is a promising novel strategy and that the sublingual immunization can be a favorite immunization route for HIV mucosal vaccines.

Western equine encephalitis virus virus-like particles from an insect cell-baculovirus system elicit the strong immune responses in mice

Western equine encephalitis virus (WEEV) causes lethal encephalitis in humans and equines, and it poses a serious public health threat in many countries. Therefore, the development of an efficient vaccine remains an important challenge for the prevention of WEEV infection. This study presents the first description of WEEV virus-like particles (VLPs) generated from insect cells using recombinant baculoviruses. WEEV VLPs with 206 adjuvant could trigger a strong cellular immune response; increase the levels of IL-2, IL-4 and IFN-γ; and induce a high level of neutralizing antibodies against WEEV in mice. These data showed that the insect cell-baculovirus system is suitable for the production of WEEV VLPs and that these VLPs could elicit the strong immunogenicity in mice. These results suggest a new, nonreplicating, and effective vaccine candidate against WEEV infection.

The current and future role of nanovaccines in HIV-1 vaccine development

Introduction: An efficacious vaccine for HIV-1 has been sought for over 30 years to eliminate the virus from the human population. Many challenges have occurred in the attempt to produce a successful immunogen, mainly caused by the basic biology of the virus. Immunogens have been developed focusing on inducing one or more of the following types of immune responses; neutralizing antibodies, non-neutralizing antibodies, and T-cell mediated responses. One way to better present and develop an immunogen for HIV-1 is through the use of nanotechnology and nanoparticles.Areas covered: This article gives a basic overview of the HIV-1 vaccine field, as well as nanotechnology, specifically nanovaccines. It then covers the application of nanovaccines made from biological macromolecules to HIV-1 vaccine development for neutralizing antibodies, non-neutralizing antibodies, and T-cell-mediated responses.Expert opinion: Nanovaccines are an area that is ripe for further exploration in HIV-1 vaccine field. Not only are nanovaccines capable of carrying and presenting antigens in native-like conformations, but they have also repeatedly been shown to increase immunogenicity over recombinant antigens alone. Only through further research can the true role of nanovaccines in the development of an efficacious HIV-1 vaccine be established.

CTLA-4 Blockade, during HIV Virus-Like Particles Immunization, Alters HIV-Specific B-Cell Responses

Studies have shown that blockade of CTLA-4 promoted the expansion of germinal center B-cells in viral infection or immunization with model antigens. Few studies have evaluated the immunological consequences of CTLA-4 blockade during immunization against relevant vaccine candidates. Here, we investigated the effects of CTLA-4 blockade on HIV virus-like particles (VLPs) vaccination in a C57BL/6J mouse model. We found that CTLA-4 blockade during HIV VLP immunization resulted in increased CD4+ T-cell activation, promoted the expansion of HIV envelope (Env)-specific follicular helper T cell (Tfh) cells, and significantly increased HIV Gag- and Env-specific IgG with higher avidity and antibody-dependent cellular cytotoxicity (ADCC) capabilities. Furthermore, after only a single immunization, CTLA-4 blockade accelerated T-cell dependent IgG class switching and the induction of significantly high serum levels of the B-cell survival factor, A proliferation-inducing ligand (APRIL). Although no significant increase in neutralizing antibodies was observed, increased levels of class-switched Env- and Gag-specific IgG are indicative of increased polyclonal B-cell activation, which demonstrated the ability to mediate and enhance ADCC in this study. Altogether, our findings show that CTLA-4 blockade can increase the levels of HIV antigen-specific B-cell and antigen-specific Tfh cell activity and impact humoral immune responses when combined with a clinically relevant HIV VLP-based vaccine.

Expression of CD40L by the ALVAC-Simian Immunodeficiency Virus Vector Abrogates T Cell Responses in Macaques

Immunization with recombinant ALVAC/gp120 alum vaccine provided modest protection from human immunodeficiency virus type 1 (HIV-1) and simian immunodeficiency virus (SIV) acquisition in humans and macaques. Vaccine-mediated protection was associated with the elicitation of IgG against the envelope V2 loop and of envelope-specific CD4⁺ T cell responses. We hypothesized that the simultaneous expression of the costimulatory molecule CD40L (CD154) by the ALVAC-HIV vector could increase both protective humoral and cellular responses. We engineered an ALVAC-SIV coexpressing CD40L with SIV_mac251 (ALVAC-SIV/CD40L) gag, pol, and env genes. We compared its immunogenicity in macaques with that of a canonical ALVAC-SIV, with both given as a vector-prime/gp120 in alum boost strategy. The ALVAC-SIV/CD40L was superior to the ALVAC-SIV regimen in inducing binding and tier 1 neutralizing antibodies against the gp120. The increase in humoral responses was associated with the expression of the membrane-bound form of the CD40L by CD4⁺ T cells in lymph nodes. Unexpectedly, the ALVAC-SIV/CD40L vector had a blunting effect on CD4⁺ Th1 helper responses and instead favored the induction of myeloid-derived suppressor cells, the immune-suppressive interleukin-10 (IL-10) cytokine, and the down-modulatory tryptophan catabolism. Ultimately, this strategy failed to protect macaques from SIV acquisition. Taken together, these results underlie the importance of balanced vaccine-induced activating versus suppressive immune responses in affording protection from HIV.IMPORTANCE CD40-CD40 ligand (CD40L) interaction is crucial for inducing effective cytotoxic and humoral responses against pathogens. Because of its immunomodulatory function, CD40L has been used to enhance immune responses to vaccines, including candidate vaccines for HIV. The only successful vaccine ever tested in humans utilized a strategy combining canarypox virus-based vector (ALVAC) together with an envelope protein (gp120) adjuvanted in alum. This strategy showed limited efficacy in preventing HIV-1/SIV acquisition in humans and macaques. In both species, protection was associated with vaccine-induced antibodies against the HIV envelope and CD4⁺ T cell responses, including type 1 antiviral responses. In this study, we tested whether augmenting CD40L expression by coexpressing it with the ALVAC vector could increase the protective immune responses. Although coexpression of CD40L did increase humoral responses, it blunted type 1 CD4⁺ T cell responses against the SIV envelope protein and failed to protect macaques from viral infection.

Incorporation of CD40 ligand or granulocyte-macrophage colony stimulating factor into Hantaan virus (HTNV) virus-like particles significantly enhances the long-term immunity potency against HTNV infection

PURPOSE

Hantavirus infections cause severe haemorrhagic fever with renal syndrome (HFRS) in humans and are associated with high fatality rates. In 2017, numerous outbreaks were reported in China and Germany. This represents a significant public-healthcare issue with no effective HFRS vaccines that offer a long-term immune response. In this study, we investigated the long-term humoral and cellular immune responses and protective immunity of Hantaan virus (HTNV) granulocyte-macrophage colony stimulating factor (GM-CSF) and CD40 ligand (CD40L) virus-like particles (VLPs) in mice.

METHODOLOGY

GM-CSF and CD40L VLPs were constructed via co-transfection of pCI-S and pCI-M-CD40L, and pCI-S and pCI-M-GM-CSF, into dihydrofolatereductase (dhfr)-deficient Chinese hamster ovary cells, respectively. Mice were immunized with HTNV VLPs 2 weeks apart. The animals were challenged 6 months after immunization. Specific and neutralizing antibodies were assessed by ELISA; IFN-γ was measured by enzyme-linked immunospot (ELISpot) assay and effectiveness by cytotoxic T lymphocyte (CTL) cytotoxicity assays. Nucleic acid loads of HTNV were tested by quantitative real-time PCR and viral antigen was detected via indirect ELISA. Pathological alterations were detected via haematoxylin-eosin staining.

RESULTS

GM-CSF and CD40L VLPs provided stable, long-term protection with a high titre of neutralizing antibody in mice 6 months after immunization. Furthermore, VLPs increased HTNV-specific cellular immune responses via higher expression of IFN-γ and CTL responses. HTNV challenge assay results showed long-term protection against HFRS. No significant pathological alteration was observed in the organs of mice after immunization.

CONCLUSION

This is, to the best of our knowledge, the first report demonstrating the long-term potency of HTNV VLP vaccines against HTNV infection and offers new insights into HTNV vaccine development.

Efficacy of different hemodialysis methods on dendritic cell marker CD40 and CD80 and platelet activation marker CD62P and P10 in patients with chronic renal failure

BACKGROUND

Chronic renal failure (CRF) has become a major public health concern, which increases the risk of stroke and systemic thromboembolism. Therefore, therapeutic strategies are in urgent requirement. This study was conducted for investigating efficacy of hemodialysis (HD), hemodiafiltration (HDF), and hemoperfusion (HP) in patients with CRF and the correlation with the presence of complications following HD therapy.

METHODS

The therapeutic effect, living quality, biochemical indicators, and dry weight were detected before and after the treatment regimens. Flow cytometry was conducted to detect expressions of dendritic cell markers (CD40 and CD80) and platelet activation markers (CD62P and P10), and the relationship between their expression and therapeutic effect as well as the association of these expressions with complications was analyzed.

RESULTS

After HD therapy, patients presented with decreased serum creatinine, serum phosphorus, triglyceride, parathyroid hormone, and β₂ -MG expression; increased hemoglobin, plasma albumin expressions, and dry weight; and enhanced therapeutic effect and living quality. CD62P and P10 expressions decreased, while CD40 and CD80 expressions increased following HD therapy. The therapeutic effect improved in patients with low expressions of CD40 and CD80 and high expressions of CD62P and P10 following HP treatment and complications were lower after treatment of HDF and HP.

CONCLUSION

The aforementioned results indicated that CRF patients treated with HP exhibited higher expression of CD40 and CD80 and lower expression of CD62P and P10, suggesting that HP is conferred to have better efficacy than HDF and HD. Therefore, HP may be a promising clinical regimen for treatment of CRF patients.

Protein based therapeutic delivery agents: Contemporary developments and challenges

As unique biopolymers, proteins can be employed for therapeutic delivery. They bear important features such as bioavailability, biocompatibility, and biodegradability with low toxicity serving as a platform for delivery of various small molecule therapeutics, gene therapies, protein biologics and cells. Depending on size and characteristic of the therapeutic, a variety of natural and engineered proteins or peptides have been developed. This, coupled to recent advances in synthetic and chemical biology, has led to the creation of tailor-made protein materials for delivery. This review highlights strategies employing proteins to facilitate the delivery of therapeutic matter, addressing the challenges for small molecule, gene, protein and cell transport.

Overcoming T. gondii infection and intracellular protein nanocapsules as biomaterials for ultrasonically controlled drug release

One of the pivotal matters of concern in intracellular drug delivery is the preparation of biomaterials containing drugs that are compatible with the host target.

Incorporation of GM-CSF or CD40L Enhances the Immunogenicity of Hantaan Virus-Like Particles

A safe and effective Hantaan virus (HTNV) vaccine is highly desirable because HTNV causes an acute and often fatal disease (hemorrhagic fever with renal syndrome, HFRS). Since the immunity of the inactivated vaccine is weak and the safety is poor, HTNV virus-like particles (VLPs) offer an attractive and safe alternative. These particles lack the viral genome but are perceived by the immune system as virus particles. We hypothesized that adding immunostimulatory signals to VLPs would enhance their efficacy. To accomplish this enhancement, we generated chimeric HTNV VLPs containing glycosylphosphatidylinositol (GPI)-anchored granulocyte macrophage colony-stimulating factor (GM-CSF) or CD40 ligand (CD40L) and investigated their biological activity in vitro. The immunization of mice with chimeric HTNV VLPs containing GM-CSF or CD40L induced stronger humoral immune responses and cellular immune responses compared to the HTNV VLPs and Chinese commercial inactivated hantavirus vaccine. Chimeric HTNV VLPs containing GM-CSF or CD40L also protected mice from an HTNV challenge. Altogether, our results suggest that anchoring immunostimulatory molecules into HTNV VLPs can be a potential approach for the control and prevention of HFRS.

Bioengineered protein-based nanocage for drug delivery

Nature, in its wonders, presents and assembles the most intricate and delicate protein structures and this remarkable phenomenon occurs in all kingdom and phyla of life. Of these proteins, cage-like multimeric proteins provide spatial control to biological processes and also compartmentalizes compounds that may be toxic or unstable and avoids their contact with the environment. Protein-based nanocages are of particular interest because of their potential applicability as drug delivery carriers and their perfect and complex symmetry and ideal physical properties, which have stimulated researchers to engineer, modify or mimic these qualities. This article reviews various existing types of protein-based nanocages that are used for therapeutic purposes, and outlines their drug-loading mechanisms and bioengineering strategies via genetic and chemical functionalization. Through a critical evaluation of recent advances in protein nanocage-based drug delivery in vitro and in vivo, an outlook for de novo and in silico nanocage design, and also protein-based nanocage preclinical and future clinical applications will be presented.

Stimulation through CD40 and TLR-4 Is an Effective Host Directed Therapy against Mycobacterium tuberculosis

Tuberculosis (TB) is the leading cause of morbidity and mortality among all infectious diseases. Failure of Bacillus Calmette Guerin as a vaccine and serious side-effects and toxicity due to long-term TB drug regime are the major hurdles associated with TB control. The problem is further compounded by the emergence of drug-resistance strains of Mycobacterium tuberculosis (Mtb). Consequently, it demands a serious attempt to explore safer and superior treatment approaches. Recently, an improved understanding of host–pathogen interaction has opened up new avenues for immunotherapy for treating TB. Although, dendritic cells (DCs) show a profound role in generating immunity against Mtb, their immunotherapeutic potential needs to be precisely investigated in controlling TB. Here, we have devised an approach of bolstering DCs efficacy against Mtb by delivering signals through CD40 and TLR-4 molecules. We found that DCs triggered through CD40 and TLR-4 showed increased secretion of IL-12, IL-6, and TNF-α. It also augmented autophagy. Interestingly, CD40 and TLR-4 stimulation along with the suboptimal dose of anti-TB drugs significantly fortified their efficacy to kill Mtb. Importantly, animals treated with the agonists of CD40 and TLR-4 boosted Th1 and Th17 immunity. Furthermore, it amplified the pool of memory CD4 T cells as well as CD8 T cells. Furthermore, substantial reduction in the bacterial burden in the lungs was observed. Notably, this adjunct therapy employing immunomodulators and chemotherapy can reinvigorate host immunity suppressed due to drugs and Mtb. Moreover, it would strengthen the potency of drugs in curing TB.

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.

DNA vaccination of poultry: The current status in 2015

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Poultry DNA vaccination studies are regularly being published since 1993.

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These studies are mainly, but not only, concerned with vaccination against viruses.

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The different strategies of improving DNA vaccine efficacies are presented.

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The fate of the vaccine plasmid, immune properties and other applications are described.

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Despite the compiling preclinical reports, a poultry DNA vaccine is yet unavailable in the market.

DNA vaccination is a promising alternative strategy for developing new human and animal vaccines. The massive efforts made these past 25 years to increase the immunizing potential of this kind of vaccine are still ongoing. A relatively small number of studies concerning poultry have been published. Even though there is a need for new poultry vaccines, five parameters must nevertheless be taken into account for their development: the vaccine has to be very effective, safe, inexpensive, suitable for mass vaccination and able to induce immune responses in the presence of maternal antibodies (when appropriate). DNA vaccination should meet these requirements. This review describes studies in this field performed exclusively on birds (chickens, ducks and turkeys). No evaluations of avian DNA vaccine efficacy performed on mice as preliminary tests have been taken into consideration. The review first describes the state of the art for DNA vaccination in poultry: pathogens targeted, plasmids used and different routes of vaccine administration. Second, it presents strategies designed to improve DNA vaccine efficacy: influence of the route of administration, plasmid dose and age of birds on their first inoculation; increasing plasmid uptake by host cells; addition of immunomodulators; optimization of plasmid backbones and codon usage; association of vaccine antigens and finally, heterologous prime-boost regimens. The final part will indicate additional properties of DNA vaccines in poultry: fate of the plasmids upon inoculation, immunological considerations and the use of DNA vaccines for purposes other than preventing infectious diseases.

The application of virus-like particles as vaccines and biological vehicles

Virus-like particles (VLPs) can be spontaneously self-assembled by viral structural proteins under appropriate conditions in vitro while excluding the genetic material and potential replication probability. In addition, VLPs possess several features including can be rapidly produced in large quantities through existing expression systems, highly resembling native viruses in terms of conformation and appearance, and displaying repeated cluster of epitopes. Their capsids can be modified via genetic insertion or chemical conjugation which facilitating the multivalent display of a homologous or heterogeneous epitope antigen. Therefore, VLPs are considered as a safe and effective candidate of prophylactic and therapeutic vaccines. VLPs, with a diameter of approximately 20 to 150 nm, also have the characteristics of nanometer materials, such as large surface area, surface-accessible amino acids with reactive moieties (e.g., lysine and glutamic acid residues), inerratic spatial structure, and good biocompatibility. Therefore, assembled VLPs have great potential as a delivery system for specifically carrying a variety of materials. This review summarized recent researches on VLP development as vaccines and biological vehicles, which demonstrated the advantages and potential of VLPs in disease control and prevention and diagnosis. Then, the prospect of VLP biology application in the future is discussed as well.

A Novel Prime and Boost Regimen of HIV Virus-Like Particles with TLR4 Adjuvant MPLA Induces Th1 Oriented Immune Responses against HIV

HIV virus-like particles (VLPs) present the HIV envelope protein in its native conformation, providing an ideal vaccine antigen. To enhance the immunogenicity of the VLP vaccine, we sought to improve upon two components; the route of administration and the additional adjuvant. Using HIV VLPs, we evaluated sub-cheek as a novel route of vaccine administration when combined with other conventional routes of immunization. Of five combinations of distinct prime and boost sequences, which included sub-cheek, intranasal, and intradermal routes of administration, intranasal prime and sub-cheek boost (IN+SC) resulted in the highest HIV-specific IgG titers among the groups tested. Using the IN+SC regimen we tested the adjuvant VesiVax Conjugatable Adjuvant Lipid Vesicles (CALV) + monophosphoryl lipid A (MPLA) at MPLA concentrations of 0, 7.5, 12.5, and 25 μg/dose in combination with our VLPs. Mice that received 12.5 or 25 μg/dose MPLA had the highest concentrations of Env-specific IgG2c (20.7 and 18.4 μg/ml respectively), which represents a Th1 type of immune response in C57BL/6 mice. This was in sharp contrast to mice which received 0 or 7.5 μg MPLA adjuvant (6.05 and 5.68 μg/ml of IgG2c respectively). In contrast to IgG2c, MPLA had minor effects on Env-specific IgG1; therefore, 12.5 and 25 μg/dose of MPLA induced the optimal IgG1/IgG2c ratio of 1.3. Additionally, the percentage of germinal center B cells increased significantly from 15.4% in the control group to 31.9% in the CALV + 25 μg MPLA group. These mice also had significantly more IL-2 and less IL-4 Env-specific CD8⁺ T cells than controls, correlating with an increased percentage of Env-specific central memory CD4⁺ and CD8⁺ T cells. Our study shows the strong potential of IN+SC as an efficacious route of administration and the effectiveness of VLPs combined with MPLA adjuvant to induce Env specific Th1-oriented HIV-specific immune responses.

Protein transfer-mediated surface engineering to adjuvantate virus-like nanoparticles for enhanced anti-viral immune responses

Recombinant virus-like nanoparticles (VLPs) are a promising nanoparticle platform to develop safe vaccines for many viruses. Herein, we describe a novel and rapid protein transfer process to enhance the potency of enveloped VLPs by decorating influenza VLPs with exogenously added glycosylphosphatidylinositol-anchored immunostimulatory molecules (GPI-ISMs). With protein transfer, the level of GPI-ISM incorporation onto VLPs is controllable by varying incubation time and concentration of GPI-ISMs added. ISM incorporation was dependent upon the presence of a GPI-anchor and incorporated proteins were stable and functional for at least 4weeks when stored at 4°C. Vaccinating mice with GPI-granulocyte macrophage colony-stimulating factor (GM-CSF)-incorporated-VLPs induced stronger antibody responses and better protection against a heterologous influenza virus challenge than unmodified VLPs. Thus, VLPs can be enriched with ISMs by protein transfer to increase the potency and breadth of the immune response, which has implications in developing effective nanoparticle-based vaccines against a broad spectrum of enveloped viruses.

FROM THE CLINICAL EDITOR

The inherent problem with current influenza vaccines is that they do not generate effective cross-protection against heterologous viral strains. In this article, the authors described the development of virus-like nanoparticles (VLPs) as influenza vaccines with enhanced efficacy for cross-protection, due to an easy protein transfer modification process.

Vpx-containing dendritic cell vaccine induces CTLs and reactivates latent HIV-1 in vitro

Eradication of human immunodeficiency virus-1 (HIV-1) from an infected individual requires a means of inducing production of virus from latently infected cells and stimulating an immune response against the infected cells. We report the development of lentiviral vectors that transduce dendritic cells (DCs) to both induce production of virus from latently infected cells and stimulate antigen-specific cytotoxic T lymphocytes (CTLs). The vectors package Vpx, a lentiviral accessory protein that counteracts the SAMHD1-mediated block to DC transduction, allowing for long-term expression of vector-encoded proteins. The vectors encode influenza or HIV-1-derived epitopes fused via a self-cleaving peptide to CD40L that releases the peptide into the endoplasmic reticulum for entry into the antigen presentation pathway. Expression of CD40L caused transduced DCs to mature and produce Th1-skewing cytokines. The DCs presented antigen to CD8 T cells, enhancing antigen-specific CTLs. Coculture of the transduced DCs with latently infected cells induced high-level virus production, an effect that was mediated by tumor necrosis factor alpha. The ability of a DC vaccine to reactivate latent HIV-1 and stimulate an adaptive immune response provide a means to reduce the size of the latent reservoir in patients. This strategy can also be applied to develop DC vaccines for other diseases.

Protein nanoparticles for therapeutic protein delivery

This review describes nanoparticles made from protein by self-assembly or desolvation as carriers for the delivery of therapeutic proteins.

Caged protein nanoparticles for drug delivery

Caged protein nanoparticles possess many desirable features for drug delivery, such as ideal sizes for endocytosis, non-toxic biodegradability, and the ability to functionalize at three distinct interfaces (external, internal, and inter-subunit) using the tools of protein engineering. Researchers have harnessed these attributes by covalently and non-covalently loading therapeutic molecules through mechanisms that facilitate release within specific microenvironments. Effective delivery depends on several factors, including specific targeting, cell uptake, release kinetics, and systemic clearance. The innate ability of the immune system to recognize and respond to proteins has recently been exploited to deliver therapeutic compounds with these platforms for immunomodulation. The diversity of drugs, loading/release mechanisms, therapeutic targets, and therapeutic efficacy are discussed in this review.

CpG/Poly (I:C) mixed adjuvant priming enhances the immunogenicity of a DNA vaccine against eastern equine encephalitis virus in mice

Eastern equine encephalitis virus (EEEV) poses a serious public health threat in many countries. Therefore, developing efficient vaccine against EEEV remains an important challenge in the field of disease control. To identify immunogenic proteins in EEEV, we constructed an expression vector containing the protein coding genes C, E3, E2, 6k, and E1 (pcDNA3.1-C-E). After verifying the target gene expression in 293 T cells, we immunized BALB/c mice with the pcDNA3.1-C-E vector as a DNA vaccine in conjunction with either CpG or poly (I:C) or a mixture of both adjuvants and monitored various aspects of the immune response. After two immunizations, the mice vaccinated with antigen plus mixed CpG/poly (I:C) adjuvant exhibited significantly stronger IFN-gamma responses and generated high-level CD4(+) cell responses for the cytokines IL-2, IL-4, and IFN-γ and CD8(+) T cell responses for the cytokines IL-2 and IFN-γ compared to the mice vaccinated with the corresponding antigen plus CpG or poly(I:C) alone. In addition, the higher antibody titers against EEEV effectively neutralized the EEEV pseudoviruses in the group immunized with antigen plus mixed CpG/poly (I:C) adjuvant after tertiary immunization. This study demonstrates that the pcDNA3.1-C-E plasmids in conjunction with mixed CpG/poly (I:C) adjuvant priming maximize the cellular immune response and specific antibody generation in mice. Moreover, this mixed adjuvant priming provides a promising strategy for enhancing the immune effectiveness of a DNA vaccine against EEEV.

Targeting concatenated HIV antigens to human CD40 expands a broad repertoire of multifunctional CD4+ and CD8+ T cells

OBJECTIVE

Targeting HIV antigens directly to dendritic cells using monoclonal antibodies against cell-surface receptors has been shown to evoke potent cellular immunity in animal models. The objective of this study was to configure an anti-human CD40 antibody fused to a string of five highly conserved CD4 and CD8 T-cell epitope-rich regions of HIV-1 Gag, Nef and Pol (αCD40.HIV5pep), and then to demonstrate the capacity of this candidate therapeutic vaccine to target these HIV peptide antigens to human dendritic cells to expand functional HIV-specific T cells.

METHODS

Antigen-specific cytokine production using intracellular flow cytometry and multiplex bead-based assay, and suppression of viral inhibition, were used to characterize the T cells expanded by αCD40.HIV5pep from HIV-infected patient peripheral blood mononuclear cell (PBMC) and dendritic cell/T-cell co-cultures.

RESULTS

This candidate vaccine expands memory CD4 and CD8 T cells specific to multiple epitopes within all five peptide regions across a wide range of major histocompatibility complex (MHC) haplotypes from HIV-infected patient PBMC and dendritic cell/T-cell co-cultures. These in vitro expanded HIV antigen-specific CD4 and CD8 T cells produce multiple cytokines and chemokines. αCD40.HIV5pep-expanded CD8 T cells have characteristics of cytotoxic effector cells and are able to kill autologous target cells and suppress HIV-1 replication in vitro.

CONCLUSION

Our data demonstrate the therapeutic potential of this CD40-targeting HIV candidate vaccine in inducing a broad repertoire of multifunctional T cells in patients.

Virus-like particles as universal influenza vaccines

Current influenza vaccines are primarily targeted to induce immunity to the influenza virus strain-specific hemagglutinin antigen and are not effective in controlling outbreaks of new pandemic viruses. An approach for developing universal vaccines is to present highly conserved antigenic epitopes in an immunogenic conformation such as virus-like particles (VLPs) together with an adjuvant to enhance the vaccine immunogenicity. In this review, the authors focus on conserved antigenic targets and molecular adjuvants that were presented in VLPs. Conserved antigenic targets that include the hemagglutinin stalk domain, the external domain of influenza M2 and neuraminidase are discussed in addition to molecular adjuvants that are engineered to be incorporated into VLPs in a membrane-anchored form.

The effect of human immunodeficiency virus-1 on monocyte-derived dendritic cell maturation and function

Dendritic cells (DC) are mediators of the adaptive immune response responsible for antigen presentation to naive T cells in secondary lymph organs. Human immunodeficiency virus (HIV-1) has been reported to inhibit the maturation of DC, but a clear link between maturation and function has not been elucidated. To understand further the effects of HIV-1 on DC maturation and function, we expanded upon previous investigations and assessed the effects of HIV-1 infection on the expression of surface molecules, carbohydrate endocytosis, antigen presentation and lipopolysaccharide (LPS) responsiveness over the course of maturation. In vitro infection with HIV-1 resulted in an increase in the expression of DC-specific intercellular adhesion molecule-3-grabbing non-integrin (DC-SIGN) as well as decreases in maturation-induced CCR7 and major histocompatibility complex (MHC)-II expression. Retention of endocytosis that normally occurs with DC maturation as well as inhibition of antigen presentation to CD8(+) T cells was also observed. Mitogen-activated protein kinase (MAPK) responsiveness to LPS as measured by phosphorylation of p38, c-Jun N-terminal kinase (JNK) and extracellular-regulated kinase (ERK)1/2 was not affected by HIV-1 infection. In summary, in-vitro HIV-1 impairs DC maturation, as defined by cell surface protein expression, with selective alterations in mature DC function. Understanding the mechanisms of DC dysfunction in HIV infection will provide further insight into HIV immune pathogenesis.

Myeloid dendritic cells in HIV-1 infection

PURPOSE OF REVIEW

Myeloid dendritic cells (mDCs) are pivotal players in HIV-1 infection. They promote transmission and spread and at the same time are critical for recognizing HIV-1 and initiating immune responses to fight infection. Notably, their immunostimulatory capabilities can be harnessed to design better HIV-1 vaccines. In this review, advances in these areas of mDC-HIV-1 interactions are summarized.

RECENT FINDINGS

New insights into HIV-1-induced dysfunction of mDCs and dysfunctional mDC effects on other cell types, as well as novel mechanisms of viral sensing by mDCs and their evasion by HIV-1, have been uncovered. These results emphasize the importance of mDCs in protection against HIV-1 infection. Targeting mDCs with vaccines and tailored adjuvants may improve the quality and anatomical location of elicited immune responses.

SUMMARY

Understanding the multiplicity of HIV-1-dendritic cell interactions together with the numerous advances in targeted therapy and vaccination will help in the rational design of approaches to treat and block infection.

CD40L-containing virus-like particle as a candidate HIV-1 vaccine targeting dendritic cells

The central role of dendritic cell (DC) in mounting an immune response to a novel antigen is now well established. We sought to demonstrate the use of a particular vaccine strategy based on directing HIV-1 Gag proteins to DCs in conjunction with an activation signal. CD40L was expressed on the surface of virus-like particles (VLPs) to target HIV-1 Gag antigens to the CD40 receptor on DCs, whereas CD40L-CD40 interaction would also result in cellular activation. Multiple CD40L VLP constructs were made and evaluated in vitro and in vivo. Indeed, one VLP that expressed CD40L to the highest level showed greatest capacity to activate DCs in vitro. Correspondingly, this CD40L-VLP also proved to be most immunogenic in mice in raising both humoral and cellular responses to HIV-1 Gag. Confirmatory studies were performed to demonstrate the increased immunogenicity of CD40L-VLP is no longer observed when tested in CD40-/- mice. Our findings lend support to the belief that vaccine strategies that both target and activate DCs could yield a superior immune response.

Cytokine adjuvants for vaccine therapy of neoplastic and infectious disease

Vaccination, the revolutionary prophylactic immunotherapy developed in the eighteenth century, has become the most successful and cost-effective of medical remedies available to modern society. Due to the remarkable accomplishments of the past century, the number of diseases and pathogens for which a traditional vaccine approach might reasonably be employed has dwindled to unprecedented levels. While this happy scenario bodes well for the future of public health, modern immunologists and vaccinologists face significant challenges if we are to address the scourge of recalcitrant pathogens like HIV and HCV and well as the significant obstacles to immunotherapy imposed by neoplastic self. Here, the authors review the clinical and preclinical literature to highlight the manner by which the host immune system can be successfully manipulated by cytokine adjuvants, thereby significantly enhancing the efficacy of a wide variety of vaccination platforms.

A stabilized HIV-1 envelope glycoprotein trimer fused to CD40 ligand targets and activates dendritic cells

Background

One reason why subunit protein and DNA vaccines are often less immunogenic than live-attenuated and whole-inactivated virus vaccines is that they lack the co-stimulatory signals provided by various components of the more complex vaccines. The HIV-1 envelope glycoprotein complex (Env) is no exception to this rule. Other factors that limit the induction of neutralizing antibodies against HIV-1 lie in the structure and instability of Env. We have previously stabilized soluble trimeric mimics of Env by introducing a disulfide bond between gp120 and gp41 and adding a trimer stabilizing mutation in gp41 (SOSIP.R6 gp140).

Results

We further stabilized the SOSIP.R6 gp140 using a GCN4-based isoleucine zipper motif, creating SOSIP.R6-IZ gp140. In order to target SOSIP.R6-IZ to immune cells, including dendritic cells, while at the same time activating these cells, we fused SOSIP.R6-IZ to the active domain of CD40 ligand (CD40L), which may serve as a 'cis-adjuvant'. The Env component of the SOSIP.R6-IZ-CD40L fusion construct bound to CD4 and neutralizing antibodies, while the CD40L moiety interacted with CD40. Furthermore, the chimeric molecule was able to signal efficiently through CD40 and induce maturation of human dendritic cells. Dendritic cells secreted IL-6, IL-10 and IL-12 in response to stimulation by SOSIP.R6-IZ-CD40L and were able to activate naïve T cells.

Conclusions

Chimeric HIV-1 gp140 - CD40L trimers can target and activate dendritic cells. Targeting and activating immune cells using CD40L and other 'cis-adjuvants' may improve subunit protein vaccine immunogenicity for HIV-1 and other infectious diseases.

An overview on the field of micro- and nanotechnologies for synthetic Peptide-based vaccines

The development of synthetic peptide-based vaccines has many advantages in comparison with vaccines based on live attenuated organisms, inactivated or killed organism, or toxins. Peptide-based vaccines cannot revert to a virulent form, allow a better conservation, and are produced more easily and safely. However, they generate a weaker immune response than other vaccines, and the inclusion of adjuvants and/or the use of vaccine delivery systems is almost always needed. Among vaccine delivery systems, micro- and nanoparticulated ones are attractive, because their particulate nature can increase cross-presentation of the peptide. In addition, they can be passively or actively targeted to antigen presenting cells. Furthermore, particulate adjuvants are able to directly activate innate immune system in vivo. Here, we summarize micro- and nanoparticulated vaccine delivery systems used in the field of synthetic peptide-based vaccines as well as strategies to increase their immunogenicity.

EBV LMP1, a viral mimic of CD40, activates dendritic cells and functions as a molecular adjuvant when incorporated into an HIV vaccine

HIV-1 does not significantly activate cellular immunity, which has made it difficult to use attenuated forms of HIV-1 as a vaccine. In contrast, EBV induces robust T cell responses in most infected individuals, perhaps as this virus contains LMP1, a viral mimic of CD40, which is a key activating molecule for DCs and macrophages. Consequently, studies were conducted using LMP1 and LMP1-CD40, a related construct formed by replacing the intracellular signaling domain of LMP1 with that of CD40. Upon electroporation into DCs, LMP1 and LMP1-CD40 mRNAs were sufficient to up-regulate costimulatory molecules and proinflammatory cytokines, indicating that these molecules can function in isolation as adjuvant-like molecules. As a first step toward an improved HIV vaccine, LMP1 and LMP1-CD40 were introduced into a HIV-1 construct to produce virions encoding these proteins. Transduction of DCs and macrophages with these viruses induced morphological changes and up-regulated costimulatory molecules and cytokine production by these cells. HIV-LMP1 enhanced the antigen-presenting function of DCs, as measured in an in vitro immunization assay. Taken together, these data show that LMP1 and LMP1-CD40 are portable gene cassettes with strong adjuvant properties that can be introduced into viruses such as HIV, which by themselves, are insufficient to induce protective cellular immunity.

Nasal vaccine innovation

The current vaccine market is gaining momentum in the development of alternative administration routes namely intranasal, oral, topical, pulmonary, vaginal, and rectal; the nasal route offers the most promising opportunity for vaccine administration. It can enhance convenience, safety, elicit both local and systemic immune responses; thus potentially provide protection from pathogens at the site of entry. Nasal vaccine innovation comes with both opportunities and challenges. The innovative strategies used by industry and researchers to overcome the hurdles are discussed in this article: these include live-attenuated vaccines, adjuvants, mucoadhesives, particulate delivery systems, virus-like particles, vaccine manufacture, challenges of regulatory authorities, and the nasal vaccine impact on market potential. Critical issues for effective nasal vaccination are the antigen-retention period that enables its interaction with the lymphatic system and choice of an adjuvant that is nontoxic and induces the required immune response. Co-adjuvanting by means of a mucoadhesive technology addresses some of these issues. ChiSys(®), a natural bioadhesive with proven intranasal safety profile, has already demonstrated efficacy for several nasally delivered vaccines including norovirus. With the looming threat of a pandemic, alternatives such as intranasal vaccination will ultimately facilitate greater public compliance and rapid mass global vaccination.

New approaches to design HIV-1 T-cell vaccines

PURPOSE OF REVIEW

Following the evidence that T-cell responses are crucial in the control of HIV-1 infection, vaccines targeting T-cell responses were tested in recent clinical trials. However, these vaccines showed a lack of efficacy. This review attempts to define the qualitative and quantitative features that are desirable for T-cell-induced responses by vaccines. We also describe strategies that could lead to achievement of this goal.

RECENT FINDINGS

Using the yellow fever vaccine as a benchmark of an efficient vaccine, recent studies identified factors of immune protection and more importantly innate immune pathways needed for the establishment of long-term protective adaptive immunity.

SUMMARY

To prevent or control HIV-1 infection, a vaccine must induce efficient and persistent antigen-specific T cells endowed with mucosal homing capacity. Such cells should have the capability to counteract HIV-1 diversity and its rapid spread from the initial site of infection. To achieve this goal, the activation of a diversified innate immune response is critical. New systems biology approaches will provide more precise correlates of immune protection that will pave the way for new approaches in T-cell-based vaccines.