Safety and comparative immunogenicity of an HIV-1 DNA vaccine in combination with plasmid interleukin 12 and impact of intramuscular electroporation for delivery

Advances in therapeutic cancer vaccines: Harnessing immune adjuvants for enhanced efficacy and future perspectives

Preventive cancer vaccines are highly effective in preventing viral infection-induced cancer, but advances in therapeutic cancer vaccines with a focus on eliminating cancer cells through immunotherapy are limited. To develop therapeutic cancer vaccines, the integration of optimal adjuvants is a potential strategy to enhance or complement existing therapeutic approaches. However, conventional adjuvants do not satisfy the criteria of clinical trials for therapeutic cancer vaccines. To improve the effects of adjuvants in therapeutic cancer vaccines, effective vaccination strategies must be formulated and novel adjuvants must be identified. This review offers an overview of the current advancements in therapeutic cancer vaccines and highlights in situ vaccination approaches that can be synergistically combined with other immunotherapies by harnessing the adjuvant effects. Additionally, the refinement of adjuvant systems using cutting-edge technologies and the elucidation of molecular mechanisms underlying immunogenic cell death to facilitate the development of innovative adjuvants have been discussed.

Personalized neoantigen vaccine and pembrolizumab in advanced hepatocellular carcinoma: a phase 1/2 trial

Programmed cell death protein 1 (PD-1) inhibitors have modest efficacy as a monotherapy in hepatocellular carcinoma (HCC). A personalized therapeutic cancer vaccine (PTCV) may enhance responses to PD-1 inhibitors through the induction of tumor-specific immunity. We present results from a single-arm, open-label, phase 1/2 study of a DNA plasmid PTCV (GNOS-PV02) encoding up to 40 neoantigens coadministered with plasmid-encoded interleukin-12 plus pembrolizumab in patients with advanced HCC previously treated with a multityrosine kinase inhibitor. Safety and immunogenicity were assessed as primary endpoints, and treatment efficacy and feasibility were evaluated as secondary endpoints. The most common treatment-related adverse events were injection-site reactions, observed in 15 of 36 (41.6%) patients. No dose-limiting toxicities or treatment-related grade ≥3 events were observed. The objective response rate (modified intention-to-treat) per Response Evaluation Criteria in Solid Tumors 1.1 was 30.6% (11 of 36 patients), with 8.3% (3 of 36) of patients achieving a complete response. Clinical responses were associated with the number of neoantigens encoded in the vaccine. Neoantigen-specific T cell responses were confirmed in 19 of 22 (86.4%) evaluable patients by enzyme-linked immunosorbent spot assays. Multiparametric cellular profiling revealed active, proliferative and cytolytic vaccine-specific CD4+ and CD8+ effector T cells. T cell receptor β-chain (TCRβ) bulk sequencing results demonstrated vaccination-enriched T cell clone expansion and tumor infiltration. Single-cell analysis revealed posttreatment T cell clonal expansion of cytotoxic T cell phenotypes. TCR complementarity-determining region cloning of expanded T cell clones in the tumors following vaccination confirmed reactivity against vaccine-encoded neoantigens. Our results support the PTCV's mechanism of action based on the induction of antitumor T cells and show that a PTCV plus pembrolizumab has clinical activity in advanced HCC. ClinicalTrials.gov identifier: NCT04251117 .

Safety and Immunogenicity of an In Vivo Muscle Electroporation Delivery System for DNA-hsp65 Tuberculosis Vaccine in Cynomolgus Monkeys

A Bacille Calmette-Guérin (BCG) is still the only licensed vaccine for the prevention of tuberculosis, providing limited protection against Mycobacterium tuberculosis infection in adulthood. New advances in the delivery of DNA vaccines by electroporation have been made in the past decade. We evaluated the safety and immunogenicity of the DNA-hsp65 vaccine administered by intramuscular electroporation (EP) in cynomolgus macaques. Animals received three doses of DNA-hsp65 at 30-day intervals. We demonstrated that intramuscular electroporated DNA-hsp65 vaccine immunization of cynomolgus macaques was safe, and there were no vaccine-related effects on hematological, renal, or hepatic profiles, compared to the pre-vaccination parameters. No tuberculin skin test conversion nor lung X-ray alteration was identified. Further, low and transient peripheral cellular immune response and cytokine expression were observed, primarily after the third dose of the DNA-hsp65 vaccine. Electroporated DNA-hsp65 vaccination is safe but provides limited enhancement of peripheral cellular immune responses. Preclinical vaccine trials with DNA-hsp65 delivered via EP may include a combination of plasmid cytokine adjuvant and/or protein prime-boost regimen, to help the induction of a stronger cellular immune response.

DNA Vaccines: History, Molecular Mechanisms and Future Perspectives

The history of DNA vaccine began as early as the 1960s with the discovery that naked DNA can transfect mammalian cells in vivo. In 1992, the evidence that such transfection could lead to the generation of antigen-specific antibody responses was obtained and supported the development of this technology as a novel vaccine platform. The technology then attracted immense interest and high hopes in vaccinology, as evidence of high immunogenicity and protection against virulent challenges accumulated from several animal models for several diseases. In particular, the capacity to induce T-cell responses was unprecedented in non-live vaccines. However, the technology suffered its major knock when the success in animals failed to translate to humans, where DNA vaccine candidates were shown to be safe but remained poorly immunogenic, or not associated with clinical benefit. Thanks to a thorough exploration of the molecular mechanisms of action of these vaccines, an impressive range of approaches have been and are currently being explored to overcome this major challenge. Despite limited success so far in humans as compared with later genetic vaccine technologies such as viral vectors and mRNA, DNA vaccines are not yet optimised for human use and may still realise their potential.

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

PURPOSE OF REVIEW

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

RECENT FINDINGS

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

SUMMARY

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

Reduced SARS-CoV-2 mRNA vaccine immunogenicity and protection in mice with diet-induced obesity and insulin resistance

BACKGROUND

Obesity and type 2 diabetes mellitus (T2DM) are associated with an increased risk of severe outcomes from infectious diseases, including coronavirus disease 2019. These conditions are also associated with distinct responses to immunization, including an impaired response to widely used severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) mRNA vaccines.

OBJECTIVE

We sought to establish a connection between reduced immunization efficacy via modeling the effects of metabolic diseases on vaccine immunogenicity that is essential for the development of more effective vaccines for this distinct vulnerable population.

METHODS

A murine model of diet-induced obesity and insulin resistance was used to model the effects of comorbid T2DM and obesity on vaccine immunogenicity and protection.

RESULTS

Mice fed a high-fat diet (HFD) developed obesity, hyperinsulinemia, and glucose intolerance. Relative to mice fed a normal diet, HFD mice vaccinated with a SARS-CoV-2 mRNA vaccine exhibited significantly lower anti-spike IgG titers, predominantly in the IgG2c subclass, associated with a lower type 1 response, along with a 3.83-fold decrease in neutralizing titers. Furthermore, enhanced vaccine-induced spike-specific CD8+ T-cell activation and protection from lung infection against SARS-CoV-2 challenge were seen only in mice fed a normal diet but not in HFD mice.

CONCLUSIONS

The study demonstrated impaired immunity following SARS-CoV-2 mRNA immunization in a murine model of comorbid T2DM and obesity, supporting the need for further research into the basis for impaired anti-SARS-CoV-2 immunity in T2DM and investigation of novel approaches to enhance vaccine immunogenicity among those with metabolic diseases.

Microneedle-Mediated Transcutaneous Immunization: Potential in Nucleic Acid Vaccination

Efforts aimed at exploring economical and efficient vaccination have taken center stage to combat frequent epidemics worldwide. Various vaccines have been developed for infectious diseases, among which nucleic acid vaccines have attracted much attention from researchers due to their design flexibility and wide application. However, the lack of an efficient delivery system considerably limits the clinical translation of nucleic acid vaccines. As mass vaccinations via syringes are limited by low patient compliance and high costs, microneedles (MNs), which can achieve painless, cost-effective, and efficient drug delivery, can provide an ideal vaccination strategy. The MNs can break through the stratum corneum barrier in the skin and deliver vaccines to the immune cell-rich epidermis and dermis. In addition, the feasibility of MN-mediated vaccination is demonstrated in both preclinical and clinical studies and has tremendous potential for the delivery of nucleic acid vaccines. In this work, the current status of research on MN vaccines is reviewed. Moreover, the improvements of MN-mediated nucleic acid vaccination are summarized and the challenges of its clinical translation in the future are discussed.

What We Learned about the Feasibility of Gene Electrotransfer for Vaccination on a Model of COVID-19 Vaccine

DNA vaccination is one of the emerging approaches for a wide range of applications, including prophylactic vaccination against infectious diseases and therapeutic vaccination against cancer. The aim of this study was to evaluate the feasibility of our previously optimized protocols for gene electrotransfer (GET)-mediated delivery of plasmid DNA into skin and muscle tissues on a model of COVID-19 vaccine. Plasmids encoding the SARS-CoV-2 proteins spike (S) and nucleocapsid (N) were used as the antigen source, and a plasmid encoding interleukin 12 (IL-12) was used as an adjuvant. Vaccination was performed in the skin or muscle tissue of C57BL/6J mice on days 0 and 14 (boost). Two weeks after the boost, blood, spleen, and transfected tissues were collected to determine the expression of S, N, IL-12, serum interferon-γ, the induction of antigen-specific IgG antibodies, and cytotoxic T-cells. In accordance with prior in vitro experiments that indicated problems with proper expression of the S protein, vaccination with S did not induce S-specific antibodies, whereas significant induction of N-specific antibodies was detected after vaccination with N. Intramuscular vaccination outperformed skin vaccination and resulted in significant induction of humoral and cell-mediated immunity. Moreover, both boost and adjuvant were found to be redundant for the induction of an immune response. Overall, the study confirmed the feasibility of the GET for DNA vaccination and provided valuable insights into this approach.

Mechanisms of ag85a/b DNA vaccine conferred immunotherapy and recovery from Mycobacterium tuberculosis-induced injury

Our previous research developed a novel tuberculosis (TB) DNA vaccine ag85a/b that showed a significant therapeutic effect on the mouse tuberculosis model by intramuscular injection (IM) and electroporation (EP). However, the action mechanisms between these two vaccine immunization methods remain unclear. In a previous study, 96 Mycobacterium tuberculosis (MTB) H₃₇ Rv-infected BALB/c mice were treated with phosphate-buffered saline, 10, 50, 100, and 200 μg ag85a/b DNA vaccine delivered by IM and EP three times at 2-week intervals, respectively. In this study, peripheral blood mononuclear cells (PBMCs) from three mice in each group were isolated to extract total RNA. The gene expression profiles were analyzed using gene microarray technology to obtain differentially expressed (DE) genes. Finally, DE genes were validated by real-time reverse transcription-quantitive polymerase chain reaction and the GEO database. After MTB infection, most of the upregulated DE genes were related to the digestion and absorption of nutrients or neuroendocrine (such as Iapp, Scg2, Chga, Amy2a5), and most of the downregulated DE genes were related to cellular structural and functional proteins, especially the structure and function proteins of the alveolar epithelial cell (such as Sftpc, Sftpd, Pdpn). Most of the abnormally upregulated or downregulated DE genes in the TB model group were recovered in the 100 and 200 μg ag85a/b DNA IM groups and four DNA EP groups. The pancreatic secretion pathway downregulated and the Rap1 signal pathway upregulated had particularly significant changes during the immunotherapy of the ag85a/b DNA vaccine on the mouse TB model. The action targets and mechanisms of IM and EP are highly consistent. Tuberculosis infection causes rapid catabolism and slow anabolism in mice. For the first time, we found that the effective dose of the ag85a/b DNA vaccine immunized whether by IM or EP could significantly up-regulate immune-related pathways and recover the metabolic disorder and the injury caused by MTB.

mRNA-Based Vaccine for COVID-19: They Are New but Not Unknown!

mRNA vaccines take advantage of the mechanism that our cells use to produce proteins. Our cells produce proteins based on the knowledge contained in our DNA; each gene encodes a unique protein. The genetic information is essential, but cells cannot use it until mRNA molecules convert it into instructions for producing specific proteins. mRNA vaccinations provide ready-to-use mRNA instructions for constructing a specific protein. BNT162b2 (Pfizer-BioNTech) and mRNA-1273 (Moderna) both are newly approved mRNA-based COVID-19 vaccines that have shown excellent protection and efficacy. In total, there are five more mRNA-based vaccine candidates for COVID-19 under different phases of clinical development. This review is specifically focused on mRNA-based vaccines for COVID-19 covering its development, mechanism, and clinical aspects.

Elicitation of immune responses against Nipah virus by an engineered synthetic DNA vaccine

Nipah virus (NiV) is a re-emerging pathogen that causes severe disease in animals and humans. Current treatment measures for NiV infection are insufficient, and there is no approved vaccine against NiV for either humans or animals. Nipah virus is listed as a high-priority pathogen for vaccine and therapeutic research by the World Health Organization (WHO). In the present study, we employed synthetic enhanced DNA technologies developed to design and produce novel consensus NiV Fusion (NiV-F) and Glycoprotein (NiV-G) antigen sequences for inclusion in synthetic DNA vaccines for NiV. The expression of each vaccine antigen was confirmed in vitro using immune-binding assays. Electroporation-enhanced intramuscular injection of each NiV-F and NiV-G into mice induced potent cellular immune responses to multiple epitopes of NiV-G and NiV-F that included antigen-specific CD8+ T cells. Both vaccines elicited high antibody titers in mice, with a single immunization sufficient to seroconvert 100% of immunized animals. Additionally, the NiV-F vaccine also induced antibodies to neutralize NiV-F-pseudotyped virus particles. These data support further study of these novel synthetic enhanced NiV nucleic acid-based antigens as potential components of an effective vaccine against the Nipah virus.

IL12 immune therapy clinical trial review: Novel strategies for avoiding CRS-associated cytokines

Interleukin 12 (IL-12) is a naturally occurring cytokine that plays a key role in inducing antitumor immune responses, including induction of antitumor immune memory. Currently, no IL-12-based therapeutic products have been approved for clinical application because of its toxicities. On the basis of this review of clinical trials using primarily wild-type IL-12 and different delivery methods, we conclude that the safe utilization of IL-12 is highly dependent on the tumor-specific localization of IL-12 post administration. In this regard, we have developed a cell membrane-anchored and tumor-targeted IL-12-T (attIL12-T) cell product for avoiding toxicity from both IL-12 and T cells-induced cytokine release syndrome in peripheral tissues. A phase I trial using this product which seeks to avoid systemic toxicity and boost antitumor efficacy is on the horizon. Of note, this product also boosts the impact of CAR-T or TCR-T cell efficacy against solid tumors, providing an alternative approach to utilize CAR-T to overcome tumor resistance.

Induction of food-specific IgG by Gene Gun-delivered DNA vaccines

Background

Shellfish and tree nut allergies are among the most prevalent food allergies, now affecting 2%–3% and 1% of the US population, respectively. Currently, there are no approved therapies for shellfish or tree nut allergies, with strict avoidance being the standard of care. However, oral immunotherapy for peanut allergy and subcutaneous immunotherapy for environmental allergens are efficacious and lead to the production of allergen-specific IgG, which causes suppression of allergen effector cell degranulation. Since allergen-specific IgG is a desired response to alleviate IgE-mediated allergies, we tested transcutaneously-delivered DNA vaccines targeting shellfish and tree nut allergens for their ability to induce antigen-specific IgG, which would have therapeutic potential for food allergies.

Methods

We assessed Gene Gun-delivered DNA vaccines targeting either crustacean shellfish or walnut/pecan allergens, with or without IL-12, in naïve mice. Three strains of mice, BALB/cJ, C3H/HeJ and CC027/GeniUnc, were evaluated for IgG production following vaccination. Vaccines were administered twice via Gene Gun, three weeks apart and then blood was collected three weeks following the final vaccination.

Results

Vaccination with shellfish allergen DNA led to increased shrimp-specific IgG in all three strains, with the highest production in C3H/HeJ from the vaccine alone, whereas the vaccine with IL-12 led to the highest IgG production in BALB/cJ and CC027/GeniUnc mice. Similar IgG production was also induced against lobster and crab allergens. For walnut/pecan vaccines, BALB/cJ and C3H/HeJ mice produced significantly higher walnut- and pecan-specific IgG with the vaccine alone compared to the vaccine with IL-12, while the CC027 mice made significantly higher IgG with the addition of IL-12. Notably, intramuscular administration of the vaccines did not lead to increased antigen-specific IgG production, indicating that Gene Gun administration is a superior delivery modality.

Conclusions

Overall, these data demonstrate the utility of DNA vaccines against two lifelong food allergies, shellfish and tree nuts, suggesting their potential as a food allergy therapy in the future.

Recent Progress in the Discovery and Development of Monoclonal Antibodies against Viral Infections

Monoclonal antibodies (mAbs), the new revolutionary class of medications, are fast becoming tools against various diseases thanks to a unique structure and function that allow them to bind highly specific targets or receptors. These specialized proteins can be produced in large quantities via the hybridoma technique introduced in 1975 or by means of modern technologies. Additional methods have been developed to generate mAbs with new biological properties such as humanized, chimeric, or murine. The inclusion of mAbs in therapeutic regimens is a major medical advance and will hopefully lead to significant improvements in infectious disease management. Since the first therapeutic mAb, muromonab-CD3, was approved by the U.S. Food and Drug Administration (FDA) in 1986, the list of approved mAbs and their clinical indications and applications have been proliferating. New technologies have been developed to modify the structure of mAbs, thereby increasing efficacy and improving delivery routes. Gene delivery technologies, such as non-viral synthetic plasmid DNA and messenger RNA vectors (DMabs or mRNA-encoded mAbs), built to express tailored mAb genes, might help overcome some of the challenges of mAb therapy, including production restrictions, cold-chain storage, transportation requirements, and expensive manufacturing and distribution processes. This paper reviews some of the recent developments in mAb discovery against viral infections and illustrates how mAbs can help to combat viral diseases and outbreaks.

A promiscuous T cell epitope-based HIV vaccine providing redundant population coverage of the HLA class II elicits broad, polyfunctional T cell responses in nonhuman primates

Over the last few decades, several emerging or reemerging viral diseases with no readily available vaccines have ravaged the world. A platform to fastly generate vaccines inducing potent and durable neutralizing antibody and T cell responses is sorely needed. Bioinformatically identified epitope-based vaccines can focus on immunodominant T cell epitopes and induce more potent immune responses than a whole antigen vaccine and may be deployed more rapidly and less costly than whole-gene vaccines. Increasing evidence has shown the importance of the CD4+ T cell response in protection against HIV and other viral infections. The previously described DNA vaccine HIVBr18 encodes 18 conserved, promiscuous epitopes binding to multiple HLA-DR-binding HIV epitopes amply recognized by HIV-1-infected patients. HIVBr18 elicited broad, polyfunctional, and durable CD4⁺and CD8+ T cell responses in BALB/c and mice transgenic to HLA class II alleles, showing cross-species promiscuity. To fully delineate the promiscuity of the HLA class II vaccine epitopes, we assessed their binding to 34 human class II (HLA-DR, DQ, and -DP) molecules, and immunized nonhuman primates. Results ascertained redundant 100% coverage of the human population for multiple peptides. We then immunized Rhesus macaques with HIVBr18 under in vivo electroporation. The immunization induced strong, predominantly polyfunctional CD4+ T cell responses in all animals to 13 out of the 18 epitopes; T cells from each animal recognized 7-11 epitopes. Our results provide a preliminary proof of concept that immunization with a vaccine encoding epitopes with high and redundant coverage of the human population can elicit potent T cell responses to multiple epitopes, across species and MHC barriers. This approach may facilitate the rapid deployment of immunogens eliciting cellular immunity against emerging infectious diseases, such as COVID-19.

Development of synthetic antigen vaccines for COVID-19

The current pandemic called COVID-19 caused by the SARS-CoV-2 virus brought the need for the search for fast alternatives to both control and fight the SARS-CoV-2 infection. Therefore, a race for a vaccine against COVID-19 took place, and some vaccines have been approved for emergency use in several countries in a record time. Ongoing prophylactic research has sought faster, safer, and precise alternatives by redirecting knowledge of other vaccines, and/or the development of new strategies using available tools, mainly in the areas of genomics and bioinformatics. The current review highlights the development of synthetic antigen vaccines, focusing on the usage of bioinformatics tools for the selection and construction of antigens on the different vaccine constructions under development, as well as strategies to optimize vaccines for COVID-19.

Control of SARS-CoV-2 infection after Spike DNA or Spike DNA+Protein co-immunization in rhesus macaques

The speed of development, versatility and efficacy of mRNA-based vaccines have been amply demonstrated in the case of SARS-CoV-2. DNA vaccines represent an important alternative since they induce both humoral and cellular immune responses in animal models and in human trials. We tested the immunogenicity and protective efficacy of DNA-based vaccine regimens expressing different prefusion-stabilized Wuhan-Hu-1 SARS-CoV-2 Spike antigens upon intramuscular injection followed by electroporation in rhesus macaques. Different Spike DNA vaccine regimens induced antibodies that potently neutralized SARS-CoV-2 in vitro and elicited robust T cell responses. The antibodies recognized and potently neutralized a panel of different Spike variants including Alpha, Delta, Epsilon, Eta and A.23.1, but to a lesser extent Beta and Gamma. The DNA-only vaccine regimens were compared to a regimen that included co-immunization of Spike DNA and protein in the same anatomical site, the latter of which showed significant higher antibody responses. All vaccine regimens led to control of SARS-CoV-2 intranasal/intratracheal challenge and absence of virus dissemination to the lower respiratory tract. Vaccine-induced binding and neutralizing antibody titers and antibody-dependent cellular phagocytosis inversely correlated with transient virus levels in the nasal mucosa. Importantly, the Spike DNA+Protein co-immunization regimen induced the highest binding and neutralizing antibodies and showed the strongest control against SARS-CoV-2 challenge in rhesus macaques.

Anti-Spike neutralizing antibodies provide strong protection against SARS-CoV-2 infection in animal models, and correlate with protection in humans, supporting the notion that induction of strong humoral immunity is key to protection. We show induction of robust antibody and T cell responses by different Spike DNA-based vaccine regimens able to effectively mediate protection and to control SARS-CoV-2 infection in the rhesus macaque model. This study provides the opportunity to compare vaccines able to induce different humoral and cellular immune responses in an effort to develop durable immunity against the SARS-CoV-2. A vaccine regimen comprising simultaneous co-immunization of DNA and Protein at the same anatomical site showed best neutralizing abilities and was more effective than DNA alone in inducing protective immune responses and controlling SARS-CoV-2 infection. Thus, an expansion of the DNA vaccine regimen to include co-immunization with Spike protein may be of advantage also for SARS-CoV-2.

Safety and Immunogenicity of an Anti-Zika Virus DNA Vaccine

BACKGROUND

Although Zika virus (ZIKV) infection is typically self-limiting, other associated complications such as congenital birth defects and the Guillain-Barré syndrome are well described. There are no approved vaccines against ZIKV infection.

METHODS

In this phase 1, open-label clinical trial, we evaluated the safety and immunogenicity of a synthetic, consensus DNA vaccine (GLS-5700) encoding the ZIKV premembrane and envelope proteins in two groups of 20 participants each. The participants received either 1 mg or 2 mg of vaccine intradermally, with each injection followed by electroporation (the use of a pulsed electric field to introduce the DNA sequence into cells) at baseline, 4 weeks, and 12 weeks.

RESULTS

The median age of the participants was 38 years, and 60% were women; 78% were White and 22% Black; in addition, 30% were Hispanic. At the interim analysis at 14 weeks (i.e., after the third dose of vaccine), no serious adverse events were reported. Local reactions at the vaccination site (e.g., injection-site pain, redness, swelling, and itching) occurred in approximately 50% of the participants. After the third dose of vaccine, binding antibodies (as measured on enzyme-linked immunosorbent assay) were detected in all the participants, with geometric mean titers of 1642 and 2871 in recipients of 1 mg and 2 mg of vaccine, respectively. Neutralizing antibodies developed in 62% of the samples on Vero-cell assay. On neuronal-cell assay, there was 90% inhibition of ZIKV infection in 70% of the serum samples and 50% inhibition in 95% of the samples. The intraperitoneal injection of postvaccination serum protected 103 of 112 IFNAR knockout mice (bred with deletion of genes encoding interferon-α and interferon-β receptors) (92%) that were challenged with a lethal dose of ZIKV-PR209 strain; none of the mice receiving baseline serum survived the challenge. Survival was independent of the neutralization titer.

CONCLUSIONS

In this phase 1, open-label clinical trial, a DNA vaccine elicited anti-ZIKV immune responses. Further studies are needed to better evaluate the safety and efficacy of the vaccine. (Funded by GeneOne Life Science and others; ZIKA-001 ClinicalTrials.gov number, NCT02809443.).

Immunogenicity of stabilized HIV-1 Env trimers delivered by self-amplifying mRNA

Self-amplifying mRNA (saRNA) represents a promising platform for nucleic acid delivery of vaccine immunogens. Unlike plasmid DNA, saRNA does not require entry into the nucleus of target cells for expression, having the capacity to drive higher protein expression compared to mRNA as it replicates within the cytoplasm. In this study, we examined the potential of stabilized native-like HIV-1 Envelope glycoprotein (Env) trimers to elicit immune responses when delivered by saRNA polyplexes (PLXs), assembled with linear polyethylenimine. We showed that Venezuelan equine encephalitis virus (VEEV) saRNA induces a stronger humoral immune response to the encoded transgene compared to Semliki Forest virus saRNA. Moreover, we characterized the immunogenicity of the soluble and membrane-bound ConSOSL.UFO Env design in mice and showed a faster humoral kinetic and an immunoglobulin G (IgG)2a skew using a membrane-bound design. The immune response generated by PLX VEEV saRNA encoding the membrane-bound Env was then evaluated in larger animal models including macaques, in which low doses induced high IgG responses. Our data demonstrated that the VEEV saRNA PLX nanoparticle formulation represents a suitable platform for the delivery of stabilized HIV-1 Env and has the potential to be used in a variety of vaccine regimens.

Therapeutic Potential of IL-15 and N-803 in HIV/SIV Infection

IL-15, a proinflammatory cytokine critical for the generation, maintenance, and homeostasis of T cell responses, is produced naturally in response to HIV/SIV infection, but has also demonstrated therapeutic potential. IL-15 can boost CD4+ and CD8+ T cell and NK cell proliferation, activation, and function. However, IL-15 treatment may cause aberrant immune activation and accelerated disease progression in certain circumstances. Moreover, the relationship between the timing of IL-15 administration and disease progression remains unclear. The IL-15 superagonist N-803 was developed to expand the therapeutic potential of IL-15 by maximizing its tissue distribution and half-life. N-803 has garnered enthusiasm recently as a way to enhance the innate and cellular immune responses to HIV/SIV by improving CD8+ T cell recognition and killing of virus-infected cells and directing immune cells to mucosal sites and lymph nodes, the primary sites of virus replication. N-803 has also been evaluated in "shock and kill" strategies due to its potential to reverse latency (shock) and enhance antiviral immunity (kill). This review examines the current literature about the effects of IL-15 and N-803 on innate and cellular immunity, viral burden, and latency reversal in the context of HIV/SIV, and their therapeutic potential both alone and combined with additional interventions such as antiretroviral therapy (ART) and vaccination.

Methods to improve the immunogenicity of plasmid DNA vaccines

DNA vaccines have emerged as innovative approaches that have great potential to overcome the limitations of current conventional vaccines. Plasmid DNA vaccines are often safer than other vaccines because they carry only antigen genetic information, are more stable and easier to produce, and can stimulate both humoral and cellular immune responses. Although the results of ongoing clinical trials are very promising, some limitations compromise the immunogenicity of these vaccines. Thus, this review describes different strategies that can be explored to improve the immunogenicity of plasmid DNA vaccines, including the optimization of the plasmid vector backbone, the use of different methods for vaccine delivery, the use of alternative administration routes and the inclusion of adjuvants. In combination, these improvements could lead to the successful clinical use of plasmid DNA vaccines.

Effects of therapeutic vaccination on the control of SIV in rhesus macaques with variable responsiveness to antiretroviral drugs

A therapeutic vaccine that induces lasting control of HIV infection could eliminate the need for lifelong adherence to antiretroviral therapy. This study investigated a therapeutic DNA vaccine delivered with a single adjuvant or a novel combination of adjuvants to augment T cell immunity in the blood and gut-associated lymphoid tissue in SIV-infected rhesus macaques. Animals that received DNA vaccines expressing SIV proteins, combined with plasmids expressing adjuvants designed to increase peripheral and mucosal T cell responses, including the catalytic subunit of the E. coli heat-labile enterotoxin, IL-12, IL-33, retinaldehyde dehydrogenase 2, soluble PD-1 and soluble CD80, were compared to mock-vaccinated controls. Following treatment interruption, macaques exhibited variable levels of viral rebound, with four animals from the vaccinated groups and one animal from the control group controlling virus at median levels of 10³ RNA copies/ml or lower (controllers) and nine animals, among all groups, exhibiting immediate viral rebound and median viral loads greater than 10³ RNA copies/ml (non-controllers). Although there was no significant difference between the vaccinated and control groups in protection from viral rebound, the variable virological outcomes during treatment interruption enabled an examination of immune correlates of viral replication in controllers versus non-controllers regardless of vaccination status. Lower viral burden in controllers correlated with increased polyfunctional SIV-specific CD8⁺ T cells in mesenteric lymph nodes and blood prior to and during treatment interruption. Notably, higher frequencies of colonic CD4⁺ T cells and lower Th17/Treg ratios prior to infection in controllers correlated with improved responses to ART and control of viral rebound. These results indicate that mucosal immune responses, present prior to infection, can influence efficacy of antiretroviral therapy and the outcome of immunotherapeutic vaccination, suggesting that therapies capable of modulating host mucosal responses may be needed to achieve HIV cure.

Multivalent DNA Vaccines as A Strategy to Combat Multiple Concurrent Epidemics: Mosquito-Borne and Hemorrhagic Fever Viruses

The emergence of multiple concurrent infectious diseases localized in the world creates a complex burden on global public health systems. Outbreaks of Ebola, Lassa, and Marburg viruses in overlapping regions of central and West Africa and the co-circulation of Zika, Dengue, and Chikungunya viruses in areas with A. aegypti mosquitos highlight the need for a rapidly deployable, safe, and versatile vaccine platform readily available to respond. The DNA vaccine platform stands out as such an application. Here, we present proof-of-concept studies from mice, guinea pigs, and nonhuman primates for two multivalent DNA vaccines delivered using in vivo electroporation (EP) targeting mosquito-borne (MMBV) and hemorrhagic fever (MHFV) viruses. Immunization with MMBV or MHFV vaccines via intradermal EP delivery generated robust cellular and humoral immune responses against all target viral antigens in all species. MMBV vaccine generated antigen-specific binding antibodies and IFNγ-secreting lymphocytes detected in NHPs up to six months post final immunization, suggesting induction of long-term immune memory. Serum from MHFV vaccinated NHPs demonstrated neutralizing activity in Ebola, Lassa, and Marburg pseudovirus assays indicating the potential to offer protection. Together, these data strongly support and demonstrate the versatility of DNA vaccines as a multivalent vaccine development platform for emerging infectious diseases.

The Key Role of Nucleic Acid Vaccines for One Health

The ongoing SARS-CoV-2 pandemic has highlighted both the importance of One Health, i.e., the interactions and transmission of pathogens between animals and humans, and the potential power of gene-based vaccines, specifically nucleic acid vaccines. This review will highlight key aspects of the development of plasmid DNA Nucleic Acid (NA) vaccines, which have been licensed for several veterinary uses, and tested for a number of human diseases, and will explain how an understanding of their immunological and real-world attributes are important for their efficacy, and how they helped pave the way for mRNA vaccines. The review highlights how combining efforts for vaccine development for both animals and humans is crucial for advancing new technologies and for combatting emerging diseases.

HIV vaccinology: 2021 update

HIV is a virus that remains a major health concern and results in an infection that has no cure even after over 30 years since its discovery. As such, HIV vaccine discovery continues to be an area of intensive research. In this review, we summarize the most recent HIV vaccine efficacy trials, clinical trials initiated within the last 3 years, and discuss prominent improvements that have been made in prophylactic HIV vaccine designs.

Intramuscular and Intradermal Electroporation of HIV-1 PENNVAX-GP® DNA Vaccine and IL-12 Is Safe, Tolerable, Acceptable in Healthy Adults

Background: Several techniques are under investigation to improve the immunogenicity of HIV-1 DNA vaccine candidates. DNA vaccines are advantageous due to their ease of design, expression of multiple antigens, and safety.

METHODS

The HVTN 098 trial assessed the PENNVAX^®-GP DNA vaccine (encoding HIV env, gag, pol) administered with or without plasmid IL-12 at 0-, 1-, 3-, and 6-month timepoints via intradermal (ID) or intramuscular (IM) electroporation (EP) in healthy, adult participants. We report on safety, tolerability, and acceptability.

RESULTS

HVTN 098 enrolled 94 participants: 85 received PENNVAX^®-GP and nine received placebo. Visual analog scale (VAS) pain scores immediately after each vaccination were lower in the ID/EP than in the IM/EP group (medians 4.1-4.6 vs. 6-6.5, p < 0.01). IM/EP participants reported greater pain and/or tenderness at the injection site. Most ID/EP participants had skin lesions such as scabs/eschars, scars, and pigmentation changes, which resolved within 6 months in 51% of participants (24/55). Eighty-two percent of IM/EP and 92% of ID/EP participant survey responses showed acceptable levels of discomfort.

CONCLUSIONS

ID/EP and IM/EP are distinct experiences; however, HIV-1 DNA vaccination by either route was safe, tolerable and acceptable by most study participants.

Harnessing Recent Advances in Synthetic DNA and Electroporation Technologies for Rapid Vaccine Development Against COVID-19 and Other Emerging Infectious Diseases

DNA vaccines are considered as a third-generation vaccination approach in which antigenic materials are encoded as DNA plasmids for direct in vivo production to elicit adaptive immunity. As compared to other platforms, DNA vaccination is considered to have a strong safety profile, as DNA plasmids neither replicate nor elicit vector-directed immune responses in hosts. While earlier work found the immune responses induced by DNA vaccines to be sub-optimal in larger mammals and humans, recent developments in key synthetic DNA and electroporation delivery technologies have now allowed DNA vaccines to elicit significantly more potent and consistent responses in several clinical studies. This paper will review findings from the recent clinical and preclinical studies on DNA vaccines targeting emerging infectious diseases (EID) including COVID-19 caused by the SARS-CoV-2 virus, and the technological advancements pivotal to the improved responses-including the use of the advanced delivery technology, DNA-encoded cytokine/mucosal adjuvants, and innovative concepts in immunogen design. With continuous advancement over the past three decades, the DNA approach is now poised to develop vaccines against COVID-19, as well as other EIDs.

IL-12 DNA Displays Efficient Adjuvant Effects Improving Immunogenicity of Ag85A in DNA Prime/MVA Boost Immunizations

Mycobacterium tuberculosis (Mtb) infection is one of the leading causes of death worldwide. The Modified Vaccinia Ankara (MVA) vaccine vector expressing the mycobacterial antigen 85A (MVA85A) was demonstrated to be safe, although it did not improve BCG efficacy, denoting the need to search for improved tuberculosis vaccines. In this work, we investigated the effect of IL-12 DNA -as an adjuvant- on an Ag85A DNA prime/MVA85A boost vaccination regimen. We evaluated the immune response profile elicited in mice and the protection conferred against intratracheal Mtb H37Rv challenge. We observed that the immunization scheme including DNA-A85A+DNA-IL-12/MVA85A induced a strong IFN-γ production to Ag85A in vitro, with a significant expansion of IFN-γ⁺CD4⁺ and IFN-γ⁺CD8⁺ anti-Ag85A lymphocytes. Furthermore, we also detected a significant increase in the proportion of specific CD8⁺CD107⁺ T cells against Ag85A. Additionally, inclusion of IL-12 DNA in the DNA-A85A/MVA85A vaccine scheme induced a marked augment in anti-Ag85A IgG levels. Interestingly, after 30 days of infection with Mtb H37Rv, DNA-A85A+DNA-IL-12/MVA85A vaccinated mice displayed a significant reduction in lung bacterial burden. Together, our findings suggest that IL-12 DNA might be useful as a molecular adjuvant in an Ag85A DNA/MVA prime-boost vaccine against Mtb infection.

DNA vaccines: prime time is now

Recently newer synthetic DNA vaccines have been rapidly advanced to clinical study and have demonstrated an impressive degree of immune potency and tolerability. Improvements in DNA delivery over prior needle and syringe approaches include jet delivery, gene gun delivery, among others. Among the most effective of these new delivery methods, advanced electroporation (EP), combined with other advances, induces robust humoral and cellular immunity in both preventative as well as therapeutic studies. Advancements in the design of the DNA inserts include leader sequence changes, RNA and codon optimizations, improved insert designs, increased concentrations of DNA, and skin delivery, appear to complement newer delivery strategies. These advances also provide a framework for the in vivo production of synthetic DNA biologics. In this review, we focus on recent studies of synthetic DNA vaccines in the clinic for the prevention or treatment of infectious diseases with a focus on adaptive electroporation for delivery, and briefly summarize novel preclinical data advancing the in vivo delivery of DNA-encoded antibody-like biologics.

Robust antibody and cellular responses induced by DNA-only vaccination for HIV

BACKGROUNDHVTN 098, a randomized, double-blind, placebo-controlled trial, evaluated the safety, tolerability, and immunogenicity of PENNVAX-GP HIV DNA vaccine, administered with or without plasmid IL-12 (pIL-12), via intradermal (ID) or intramuscular (IM) electroporation (EP) in healthy, HIV-uninfected adults. The study tested whether PENNVAX-GP delivered via ID/EP at one-fifth the dose could elicit equivalent immune responses to delivery via IM/EP and whether inclusion of pIL-12 provided additional benefit.METHODSParticipants received DNA encoding HIV-1 env/gag/pol in 3 groups: 1.6 mg ID (ID no IL-12 group, n = 20), 1.6 mg ID + 0.4 mg pIL-12 (ID + IL-12 group, n = 30), 8 mg IM + 1 mg pIL-12 (IM + IL-12 group, n = 30), or placebo (n = 9) via EP at 0, 1, 3, and 6 months. Results of cellular and humoral immunogenicity assessments are reported.RESULTSFollowing vaccination, the frequency of responders (response rate) to any HIV protein based on CD4+ T cells expressing IFN-γ or IL-2 was 96% for both the ID + IL-12 and IM + IL-12 groups; CD8+ T cell response rates were 64% and 44%, respectively. For ID delivery, the inclusion of pIL-12 increased CD4+ T cell response rate from 56% to 96%. The frequency of responders was similar (≥90%) for IgG binding antibody to gp140 consensus Env across all groups, but the magnitude was higher in the ID + IL-12 group compared with the IM + IL-12 group.CONCLUSIONPENNVAX-GP DNA induced robust cellular and humoral immune responses, demonstrating that immunogenicity of DNA vaccines can be enhanced by EP route and inclusion of pIL-12. ID/EP was dose sparing, inducing equivalent, or in some aspects superior, immune responses compared with IM/EP.TRIAL REGISTRATIONClinicalTrials.gov NCT02431767.FUNDINGThis work was supported by National Institute of Allergy and Infectious Diseases (NIAID), U.S. Public Health Service grants, an HIV Vaccine Design and Development Team contract, Integrated Preclinical/Clinical AIDS Vaccine Development Program, and an NIH award.

Acceptability and tolerability of repeated intramuscular electroporation of Multi-antigenic HIV (HIVMAG) DNA vaccine among healthy African participants in a phase 1 randomized controlled trial

Introduction

Intramuscular electroporation (IM/EP) is a vaccine delivery technique that improves the immunogenicity of DNA vaccines. We evaluated the acceptability and tolerability of electroporation among healthy African study participants.

Methods

Forty-five participants were administered a DNA vaccine (HIV-MAG) or placebo by electroporation at three visits occurring at four week-intervals. At the end of each visit, participants were asked to rate pain at four times: (1) when the device was placed on the skin and vaccine injected, before the electrical stimulation, (2) at the time of electrical stimulation and muscle contraction, and (3) at 10 minutes and (4) 30 minutes after the procedure was completed. For analyses, pain level was dichotomized as either “acceptable” (none/slight/uncomfortable) or “too much” (Intense, severe, and very severe) and examined over time using repeated measures models. Optional brief comments made by participants were summarized anecdotally.

Results

All 45 participants completed all three vaccination visits; none withdrew from the study due to the electroporation procedure. Most (76%) reported pain levels as acceptable at every time point across all vaccination visits. The majority of “unacceptable” pain was reported at the time of electrical stimulation. The majority of the participants (97%) commented that they preferred electroporation to standard injection.

Conclusion

Repeated intramuscular electroporation for vaccine delivery was found to be acceptable and feasible among healthy African HIV vaccine trial participants. The majority of participants reported an acceptable pain level at all vaccination time points. Further investigation may be warranted into the value of EP to improve immunization outcomes.

ClinicalTrials.gov NCT01496989

SwiftReg cluster registration automatically reduces flow cytometry data variability including batch effects

Biological differences of interest in large, high-dimensional flow cytometry datasets are often obscured by undesired variations caused by differences in cytometers, reagents, or operators. Each variation type requires a different correction strategy, and their unknown contributions to overall variability hinder automated correction. We now describe swiftReg, an automated method that reduces undesired sources of variability between samples and particularly between batches. A high-resolution cluster map representing the multidimensional data is generated using the SWIFT algorithm, and shifts in cluster positions between samples are measured. Subpopulations are aligned between samples by displacing cell parameter values according to registration vectors derived from independent or locally-averaged cluster shifts. Batch variation is addressed by registering batch control or consensus samples, and applying the resulting shifts to individual samples. swiftReg selectively reduces batch variation, enhancing detection of biological differences. swiftReg outputs registered datasets as standard .FCS files to facilitate further analysis by other tools.

Rebhahn et al. develop swiftReg that automatically corrects undesired sources of variability of flow cytometry data. To identify batch variation, this method registers an internal standard or consensus sample from each batch and applies the resulting registration shifts to individual samples, reducing the batch variation while preserving biological differences.

The biomedical and bioengineering potential of protein nanocompartments

Protein nanocompartments (PNCs) are self-assembling biological nanocages that can be harnessed as platforms for a wide range of nanobiotechnology applications. The most widely studied examples of PNCs include virus-like particles, bacterial microcompartments, encapsulin nanocompartments, enzyme-derived nanocages (such as lumazine synthase and the E2 component of the pyruvate dehydrogenase complex), ferritins and ferritin homologues, small heat shock proteins, and vault ribonucleoproteins. Structural PNC shell proteins are stable, biocompatible, and tolerant of both interior and exterior chemical or genetic functionalization for use as vaccines, therapeutic delivery vehicles, medical imaging aids, bioreactors, biological control agents, emulsion stabilizers, or scaffolds for biomimetic materials synthesis. This review provides an overview of the recent biomedical and bioengineering advances achieved with PNCs with a particular focus on recombinant PNC derivatives.

In Vivo Assembly of Nanoparticles Achieved through Synergy of Structure-Based Protein Engineering and Synthetic DNA Generates Enhanced Adaptive Immunity

Nanotechnologies are considered to be of growing importance to the vaccine field. Through decoration of immunogens on multivalent nanoparticles, designed nanovaccines can elicit improved humoral immunity. However, significant practical and monetary challenges in large-scale production of nanovaccines have impeded their widespread clinical translation. Here, an alternative approach is illustrated integrating computational protein modeling and adaptive electroporation-mediated synthetic DNA delivery, thus enabling direct in vivo production of nanovaccines. DNA-launched nanoparticles are demonstrated displaying an HIV immunogen spontaneously self-assembled in vivo. DNA-launched nanovaccines induce stronger humoral responses than their monomeric counterparts in both mice and guinea pigs, and uniquely elicit CD8+ effector T-cell immunity as compared to recombinant protein nanovaccines. Improvements in vaccine responses recapitulate when DNA-launched nanovaccines with alternative scaffolds and decorated antigen are designed and evaluated. Finally, evaluation of functional immune responses induced by DLnanovaccines demonstrates that, in comparison to control mice or mice immunized with DNA-encoded hemagglutinin monomer, mice immunized with a DNA-launched hemagglutinin nanoparticle vaccine fully survive a lethal influenza challenge, and have substantially lower viral load, weight loss, and influenza-induced lung pathology. Additional study of these next-generation in vivo-produced nanovaccines may offer advantages for immunization against multiple disease targets.

A Phase 1 Trial Assessing the Safety and Tolerability of a Therapeutic DNA Vaccination Against HPV16 and HPV18 E6/E7 Oncogenes After Chemoradiation for Cervical Cancer

PURPOSE

This study assessed the safety and tolerability of therapeutic immunization against the human papillomavirus (HPV) viral oncoproteins E6 and E7 in patients with cervical cancer after chemoradiation.

METHODS AND MATERIALS

MEDI0457 (INO-3112) is a DNA-based vaccine targeting E6 and E7 of HPV-16/18 that is coinjected with an IL-12 plasmid followed by electroporation with the CELLECTRA 5P device. At 2 to 4 weeks after chemoradiation, patients with newly diagnosed stage IB1-IVA (cohort 1) or persistent/recurrent (cohort 2) cervical cancers were treated with 4 immunizations of MEDI0457 every 4 weeks. The primary endpoints were incidence of adverse events and injection site reactions. Immune responses against HPV antigens were measured by ELISpot for interferon-γ (IFNγ), enzyme-linked immunosorbent assay for antibody responses and multiplexed immunofluorescence for immune cells in cervical biopsy specimens.

RESULTS

Ten patients (cohort 1, n = 7; cohort 2, n = 3) with HPV16 (n = 7) or HPV18 (n = 3) cervical cancers received MEDI0457 after chemoradiation. Treatment-related adverse events were all grade 1, primarily related to the injection site. Eight of 10 patients had detectable cellular or humoral immune responses against HPV antigens after chemoradiation and vaccination: 6 of 10 patients generated anti-HPV antibody responses and 6 of 10 patients generated IFNγ-producing T cell responses. At the completion of chemoradiation and vaccination, cervical biopsy specimens had detectable CD8⁺ T cells and decreased PD-1⁺CD8⁺, PD-L1⁺CD8⁺, and PD-L1⁺CD68⁺ subpopulations. All patients cleared detectable HPV DNA in cervical biopsies by completion of chemoradiation and vaccination.

CONCLUSIONS

Adjuvant MEDI0457 is safe and well tolerated after chemoradiation for locally advanced or recurrent cervical cancers, supporting further investigation into combining tumor-specific vaccines with radiation therapy.

Innovations in HIV-1 Vaccine Design

PURPOSE

The field of HIV-1 vaccinology has evolved during the last 30 years from the first viral vector HIV gene insert constructs to vaccination regimens using a myriad of strategies. These strategies now include germline-targeting, lineage-based, and structure-guided immunogen design. This narrative review outlines the historical context of HIV vaccinology and subsequently highlights the scientific discoveries during the last 6 years that promise to propel the field forward.

METHODS

We conducted a search of 2 electronic databases, PubMed and EMBASE, for experimental studies that involved new HIV immunogen designs between 2013 and 2019. During the title and abstract reviews, publications were excluded if they were written in language other than English and/or were a letter to the editor, a commentary, or a conference-only presentation. We then used ClinicalTrials.gov to identify completed and ongoing clinical trials using these strategies.

FINDINGS

The HIV vaccinology field has undergone periods of significant growth during the last 3 decades. Findings elucidated in preclinical studies have revealed the importance of the interaction between the cellular and humoral immune system. As a result, several new rationally designed vaccine strategies have been developed and explored in the last 6 years, including native-like envelope trimers, nanoparticle, and mRNA vaccine design strategies among others. Several of these strategies have shown enough promise in animal models to progress toward first-in-human Phase I clinical trials.

IMPLICATIONS

Rapid developments in preclinical and early-phase clinical studies suggest that a tolerable and effective HIV vaccine may be on the horizon.

Impact of Th1 CD4 Follicular Helper T Cell Skewing on Antibody Responses to an HIV-1 Vaccine in Rhesus Macaques

Generating durable humoral immunity through vaccination depends upon effective interactions of follicular helper T (Tfh) cells with germinal center (GC) B cells. Th1 polarization of Tfh cells is an important process shaping the success of Tfh-GC B cell interactions by influencing costimulatory and cytokine-dependent Tfh help to B cells. However, the question remains as to whether adjuvant-dependent modulation of Tfh cells enhances HIV-1 vaccine-induced antienvelope (anti-Env) antibody responses. We investigated whether an HIV-1 vaccine platform designed to increase the number of Th1-polarized Tfh cells enhances the magnitude and quality of anti-Env antibodies. Utilizing a novel interferon-induced protein 10 (IP-10)-adjuvanted HIV-1 DNA prime followed by a monophosphoryl lipid A and QS-21 (MPLA+QS-21)-adjuvanted Env protein boost (DIP-10 PALFQ) in macaques, we observed higher anti-Env serum IgG titers with greater cross-clade reactivity, specificity for V1V2, and effector functions than in macaques primed with DNA lacking IP-10 and boosted with MPLA-plus-alum-adjuvanted Env protein (DPALFA) The DIP-10 PALFQ vaccine regimen elicited higher anti-Env IgG1 and lower IgG4 antibody levels in serum, showing for the first time that adjuvants can dramatically impact the IgG subclass profile in macaques. The DIP-10 PALFQ regimen also increased vaginal and rectal IgA antibodies to a greater extent. Within lymph nodes, we observed augmented GC B cell responses and the promotion of Th1 gene expression profiles in GC Tfh cells. The frequency of GC Tfh cells correlated with both the magnitude and avidity of anti-Env serum IgG. Together, these data suggest that adjuvant-induced stimulation of Th1-Tfh cells is an effective strategy for enhancing the magnitude and quality of anti-Env antibody responses.IMPORTANCE The results of the RV144 trial demonstrated that vaccination could prevent HIV transmission in humans and that longevity of anti-Env antibodies may be key to this protection. Efforts to improve upon the prime-boost vaccine regimen used in RV144 have indicated that booster immunizations can increase serum anti-Env antibody titers but only transiently. Poor antibody durability hampers efforts to develop an effective HIV-1 vaccine. This study was designed to identify the specific elements involved in the immunological mechanism necessary to produce robust HIV-1-specific antibodies in rhesus macaques. By clearly defining immune-mediated pathways that improve the magnitude and functionality of the anti-HIV-1 antibody response, we will have the foundation necessary for the rational development of an HIV-1 vaccine.

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.

Learning to learn from data: Using deep adversarial learning to construct optimal statistical procedures

Traditionally, statistical procedures have been derived via analytic calculations whose validity often relies on sample size growing to infinity. We use tools from deep learning to develop a new approach, adversarial Monte Carlo meta-learning, for constructing optimal statistical procedures. Statistical problems are framed as two-player games in which Nature adversarially selects a distribution that makes it difficult for a statistician to answer the scientific question using data drawn from this distribution. The players' strategies are parameterized via neural networks, and optimal play is learned by modifying the network weights over many repetitions of the game. Given sufficient computing time, the statistician's strategy is (nearly) optimal at the finite observed sample size, rather than in the hypothetical scenario where sample size grows to infinity. In numerical experiments and data examples, this approach performs favorably compared to standard practice in point estimation, individual-level predictions, and interval estimation.

Immune Therapy Targeting E6/E7 Oncogenes of Human Paillomavirus Type 6 (HPV-6) Reduces or Eliminates the Need for Surgical Intervention in the Treatment of HPV-6 Associated Recurrent Respiratory Papillomatosis

: Background: Recurrent respiratory papillomatosis (RRP) is a rare disorder characterized by the generation of papillomas of the aerodigestive tract, usually associated with human papilloma virus (HPV) subtypes 6, 11. INO-3106 is a DNA plasmid-based immunotherapy targeting E6 and E7 proteins of HPV6, in order to create a robust immune T cell response.

METHODS

Testing of INO-3016 in animal models confirmed immunogenicity of the DNA-based therapy. A single-site open-label Phase 1 study was initiated for patients with HPV6-positive RRP. Patients were dosed with INO-3106 with or without INO-9012, a DNA plasmid immunotherapy that encodes IL-12, delivered intramuscularly (IM) in combination with electroporation (EP) with the CELLECTRA^® device. Patients received an escalating dose of INO-3106, 3 mg once and then 6 mg for three additional doses, each dose three weeks apart, with the third and fourth doses co-administered with INO-9012. The primary objective of the study was to evaluate the safety and tolerability of INO-3106 with and without INO-9012. The secondary objective was to determine cellular immune responses to INO-3106 with and without INO-9012. Exploratory objectives included preliminary clinical efficacy to the therapy.

RESULTS

Three patients were enrolled in this study, of which two had RRP. Study therapy was well-tolerated, with no related serious adverse events and all related adverse events (AEs) were low-grade. Injection site pain was the most common related AE reported. Immunogenicity was evidenced by multiple immune assays showing engagement and expansion of an HPV6-specific cellular response, including cytotoxic T cells. Preliminary efficacy was demonstrated in patients with RRP in the form of reduction in need for surgical intervention for papilloma growth. Prior to intervention, both patients required surgical intervention approximately every 180 days. One patient demonstrated a greater than three-fold increase in surgery avoidance (584 days) and the other patient remains completely surgery-free as of the last contact at 915 days, a greater than 5-fold increase in surgery interval.

CONCLUSION

INO-3106 with and without INO-9012 was well tolerated, immunogenic and demonstrated preliminary efficacy in patients with HPV6-associated RRP aerodigestive lesions. Further clinical study is indicated.

Synthetic DNA Vaccines Adjuvanted with pIL-33 Drive Liver-Localized T Cells and Provide Protection from Plasmodium Challenge in a Mouse Model

The need for a malaria vaccine is indisputable. A single vaccine for Plasmodium pre-erythrocytic stages targeting the major sporozoite antigen circumsporozoite protein (CSP) has had partial success. Additionally, CD8+ T cells targeting liver-stage (LS) antigens induced by live attenuated sporozoite vaccines were associated with protection in human challenge experiments. To further evaluate protection mediated by LS antigens, we focused on exported pre-erythrocytic proteins (exported protein 1 (EXP1), profilin (PFN), exported protein 2 (EXP2), inhibitor of cysteine proteases (ICP), transmembrane protein 21 (TMP21), and upregulated in infective sporozoites-3 (UIS3)) expressed in all Plasmodium species and designed optimized, synthetic DNA (synDNA) immunogens. SynDNA antigen cocktails were tested with and without the molecular adjuvant plasmid IL-33. Immunized animals developed robust T cell responses including induction of antigen-specific liver-localized CD8+ T cells, which were enhanced by the co-delivery of plasmid IL-33. In total, 100% of mice in adjuvanted groups and 71%–88% in non-adjuvanted groups were protected from blood-stage disease following Plasmodium yoelii sporozoite challenge. This study supports the potential of synDNA LS antigens as vaccine components for malaria parasite infection.

Analyzing cellular immunogenicity in vaccine clinical trials: a new statistical method including non-specific responses for accurate estimation of vaccine effect

Evaluation of immunogenicity is a key step in the clinical development of novel vaccines. T-cell responses to vaccine candidates are typically assessed by intracellular cytokine staining (ICS) using multiparametric flow cytometry. A conventional statistical approach to analyze ICS data is to compare, between vaccine regimens or between baseline and post-vaccination of the same regimen depending on the trial design, the percentages of cells producing a cytokine of interest after ex vivo stimulation of peripheral blood mononuclear cells (PBMC) with vaccine antigens, after subtracting the non-specific response (of unstimulated cells) of each sample. Subtraction of the non-specific response is aimed at capturing the specific response to the antigen, but raises methodological issues related to measurement error and statistical power. We describe here a new statistical approach to analyze ICS data from vaccine trials. We propose a bivariate linear regression model for estimating the non-specific and antigen-specific ICS responses. We benchmarked the performance of the model in terms of both bias and control of type-I and -II errors in comparison with conventional approaches, and applied it to simulated data as well as real pre- and post-vaccination data from two recent HIV vaccine trials (ANRS VRI01 in healthy volunteers and therapeutic VRI02 ANRS 149 LIGHT in HIV-infected participants). The model was as good as the conventional approaches (with or without subtraction of the non-specific response) in all simulation scenarios in terms of statistical performance, whereas the conventional approaches did not provide robust results across all scenarios. The proposed model estimated the T-cell responses to the antigens without any effect of the non-specific response on the specific response, irrespective of the correlation between the non-specific and specific responses. This novel method of analyzing T-cell immunogenicity data based on bivariate modeling is more flexible than conventional methods, and so yields more detailed results and enables accurate interpretation of vaccine-induced response.

The Genetic Adjuvants Interleukin-12 and Granulocyte-Macrophage Colony Stimulating Factor Enhance the Immunogenicity of an Ebola Virus Deoxyribonucleic Acid Vaccine in Mice

In previous studies, we showed that deoxyribonucleic acid (DNA) vaccines expressing codon-optimized filovirus envelope glycoprotein genes protect mice and nonhuman primates from viral challenge when delivered by intramuscular (IM) electroporation (EP). To determine whether we could achieve equivalent immunogenicity and protective efficacy by a simplified delivery method, we generated DNA vaccine plasmids expressing genetic adjuvants to potentiate immune responses. We tested the Th1-inducing cytokine interleukin-12 and the granulocyte growth factor granulocyte-macrophage colony stimulating factor, both of which have demonstrated significant adjuvant effect when included in clinical DNA vaccine formulations. In addition, because interferon (IFN)-αβ is required for DNA vaccine-induced immunity, we tested inclusion of a potent stimulator of the IFN-αβ pathway. Our data suggest that IM vaccination of mice with plasmid DNA encoding genetic adjuvants enhances vaccine immunogenicity, resulting in increased anti-Ebola virus (EBOV) immunoglobulin G and T-cell responses. Codelivery of genetic adjuvants also improved EBOV neutralizing capability compared with vaccine alone. Finally, IM vaccination with plasmid EBOV and genetic adjuvants provided complete protection against EBOV challenge. Overall, our data suggest that codelivery of genetic adjuvants with filovirus DNA vaccines using IM delivery can provide comparable efficacy to the same DNA vaccines when delivered using IM-EP devices.

Development of a SFTSV DNA vaccine that confers complete protection against lethal infection in ferrets

Although the incidence of severe fever with thrombocytopenia syndrome virus (SFTSV) infection has increased from its discovery with a mortality rate of 10-20%, no effective vaccines are currently available. Here we describe the development of a SFTSV DNA vaccine, its immunogenicity, and its protective efficacy. Vaccine candidates induce both a neutralizing antibody response and multifunctional SFTSV-specific T cell response in mice and ferrets. When the vaccine efficacy is investigated in aged-ferrets that recapitulate fatal clinical symptoms, vaccinated ferrets are completely protected from lethal SFTSV challenge without developing any clinical signs. A serum transfer study reveals that anti-envelope antibodies play an important role in protective immunity. Our results suggest that Gn/Gc may be the most effective antigens for inducing protective immunity and non-envelope-specific T cell responses also can contribute to protection against SFTSV infection. This study provides important insights into the development of an effective vaccine, as well as corresponding immune parameters, to control SFTSV infection.

Immunogenicity of RNA Replicons Encoding HIV Env Immunogens Designed for Self-Assembly into Nanoparticles

RNA replicons are a promising platform technology for vaccines. To evaluate the potential of lipid nanoparticle-formulated replicons for delivery of HIV immunogens, we designed and tested an alphavirus replicon expressing a self-assembling protein nanoparticle immunogen, the glycoprotein 120 (gp120) germline-targeting engineered outer domain (eOD-GT8) 60-mer. The eOD-GT8 immunogen is a germline-targeting antigen designed to prime human B cells capable of evolving toward VRC01-class broadly neutralizing antibodies. Replicon RNA was encapsulated with high efficiency in 1,2-dioleoyl-3-trimethylammonium-propane (DOTAP)-based lipid nanoparticles, which provided effective delivery in the muscle and expression of luciferase lasting ∼30 days in normal mice, contrasting with very brief and low levels of expression obtained by delivery of equivalent modified mRNA (modRNA). eOD-GT8 60-mer-encoding replicons elicited high titers of gp120-specific antibodies following a single injection in mice, and increased levels of antigen-specific germinal center B cells compared with protein immunization. Immunization of transgenic mice expressing human inferred-germline VRC01 heavy chain B cell receptors that are the targets of the eOD antigen led to priming of B cells and somatic hypermutation consistent with VRC01-class antibody development. Altogether, these data suggest replicon delivery of Env immunogens may be a promising avenue for HIV vaccine development.

Enhanced immunogenicity and protective efficacy of a tetravalent dengue DNA vaccine using electroporation and intradermal delivery

Phase 1 clinical trials with a DNA vaccine for dengue demonstrated that the vaccine is safe and well tolerated, however it produced less than optimal humoral immune responses. To determine if the immunogenicity of the tetravalent dengue DNA vaccine could be enhanced, we explored alternate, yet to be tested, methods of vaccine administration in non-human primates. Animals were vaccinated on days 0, 28 and 91 with either a low (1 mg) or high (5 mg) dose of vaccine by the intradermal or intramuscular route, using either needle-free injection or electroporation devices. Neutralizing antibody, IFN-γ T cell and memory B cell responses were compared to a high dose group vaccinated with a needle-free intramuscular injection delivery device similar to what had been used in previous preclinical and clinical studies. All previously untested vaccination methodologies elicited improved immune responses compared to the high dose needle-free intramuscular injection delivery group. The highest neutralizing antibody responses were observed in the group that was vaccinated with the high dose formulation via intradermal electroporation. The highest IFN-γ T cell responses were also observed in the high dose intradermal electroporation group and the CD8⁺ T cells were the dominant contributors for the IFNγ response. Memory B cells were detected for all four serotypes. More than a year after vaccination, groups were challenged with dengue-1 virus. Both the low and high dose intradermal electroporation groups had significantly fewer days of dengue-1 virus RNAemia compared to the control group. The results from this study demonstrate that using either an electroporation device and/or the intradermal route of delivery increases the immune response generated by this vaccine in non-human primates and should be explored in humans.

Designed DNA-Encoded IL-36 Gamma Acts as a Potent Molecular Adjuvant Enhancing Zika Synthetic DNA Vaccine-Induced Immunity and Protection in a Lethal Challenge Model

Identification of novel molecular adjuvants which can boost and enhance vaccine-mediated immunity and provide dose-sparing potential against complex infectious diseases and for immunotherapy in cancer is likely to play a critical role in the next generation of vaccines. Given the number of challenging targets for which no or only partial vaccine options exist, adjuvants that can address some of these concerns are in high demand. Here, we report that a designed truncated Interleukin-36 gamma (IL-36 gamma) encoded plasmid can act as a potent adjuvant for several DNA-encoded vaccine targets including human immunodeficiency virus (HIV), influenza, and Zika in immunization models. We further show that the truncated IL-36 gamma (opt-36γt) plasmid provides improved dose sparing as it boosts immunity to a suboptimal dose of a Zika DNA vaccine, resulting in potent protection against a lethal Zika challenge.