A Phase I Double Blind, Placebo-Controlled, Randomized Study of the Safety and Immunogenicity of Electroporated HIV DNA with or without Interleukin 12 in Prime-Boost Combinations with an Ad35 HIV Vaccine in Healthy HIV-Seronegative African Adults

Improved efficacy of therapeutic HPV DNA vaccine using intramuscular injection with electroporation compared to conventional needle and needle-free jet injector methods

BACKGROUND

We have previously developed a candidate therapeutic HPV DNA vaccine (pBI-11) encoding mycobacteria heat shock protein 70 linked to HPV16/18 E6/E7 proteins for the control of advanced HPV-associated oropharyngeal cancer (NCT05799144). While naked DNA vaccines are readily produced, stable, and well tolerated, their potency is limited by the delivery efficiency. Here we compared three different IM delivery strategies, including intramuscular (IM) injection, either with a needle alone or with electroporation at the injection site, and a needle-free injection system (NFIS), for their ability to elicit gene expression and to improve the potency of pBI-11 DNA vaccine.

RESULTS

We found that electroporation after IM injection significantly increases gene expression from a luciferase-encoding DNA construct compared to IM injection alone or NFIS. We also showed that single administration of pBI-11 DNA via electroporation-mediated delivery generates the greatest increase in HPV antigen-specific CD8 + T cell-mediated immune responses, resulting in the most potent antitumor effect compared to the other two methods. We further compared the response to three repeat immunizations via each of these different methods. We found that electroporation-mediated delivery of pBI-11 DNA generates the greatest HPV antigen-specific CD8 + T cell immune responses and therapeutic antitumor effects compared to the other two methods. Monitoring of mouse behaviors and body weight, and necropsy indicated that electroporation-mediated delivery of clinical grade pBI-11 DNA vaccine was well-tolerated and presented no evident local or systemic toxicity.

CONCLUSIONS

These findings provide rationale for clinical testing of pBI-11 DNA vaccine delivered by electroporation for the control of HPV16/18-associated infections and/or cancers.

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.

Adenovirus DNA Polymerase Loses Fidelity on a Stretch of Eleven Homocytidines during Pre-GMP Vaccine Preparation

In this study, we invented and construct novel candidate HIV-1 vaccines. Through genetic and protein engineering, we unknowingly constructed an HIV-1-derived transgene with a homopolymeric run of 11 cytidines, which was inserted into an adenovirus vaccine vector. Here, we describe the virus rescue, three rounds of clonal purification and preparation of good manufacturing practise (GMP) starting material assessed for genetic stability in five additional virus passages. Throughout these steps, quality control assays indicated the presence of the transgene in the virus genome, expression of the correct transgene product and immunogenicity in mice. However, DNA sequencing of the transgene revealed additional cytidines inserted into the original 11-cytidine region, and the GMP manufacture had to be aborted. Subsequent analyses indicated that as little as 1/25th of the virus dose used for confirmation of protein expression (10⁶ cells at a multiplicity of infection of 10) and murine immunogenicity (10⁸ infectious units per animal) met the quality acceptance criteria. Similar frameshifts in the expressed proteins were reproduced in a one-reaction in vitro transcription/translation employing phage T7 polymerase and E. coli ribosomes. Thus, the most likely mechanism for addition of extra cytidines into the ChAdOx1.tHIVconsv6 genome is that the adenovirus DNA polymerase lost its fidelity on a stretch of 11 cytidines, which informs future adenovirus vaccine designs.

Performance of International AIDS Vaccine Initiative African clinical research laboratories in standardised ELISpot and peripheral blood mononuclear cell processing in support of HIV vaccine clinical trials

Background

Standardisation of procedures for performing cellular functional assays across laboratories participating in multicentre clinical trials is key for generating comparable and reliable data.

Objective

This article describes the performance of accredited laboratories in Africa and Europe on testing done in support of clinical trials.

Methods

For enzyme-linked immunospot assay (ELISpot) proficiency, characterised peripheral blood mononuclear cells (PBMCs) obtained from 48 HIV-negative blood donors in Johannesburg, South Africa, were sent to participating laboratories between February 2010 and February 2014. The PBMCs were tested for responses against cytomegalovirus, Epstein Barr and influenza peptide pools in a total of 1751 assays. In a separate study, a total of 1297 PBMC samples isolated from healthy HIV-negative participants in clinical trials of two prophylactic HIV vaccine candidates in Kenya, Uganda, Rwanda and Zambia were analysed for cell viability, cell yield and cell recovery from frozen PBMCs.

Results

Most (99%) of the 1751 ELISpot proficiency assays had data within acceptable ranges with low responses to mock stimuli. No significant statistical difference were observed in ELISpot responses at the five laboratories actively conducting immunological analyses. Of the 1297 clinical trial PBMCs processed, 94% had cell viability above 90% and 96% had cell yield above 0.7 million per mL of blood in freshly isolated cells. All parameters were within the predefined acceptance criteria.

Conclusion

We demonstrate that multiple laboratories can generate reliable, accurate and comparable data by using standardised procedures, having regular training, having regular equipment maintenance and using centrally sourced reagents.

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.

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

Specificity of CD8+ T-Cell Responses Following Vaccination with Conserved Regions of HIV-1 in Nairobi, Kenya

Sub-Saharan Africa carries the biggest burden of the human immunodeficiency virus type 1 (HIV-1)/AIDS epidemic and is in an urgent need of an effective vaccine. CD8+ T cells are an important component of the host immune response to HIV-1 and may need to be harnessed if a vaccine is to be effective. CD8+ T cells recognize human leukocyte antigen (HLA)-associated viral epitopes and the HLA alleles vary significantly among different ethnic groups. It follows that definition of HIV-1-derived peptides recognized by CD8+ T cells in the geographically relevant regions will critically guide vaccine development. Here, we study fine details of CD8+ T-cell responses elicited in HIV-1/2-uninfected individuals in Nairobi, Kenya, who received a candidate vaccine delivering conserved regions of HIV-1 proteins called HIVconsv. Using 10-day cell lines established by in vitro peptide restimulation of cryopreserved PBMC and stably HLA-transfected 721.221/C1R cell lines, we confirm experimentally many already defined epitopes, for a number of epitopes we define the restricting HLA molecule(s) and describe four novel HLA-epitope pairs. We also identify specific dominance patterns, a promiscuous T-cell epitope and a rescue of suboptimal T-cell epitope induction in vivo by its functional variant, which all together inform vaccine design.

Innate signalling molecules as genetic adjuvants do not alter the efficacy of a DNA-based influenza A vaccine

In respect to the heterogeneity among influenza A virus strains and the shortcomings of current vaccination programs, there is a huge interest in the development of alternative vaccines that provide a broader and more long-lasting protection. Gene-based approaches are considered as promising candidates for such flu vaccines. In our study, innate signalling molecules from the RIG-I and the NALP3 pathways were evaluated as genetic adjuvants in intramuscular DNA immunizations. Plasmids encoding a constitutive active form of RIG-I (cRIG-I), IPS-1, IL-1β, or IL-18 were co-administered with plasmids encoding the hemagglutinin and nucleoprotein derived from H1N1/Puerto Rico/8/1934 via electroporation in BALB/c mice. Immunogenicity was analysed in detail and efficacy was demonstrated in homologous and heterologous influenza challenge experiments. Although the biological activities of the adjuvants have been confirmed by in vitro reporter assays, their single or combined inclusion in the vaccine did not result in superior vaccine efficacy. With the exception of significantly increased levels of antigen-specific IgG1 after the co-administration of IL-1β, there were only minor alterations concerning the immunogenicity. Since DNA electroporation alone induced substantial inflammation at the injection site, as demonstrated in this study using Mx2-Luc reporter mice, it might override the adjuvants´ contribution to the inflammatory microenvironment and thereby minimizes the influence on the immunogenicity. Taken together, the DNA immunization was protective against subsequent challenge infections but could not be further improved by the genetic adjuvants analysed in this study.

Aiming for protective T-cell responses: a focus on the first generation conserved-region HIVconsv vaccines in preventive and therapeutic clinical trials

Introduction: Despite life-saving antiretroviral drugs, an effective HIV-1 vaccine is the best solution and likely a necessary component of any strategy for halting the AIDS epidemic. The currently prevailing aim is to pursue antibody-mediated vaccine protection. With ample evidence for the ability of T cells to control HIV-1 replication, their protective potential should be also harnessed by vaccination. The challenge is to elicit not just any, but protective T cells.Areas covered: This article reviews the clinical experience with the first-generation conserved-region immunogen HIVconsv delivered by combinations of plasmid DNA, simian adenovirus, and poxvirus MVA. The aim of our strategy is to induce strong and broad T cells targeting functionally important parts of HIV-1 proteins common to global variants. These vaccines were tested in eight phase 1/2 preventive and therapeutic clinical trials in Europe and Africa, and induced high frequencies of broadly specific CD8⁺ T cells capable of in vitro inhibition of four major HIV-1 clades A, B, C and D, and in combination with latency-reactivating agent provided a signal of drug-free virological control in early treated patients.Expert opinion: A number of critical T-cell traits have to come together at the same time to achieve control over HIV-1.

Safety and tolerability of HIV-1 multiantigen pDNA vaccine given with IL-12 plasmid DNA via electroporation, boosted with a recombinant vesicular stomatitis virus HIV Gag vaccine in healthy volunteers in a randomized, controlled clinical trial

BACKGROUND

The addition of plasmid cytokine adjuvants, electroporation, and live attenuated viral vectors may further optimize immune responses to DNA vaccines in heterologous prime-boost combinations. The objective of this study was to test the safety and tolerability of a novel prime-boost vaccine regimen incorporating these strategies with different doses of IL-12 plasmid DNA adjuvant.

METHODS

In a phase 1 study, 88 participants received an HIV-1 multiantigen (gag/pol, env, nef/tat/vif) DNA vaccine (HIV-MAG, 3000 μg) co-administered with IL-12 plasmid DNA adjuvant at 0, 250, 1000, or 1500 μg (N = 22/group) given intramuscularly with electroporation (Ichor TriGrid™ Delivery System device) at 0, 1 and 3 months; followed by attenuated recombinant vesicular stomatitis virus, serotype Indiana, expressing HIV-1 Gag (VSV-Gag), 3.4 ⊆ 107 plaque-forming units (PFU), at 6 months; 12 others received placebo. Injections were in both deltoids at each timepoint. Participants were monitored for safety and tolerability for 15 months.

RESULTS

The dose of IL-12 pDNA did not increase pain scores, reactogenicity, or adverse events with the co-administered DNA vaccine, or following the VSV-Gag boost. Injection site pain and reactogenicity were common with intramuscular injections with electroporation, but acceptable to most participants. VSV-Gag vaccine often caused systemic reactogenicity symptoms, including a viral syndrome (in 41%) of fever, chills, malaise/fatigue, myalgia, and headache; and decreased lymphocyte counts 1 day after vaccination.

CONCLUSIONS

HIV-MAG DNA vaccine given by intramuscular injection with electroporation was safe at all doses of IL-12 pDNA. The VSV-Gag vaccine at this dose was associated with fever and viral symptoms in some participants, but the vaccine regimens were safe and generally well-tolerated.

TRIAL REGISTRATION

Clinical Trials.gov NCT01578889.

Long-term follow-up of HIV-1-infected adults who received the F4/AS01B HIV-1 vaccine candidate in two randomised controlled trials

This Phase I/II, open, long-term follow-up study was conducted in antiretroviral therapy (ART)-naïve (N = 212) and ART-treated (N = 19) human immunodeficiency virus 1 (HIV-1)-infected adults, who received an HIV-1 investigational vaccine (F4/AS01_B) or placebo in two previous studies (NCT00814762 and NCT01218113). After a minimum of two years and a maximum of four years of follow-up post-vaccination per patient, no significant differences were observed between F4/AS01_B and placebo groups in terms of viral load, CD4⁺ T-cell count and incidence of specific clinical events. Vaccine-induced polyfunctional CD4⁺ T-cells persisted up to study end and no relevant vaccine-related safety events were reported in F4/AS01_B groups. This study has been registered at ClinicalTrials.gov (NCT01092611).

Novel viral vectors in infectious diseases

Since the development of vaccinia virus as a vaccine vector in 1984, the utility of numerous viruses in vaccination strategies has been explored. In recent years, key improvements to existing vectors such as those based on adenovirus have led to significant improvements in immunogenicity and efficacy. Furthermore, exciting new vectors that exploit viruses such as cytomegalovirus (CMV) and vesicular stomatitis virus (VSV) have emerged. Herein, we summarize these recent developments in viral vector technologies, focusing on novel vectors based on CMV, VSV, measles and modified adenovirus. We discuss the potential utility of these exciting approaches in eliciting protection against infectious diseases.

In vivo electroporation enhances vaccine-mediated therapeutic control of human papilloma virus-associated tumors by the activation of multifunctional and effector memory CD8+ T cells

In vivo electroporation (EP) has reignited the clinical interest on DNA vaccines as immunotherapeutic approaches to control different types of cancer. EP has been associated with increased immune response potency, but its capacity in influencing immunomodulation remains unclear. Here we evaluated the impact of in vivo EP on the induction of cellular immune responses and therapeutic effects of a DNA vaccine targeting human papillomavirus-induced tumors. Our results demonstrate that association of EP with the conventional intramuscular administration route promoted a more efficient activation of multifunctional and effector memory CD8⁺ T cells with enhanced cytotoxic activity. Furthermore, EP increased tumor infiltration of CD8⁺ T cells and avoided tumor recurrences. Finally, our results demonstrated that EP promotes local migration of antigen presenting cells that enhances with vaccine co-delivery. Altogether the present evidences shed further light on the in vivo electroporation action and its impact on the immunogenicity of DNA vaccines.

Workshop report: Nucleic acid delivery devices for HIV vaccines: Workshop proceedings, National Institute of Allergy and Infectious Diseases, Bethesda, Maryland, USA, May 21, 2015

On May 21st, 2015, the U.S. National Institute of Allergy and Infectious Diseases (NIAID) convened a workshop on delivery devices for nucleic acid (NA) as vaccines in order to review the landscape of past and future technologies for administering NA (e.g., DNA, RNA, etc.) as antigen into target tissues of animal models and humans. Its focus was on current and future applications for preventing and treating human immunodeficiency virus (HIV) infection and acquired immune deficiency syndrome (AIDS) disease, among other infectious-disease priorities. Meeting participants presented the results and experience of representative clinical trials of NA vaccines using a variety of alternative delivery devices, as well as a broader group of methods studied in animal models and at bench top, to improve upon the performance and/or avoid the drawbacks of conventional needle-syringe (N-S) delivery. The subjects described and discussed included (1) delivery targeted into oral, cutaneous/intradermal, nasal, upper and lower respiratory, and intramuscular tissues; (2) devices and techniques for jet injection, solid, hollow, and dissolving microneedles, patches for topical passive diffusion or iontophoresis, electroporation, thermal microporation, nasal sprayers, aerosol upper-respiratory and pulmonary inhalation, stratum-corneum ablation by ultrasound, chemicals, and mechanical abrasion, and kinetic/ballistic delivery; (3) antigens, adjuvants, and carriers such as DNA, messenger RNA, synthesized plasmids, chemokines, wet and dry aerosols, and pollen-grain and microparticle vectors; and (4) the clinical experience and humoral, cellular, and cytokine immune responses observed for many of these target tissues, technologies, constructs, and carriers. This report summarizes the presentations and discussions from the workshop (https://web.archive.org/web/20160228112310/https://www.blsmeetings.net/NucleicAcidDeliveryDevices/), which was webcast live in its entirety and archived online (http://videocast.nih.gov/summary.asp?live=16059).

DNA Priming Increases Frequency of T-Cell Responses to a Vesicular Stomatitis Virus HIV Vaccine with Specific Enhancement of CD8+ T-Cell Responses by Interleukin-12 Plasmid DNA

The HIV Vaccine Trials Network (HVTN) 087 vaccine trial assessed the effect of increasing doses of pIL-12 (interleukin-12 delivered as plasmid DNA) adjuvant on the immunogenicity of an HIV-1 multiantigen (MAG) DNA vaccine delivered by electroporation and boosted with a vaccine comprising an attenuated vesicular stomatitis virus expressing HIV-1 Gag (VSV-Gag). We randomized 100 healthy adults to receive placebo or 3 mg HIV-MAG DNA vaccine (ProfectusVax HIV-1 gag/pol or ProfectusVax nef/tat/vif, env) coadministered with pIL-12 at 0, 250, 1,000, or 1,500 μg intramuscularly by electroporation at 0, 1, and 3 months followed by intramuscular inoculation with 3.4 × 10⁷ PFU VSV-Gag vaccine at 6 months. Immune responses were assessed after the prime and boost and 6 months after the last vaccination. High-dose pIL-12 increased the magnitude of CD8⁺ T-cell responses postboost compared to no pIL-12 (P = 0.02), while CD4⁺ T-cell responses after the prime were higher in the absence of pIL-12 than with low- and medium-dose pIL-12 (P ≤ 0.05). The VSV boost increased Gag-specific CD4⁺ and CD8⁺ T-cell responses in all groups (P < 0.001 for CD4⁺ T cells), inducing a median of four Gag epitopes in responders. Six to 9 months after the boost, responses decreased in magnitude, but CD8⁺ T-cell response rates were maintained. The addition of a DNA prime dramatically improved responses to the VSV vaccine tested previously in the HVTN 090 trial, leading to broad epitope targeting and maintained CD8⁺ T-cell response rates at early memory. The addition of high-dose pIL-12 given with a DNA prime by electroporation and boosted with VSV-Gag increased the CD8⁺ T-cell responses but decreased the CD4⁺ responses. This approach may be advantageous in reshaping the T-cell responses to a variety of chronic infections or tumors. (This study has been registered at ClinicalTrials.gov under registration no. NCT01578889.).

Melanoma treatment with intratumoral electroporation of tavokinogene telseplasmid (pIL-12, tavokinogene telseplasmid)

Tumors evade detection and/or clearance by the immune system via multiple mechanisms. IL-12 is a potent immunomodulatory cytokine that plays a central role in immune priming. However, systemic delivery of IL-12 can result in life-threatening toxicity and therefore has shown limited efficacy at doses that can be safely administered. We developed an electroporation technique to produce highly localized IL-12 expression within tumors leading to regression of both treated and untreated lesions in animal models and in patients with a favorable safety profile. Furthermore, intratumoral tavokinogene telseplasmid electroporation can drive cellular immune responses, converting 'cold' tumors into 'hot' tumors. Clinical trials are ongoing to determine whether intratumoral tavokinogene telseplasmid electroporation synergizes with checkpoint blockade therapy in immunologically cold tumors predicted not to respond to PD-1 antibody monotherapy.

Combined skin and muscle vaccination differentially impact the quality of effector T cell functions: the CUTHIVAC-001 randomized trial

Targeting of different tissues via transcutaneous (TC), intradermal (ID) and intramuscular (IM) injection has the potential to tailor the immune response to DNA vaccination. In this Phase I randomised controlled clinical trial in HIV-1 negative volunteers we investigate whether the site and mode of DNA vaccination influences the quality of the cellular immune responses. We adopted a strategy of concurrent immunization combining IM injection with either ID or TC administration. As a third arm we assessed the response to IM injection administered with electroporation (EP). The DNA plasmid encoded a MultiHIV B clade fusion protein designed to induce cellular immunity. The vaccine and regimens were well tolerated. We observed differential shaping of vaccine induced virus-specific CD4 + and CD8 + cell-mediated immune responses. DNA given by IM + EP promoted strong IFN-γ responses and potent viral inhibition. ID + IM without EP resulted in a similar pattern of response but of lower magnitude. By contrast TC + IM (without EP) shifted responses towards a more Th-17 dominated phenotype, associated with mucosal and epidermal protection. Whilst preliminary, these results offer new perspectives for differential shaping of desired cellular immunity required to fight the wide range of complex and diverse infectious diseases and cancers.

Factors Associated with the Size of HIV DNA Reservoir

OBJECTIVE

To review the recent literatures related to the factors associated with the size of the HIV reservoir and their clinical significance.

DATA SOURCES

Literatures related to the size of HIV DNA was collected from PubMed published from 1999 to June 2016.

STUDY SELECTION

All relevant articles on the HIV DNA and reservoir were collected and reviewed, with no limitation of study design.

RESULTS

The composition and development of the HIV-1 DNA reservoir in either treated or untreated patients is determined by integrated mechanism comprising viral characteristics, immune system, and treatment strategies. The HIV DNA reservoir is a combination of latency and activity. The residual viremia from the stochastic activation of the reservoir acts as the fuse, continuing to stimulate the immune system to maintain the activated microenvironment for the rebound of competent virus once treatment with antiretroviral therapy is discontinued.

CONCLUSION

The size of the HIV-1 DNA pool and its composition has great significance in clinical treatment and disease progression.

An Interleukin 12 Adjuvanted Herpes Simplex Virus 2 DNA Vaccine Is More Protective Than a Glycoprotein D Subunit Vaccine in a High-Dose Murine Challenge Model

Vaccination is a proven intervention against human viral diseases; however, success against Herpes Simplex Virus 2 (HSV-2) remains elusive. Most HSV-2 vaccines tested in humans to date contained just one or two immunogens, such as the virion attachment receptor glycoprotein D (gD) and/or the envelope fusion protein, glycoprotein B (gB). At least three factors may have contributed to the failures of subunit-based HSV-2 vaccines. First, immune responses directed against one or two viral antigens may lack sufficient antigenic breadth for efficacy. Second, the antibody responses elicited by these vaccines may have lacked necessary Fc-mediated effector functions. Third, these subunit vaccines may not have generated necessary protective cellular immune responses. We hypothesized that a polyvalent combination of HSV-2 antigens expressed from a DNA vaccine with an adjuvant that polarizes immune responses toward a T helper 1 (Th1) phenotype would compose a more effective vaccine. We demonstrate that delivery of DNA expressing full-length HSV-2 glycoprotein immunogens by electroporation with the adjuvant interleukin 12 (IL-12) generates substantially greater protection against a high-dose HSV-2 vaginal challenge than a recombinant gD subunit vaccine adjuvanted with alum and monophosphoryl lipid A (MPL). Our results further show that DNA vaccines targeting optimal combinations of surface glycoproteins provide better protection than gD alone and provide similar survival benefits and disease symptom reductions compared with a potent live attenuated HSV-2 0ΔNLS vaccine, but that mice vaccinated with HSV-2 0ΔNLS clear the virus much faster. Together, our data indicate that adjuvanted multivalent DNA vaccines hold promise for an effective HSV-2 vaccine, but that further improvements may be required.

First-in-Human Evaluation of the Safety and Immunogenicity of an Intranasally Administered Replication-Competent Sendai Virus-Vectored HIV Type 1 Gag Vaccine: Induction of Potent T-Cell or Antibody Responses in Prime-Boost Regimens

Background. We report the first-in-human safety and immunogenicity assessment of a prototype intranasally administered, replication-competent Sendai virus (SeV)–vectored, human immunodeficiency virus type 1 (HIV-1) vaccine.

Methods. Sixty-five HIV-1–uninfected adults in Kenya, Rwanda, and the United Kingdom were assigned to receive 1 of 4 prime-boost regimens (administered at 0 and 4 months, respectively; ratio of vaccine to placebo recipients, 12:4): priming with a lower-dose SeV-Gag given intranasally, followed by boosting with an adenovirus 35–vectored vaccine encoding HIV-1 Gag, reverse transcriptase, integrase, and Nef (Ad35-GRIN) given intramuscularly (S_LA); priming with a higher-dose SeV-Gag given intranasally, followed by boosting with Ad35-GRIN given intramuscularly (S_HA); priming with Ad35-GRIN given intramuscularly, followed by boosting with a higher-dose SeV-Gag given intranasally (AS_H); and priming and boosting with a higher-dose SeV-Gag given intranasally (S_HS_H).

Results. All vaccine regimens were well tolerated. Gag-specific IFN-γ enzyme-linked immunospot–determined response rates and geometric mean responses were higher (96% and 248 spot-forming units, respectively) in groups primed with SeV-Gag and boosted with Ad35-GRIN (S_LA and S_HA) than those after a single dose of Ad35-GRIN (56% and 54 spot-forming units, respectively) or SeV-Gag (55% and 59 spot-forming units, respectively); responses persisted for ≥8 months after completion of the prime-boost regimen. Functional CD8⁺ T-cell responses with greater breadth, magnitude, and frequency in a viral inhibition assay were also seen in the S_LA and S_HA groups after Ad35-GRIN boost, compared with those who received either vaccine alone. SeV-Gag did not boost T-cell counts in the AS_H group. In contrast, the highest Gag-specific antibody titers were seen in the AS_H group. Mucosal antibody responses were sporadic.

Conclusions. SeV-Gag primed functional, durable HIV-specific T-cell responses and boosted antibody responses. The prime-boost sequence appears to determine which arm of the immune response is stimulated.

Clinical Trials Registration. NCT01705990.

Electroporation enhances protective immune response of a DNA vaccine against Japanese encephalitis in mice and pigs

Japanese encephalitis virus (JEV) is a pathogenic cause of Japanese Encephalitis (JE), which is a zoonotic disease transmitted by mosquitoes and amplified by pigs. Infection of JEV may lead to severe neurological sequelae, even death in humans and reproductive disorders in pigs. Vaccination is the only way to control JEV infection in humans. For pigs play important role in the JEV transmission cycle, developing a new veterinary vaccine is considered as a useful strategy for cutting off the transmission route of JEV. We have previously reported that DNA vaccine pCAG-JME, expressing prM-E proteins of JEV, is effective in mice through intramuscular injection (IM). However, the poor immunogenicity, due to low expression of immunogen, is the major obstacle for the development of DNA vaccine in large animals. In the present study, therefore, we immunized mice and pigs with pCAG-JME intramuscularly accompanied with electroporation (EP) stimulation, the attractive gene delivery approach. As compared with IM, EP-mediated vaccination markedly increased the expression of immunogen in the injection site and induced a dose- and time-dependent immune response. 100% survival rate was observed in groups vaccinated with doses ranged from 10 to 100μg, indicating that 10μg of DNA with EP for individual was enough for inducing effective protection in mice. Surprisingly, survival rate and end-point titers of anti-JEV antibodies were higher in mice even at lower dose of DNA (5μg) than that in mice inoculated 100μg through IM. Notably, the prM-E antigens also induced high antibody response in pig, while the neutralizing antibody titer achieved 1:320. Our results suggested that EP-mediated DNA immunization might act as an effective strategy against JEV, at least in pig, and that EP has a potential application prospect in DNA vaccination.

Retinaldehyde dehydrogenase 2 as a molecular adjuvant for enhancement of mucosal immunity during DNA vaccination

In order for vaccines to induce efficacious immune responses against mucosally transmitted pathogens, such as HIV-1, activated lymphocytes must efficiently migrate to and enter targeted mucosal sites. We have previously shown that all-trans retinoic acid (ATRA) can be used as a vaccine adjuvant to enhance mucosal CD8⁺ T cell responses during vaccination and improve protection against mucosal viral challenge. However, the ATRA formulation is incompatible with most recombinant vaccines, and the teratogenic potential of ATRA at high doses limits its usage in many clinical settings. We hypothesized that increasing in vivo production of retinoic acid (RA) during vaccination with a DNA vector expressing retinaldehyde dehydrogenase 2 (RALDH2), the rate-limiting enzyme in RA biosynthesis, could similarly provide enhanced programming of mucosal homing to T cell responses while avoiding teratogenic effects. Administration of a RALDH2- expressing plasmid during immunization with a HIVgag DNA vaccine resulted in increased systemic and mucosal CD8⁺ T cell numbers with an increase in both effector and central memory T cells. Moreover, mice that received RALDH2 plasmid during DNA vaccination were more resistant to intravaginal challenge with a recombinant vaccinia virus expressing the same HIVgag antigen (VACVgag). Thus, RALDH2 can be used as an alternative adjuvant to ATRA during DNA vaccination leading to an increase in both systemic and mucosal T cell immunity and better protection from viral infection at mucosal sites.

Broad HIV-1 inhibition in vitro by vaccine-elicited CD8(+) T cells in African adults

We are developing a pan-clade HIV-1 T-cell vaccine HIVconsv, which could complement Env vaccines for prophylaxis and be a key to HIV cure. Our strategy focuses vaccine-elicited effector T-cells on functionally and structurally conserved regions (not full-length proteins and not only epitopes) of the HIV-1 proteome, which are common to most global variants and which, if mutated, cause a replicative fitness loss. Our first clinical trial in low risk HIV-1-negative adults in Oxford demonstrated the principle that naturally mostly subdominant epitopes, when taken out of the context of full-length proteins/virus and delivered by potent regimens involving combinations of simian adenovirus and poxvirus modified vaccinia virus Ankara, can induce robust CD8(+) T cells of broad specificities and functions capable of inhibiting in vitro HIV-1 replication. Here and for the first time, we tested this strategy in low risk HIV-1-negative adults in Africa. We showed that the vaccines were well tolerated and induced high frequencies of broadly HIVconsv-specific plurifunctional T cells, which inhibited in vitro viruses from four major clades A, B, C, and D. Because sub-Saharan Africa is globally the region most affected by HIV-1/AIDS, trial HIV-CORE 004 represents an important stage in the path toward efficacy evaluation of this highly rational and promising vaccine strategy.

Adenovirus-based HIV-1 vaccine candidates tested in efficacy trials elicit CD8+ T cells with limited breadth of HIV-1 inhibition

OBJECTIVES

The ability of HIV-1 vaccine candidates MRKAd5, VRC DNA/Ad5 and ALVAC/AIDSVAX to elicit CD8 T cells with direct antiviral function was assessed and compared with HIV-1-infected volunteers.

DESIGN

Adenovirus serotype 5 (Ad5)-based regimens MRKAd5 and VRC DNA/Ad5, designed to elicit HIV-1-specific T cells, are immunogenic but failed to prevent infection or impact on viral loads in volunteers infected subsequently. Failure may be due in part to a lack of CD8 T cells with effective antiviral functions.

METHODS

An in-vitro viral inhibition assay tested the ability of bispecific antibody expanded CD8 T cells from peripheral blood mononuclear cells to inhibit replication of a multiclade panel of HIV-1 isolates in autologous CD4 T cells. HIV-1 proteins recognized by CD8 T cells were assessed by IFNγ enzyme-linked immunospot assay.

RESULTS

Ad5-based regimens elicited CD8 T cells that inhibited replication of HIV-1 IIIB isolate with more limited inhibition of other isolates. IIIB isolate Gag and Pol genes have high sequence identities (>96%) to vector HIV-1 gene inserts, and these were the predominant HIV-1 proteins recognized by CD8 T cells. Virus inhibition breadth was greater in antiretroviral naïve HIV-1-infected volunteers naturally controlling viremia (plasma viral load < 10 000/ml). HIV-1-inhibitory CD8 T cells were not elicited by the ALVAC/AIDSVAX regimen.

CONCLUSION

The Ad5-based regimens, although immunogenic, elicited CD8 T cells with limited HIV-1-inhibition breadth. Effective T-cell-based vaccines should presumably elicit broader HIV-1-inhibition profiles. The viral inhibition assay can be used in vaccine design and to prioritize promising candidates with greater inhibition breadth for further clinical trials.

New developments in an old strategy: heterologous vector primes and envelope protein boosts in HIV vaccine design

Prime/boost vaccination strategies for HIV/SIV vaccine development have been used since the early 1990s and have become an established method for eliciting cell and antibody mediated immunity. Here we focus on induction of protective antibodies, both broadly neutralizing and non-neutralizing, with the viral envelope being the key target antigen. Prime/boost approaches are complicated by the diversity of autologous and heterologous priming vectors, and by various forms of envelope booster immunogens, many still in development as structural studies aim to design stable constructs with exposure of critical epitopes for protective antibody elicitation. This review discusses individual vaccine components, reviews recent prime/boost strategies and their outcomes, and highlights complicating factors arising as greater knowledge concerning induction of adaptive, protective immunity is acquired.

Partial correction of the dwarf phenotype by non-viral transfer of the growth hormone gene in mice: Treatment age is critical

Non-viral transfer of the growth hormone gene to different muscles of immunodeficient dwarf (lit/scid) mice is under study with the objective of improving phenotypic correction via this particular gene therapy approach. Plasmid DNA was administered into the exposed quadriceps or non-exposed tibialis cranialis muscle of lit/scid mice followed by electroporation, monitoring several growth parameters. In a 6-month bioassay, 50μg DNA were injected three times into the quadriceps muscle of 80-day old mice. A 50% weight increase, with a catch-up growth of 21%, together with a 16% increase for nose-to-tail and tail lengths (catch-up=19-21%) and a 24-28% increase for femur length (catch-up=53-60%), were obtained. mIGF1 serum levels were ~7-fold higher than the basal levels for untreated mice, but still ~2-fold lower than in non-dwarf scid mice. Since treatment age was found to be particularly important in a second bioassay utilizing 40-day old mice, these pubertal mice were compared in a third bioassay with adult (80-day old) mice, all treated twice with 50μg DNA injected into each tibialis cranialis muscle, via a less invasive approach. mIGF1 concentrations at the same level as co-aged scid mice were obtained 15days after administration in pubertal mice. Catch-up growth, based on femur length (77%), nose-to-tail (36%) and tail length (39%) increases was 40 to 95% higher than those obtained upon treating adult mice. These data pave the way for the development of more effective pre-clinical assays in pubertal dwarf mice for the treatment of GH deficiency via plasmid-DNA muscular administration.

Can follicular helper T cells be targeted to improve vaccine efficacy?

The success of most vaccines relies on the generation of antibodies to provide protection against subsequent infection; this in turn depends on a robust germinal centre (GC) response that culminates in the production of long-lived antibody-secreting plasma cells. The size and quality of the GC response are directed by a specialised subset of CD4 ⁺ T cells: T follicular helper (Tfh) cells. Tfh cells provide growth and differentiation signals to GC B cells and mediate positive selection of high-affinity B cell clones in the GC, thereby determining which B cells exit the GC as plasma cells and memory B cells. Because of their central role in the production of long-lasting humoral immunity, Tfh cells represent an interesting target for rational vaccine design.

Clinical potential of electroporation for gene therapy and DNA vaccine delivery

INTRODUCTION

Electroporation allows efficient delivery of DNA into cells and tissues, thereby improving the expression of therapeutic or immunogenic proteins that are encoded by plasmid DNA. This simple and versatile method holds a great potential and could address unmet medical needs such as the prevention or treatment of many cancers or infectious diseases.

AREAS COVERED

This review explores the electroporation mechanism and the parameters affecting its efficacy. An analysis of past and current clinical trials focused on DNA electroporation is presented. The pathologies addressed, the protocol used, the treatment outcome and the tolerability are highlighted. In addition, several of the possible optimization strategies for improving patient compliance and therapeutic efficacy are discussed such as plasmid design, use of genetic adjuvants for DNA vaccines, choice of appropriate delivery site and electrodes as well as pulse parameters.

EXPERT OPINION

The growing number of clinical trials and the results already available underline the strong potential of DNA electroporation which combines both safety and efficiency. Nevertheless, it remains critical to further increase fundamental knowledge to refine future strategies, to develop concerted and common DNA electroporation protocols and to continue exploring new electroporation-based therapeutic options.