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

Impact of ITPA gene polymorphism for predicting anemia and treatment outcome in HCV infected patients taking Sofosbuvir Ribavirin therapy

BACKGROUND

Globally, 80 million people are suffering from chronic Hepatitis C virus (HCV) infection. Sofosbuvir ribavirin-based anti-HCV therapy is associated with anemia and other adverse effects. Polymorphisms of Inosine triphosphatase (ITPA) gene may cause functional impairment in the Inosine triphosphate pyrophosphatase enzyme, resulting in enhanced sustained viral response (SVR) and protection from ribavirin-associated anemia in patients on therapy. The study objective was to investigate the effect of Inosine triphosphatase gene polymorphism on SVR achievement, hemoglobin decline and ribavirin dose reduction in patients on therapy.

METHODS

This prospective cohort study was of 170 hepatitis C infected patients received 6-month sofosbuvir ribavirin therapy. Patient viral load, reduction in ribavirin amount, liver function test, and complete blood count were noted monthly. Inosine triphosphatase variants rs1127354 and rs7270101 were assessed through the restriction fragment length polymorphism and confirmed using Sanger sequencing. The impact of polymorphism on cumulative reduction of ribavirin, and anti-HCV therapy outcome were studied.

RESULTS

A total of 74.3% of patients had ITPA rs1127354 CC genotype, 25.7% were CA and AA 0%. The frequency of ITPA genotype rs7270101-AA was 95%, AC 5%, and CC was 0%. ITPA rs1127354-CA had a notably positive impact on SVR achievement with a zero-relapse rate. ITPA rs1127354-CA genotype was significantly (P ˂0.05) protective against ≥ 2 g/dl Hb reduction from baseline to 1st, 2nd and 6th months of therapy. During treatment, Hb reduction ≥ 10 g/dl was frequently observed in rs1127354-CC genotype and rs7270101-AA genotype patients. Ribavirin dose reduction was significantly (P ˂0.05) high in rs1127354-CC genotype as compared to genotype CA whereas no significant difference was observed in ribavirin dose reduction in rs7270101 AA and non-AA genotype. Patient baseline characteristics such as age, body mass index, rs1127354-CC genotype, and baseline Hb were significantly associated with significant Hb reduction.

CONCLUSION

Pretreatment evaluation of ITPA polymorphism can be a diagnostic tool to find out patients at risk of anemia and improve treatment adherence. ITPA genotype rs1127354-CA contributes to improved compliance with ribavirin dose and protects against hemoglobin decline in HCV patients while taking ribavirin-based therapy. However, ITPA rs1127354, rs7270101 polymorphism have no significant impact on SVR achievement.

Comparison of Effects of Multiple Adjuvants and Immunization Routes on the Immunogenicity and Protection of HSV-2 gD Subunit Vaccine

Genital herpes caused by herpes simplex virus type 2 (HSV-2) poses a global health issue. HSV-2 infection increases the risk of acquiring HIV infection. Studies have demonstrated that HSV-2 subunit vaccines have potential benefits, but require adjuvants to induce a balanced Th1/Th2 response. To develop a novel, effective vaccine, in this study, a truncated glycoprotein D (aa 1-285) of HSV-2 was formulated with an Al(OH)₃ adjuvant, three squalene adjuvants, MF59, AS03, and AS02, or a mucosal adjuvant, bacterium-like particles (BLPs). The immunogenicity of these subunit vaccines was evaluated in mice. After three immunizations, vaccines formulated with Al(OH)_3, MF59, AS03, and AS02 (intramuscularly) induced higher titers of neutralizing antibody than that formulated without adjuvant, and in particular, mice immunized with the vaccine plus AS02 had the highest neutralizing antibody titers and tended to produce a more balanced immune reaction than others. Intranasal gD2-PA-BLPs also induced excellent IgA levels and a more balanced Th1 and Th2 responses than intranasal gD2. After challenge with a lethal dose of HSV-2, all five adjuvants exhibited a positive effect in improving the survival rate. AS02 and gD2-PA-BLPs enhanced survival by 50% and 25%, respectively, when compared with the vaccine without adjuvant. AS02 was the only adjuvant that resulted in complete vaginal virus clearance and genital lesion healing within eight days. These results demonstrate the potential of using AS02 as a subunit vaccine adjuvant, and BLPs as a mucosal vaccine adjuvant.

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.

Rational Design of Live-Attenuated Vaccines against Herpes Simplex Viruses

Diseases caused by human herpes simplex virus types 1 and 2 (HSV-1 and HSV-2) affect millions of people worldwide and range from fatal encephalitis in neonates and herpes keratitis to orofacial and genital herpes, among other manifestations. The viruses can be shed efficiently by asymptomatic carriers, causing increased rates of infection. Viral transmission occurs through direct contact of mucosal surfaces followed by initial replication of the incoming virus in skin tissues. Subsequently, the viruses infect sensory neurons in the trigeminal and lumbosacral dorsal root ganglia, where they are primarily maintained in a transcriptionally repressed state termed "latency", which persists for the lifetime of the host. HSV DNA has also been detected in other sympathetic ganglia. Periodically, latent viruses can reactivate, causing ulcerative and often painful lesions primarily at the site of primary infection and proximal sites. In the United States, recurrent genital herpes alone accounts for more than a billion dollars in direct medical costs per year, while there are much higher costs associated with the socio-economic aspects of diseased patients, such as loss of productivity due to mental anguish. Currently, there are no effective FDA-approved vaccines for either prophylactic or therapeutic treatment of human herpes simplex infections, while several recent clinical trials have failed to achieve their endpoint goals. Historically, live-attenuated vaccines have successfully combated viral diseases, including polio, influenza, measles, and smallpox. Vaccines aimed to protect against the devastation of smallpox led to the most significant achievement in medical history: the eradication of human disease by vaccination. Recently, novel approaches toward developing safe and effective live-attenuated vaccines have demonstrated high efficacy in various preclinical models of herpetic disease. This next generation of live-attenuated vaccines has been tailored to minimize vaccine-associated side effects and promote effective and long-lasting immune responses. The ultimate goal is to prevent or reduce primary infections (prophylactic vaccines) or reduce the frequency and severity of disease associated with reactivation events (therapeutic vaccines). These vaccines' "rational" design is based on our current understanding of the immunopathogenesis of herpesviral infections that guide the development of vaccines that generate robust and protective immune responses. This review covers recent advances in the development of herpes simplex vaccines and the current state of ongoing clinical trials in pursuit of an effective vaccine against herpes simplex virus infections and associated diseases.

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.

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.

Protective immunity following vaccination with a recombinant multiple-epitope protein of bovine herpesvirus type I in a rabbit model

Bovine herpesvirus type 1 (BoHV-1) causes considerable economic losses to the cow industry. Vaccination remains an effective strategy to control the diseases associated with BoHV-1. However, live vaccines present safety concerns, especially in pregnant cows; thus, nonreplicating vaccines have been developed to control the disease. The envelope glycoproteins of BoHV-1 induce a protective immune response. In this work, selected epitopes on glycoproteins gD, gC, and gB were constructed in triplicate with linker peptides. Vaccination of rabbits demonstrated that P2-gD/gC/gB with AAYAAY induced higher specific antibodies than that with GGGGS linker. P2-gD/gC/gB with AAYAAY linker was fused with bovine interleukin-6 (BoIL-6) or rabbit IL-6 (RaIL-6) and bacterially expressed. Rabbits were intramuscularly immunized with 100 μg of P2-gD/gC/gB-BoIL-6, P2-gD/gC/gB-RaIL-6, P2-gD/gC/gB, P2-gD/gC/gB plus BoIL-6, P2-(gD-a)3-BoIL-6, or P2-(gD-a)3 emulsified with ISA 206 adjuvant thrice at 3-week intervals. P2-gD/gC/gB-BoIL-6 generated a higher titer of BoHV-1-specific antibodies, neutralizing antibodies, interferon (IFN)-γ, and IL-4 compared with P2-gD/gC/gB plus BoIL-6, P2-gD/gC/gB-RaIL-6, or other formulation. P2-gD/gC/gB-BoIL-6 triggered similar levels of antibodies and significantly higher titer of IFN-γ and IL-4 compared with inactivated bovine viral diarrhea (BVD)-infectious bovine rhinotracheitis (IBR) vaccine. Rabbits vaccinated with P2-gD/gC/gB-BoIL-6 dramatically reduced viral shedding and tissue lesions in lungs and trachea after viral challenge and reactivation compared with those with P2-gD/gC/gB plus BoIL-6 or P2-gD/gC/gB-RaIL-6. P2-gD/gC/gB-BoIL-6 provided protective effects against viral shedding and tissue pathogenesis similar to those of the inactivated vaccine. The data confirmed the safety and immunogenicity of multiple-epitope recombinant protein and a potential vaccine candidate to control the disease, especially for pregnant cattle.

The Murine Intravaginal HSV-2 Challenge Model for Investigation of DNA Vaccines

DNA vaccines have been licensed in veterinary medicine and have promise for humans. This format is relatively immunogenic in mice and guinea pigs, the two principle HSV-2 animal models, permitting rapid assessment of vectors, antigens, adjuvants, and delivery systems. Limitations include the relatively poor immunogenicity of naked DNA in humans and the profound differences in HSV-2 pathogenesis between host species. Herein, we detail lessons learned investigating candidate DNA vaccines in the progesterone-primed female mouse vaginal model of HSV-2 infection as a guide to investigators in the field.

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.

The genetic adjuvant IL-12 enhances the protective efficacy of a DNA vaccine for Venezuelan equine encephalitis virus delivered by intramuscular injection in mice

We have previously shown that DNA vaccines expressing codon-optimized alphavirus envelope glycoprotein genes protect both mice and non-human primates from viral challenge when delivered by intramuscular electroporation (IM-EP). To determine if we could achieve equivalent immunogenicity and protective efficacy in the absence of electroporation, we co-delivered our Venezuelan equine encephalitis virus (VEEV) DNA vaccine with DNA plasmids expressing genetic adjuvants designed to augment immune responses. We tested the T_h1-inducing cytokine IL-12 as well as the granulocyte growth factor GM-CSF, both of which have demonstrated significant adjuvant effect when included in clinical DNA vaccine formulations. Additionally, as multiple reports have described the necessity of IFN-αβ in DNA vaccine immunogenicity, we tested vaccine plasmids encoding a potent stimulator of the IFN-αβ pathway. Our data suggest that IM vaccination of mice with plasmid DNA encoding genetic adjuvants enhances VEEV vaccine immunogenicity, resulting in improved T cell responses, as well as skewing of the anti-VEEV IgG antibody isotype. Additionally, IM vaccination of VEEV DNA vaccine and IL-12 provided complete protection against aerosol VEEV challenge. Overall, our data suggest that co-delivery of genetic adjuvants with alphavirus DNA vaccines using IM delivery can influence the type of immune response obtained and provide comparable protective immunity to that achieved by IM-EP delivery of the vaccine without adjuvants.

Advancements in DNA vaccine vectors, non-mechanical delivery methods, and molecular adjuvants to increase immunogenicity

A major advantage of DNA vaccination is the ability to induce both humoral and cellular immune responses. DNA vaccines are currently used in veterinary medicine, but have not achieved widespread acceptance for use in humans due to their low immunogenicity in early clinical studies. However, recent clinical data have re-established the value of DNA vaccines, particularly in priming high-level antigen-specific antibody responses. Several approaches have been investigated for improving DNA vaccine efficacy, including advancements in DNA vaccine vector design, the inclusion of genetically engineered cytokine adjuvants, and novel non-mechanical delivery methods. These strategies have shown promise, resulting in augmented adaptive immune responses in not only mice, but also in large animal models. Here, we review advancements in each of these areas that show promise for increasing the immunogenicity of DNA vaccines.

Advancements in DNA vaccine vectors, non-mechanical delivery methods, and molecular adjuvants to increase immunogenicity

A major advantage of DNA vaccination is the ability to induce both humoral and cellular immune responses. DNA vaccines are currently used in veterinary medicine, but have not achieved widespread acceptance for use in humans due to their low immunogenicity in early clinical studies. However, recent clinical data have re-established the value of DNA vaccines, particularly in priming high-level antigen-specific antibody responses. Several approaches have been investigated for improving DNA vaccine efficacy, including advancements in DNA vaccine vector design, the inclusion of genetically engineered cytokine adjuvants, and novel non-mechanical delivery methods. These strategies have shown promise, resulting in augmented adaptive immune responses in not only mice, but also in large animal models. Here, we review advancements in each of these areas that show promise for increasing the immunogenicity of DNA vaccines.