Factors Which Contribute to the Immunogenicity of Non-replicating Adenoviral Vectored Vaccines

Cutaneous adverse reactions associated with COVID-19 vaccines: Current evidence and potential immune mechanisms

As the number of vaccinated individuals has increased, there have been increasing reports of cutaneous hypersensitivity reactions. The main COVID-19 vaccines administered include messenger ribonucleic acid vaccines, non-replicating viral vector vaccines, inactivated whole-virus vaccines, and protein-based vaccines. These vaccines contain active components such as polyethylene glycol, polysorbate 80, aluminum, tromethamine, and disodium edetate dihydrate. Recent advances in understanding the coordination of inflammatory responses by specific subsets of lymphocytes have led to a new classification based on immune response patterns. We categorize these responses into four patterns: T helper (Th)1-, Th2-, Th17/22-, and Treg-polarized cutaneous inflammation after stimulation of COVID-19 vaccines. Although the association between COVID-19 vaccination and these cutaneous adverse reactions remains controversial, the occurrence of rare dermatoses and their short intervals suggest a possible relationship. Despite the potential adverse reactions, the administration of COVID-19 vaccines is crucial in the ongoing battle against severe acute respiratory syndrome coronavirus 2.

Codon-optimization in gene therapy: promises, prospects and challenges

Codon optimization has evolved to enhance protein expression efficiency by exploiting the genetic code's redundancy, allowing for multiple codon options for a single amino acid. Initially observed in E. coli, optimal codon usage correlates with high gene expression, which has propelled applications expanding from basic research to biopharmaceuticals and vaccine development. The method is especially valuable for adjusting immune responses in gene therapies and has the potenial to create tissue-specific therapies. However, challenges persist, such as the risk of unintended effects on protein function and the complexity of evaluating optimization effectiveness. Despite these issues, codon optimization is crucial in advancing gene therapeutics. This study provides a comprehensive review of the current metrics for codon-optimization, and its practical usage in research and clinical applications, in the context of gene therapy.

Advancements in Viral Gene Therapy for Gaucher Disease

Gaucher disease, an autosomal recessively inherited lysosomal storage disorder, results from biallelic mutations in the GBA1 gene resulting in deficient activity of the enzyme glucocerebrosidase. In Gaucher disease, the reduced levels and activity of glucocerebrosidase lead to a disparity in the rates of formation and breakdown of glucocerebroside and glucosylsphingosine, resulting in the accumulation of these lipid substrates in the lysosome. This gives rise to the development of Gaucher cells, engorged macrophages with a characteristic wrinkled tissue paper appearance. There are both non-neuronopathic (type 1) and neuronopathic (types 2 and 3) forms of Gaucher disease, associated with varying degrees of severity. The visceral and hematologic manifestations of Gaucher disease respond well to both enzyme replacement therapy and substrate reduction therapy. However, these therapies do not improve the neuronopathic manifestations, as they cannot cross the blood-brain barrier. There is now an established precedent for treating lysosomal storage disorders with gene therapy strategies, as many have the potential to cross into the brain. The range of the gene therapies being employed is broad, but this review aimed to discuss the progress, advances, and challenges in developing viral gene therapy as a treatment for Gaucher disease.

Intravenous Administration of Ad26.COV2.S Does Not Induce Thrombocytopenia or Thrombotic Events or Affect SARS-CoV-2 Spike Protein Bioavailability in Blood Compared with Intramuscular Vaccination in Rabbits

Vaccine-induced immune thrombotic thrombocytopenia (VITT) is a very rare but serious adverse reaction that can occur after Ad26.COV2.S vaccination in humans, leading to thrombosis at unusual anatomic sites. One hypothesis is that accidental intravenous (IV) administration of Ad26.COV2.S or drainage of the vaccine from the muscle into the circulatory system may result in interaction of the vaccine with blood factors associated with platelet activation, leading to VITT. Here, we demonstrate that, similar to intramuscular (IM) administration of Ad26.COV2.S in rabbits, IV dosing was well tolerated, with no significant differences between dosing routes for the assessed hematologic, coagulation time, innate immune, or clinical chemistry parameters and no histopathologic indication of thrombotic events. For both routes, all other non-adverse findings observed were consistent with a normal vaccine response and comparable to those observed for unrelated or other Ad26-based control vaccines. However, Ad26.COV2.S induced significantly higher levels of C-reactive protein on day 1 after IM vaccination compared with an Ad26-based control vaccine encoding a different transgene, suggesting an inflammatory effect of the vaccine-encoded spike protein. Although based on a limited number of animals, these data indicate that an accidental IV injection of Ad26.COV2.S may not represent an increased risk for VITT.

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.

Comparative analysis of the impact of 40 adenovirus types on dendritic cell activation and CD8+ T cell proliferation capacity for the identification of favorable immunization vector candidates

For the development of new adenovirus (AdV)-based vectors, it is important to understand differences in immunogenicity. In a side-by-side in vitro analysis, we evaluated the effect of 40 AdV types covering human AdV (HAdV) species A through G on the expression of 11 activation markers and the secretion of 12 cytokines by AdV-transduced dendritic cells, and the effect on CD8+ T cell proliferation capacity. We found that the expression of activation markers and cytokines differed widely between the different HAdV types, and many types were able to significantly impair the proliferation capacity of CD8+ T cells. Univariate and multivariate regression analyses suggested an important role of type I interferons in mediating this suppression of CD8+ T cells, which we confirmed experimentally in a proliferation assay using a type I interferon receptor blocking antibody. Using Bayesian statistics, we calculated a prediction model that suggests HAdV types HAdV-C1, -D8, -B7, -F41, -D33, -C2, -A31, -B3 and -D65 as the most favorable candidates for vaccine vector development.

Host Interactions with Engineered T-cell Micropharmacies

Genetically engineered, cytotoxic, adoptively transferred T cells localize to antigen-positive cancer cells inside patients, but tumor heterogeneity and multiple immune escape mechanisms have prevented the eradication of most solid tumor types. More effective, multifunctional engineered T cells are in development to overcome the barriers to the treatment of solid tumors, but the interactions of these highly modified cells with the host are poorly understood. We previously engineered prodrug-activating enzymatic functions into chimeric antigen receptor (CAR) T cells, endowing them with a killing mechanism orthogonal to conventional T-cell cytotoxicity. These drug-delivering cells, termed Synthetic Enzyme-Armed KillER (SEAKER) cells, demonstrated efficacy in mouse lymphoma xenograft models. However, the interactions of an immunocompromised xenograft with such complex engineered T cells are distinct from those in an immunocompetent host, precluding an understanding of how these physiologic processes may affect the therapy. Herein, we expanded the repertoire of SEAKER cells to target solid-tumor melanomas in syngeneic mouse models using specific targeting with T-cell receptor (TCR)-engineered T cells. We demonstrate that SEAKER cells localized specifically to tumors, and activated bioactive prodrugs, despite host immune responses. We additionally show that TCR-engineered SEAKER cells were efficacious in immunocompetent hosts, demonstrating that the SEAKER platform is applicable to many adoptive cell therapies.

AdhMMP8 Vector Administration in Muscle: An Alternate Strategy to Regress Hepatic Fibrosis

The development of several vaccines against the SARS-CoV2 virus and their application in millions of people have shown efficacy and safety in the transfer of genes to muscle turning this tissue into a protein-producing factory. Established advanced liver fibrosis, is characterized by replacement of hepatic parenchyma by tissue scar, mostly collagen type I, with increased profibrogenic and proinflammatory molecules gene expression. Matrix metalloproteinase 8 (MMP-8) is an interstitial collagen-degrading proenzyme acting preferentially on collagen type I when activated. This study was carried out to elucidate the effect of an intramuscularly delivered adenoviral vector containing proMMP-8 gene cDNA (AdhMMP8) in male Wistar rats with experimental advanced liver fibrosis induced by thioacetamide. Therapeutic effects were monitored after 1, 2, or 3 weeks of a single dose (3 × 1011 vp/kg) of AdhMMP8. Circulating and liver concentration of MMP-8 protein remained constant; hepatic fibrosis decreased up to 48%; proinflammatory and profibrogenic genes expression diminished: TNF-α 2.28-fold, IL-1 1.95-fold, Col 1A1 4-fold, TGF-β1 3-fold and CTGF 2-fold; and antifibrogenic genes expression raised, MMP-9 2.8-fold and MMP-1 10-fold. Our data proposes that the administration of AdhMMP8 in muscle is safe and effective in achieving liver fibrosis regression at a comparable extent as when the adenoviral vector is delivered systemically to reach the liver, using a minimally invasive procedure.

The co-delivery of adenovirus-based immune checkpoint vaccine elicits a potent anti-tumor effect in renal carcinoma

Immune-based checkpoint therapy has made significant progress in cancer treatment, but its therapeutic effect is limited. A replication-defective adenovirus (Ad) vaccine encoding tumor antigen carbonic anhydrase IX (CAIX) combined with Ad-encoding immune checkpoint PD-L1 was developed to treat renal carcinoma. Three tumor models, subcutaneous, lung metastasis and orthotopic tumor were established, and Ad vaccines were used to immunize them and evaluate the vaccine's therapeutic effect. Compared to the single Ad vaccine group, the subcutaneous tumor growth was significantly reduced in Ad-CAIX/Ad-PD-L1 combination group. Co-immunization of Ad-CAIX/Ad-PD-L1 enhanced the induction and maturation of CD11c+ or CD8+CD11c+ DCs in the spleen and tumor and promoted the strong tumor-specific CD8+ T cell immune responses. In vivo CD8 T cell deletion assay showed that the anti-tumor effect of the Ad-CAIX/Ad-PD-L1 vaccine was mainly dependent on functional CD8+ T cell immune responses. Furthermore, the Ad-CAIX/Ad-PD-L1 vaccine effectively inhibited tumor growth and lung metastasis in metastatic or orthotopic models. These results indicate that the combination strategy of the immune checkpoint vaccine shows promising potential as an approach for malignant tumor therapy.

An Oil-Based Adjuvant Improves Immune Responses Induced by Canine Adenovirus-Vectored Vaccine in Mice

There is a significant need for highly effective vaccines against emerging and common veterinary infectious diseases. Canine adenovirus type 2 (CAV2) vectors allow rapid development of multiple vaccines and have demonstrated their potential in animal models. In this study, we compared the immunogenicity of a non-replicating CAV2 vector encoding the rabies virus glycoprotein with and without MontanideTM ISA 201 VG, an oil-based adjuvant. All vaccinated mice rapidly achieved rabies seroconversion, which was associated with complete vaccine protection. The adjuvant increased rabies antibody titers without any significant effect on the anti-CAV2 serological responses. An RT2 Profiler™ PCR array was conducted to identify host antiviral genes modulated in the blood samples 24 h after vaccination. Functional analysis of differentially expressed genes revealed the up-regulation of the RIG-I, TLRs, NLRs, and IFNs signaling pathways. These results demonstrate that a water-in-oil-in-water adjuvant can shape the immune responses to an antigen encoded by an adenovirus, thereby enhancing the protection conferred by live recombinant vaccines. The characterization of early vaccine responses provides a better understanding of the mechanisms underlying the efficacy of CAV2-vectored vaccines.

Bioprocessing and the Production of Antiviral Biologics in the Prevention and Treatment of Viral Infectious Disease

Emerging, re-emerging and zoonotic viral pathogens represent a serious threat to human health, resulting in morbidity, mortality and potentially economic instability at a global scale. Certainly, the recent emergence of the novel SARS-CoV-2 virus (and its variants) highlighted the impact of such pathogens, with the pandemic creating unprecedented and continued demands for the accelerated production of antiviral therapeutics. With limited effective small molecule therapies available for metaphylaxis, vaccination programs have been the mainstay against virulent viral species. Traditional vaccines remain highly effective at providing high antibody titres, but are, however, slow to manufacture in times of emergency. The limitations of traditional vaccine modalities may be overcome by novel strategies, as outlined herein. To prevent future disease outbreaks, paradigm shift changes in manufacturing and distribution are necessary to advance the production of vaccines, monoclonal antibodies, cytokines and other antiviral therapies. Accelerated paths for antivirals have been made possible due to advances in bioprocessing, leading to the production of novel antiviral agents. This review outlines the role of bioprocessing in the production of biologics and advances in mitigating viral infectious disease. In an era of emerging viral diseases and the proliferation of antimicrobial resistance, this review provides insight into a significant method of antiviral agent production which is key to protecting public health.

Risk assessment of retinal vascular occlusion after COVID-19 vaccination

Coronavirus disease 2019 (COVID-19) vaccines are associated with several ocular manifestations. Emerging evidence has been reported; however, the causality between the two is debatable. We aimed to investigate the risk of retinal vascular occlusion after COVID-19 vaccination. This retrospective cohort study used the TriNetX global network and included individuals vaccinated with COVID-19 vaccines between January 2020 and December 2022. We excluded individuals with a history of retinal vascular occlusion or those who used any systemic medication that could potentially affect blood coagulation prior to vaccination. To compare the risk of retinal vascular occlusion, we employed multivariable-adjusted Cox proportional hazards models after performing a 1:1 propensity score matching between the vaccinated and unvaccinated cohorts. Individuals with COVID-19 vaccination had a higher risk of all forms of retinal vascular occlusion in 2 years after vaccination, with an overall hazard ratio of 2.19 (95% confidence interval 2.00-2.39). The cumulative incidence of retinal vascular occlusion was significantly higher in the vaccinated cohort compared to the unvaccinated cohort, 2 years and 12 weeks after vaccination. The risk of retinal vascular occlusion significantly increased during the first 2 weeks after vaccination and persisted for 12 weeks. Additionally, individuals with first and second dose of BNT162b2 and mRNA-1273 had significantly increased risk of retinal vascular occlusion 2 years following vaccination, while no disparity was detected between brand and dose of vaccines. This large multicenter study strengthens the findings of previous cases. Retinal vascular occlusion may not be a coincidental finding after COVID-19 vaccination.

Host-cell Interactions of Engineered T cell Micropharmacies

Genetically engineered, cytotoxic, adoptive T cells localize to antigen positive cancer cells inside patients, but tumor heterogeneity and multiple immune escape mechanisms have prevented the eradication of most solid tumor types. More effective, multifunctional engineered T cells are in development to overcome the barriers to the treatment of solid tumors, but the interactions of these highly modified cells with the host are poorly understood. We previously engineered prodrug-activating enzymatic functions into chimeric antigen receptor (CAR) T cells, endowing them with an orthogonal killing mechanism to conventional T-cell cytotoxicity. These drug-delivering cells, termed Synthetic Enzyme-Armed KillER (SEAKER) cells, demonstrated efficacy in mouse lymphoma xenograft models. However, the interactions of an immunocompromised xenograft with such complex engineered T cells are distinct from those in an immunocompetent host, precluding an understanding of how these physiologic processes may affect the therapy. Here, we also expand the repertoire of SEAKER cells to target solid-tumor melanomas in syngeneic mouse models using specific targeting with TCR-engineered T cells. We demonstrate that SEAKER cells localize specifically to tumors, and activate bioactive prodrugs, despite host immune responses. We additionally show that TCR-engineered SEAKER cells are efficacious in immunocompetent hosts, demonstrating that the SEAKER platform is applicable to many adoptive cell therapies.

COVID-19 adenovirus vector vaccine induces higher interferon and pro-inflammatory responses than mRNA vaccines in human PBMCs, macrophages and moDCs

BACKGROUND

During the COVID-19 pandemic multiple vaccines were rapidly developed and widely used throughout the world. At present there is very little information on COVID-19 vaccine interactions with primary human immune cells such as peripheral blood mononuclear cells (PBMCs), monocyte-derived macrophages and dendritic cells (moDCs).

METHODS

Human PBMCs, macrophages and moDCs were stimulated with different COVID-19 vaccines, and the expression of interferon (IFN-λ1, IFN-α1), pro-inflammatory (IL-1β, IL-6, IL-8, IL-18, CXCL-4, CXCL-10, TNF-α) and Th1-type cytokine mRNAs (IL-2, IFN-γ) were analyzed by qPCR. In addition, the expression of vaccine induced spike (S) protein and antiviral molecules were studied in primary immune cells and in A549 lung epithelial cells.

RESULTS

Adenovirus vector (Ad-vector) vaccine AZD1222 induced high levels of IFN-λ1, IFN-α1, CXCL-10, IL-6, and TNF-α mRNAs in PBMCs at early time points of stimulation while the expression of IFN-γ and IL-2 mRNA took place at later times. AZD1222 also induced IFN-λ1, CXCL-10 and IL-6 mRNA expression in monocyte-derived macrophages and DCs in a dose-dependent fashion. AZD1222 also activated the phosphorylation of IRF3 and induced MxA expression. BNT162b2 and mRNA-1273 mRNA vaccines failed to induce or induced very weak cytokine gene expression in all cell models. None of the vaccines enhanced the expression of CXCL-4. AZD1222 and mRNA-1273 vaccines induced high expression of S protein in all studied cells.

CONCLUSIONS

Ad-vector vaccine induces higher IFN and pro-inflammatory responses than the mRNA vaccines in human immune cells. This data shows that AZD1222 readily activates IFN and pro-inflammatory cytokine gene expression in PBMCs, macrophages and DCs, but fails to further enhance CXCL-4 mRNA expression.

Intranasal administration of adenoviral vaccines expressing SARS-CoV-2 spike protein improves vaccine immunity in mouse models

The ongoing SARS-CoV-2 pandemic is controlled but not halted by public health measures and mass vaccination strategies which have exclusively relied on intramuscular vaccines. Intranasal vaccines can prime or recruit to the respiratory epithelium mucosal immune cells capable of preventing infection. Here we report a comprehensive series of studies on this concept using various mouse models, including HLA class II-humanized transgenic strains. We found that a single intranasal (i.n.) dose of serotype-5 adenoviral vectors expressing either the receptor binding domain (Ad5-RBD) or the complete ectodomain (Ad5-S) of the SARS-CoV-2 spike protein was effective in inducing i) serum and bronchoalveolar lavage (BAL) anti-spike IgA and IgG, ii) robust SARS-CoV-2-neutralizing activity in the serum and BAL, iii) rigorous spike-directed T helper 1 cell/cytotoxic T cell immunity, and iv) protection of mice from a challenge with the SARS-CoV-2 beta variant. Intramuscular (i.m.) Ad5-RBD or Ad5-S administration did not induce serum or BAL IgA, and resulted in lower neutralizing titers in the serum. Moreover, prior immunity induced by an intramuscular mRNA vaccine could be potently enhanced and modulated towards a mucosal IgA response by an i.n. Ad5-S booster. Notably, Ad5 DNA was found in the liver or spleen after i.m. but not i.n. administration, indicating a lack of systemic spread of the vaccine vector, which has been associated with a risk of thrombotic thrombocytopenia. Unlike in otherwise genetically identical HLA-DQ6 mice, in HLA-DQ8 mice Ad5-RBD vaccine was inferior to Ad5-S, suggesting that the RBD fragment does not contain a sufficient collection of helper-T cell epitopes to constitute an optimal vaccine antigen. Our data add to previous promising preclinical results on intranasal SARS-CoV-2 vaccination and support the potential of this approach to elicit mucosal immunity for preventing transmission of SARS-CoV-2.

Adenoviral vectored vaccination protects against Crimean-Congo Haemorrhagic Fever disease in a lethal challenge model

BACKGROUND

The tick-borne bunyavirus, Crimean-Congo Haemorrhagic Fever virus (CCHFV), can cause severe febrile illness in humans and has a wide geographic range that continues to expand due to tick migration. Currently, there are no licensed vaccines against CCHFV for widespread usage.

METHODS

In this study, we describe the preclinical assessment of a chimpanzee adenoviral vectored vaccine (ChAdOx2 CCHF) which encodes the glycoprotein precursor (GPC) from CCHFV.

FINDINGS

We demonstrate here that vaccination with ChAdOx2 CCHF induces both a humoral and cellular immune response in mice and 100% protection in a lethal CCHF challenge model. Delivery of the adenoviral vaccine in a heterologous vaccine regimen with a Modified Vaccinia Ankara vaccine (MVA CCHF) induces the highest levels of CCHFV-specific cell-mediated and antibody responses in mice. Histopathological examination and viral load analysis of the tissues of ChAdOx2 CCHF immunised mice reveals an absence of both microscopic changes and viral antigen associated with CCHF infection, further demonstrating protection against disease.

INTERPRETATION

There is the continued need for an effective vaccine against CCHFV to protect humans from lethal haemorrhagic disease. Our findings support further development of the ChAd platform expressing the CCHFV GPC to seek an effective vaccine against CCHFV.

FUNDING

This research was supported by funding from the Biotechnology and Biological Sciences Research Council (UKRI-BBSRC) [BB/R019991/1 and BB/T008784/1].

Nanovaccines for cancer immunotherapy: Focusing on complex formation between adjuvant and antigen

As an interesting cancer immunotherapy approach, cancer vaccines have been developed to deliver tumor antigens and adjuvants to antigen-presenting cells (APCs). Although the safety and easy production shifted the vaccine designing platforms toward the subunit vaccines, their efficacy is limited due to inefficient vaccine delivery. Nanotechnology-based vaccines, called nanovaccines, address the delivery limitations through co-delivery of antigens and adjuvants into lymphoid organs and APCs and their intracellular release, leading to cross-presentation of antigens and induction of potent anti-tumor immune responses. Although the nanovaccines, either as encapsulating agents or biomimetic nanoparticles, exert the desired anti-tumor activities, there is evidence that the mixing formulation to form nanocomplexes between antigens and adjuvants based on the electrostatic interactions provokes high levels of immune responses owing to Ags' availability and faster release. Here, we summarized the various platforms for developing cancer vaccines and the advantages of using delivery systems. The cancer nanovaccines, including nanoparticle-based and biomimetic-based nanovaccines, are discussed in detail. Finally, we focused on the nanocomplexes formation between antigens and adjuvants as promising cancer nanovaccine platforms.

Adenoviral Vector-Based Vaccine Platform for COVID-19: Current Status

The coronavirus disease (COVID-19) breakout had an unimaginable worldwide effect in the 21st century, claiming millions of lives and putting a huge burden on the global economy. The potential developments in vaccine technologies following the determination of the genetic sequence of SARS-CoV-2 and the increasing global efforts to bring potential vaccines and therapeutics into the market for emergency use have provided a small bright spot to this tragic event. Several intriguing vaccine candidates have been developed using recombinant technology, genetic engineering, and other vaccine development technologies. In the last decade, a vast amount of the vaccine development process has diversified towards the usage of viral vector-based vaccines. The immune response elicited by such vaccines is comparatively higher than other approved vaccine candidates that require a booster dose to provide sufficient immune protection. The non-replicating adenoviral vectors are promising vaccine carriers for infectious diseases due to better yield, cGMP-friendly manufacturing processes, safety, better efficacy, manageable shipping, and storage procedures. As of April 2022, the WHO has approved a total of 10 vaccines around the world for COVID-19 (33 vaccines approved by at least one country), among which three candidates are adenoviral vector-based vaccines. This review sheds light on the developmental summary of all the adenoviral vector-based vaccines that are under emergency use authorization (EUA) or in the different stages of development for COVID-19 management.

Recombinant Pichinde viral vector expressing tuberculosis antigens elicits strong T cell responses and protection in mice

Introduction

Tuberculosis (TB) caused by Mycobacterium tuberculosis (Mtb) remains a major global health threat. The only available vaccine Bacille Calmette-Guérin (BCG) does not prevent adult pulmonary TB. New effective TB vaccines should aim to stimulate robust T cell responses in the lung mucosa to achieve high protective efficacy. We have previously developed a novel viral vaccine vector based on recombinant Pichinde virus (PICV), a non-pathogenic arenavirus with low seroprevalence in humans, and have demonstrated its efficacy to induce strong vaccine immunity with undetectable anti-vector neutralization activity.

Methods

Using this tri-segmented PICV vector (rP18tri), we have generated viral vectored TB vaccines (TBvac-1, TBvac-2, and TBvac-10) encoding several known TB immunogens (Ag85B, EsxH, and ESAT-6/EsxA). A P2A linker sequence was used to allow for the expression of two proteins from one open-reading-frame (ORF) on the viral RNA segments. The immunogenicity of TBvac-2 and TBvac-10 and the protective efficacy of TBvac-1 and TBvac-2 were evaluated in mice.

Results

Both viral vectored vaccines elicited strong antigen-specific CD4 and CD8 T cells through intramuscular (IM) and intranasal (IN) routes as evaluated by MHC-I and MHC-II tetramer analyses, respectively. The IN inoculation route helped to elicit strong lung T cell responses. The vaccine-induced antigen-specific CD4 T cells are functional, expressing multiple cytokines as detected by intracellular cytokine staining. Finally, immunization with TBvac-1 or TBvac-2, both expressing the same trivalent antigens (Ag85B, EsxH, ESAT6/EsxA), reduced Mtb lung tissue burden and dissemination in an aerosol challenge mouse model.

Conclusions

The novel PICV vector-based TB vaccine candidates can express more than two antigens via the use of P2A linker sequence and elicit strong systemic and lung T cell immunity with protective efficacy. Our study suggests the PICV vector as an attractive vaccine platform for the development of new and effective TB vaccine candidates.

Cell entry and innate sensing shape adaptive immune responses to adenovirus-based vaccines

Nonreplicating adenovirus-based vectors have been successfully implemented as prophylactic vaccines against infectious viral diseases and induce protective cellular and humoral responses. Differences in the mechanisms of cellular entry or endosomal escape of these vectors contribute to differences in innate immune sensing between adenovirus species. Innate immune responses to adenovirus-based vaccines, such as interferon signaling, have been reported to affect the development of adaptive responses in preclinical studies, although limited data are available in humans. Understanding the mechanisms of these early events is critical for the development of vaccines that elicit effective and durable adaptive immune responses while maintaining an acceptable reactogenicity profile.

mRNA vaccines: The future of prevention of viral infections?

Messenger RNA (mRNA) vaccines against COVID-19 are the first authorized biological preparations developed using this platform. During the pandemic, their administration has been proven to be a life-saving intervention. Here, we review the main advantages of using mRNA vaccines, identify further technological challenges to be met during the development of the mRNA platform, and provide an update on the clinical progress on leading mRNA vaccine candidates against different viruses that include influenza viruses, human immunodeficiency virus 1, respiratory syncytial virus, Nipah virus, Zika virus, human cytomegalovirus, and Epstein-Barr virus. The prospects and challenges of manufacturing mRNA vaccines in low-income countries are also discussed. The ongoing interest and research in mRNA technology are likely to overcome some existing challenges for this technology (e.g., related to storage conditions and immunogenicity of some components of lipid nanoparticles) and enhance the portfolio of vaccines against diseases for which classical formulations are already authorized. It may also open novel pathways of protection against infections and their consequences for which no safe and efficient immunization methods are currently available.

Lung-Targeted Transgene Expression of Nanocomplexed Ad5 Enhances Immune Response in the Presence of Preexisting Immunity

Recombinant adenovirus serotype 5 (Ad5) vector has been widely applied in vaccine development targeting infectious diseases, such as Ebola virus disease and coronavirus disease 2019 (COVID-19). However, the high prevalence of preexisting anti-vector immunity compromises the immunogenicity of Ad5-based vaccines. Thus, there is a substantial unmet need to minimize preexisting immunity while improving the insert-induced immunity of Ad5 vectors. Herein, we address this need by utilizing biocompatible nanoparticles to modulate Ad5-host interactions. We show that positively charged human serum albumin nanoparticles ((+)HSAnp), which are capable of forming a complex with Ad5, significantly increase the transgene expression of Ad5 in both coxsackievirus-adenovirus receptor-positive and -negative cells. Furthermore, in charge- and dose-dependent manners, Ad5/(+)HSAnp complexes achieve robust (up to 227-fold higher) and long-term (up to 60 days) transgene expression in the lungs of mice following intranasal instillation. Importantly, in the presence of preexisting anti-Ad5 immunity, complexed Ad5-based Ebola and COVID-19 vaccines significantly enhance antigen-specific humoral response and mucosal immunity. These findings suggest that viral aggregation and charge modification could be leveraged to engineer enhanced viral vectors for vaccines and gene therapies.

T-Cell Immunity in COVID-19-Recovered Individuals and Individuals Vaccinated with the Combined Vector Vaccine Gam-COVID-Vac

The COVID-19 pandemic has required extensive research on the new coronavirus SARS-CoV-2 and the creation of new highly effective vaccines. The presence of T-cells in the body that respond to virus antigens suggests adequate antiviral immunity. We investigated T-cell immunity in individuals who recovered from mild and moderate COVID-19 and in individuals vaccinated with the Gam-COVID-Vac combined vector vaccine. The ELISPOT method was used to determine the number of T-cells responding with IFN-γ synthesis to stimulation by peptides containing epitopes of the S-protein or N-, M-, ORF3, and ORF7 proteins, using peripheral blood mononuclear cells (PBMCs). At the same time, the multiplex method was used to determine the accumulation of IFN-γ and other cytokines in the culture medium. According to the data obtained, the proportion of positive conclusions about the T-cell immune response to SARS-CoV-2 antigens in control, recovered, and vaccinated individuals was 12%, 70%, and 52%, respectively. At the same time, more than half of the vaccinated individuals with a T-cell response were sensitized to the antigens of N-, M-, ORF3, and ORF7 proteins not produced by Gam-COVID-Vac, indicating a high likelihood of asymptomatic SARS-CoV-2 infection. Increased IFN-γ release by single sensitized T-cells in response to specific stimulation in recovered and vaccinated individuals did not result in the accumulation of this and other cytokines in the culture medium. These findings suggest a balance between cytokine production and utilization by immunocompetent cells as a prerequisite for providing a controlled cytokine signal and avoiding a "cytokine storm".

Non-coding RNAs in stroke pathology, diagnostics, and therapeutics

Ischemic stroke is a leading cause of death and disability worldwide. Methods to alleviate functional deficits after ischemic stroke focus on restoration of cerebral blood flow to the affected area. However, pharmacological or surgical methods such as thrombolysis and thrombectomy have a narrow effective window. Harnessing and manipulating neurochemical processes of recovery may provide an alternative to these methods. Recently, non-coding RNA (ncRNA) have been increasingly investigated for their contributions to the pathology of diseases and potential for diagnostic and therapeutic applications. Here we will review several ncRNA - H19, MALAT1, ANRIL, NEAT1, pseudogenes, small nucleolar RNA, piwi-interacting RNA and circular RNA - and their involvement in stroke pathology. We also examine these ncRNA as potential diagnostic biomarkers, particularly in circulating blood, and as targets for therapeutic interventions. An important aspect of this is a discussion of potential methods of treatment delivery to allow for targeting of interventions past the blood-brain barrier, including lipid nanoparticles, polymer nanoparticles, and viral and non-viral vectors. Overall, several long non-coding RNA (lncRNA) discussed here have strong implications for the development of pathology and functional recovery after ischemic stroke. LncRNAs H19 and ANRIL show potential as diagnostic biomarkers, while H19 and MALAT1 may prove to be effective therapeutics for both minimising damage as well as promoting recovery. Other ncRNA have also been implicated in ischemic stroke but are currently too poorly understood to make inferences for diagnosis or treatment. Whilst the field of ncRNAs is relatively new, significant work has already highlighted that ncRNAs represent a promising novel investigative tool for understanding stroke pathology, could be used as diagnostic biomarkers, and as targets for therapeutic interventions.

Seroprevalence of Binding and Neutralizing Antibodies against 39 Human Adenovirus Types in Patients with Neuromuscular Disorders

High pre-existing antibodies against viral vectors reduce their functionality and may lead to adverse complications. To circumvent this problem in future gene therapy approaches, we tested the seroprevalence of a large range of human adenovirus types in patients with neuromuscular disorders (NMDs) to find appropriate viral vector candidates for gene replacement therapy for NMDs. Binding and neutralizing antibodies against 39 human adenovirus types were tested in the sera of 133 patients with NMDs and 76 healthy controls aged 17-92 years. The influence of age, sex, and NMDs on antibody levels was analyzed. The seroprevalence of different adenoviruses in the cohort varied widely. The highest levels of binding antibodies were detected against HAdV-D27, -C1, -D24, -D70, -B14, -C6, -D13, -B34, and -E4, whereas the lowest reactivity was detected against HAdV-F41, -A31, -B11, -D75, -D8, -D65, -D26, -D80, and -D17. The highest neutralizing reactivity was observed against HAdV-B3, -C2, -E4, -C1, -G52, -C5, and -F41, whereas the lowest neutralizing reactivity was observed against HAdV-D74, -B34, -D73, -B37, -D48, -D13, -D75, -D8, -B35, and -B16. We detected no influence of sex and only minor differences between different age groups. Importantly, there were no significant differences between healthy controls and patients with NMDs. Our data show that patients with NMDs have very similar levels of binding and neutralizing antibodies against HAdV compared to healthy individuals, and we identified HAdV-A31, -B16, -B34, -B35, -D8, -D37, -D48, -D73, -D74, -D75, and -D80 as promising candidates for future vector development due to their low binding and neutralizing antibody prevalence.

Modular capsid decoration boosts adenovirus vaccine-induced humoral immunity against SARS-CoV-2

Adenovirus vector vaccines have been widely and successfully deployed in response to coronavirus disease 2019 (COVID-19). However, despite inducing potent T cell immunity, improvement of vaccine-specific antibody responses upon homologous boosting is modest compared with other technologies. Here, we describe a system enabling modular decoration of adenovirus capsid surfaces with antigens and demonstrate potent induction of humoral immunity against these displayed antigens. Ligand attachment via a covalent bond was achieved using a protein superglue, DogTag/DogCatcher (similar to SpyTag/SpyCatcher), in a rapid and spontaneous reaction requiring only co-incubation of ligand and vector components. DogTag was inserted into surface-exposed loops in the adenovirus hexon protein to allow attachment of DogCatcher-fused ligands on virus particles. Efficient coverage of the capsid surface was achieved using various ligands, with vector infectivity retained in each case. Capsid decoration shielded particles from vector neutralizing antibodies. In prime-boost regimens, adenovirus vectors decorated with the receptor-binding domain of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) spike induced >10-fold higher SARS-CoV-2 neutralization titers compared with an undecorated vector encoding spike. Importantly, decorated vectors achieved equivalent or superior T cell immunogenicity against encoded antigens compared with undecorated vectors. We propose capsid decoration using protein superglues as a novel strategy to improve efficacy and boostability of adenovirus-based vaccines and therapeutics.

Adenovirus vector and mRNA vaccines: Mechanisms regulating their immunogenicity

Replication-incompetent adenovirus (Ad) vector and mRNA-lipid nanoparticle (LNP) constructs represent two modular vaccine platforms that have attracted substantial interest over the past two decades. Due to the COVID-19 pandemic and the rapid development of multiple successful vaccines based on these technologies, there is now clear real-world evidence of the utility and efficacy of these platforms. Considerable optimization and refinement efforts underpin the successful application of these technologies. Despite this, our understanding of the specific pathways and processes engaged by these vaccines to stimulate the immune response remains incomplete. This review will synthesize our current knowledge of the specific mechanisms by which CD8⁺ T cell and antibody responses are induced by each of these vaccine platforms, and how this can be impacted by specific vaccine construction techniques. Key gaps in our knowledge are also highlighted, which can hopefully focus future studies.

Sequential use of Ad26-based vaccine regimens in NHP to induce immunity against different disease targets

The adenovirus (Ad)26 serotype–based vector vaccine Ad26.COV2.S has been used in millions of subjects for the prevention of COVID-19, but potentially elicits persistent anti-vector immunity. We investigated if vaccine-elicited immunity to Ad26 vector–based vaccines significantly influences antigen-specific immune responses induced by a subsequent vaccination with Ad26 vector–based vaccine regimens against different disease targets in non-human primates. A homologous Ad26 vector–based vaccination regimen or heterologous regimens (Ad26/Ad35 or Ad26/Modified Vaccinia Ankara [MVA]) induced target pathogen–specific immunity in animals, but also persistent neutralizing antibodies and T-cell responses against the vectors. However, subsequent vaccination (interval, 26–57 weeks) with homologous and heterologous Ad26 vector–based vaccine regimens encoding different target pathogen immunogens did not reveal consistent differences in humoral or cellular immune responses against the target pathogen, as compared to responses in naïve animals. These results support the sequential use of Ad26 vector–based vaccine regimens targeting different diseases.

Single-dose of a replication-competent adenovirus-vectored vaccine provides sterilizing protection against Rift Valley fever virus challenge

Rift Valley fever virus (RVFV) is one of the most important virulent pathogens causing severe disease in animals and humans. However, there is currently no approved vaccine to prevent RVFV infection in humans. The use of human adenovirus serotype 4 (Ad4) as a vector for an RVFV vaccine has not been reported. Here, we report the generation of a replication-competent recombinant Ad4 vector expressing codon-optimized forms of the RVFV glycoproteins Gn and Gc (named Ad4-GnGc). Intramuscular immunization with Ad4-GnGc elicited robust neutralizing antibodies against RVFV and cellular immune responses in mice. A single low-dose vaccination with Ad4-GnGc completely protected interferon-α/β receptor-deficient A129 mice from lethal RVFV infection. More importantly, Ad4-GnGc efficacy was not affected by pre-existing immunity to adenovirus serotype 5, which currently exists widely in populations. These results suggest that Ad4-GnGc is a promising vaccine candidate against RVFV.

Molecular Targeting of the Most Functionally Complex Gene in Precision Oncology: p53

While chemotherapy is a key treatment strategy for many solid tumors, it is rarely curative, and most tumor cells eventually become resistant. Because of this, there is an unmet need to develop systemic treatments that capitalize on the unique mutational landscape of each patient's tumor. The most frequently mutated protein in cancer, p53, has a role in nearly all cancer subtypes and tumorigenesis stages and therefore is one of the most promising molecular targets for cancer treatment. Unfortunately, drugs targeting p53 have seen little clinical success despite promising preclinical data. Most of these drug compounds target specific aspects of p53 inactivation, such as through inhibiting negative regulation by the mouse double minute (MDM) family of proteins. These treatment strategies fail to address cancer cells' adaptation mechanisms and ignore the impact that p53 loss has on the entire p53 network. However, recent gene therapy successes show that targeting the p53 network and cellular dysfunction caused by p53 inactivation is now possible and may soon translate into successful clinical responses. In this review, we discuss p53 signaling complexities in cancer that have hindered the development and use of p53-targeted drugs. We also describe several current therapeutics reporting promising preclinical and clinical results.

How do the severe acute respiratory coronavirus 2 (SARS-CoV-2) and its variants escape the host protective immunity and mediate pathogenesis?

Background

To protect the global population from the ongoing COVID-19 pandemic caused by the severe acute respiratory β-coronavirus 2 (SARS-CoV-2), a number of vaccines are currently being used in three dosages (i.e., along with the booster dose) to induce the immunity required to combat the SARS-CoV-2 and its variants. So far, several antivirals and the commercial vaccines have been found to evoke the required humoral and cellular immunity within a huge population around world. However, an important aspect to consider is the avoidance mechanism of the host protective immunity by SARS-CoV-2 variants.

Main body of the abstract

Indeed, such an immune escape strategy has been noticed previously in case of SARS-CoV-1 and the Middle East Respiratory Syndrome coronavirus (MERS-CoV). Regarding the SARS-CoV-2 variants, the most important aspect on vaccine development is to determine whether the vaccine is actually capable to elicit the immune response or not, especially the viral spike (S) protein.

Short conclusion

Present review thus focused on such elicitation of immunity as well as pondered to the avoidance of host immunity by the SARS-CoV-2 Wuhan strain and its variants.

Safety and immunogenicity of intradermal administration of fractional dose CoronaVac®, ChAdOx1 nCoV-19 and BNT162b2 as primary series vaccination

There is a limited supply of COVID-19 vaccines, with less than 20% of eligible populations in low-income countries having received one dose. Intradermal delivery of fractional dose vaccines is one way to improve global vaccine access, but no studies have reported data on intradermal delivery of COVID-19 primary series vaccination. We conducted a pilot study to examine the safety and immunogenicity of three intradermal primary series regimens – heterologous regimen of CoronaVac and ChAdOx1 (CoronaVac-ChAdOx1), homologous regimen of ChAdOx1 (ChAdOx1-ChAdOx1), and homologous regimen of BNT162b2 (BNT162b2-BNT162b2). Each dose was 1/5^th or 1/6^th of the standard dose. Two additional exploratory arms of intradermal vaccination for the second dose following an intramuscular first dose of ChAdOx1 and BNT162b2 were included. Intradermal vaccination was found to be immunogenic and safe. The antibody responses generated by the intradermal primary series were highest in the BNT162b2 arms. The anti-receptor binding domain (anti-RBD) IgG concentration following fractional dose intradermal vaccination was similar to that of standard dose intramuscular vaccination of the same regimen for all study arms except for BNT162b2. The BNT162b2 intradermal series generated a lower antibody concentration than the reference intramuscular series, despite generating the highest antibody concentration of all three intradermal primary series regimens. Neutralizing antibody responses against the SARS-CoV-2 ancestral strain were consistent with what was observed for anti-RBD IgG, with lower titers for SARS-CoV-2 variants. Neutralizing titers were lowest against the omicron variant, being undetectable in about a quarter of study participants. T-cell responses against spike- and nucleocapsid-membrane-open reading frame proteins were also detected following intradermal vaccination. Adverse effects following intradermal vaccination were generally comparable with post-intramuscular vaccination effects. Taken together, our data suggest that intradermal vaccination using 1/5^th or 1/6^th of standard COVID-19 intramuscular vaccination dosing were immunogenic with tendency of lower systemic adverse reactions than intramuscular vaccination. Our findings have implications in settings where COVID-19 vaccines are in shortage.

SARS-CoV-2 mRNA-vaccine candidate; COReNAPCIN®, induces robust humoral and cellular immunity in mice and non-human primates

At the forefront of biopharmaceutical industry, the messenger RNA (mRNA) technology offers a flexible and scalable platform to address the urgent need for world-wide immunization in pandemic situations. This strategic powerful platform has recently been used to immunize millions of people proving both of safety and highest level of clinical efficacy against infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Here we provide preclinical report of COReNAPCIN^®; a vaccine candidate against SARS-CoV-2 infection. COReNAPCIN^® is a nucleoside modified mRNA-based vaccine formulated in lipid nanoparticles (LNPs) for encoding the full-length prefusion stabilized SARS-CoV-2 spike glycoprotein on the cell surface. Vaccination of C57BL/6 and BALB/c mice and rhesus macaque with COReNAPCIN^® induced strong humoral responses with high titers of virus-binding and neutralizing antibodies. Upon vaccination, a robust SARS-CoV-2 specific cellular immunity was also observed in both mice and non-human primate models. Additionally, vaccination protected rhesus macaques from symptomatic SARS-CoV-2 infection and pathological damage to the lung upon challenging the animals with high viral loads of up to 2 × 10⁸ live viral particles. Overall, our data provide supporting evidence for COReNAPCIN^® as a potent vaccine candidate against SARS-CoV-2 infection for clinical studies.

Epidemiological aspects of headache after different types of COVID ‐19 vaccines: An online survey

Background

Methods

Results

Conclusion

Vaccines against Emerging and Neglected Infectious Diseases: An Overview

Neglected Tropical Diseases (NTDs) are a group of diseases that are highly prevalent in tropical and subtropical regions, and closely associated with poverty and marginalized populations. Infectious diseases affect over 1.6 billion people annually, and vaccines are the best prophylactic tool against them. Along with NTDs, emerging and reemerging infectious diseases also threaten global public health, as they can unpredictably result in pandemics. The recent advances in vaccinology allowed the development and licensing of new vaccine platforms that can target and prevent these diseases. In this work, we discuss the advances in vaccinology and some of the difficulties found in the vaccine development pipeline for selected NTDs and emerging and reemerging infectious diseases, including HIV, Dengue, Ebola, Chagas disease, malaria, leishmaniasis, zika, and chikungunya.

Viral vector vaccines

Over the past two years, the SARS-CoV-2 pandemic has highlighted the impact that emerging pathogens can have on global health. The development of new and effective vaccine technologies is vital in the fight against such threats. Viral vectors are a relatively new vaccine platform that relies on recombinant viruses to deliver selected immunogens into the host. In response to the SARS-CoV-2 pandemic, the development and subsequent rollout of adenoviral vector vaccines has shown the utility, impact, scalability and efficacy of this platform. Shown to elicit strong cellular and humoral immune responses in diverse populations, these vaccine vectors will be an important approach against infectious diseases in the future.

Assessment of neutralizing antibody responses after natural SARS-CoV-2 infection and vaccination in congolese individuals

Background

Assessing immune responses after vaccination is part of the evaluation package of vaccine effectiveness in the real world. Regarding SARS-CoV-2, neutralizing antibody levels has been shown to be a good indicator of antibody immune response boosting. So far, limited data have been reported from Africa including in Central Africa. The objective of this study was to provide data on anti-S1 spike total IgG and neutralizing antibodies in vaccinated and non-vaccinated including naturally infected Congolese population during B.1.214.1 and B.1.617.2 variant waves.

Methods

Recruited patients were divided into 4 groups: (1) Naturally infected by the B.1.214.1 variant on January 2021 and followed up until September 2021. These patients have been vaccinated at month 07 and then followed up for 2 months post vaccination; (2) Naturally infected by the B.1.617.2 variant from June 2021; (3) unvaccinated SARS-CoV-2 individuals with no history of prior SARS-CoV-2 infection; (4) fully vaccinated individuals with sinopharm/BBIP-CorV or Janssen/Ad26.COV2.S. SARS-CoV-2 was detected by qRT-PCR and sequenced using Next-Generation Sequencing. ELISA method was used for detecting IgG, and neutralizing Antibody against SARS-CoV-2 antigens using commercial neutralizing assay.

Results

Individuals infected by the B.1214.1 variant elicited consistently high IgG titers at 02, 03 and 06 months. Two months post vaccination with BBIP-CorV, participants showed a significant increase by × 2.5 fold (p < 0.0001) of total IgG and X1.5 fold for neutralizing antibody capacity. This study showed that natural infection with B1.617.2 (delta) variant was more immunogenic compared to those being infected with B1.214.2 variant.

We found a significantly higher concentration in anti-SARS-CoV-2 IgG (p < 0.0002) and antibodies neutralization capacity (P < 0.0001) in fully vaccinated compared to unvaccinated participants. Two months post vaccination, individuals who received Janssen/Ad26.COV2.S presented higher (p = 0.01) total IgG to spike protein compared to BBIP-CorV.

Conclusion

Both natural infection and vaccination with BBIP-CorV and Janssen/Ad26.COV2.S induced antibody response in Congolese population. In addition, Janssen/Ad26.COV2.S was more immunogenic than Sinopharm/BBIP-CorV. There is a need to investigate the duration of these antibodies both in previously infected and naive vaccinated Congolese to allow public heath stakeholders to make evidence-based decision on vaccine schedule for the Congolese population.

Adenovirus vector-based vaccines as forefront approaches in fighting the battle against flaviviruses

Flaviviruses are arthropod-borne viruses (arboviruses) that have been recently considered among the significant public health problems in defined geographical regions. In this line, there have been vaccines approved for some flaviviruses including dengue virus (DENV), Japanese encephalitis virus (JEV), yellow fever virus (YFV), and tick-borne encephalitis virus (TBEV), although the efficiency of such vaccines thought to be questionable. Surprisingly, there are no effective vaccine for many other hazardous flaviviruses, including West Nile and Zika viruses. Furthermore, in spite of approved vaccines for some flaviviruses, for example DENV, alternative prophylactic vaccines seem to be still needed for the protection of a broader population, and it originates from the unsatisfying safety, and the efficacy of vaccines that have been introduced. Thus, adenovirus vector-based vaccine candidates are suggested to be effective, safe, and reliable. Interestingly, recent widespread use of adenovirus vector-based vaccines for the COVID-19 pandemic have highlighted the importance and feasibility of their widespread application. In this review, the applicability of adenovirus vector-based vaccines, as promising approaches to harness the diseases caused by Flaviviruses, is discussed.

Adenoviral-Vectored Centralized Consensus Hemagglutinin Vaccine Provides Broad Protection against H2 Influenza a Virus

Several influenza pandemics have occurred in the past century, one of which emerged in 1957 from a zoonotic transmission of H2N2 from an avian reservoir into humans. This pandemic caused 2–4 million deaths and circulated until 1968. Since the disappearance of H2N2 from human populations, there has been waning immunity against H2, and this subtype is not currently incorporated into seasonal vaccines. However, H2 influenza remains a pandemic threat due to consistent circulation in avian reservoirs. Here, we describe a method of pandemic preparedness by creating an adenoviral-vectored centralized consensus vaccine design against human H2 influenza. We also assessed the utility of serotype-switching to enhance the protective immune responses seen with homologous prime-boosting strategies. Immunization with an H2 centralized consensus showed a wide breadth of antibody responses after vaccination, protection against challenge with a divergent human H2 strain, and significantly reduced viral load in the lungs after challenge. Further, serotype switching between two species C adenoviruses enhanced protective antibody titers after heterologous boosting. These data support the notion that an adenoviral-vectored H2 centralized consensus vaccine has the ability to provide broadly cross-reactive immune responses to protect against divergent strains of H2 influenza and prepare for a possible pandemic.

A single-shot adenoviral vaccine provides hemagglutinin stalk-mediated protection against heterosubtypic influenza challenge in mice

Conventional influenza vaccines fail to confer broad protection against diverse influenza A viruses with pandemic potential. Efforts to develop a universal influenza virus vaccine include refocusing immunity towards the highly conserved stalk domain of the influenza virus surface glycoprotein, hemagglutinin (HA). We constructed a non-replicating adenoviral (Ad) vector, encoding a secreted form of H1 HA, to evaluate HA stalk-focused immunity. The Ad5_H1 vaccine was tested in mice for its ability to elicit broad, cross-reactive protection against homologous, heterologous, and heterosubtypic lethal challenge in a single-shot immunization regimen. Ad5_H1 elicited hemagglutination inhibition (HI+) active antibodies (Abs), which conferred 100% sterilizing protection from homologous H1N1 challenge. Furthermore, Ad5_H1 rapidly induced H1-stalk-specific Abs with Fc-mediated effector function activity, in addition to stimulating both CD4+ and CD8+ stalk-specific T cell responses. This phenotype of immunity provided 100% protection from lethal challenge with a head-mismatched, reassortant influenza virus bearing a chimeric HA, cH6/1, in a stalk-mediated manner. Most importantly, 100% protection from mortality following lethal challenge with a heterosubtypic avian influenza virus, H5N1, was observed following a single immunization with Ad5_H1. In conclusion, Ad-based influenza vaccines can elicit significant breadth of protection in naive animals and could be considered for pandemic preparedness and stockpiling.

Relationship between blood clots and COVID-19 vaccines: A literature review

SARS-CoV-2 pandemic is one of the most critical pandemics during human civilization. Several therapeutic strategies for COVID-19 management have been offered; nonetheless, none of them seems to be sufficiently beneficial. In effect, vaccines have been proffered as a viable option. The critical issue now is to concentrate on protecting individuals against illness through immunization. One of the causes for concern among the researchers, physicians, and generally the whole community from the onset of vaccination has been the adverse effects (specifically blood clots) that may be observed after the injection of the COVID-19 vaccine. In some countries, such concerns have even resulted in the temporary or permanent discontinuation or abandonment of the application of some vaccines (especially AstraZeneca and Janssen). By evaluating rigorous studies published on this subject, the present article is aimed at identifying the association between blood clot incidence and COVID-19 vaccination. Various methods for producing the COVID-19 vaccines are analyzed, along with their possible pros and cons as well as common and rare side effects, especially VITT and blood clots. Finally, the differences of various vaccines on thrombotic events, WHO recommendations for VITT treatment, and blood clots statics are discussed.

Replicating Viral Vector-Based Vaccines for COVID-19: Potential Avenue in Vaccination Arena

The “severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)” is the third member of human coronavirus (CoV) that is held accountable for the current “coronavirus disease 2019 (COVID-19)” pandemic. In the past two decades, the world has witnessed the emergence of two other similar CoVs, namely SARS-CoV in 2002 and MERS-CoV in 2013. The extent of spread of these earlier versions was relatively low in comparison to SARS-CoV-2. Despite having numerous reports inclined towards the zoonotic origin of the virus, one cannot simply sideline the fact that no animal originated CoV is thus far identified that is considered similar to the initial edition of SARS-CoV-2; however, under-sampling of the diverse variety of coronaviruses remains a concern. Vaccines are proved to be an effective tool for bringing the end to such a devastating pandemic. Many vaccine platforms are explored for the same but in this review paper, we will discuss the potential of replicating viral vectors as vaccine carriers for SARS-CoV-2.

Human Adenovirus Type 26 Induced IL-6 Gene Expression in an αvβ3 Integrin- and NF-κB-Dependent Manner

The low seroprevalent human adenovirus type 26 (HAdV26)-based vaccine vector was the first adenovirus-based vector to receive marketing authorization from European Commission. HAdV26-based vaccine vectors induce durable humoral and cellular immune responses and, as such, represent a highly valuable tool for fighting infectious diseases. Despite well-described immunogenicity in vivo, the basic biology of HAdV26 still needs some refinement. The aim of this study was to determine the pro-inflammatory cytokine profile of epithelial cells infected with HAdV26 and then investigate the underlying molecular mechanism. The expression of studied genes and proteins was assessed by quantitative polymerase chain reaction, western blot, and enzyme-linked immunosorbent assay. Confocal microscopy was used to visualize HAdV26 cell uptake. We found that HAdV26 infection in human epithelial cells triggers the expression of pro-inflammatory cytokines and chemokines, namely IL-6, IL-8, IL-1β, and TNF-α, with the most pronounced difference shown for IL-6. We investigated the underlying molecular mechanism and observed that HAdV26-induced IL-6 gene expression is αvβ3 integrin dependent and NF-κB mediated. Our findings provide new data regarding pro-inflammatory cytokine and chemokine expression in HAdV26-infected epithelial cells, as well as details concerning HAdV26-induced host signaling pathways. Information obtained within this research increases our current knowledge of HAdV26 basic biology and, as such, can contribute to further development of HAdV26-based vaccine vectors.

[An impact of COVID-19 on the course of epilepsy]

To compare an impact of coronavirus disease and Sputnik V COVID-19 vaccine on the dynamics of epilepsy. The study is part of the ongoing «Epilepsy and COVID-19» independent research which recruited patients with epilepsy into two groups: group 1 - COVID-19 survivors and group 2 - patients vaccinated with a COVID-19 vaccine. The study compares two clinical cases: seizure recurrence with COVID-19 disease in a young patient and good tolerability of vaccination in a female elderly patient following surgical management of pharmacoresistant epilepsy with concomitant pathology. In group 1, a 32-year-old patient with idiopathic generalized epilepsy and 3-year seizure remission had generalized seizure recurrence with electroencephalographic deterioration against the backdrop of mild COVID-19. In group 2, a 59-year-old patient, with focal pharmacoresistant epilepsy, and 3-year seizure remission after surgical management, and comorbid endocrine dysfunction showed no side-effects with Sputnik V COVID-19 vaccination and maintained clinical and electroencephalographic remission. The study revealed that the Sputnik V vaccine was well tolerated, and that seizure remission was maintained after epilepsy surgery in an elderly patient with comorbidity, as well as there was the possibility of seizure recurrence in younger patients with mild COVID-19. The findings will aid practitioners in making decisions on how to manage epilepsy patients. More study into the impact of the disease and COVID-19 vaccination on epilepsy dynamics in a larger sample is required.

Restriction-Assembly: A Solution to Construct Novel Adenovirus Vector

Gene therapy and vaccine development need more novel adenovirus vectors. Here, we attempt to provide strategies to construct adenovirus vectors based on restriction-assembly for researchers with little experience in this field. Restriction-assembly is a combined method of restriction digestion and Gibson assembly, by which the major part of the obtained plasmid comes from digested DNA fragments instead of PCR products. We demonstrated the capability of restriction-assembly in manipulating the genome of simian adenovirus 1 (SAdV-1) in this study. A PCR product of the plasmid backbone was combined with SAdV-1 genomic DNA to construct an infectious clone, plasmid pKSAV1, by Gibson assembly. Restriction-assembly was performed repeatedly in the steps of intermediate plasmid isolation, modification, and restoration. The generated adenoviral plasmid was linearized by restriction enzyme digestion and transfected into packaging 293 cells to rescue E3-deleted replication-competent SAdV1XE3-CGA virus. Interestingly, SAdV1XE3-CGA could propagate in human chronic myelogenous leukemia K562 cells. The E1 region was similarly modified to generate E1/E3-deleted replication-defective virus SAdV1-EG. SAdV1-EG had a moderate gene transfer ability to adherent mammalian cells, and it could efficiently transduce suspension cells when compared with the human adenovirus 5 control vector. Restriction-assembly is easy to use and can be performed without special experimental materials and instruments. It is highly effective with verifiable outcomes at each step. More importantly, restriction-assembly makes the established vector system modifiable, upgradable and under sustainable development, and it can serve as the instructive method or strategy for the synthetic biology of adenoviruses.

Fighting Fire with Fire: Immunogenicity of Viral Vectored Vaccines against COVID-19

The persistent expansion of the coronavirus disease 2019 (COVID-19) global pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) requires the rapid development of safe and effective countermeasures to reduce transmission, morbidity, and mortality. Several highly efficacious vaccines are actively being deployed around the globe to expedite mass vaccination and control of COVID-19. Notably, viral vectored vaccines (VVVs) are among the first to be approved for global distribution and use. In this review, we examine the humoral, cellular, and innate immune responses elicited by viral vectors, and the immune correlates of protection against COVID-19 in preclinical and clinical studies. We also discuss the durability and breadth of immune response induced by VVVs and boosters. Finally, we present challenges associated with VVVs and offer solutions for overcoming certain limitations of current vaccine regimens. Collectively, this review provides the rationale for expanding the portfolio of VVVs against SARS-CoV-2.

The Complexity of SARS-CoV-2 Infection and the COVID-19 Pandemic

The pandemic caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) led to the death of millions of people worldwide and thousands more infected individuals developed sequelae due to the disease of the new coronavirus of 2019 (COVID-19). The development of several studies has contributed to the knowledge about the evolution of SARS-CoV2 infection and the disease to more severe forms. Despite this information being debated in the scientific literature, many mechanisms still need to be better understood in order to control the spread of the virus and treat clinical cases of COVID-19. In this article, we carried out an extensive literature review in order to bring together, in a single article, the biological, social, genetic, diagnostic, therapeutic, immunization, and even socioeconomic aspects that impact the SAR-CoV-2 pandemic. This information gathered in this article will enable a broad and consistent reading of the main aspects related to the current pandemic.

Immune responses following the first dose of the Sputnik V (Gam-COVID-Vac)

As the first dose of Gam-COVID-Vac, is currently used as a single dose vaccine in some countries, we investigated the immunogenicity of this at 4 weeks (327 naïve individuals). 88.7% seroconverted, with significantly lower seroconversion rates in those over 60 years (p = 0.004) and significantly lower than previously seen with AZD1222 (p = 0.018). 82.6% developed ACE2 receptor blocking antibodies, although levels were significantly lower than following natural infection (p = 0.0009) and a single dose of AZD1222 (p < 0.0001). Similar titres of antibodies were observed to the receptor binding domain of WT, B.1.1.7 and B.1.617.2 compared to AZD1222, while the levels for B.1.351 were significantly higher (p = 0.006) for Gam-COVID-Vac. 30% developed ex vivo IFNγ ELISpot responses (significantly lower than AZD1222), and high frequency of CD107a expressing T cells along with memory B cell responses. Although single dose of Gam-COVID-Vac was highly immunogenic, administration of a second dose is likely to be beneficial.

COVID-19 Vaccines: Adenoviral Vectors

The worldwide pandemic of coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has led to the unprecedented pace of development of multiple vaccines. This review evaluates how adenovirus (Ad) vector platforms have been leveraged in response to this pandemic. Ad vectors have been used in the past for vaccines against other viruses, most notably HIV and Ebola, but they never have been produced, distributed, or administered to humans at such a large scale. Several different serotypes of Ads encoding SARS-CoV-2 Spike have been tested and found to be efficacious against COVID-19. As vaccine rollouts continue and the number of people receiving these vaccines increases, we will continue to learn about this vaccine platform for COVID-19 prevention and control.