An enhanced system for construction of adenoviral vectors by the two-plasmid rescue method

A novel simian adenovirus-vectored COVID-19 vaccine elicits effective mucosal and systemic immunity in mice by intranasal and intramuscular vaccination regimens

IMPORTANCE

The essential goal of vaccination is to generate potent and long-term protection against diseases. Several factors including vaccine vector, delivery route, and boosting regimen influence the outcome of prime-boost immunization approaches. The immunization regimens by constructing a novel simian adenovirus-vectored COVID-19 vaccine and employing combination of intranasal and intramuscular inoculations could elicit mucosal neutralizing antibodies against five mutant strains in the respiratory tract and strong systemic immunity. Immune protection could last for more than 32 weeks. Vectored vaccine construction and immunization regimens have positively impacted respiratory disease prevention.

Rapid Construction of an Infectious Clone of Fowl Adenovirus Serotype 4 Isolate

Adenovirus vectors possess a good safety profile, an extensive genome, a range of host cells, high viral yield, and the ability to elicit broad humoral and cellular immune responses. Adenovirus vectors are widely used in infectious disease research for future vaccine development and gene therapy. In this study, we obtained a fowl adenovirus serotype 4 (FAdV-4) isolate from sick chickens with hepatitis-hydropericardium syndrome (HHS) and conducted animal regression text to clarify biological pathology. We amplified the transfer vector and extracted viral genomic DNA from infected LMH cells, then recombined the mixtures via the Gibson assembly method in vitro and electroporated them into EZ10 competent cells to construct the FAdV-4 infectious clone. The infectious clones were successfully rescued in LMH cells within 15 days of transfection. The typical cytopathic effect (CPE) and propagation titer of FAdV-4 infectious clones were also similar to those for wild-type FAdV-4. To further construct the single-cycle adenovirus (SC-Ad) vector, we constructed SC-Ad vectors by deleting the gene for IIIa capsid cement protein. The FAdV4 infectious clone vector was introduced into the ccdB cm expression cassette to replace the IIIa gene using a λ-red homologous recombination technique, and then the ccdB cm expression cassette was excised by PmeI digestion and self-ligation to obtain the resulting plasmids as SC-Ad vectors.

A review of transgenic animal techniques and their applications

Nowadays, breakthroughs in molecular biology are happening at an unprecedented rate. One of them is the ability to engineer transgenic animals. A transgenic animal is one whose genome has been changed to carry genes from another species or to use techniques for animal genome editing for specific traits. Animal features can be changed by purposefully altering the gene (or genes). A mouse was the first successful transgenic animal. Then pigs, sheep, cattle, and rabbits came a few years later. The foreign-interested genes that will be used in animal transgenic techniques are prepared using a variety of methods. The produced gene of interest is placed into a variety of vectors, including yeast artificial chromosomes, bacterial plasmids, and cosmids. Several techniques, including heat shock, electroporation, viruses, the gene gun, microinjection, and liposomes, are used to deliver the created vector, which includes the interesting gene, into the host cell. Transgenesis can be carried out in the gonads, sperm, fertilized eggs, and embryos through DNA microinjection, retroviruses, stem cells, and cloning. The most effective transgenic marker at the moment is fluorescent protein. Although transgenesis raises a number of ethical concerns, this review concentrates on the fundamentals of animal transgenesis and its usage in industry, medicine, and agriculture. Transgenesis success is confirmed by the integration of an antibiotic resistance gene, western and southern blots, PCR, and ELISA. If technology solves social and ethical problems, it will be the most promising in the future.

An Optimized CRISPR/Cas9 Adenovirus Vector (AdZ-CRISPR) for High-Throughput Cloning of sgRNA, Using Enhanced sgRNA and Cas9 Variants

Recombinant adenovirus vectors enable highly efficient gene delivery in vitro and in vivo. As a result, they are widely used in gene therapy, vaccination, and anticancer applications. We have previously developed the AdZ vector system, which uses recombineering to permit high-throughput cloning of transgenes into Adenovirus vectors, simplifies alteration of the vector backbone, and enables rapid recovery of infectious virus, even if a transgene is incompatible with vector replication. In this study, we adapt this vector system to enable high-throughput cloning of sequences for CRISPR/Cas9 editing. Vectors were optimized to ensure efficient cloning, and high editing efficiency using spCas9 and single guide RNA (sgRNA) sequences in a single vector. Using a multiplicity of infection of 50, knockout efficiencies of up to 80% could be achieved with a single sgRNA. Vectors were further enhanced by altering the spCas9 sequence to match that of SniperCas9, which has reduced off-target activity, but maintains on-target efficiency, and by applying modifications to the sgRNA sequence that significantly enhance editing efficiency. Thus, the AdZ-CRISPR vectors offer highly efficient knockout, even in hard to transfect cells, and enables large-scale CRISPR/Cas9 projects to be undertaken easily and quickly.

ATP6AP2 knockdown in cardiomyocyte deteriorates heart function via compromising autophagic flux and NLRP3 inflammasome activation

Moderate autophagy can remove damaged proteins and organelles. In some inflammatory diseases, autophagy plays a protective role by inhibiting the NOD-like receptor family pyrin domain containing 3(NLRP3). (Pro)renin receptor (PRR, or ATP6AP2) is a critical component of the V-ATPase required for autophagy. It remains controversial about ATP6AP2 in the pathological process. The impact of ATP6AP2 on NLRP3 inflammasome and autophagic flux remains unknown under pressure overload stress. This research explores the potential link between ATP6AP2, autophagic flux, and NLRP3. There was upregulation of ATP6AP2 from 5-day post-TAC, and this expression remained at a high level until 8-weeks post-TAC in wild mice. Meanwhile, autophagic flux switched from early compensatory activation to blocking in the heart failure phase. NLRP3 activation can be seen at 8-week post-TAC. Adenovirus-mediated knockdown of ATP6AP2(shR-ATP6AP2) accelerated the progress of heart failure. After TAC was induced, shR-ATP6AP2 significantly deteriorated heart function and fibrosis compared with the shR-Scr group. Meanwhile, there was an elevated expression of NLRP3 and autophagic flux blockage. A transgenic mouse(Tg) with cardio-restricted ATP6AP2/(P)RR overexpression was constructed. Although high expression in cardiac tissue, there were no spontaneous functional abnormalities under the basal state. Cardiac function, fibrosis, hypertrophy remained identical to the control TAC group. However, SQSTM1/P62 was reduced, which indicated the relief of autophagic flux blockage. Further, Neonatal rat ventricular myocyte (NRVMs) transfected with shR-ATP6AP2 showed more susceptibility than sh-Scr NRVMs to phenylephrine-induced cell death. More reactive oxygen species (ROS) or mito-ROS accumulated in the shR-ATP6AP2 group when phenylephrine stimulation. Blocking NLRP3 activation in vivo partly rescued cardiac dysfunction and fibrosis. In conclusion, ATP6AP2 upregulation is a compensatory response to pressure overload. If not effectively compensated, it compromises autophagic flux, leads to dysfunctional mitochondria accumulation, further produces ROS to activate NLRP3, eventually accelerates heart failure.

Review: Development of SARS-CoV-2 immuno-enhanced COVID-19 vaccines with nano-platform

Vaccination is the most effective way to prevent coronavirus disease 2019 (COVID-19). Vaccine development approaches consist of viral vector vaccines, DNA vaccine, RNA vaccine, live attenuated virus, and recombinant proteins, which elicit a specific immune response. The use of nanoparticles displaying antigen is one of the alternative approaches to conventional vaccines. This is due to the fact that nano-based vaccines are stable, able to target, form images, and offer an opportunity to enhance the immune responses. The diameters of ultrafine nanoparticles are in the range of 1-100 nm. The application of nanotechnology on vaccine design provides precise fabrication of nanomaterials with desirable properties and ability to eliminate undesirable features. To be successful, nanomaterials must be uptaken into the cell, especially into the target and able to modulate cellular functions at the subcellular levels. The advantages of nano-based vaccines are the ability to protect a cargo such as RNA, DNA, protein, or synthesis substance and have enhanced stability in a broad range of pH, ambient temperatures, and humidity for long-term storage. Moreover, nano-based vaccines can be engineered to overcome biological barriers such as nonspecific distribution in order to elicit functions in antigen presenting cells. In this review, we will summarize on the developing COVID-19 vaccine strategies and how the nanotechnology can enhance antigen presentation and strong immunogenicity using advanced technology in nanocarrier to deliver antigens. The discussion about their safe, effective, and affordable vaccines to immunize against COVID-19 will be highlighted.

CircRNF111 Protects Against Insulin Resistance and Lipid Deposition via Regulating miR-143-3p/IGF2R Axis in Metabolic Syndrome

Abnormal expression of circRNAs (circular RNAs), a subclass of non-coding RNAs, has been documented in numerous human diseases. Herein, we explored whether circRNAs act as ceRNAs (competing endogenous RNAs) to modulate the pathological process-insulin resistance, as well as dyslipidemia of MetS (Metabolic Syndrome). The profile of circRNAs in serume of MetS and control samples was characterized by circRNA deep sequencing. We identified circRNF111 as a key downregulated circRNA involved in MetS. The decreased expression of circRNF111 in the serum samples of MetS was directly linked to excessive insulin resistance and dyslipidemia. Loss-of-function experiments showed that circRNF111 knockdown inhibited the glucose uptake and the Akt signaling pathway, meanwhile increased the deposition of triglycerides in adipogenic differentiated hADSCs (human adipose-derived stem cells). Mechanistically, circRNF111 sponged miR-143-3p and functioned via targeting miR-143-3p along with its downstream target gene IGF2R. The role along with the mechanism of circRNF111 sponging miR-143-3p in MetS was also explored in obese mice triggered by high-fat die. Therefore, our data suggest a protective role of the novel circRNA-circRNF111 in MetS progression. CircRNF111 inhibition enhances insulin resistance and lipid deposition in MetS through regulating miR-143-3p-IGF2R cascade. This provides a promising therapeutic approach for MetS.

Mechanisms that allow vaccination against an oncolytic vesicular stomatitis virus-encoded transgene to enhance safety without abrogating oncolysis

Vaccination can prevent viral infections via virus-specific T cells, among other mechanisms. A goal of oncolytic virotherapy is replication of oncolytic viruses (OVs) in tumors, so pre-existing T cell immunity against an OV-encoded transgene would seem counterproductive. We developed a treatment for melanomas by pre-vaccinating against an oncolytic vesicular stomatitis virus (VSV)-encoded tumor antigen. Surprisingly, when the VSV-vectored booster vaccine was administered at the peak of the primary effector T cell response, oncolysis was not abrogated. We sought to determine how oncolysis was retained during a robust T cell response against the VSV-encoded transgene product. A murine melanoma model was used to identify two mechanisms that enable this phenomenon. First, tumor-infiltrating T cells had reduced cytopathic potential due to immunosuppression. Second, virus-induced lymphopenia acutely removed virus-specific T cells from tumors. These mechanisms provide a window of opportunity for replication of oncolytic VSV and rationale for a paradigm change in oncolytic virotherapy, whereby immune responses could be intentionally induced against a VSV-encoded melanoma-associated antigen to improve safety without abrogating oncolysis.

Combined vaccination and immunostimulatory antibodies provides durable cure of murine melanoma and induces transcriptional changes associated with positive outcome in human melanoma patients

We have developed a recombinant adenovirus vaccine encoding dopachrome tautomerase (rHuAd5-hDCT) that produces robust DCT-specific immunity, but only provides modest suppression of murine melanoma. In the current study, an agonist antibody against 4-1BB was shown to enhance rHuAd5-hDCT efficacy and evoke tumor regression, but most tumors ultimately relapsed. The vaccine triggered upregulation of the immune inhibitory PD-1 signaling pathway and PD-1 blockade dramatically enhanced the rHuAd5-hDCT + anti-4-1BB strategy, resulting in complete regression of growing tumors in > 70% of recipients. The impact of the combined anti-4-1BB/anti-PD-1 treatment did not manifest as a dramatic enhancement in either the magnitude or functionality of DCT-specific tumor infiltrating lymphocytes relative to either treatment alone. Rather, a synergistic enhancement in intratumoral cytokine expression was observed, suggesting that the benefit of the combined therapy was a local event within the tumor. Global transcriptional analysis revealed immunological changes within the tumor following the curative vaccination, which extended beyond the T cell compartment. We identified an immune signature of 85 genes associated with clearance of murine melanoma that correlated with improved survival outcome in two independent cohorts of human melanoma patients. Our data reinforce the concept that successful vaccination must overcome local hurdles in the tumor microenvironment that are not manifest within the periphery. Further, tumor rejection following vaccination involves more than simply T cells. Finally, the association of our immune signature with positive survival outcome in human melanoma patients suggests that similar vaccination strategies may be promising for melanoma treatment.

Pro-Renin Receptor Overexpression Promotes Angiotensin II-Induced Abdominal Aortic Aneurysm Formation in Apolipoprotein E-Knockout Mice

The pro-renin receptor (PRR) is an important novel component of the renin-angiotensin (Ang) system that has multiple functions, which are not yet completely understood. In this study, we aimed to explore the effect of PRR on the formation of Ang II-induced abdominal aortic aneurysm (AAA) in apolipoprotein E-knockout mice. We used Ang II (1.44 mg/kg/day) infusion to induce AAA followed by a treatment of saline, telmisartan, no treatment, Ad-EGFP, Ad-PRR, or Ad-PRR plus telmisartan. The incidence of AAA was 35%, 60%, 65%, 90%, and 55% in the Telmisartan, Vehicle, Ad-EGFP, Ad-PRR, and Ad-PRR+Telmisartan groups, respectively. Compared with the Vehicle and Ad-EGFP groups, PRR overexpression markedly increased macrophage infiltration; levels of proinflammatory cytokines, including monocyte chemoattractant protein-1 (MCP-1) and tumor necrosis factor-α (TNF-α); the expression and activity of MMP2 and MMP9; NOX2 and NOX4 protein and mRNA expression; nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activity; extracellular-signal-regulated kinase (ERK) and P38MAPK expression; but decreased smooth muscle cells content in AAA. However, telmisartan reversed the adverse effects of PRR. In addition, ERK inhibitor PD98059 eliminated the acceleration of Ang II-induced AAA formation by PRR, and coadministration of telmisartan and PD98059 further abolished the adverse effects of PRR on Ang II-induced AAA formation. Thus, PRR plays an important role in the pathological development of AAA via both Ang II-dependent and Ang II-independent activation of ERK pathways. These results suggest that inhibition of PRR activation may be a promising approach to the treatment of AAA.

CircRNA_014511 affects the radiosensitivity of bone marrow mesenchymal stem cells by binding to miR-29b-2-5p

Hematopoietic stem cell transplantation is commonly used in patients with certain hematological or bone marrow tumors. Total body irradiation combined with chemotherapy is part of the preconditioning protocol that was the most commonly used before hematopoietic stem cell transplantation. However, total body irradiation preconditioning damages other normal cells in bone marrow. Therefore, exploring the mechanism of radiation resistance in bone marrow mesenchymal stem cells is of great significance for recovering the hematopoietic function after cell transplantation. This study aimed to demonstrate the miR-29b adsorption of circRNA_014511 and explore the effect of circRNA_014511 on radiosensitivity of bone marrow mesenchymal stem cells. In this study, circRNA_014511 overexpression vector was constructed and transfected into bone marrow mesenchymal stem cells, miR-29b-2-5p and P53 were found to be decreased, which could be reversed by miR29b-mimics. Dual luciferase reporter assay confirmed the binding of circRNA_014511 and mmu-miR-29b-2-5p. Flow cytometry analysis showed the apoptosis rate of bone marrow mesenchymal stem cells overexpressing circRNA_014511 was significantly decreased. In the circRNA_014511 transfection group, after cells were subjected to 6Gy irradiation, G2 phase arrest appeared, the expression of P21 and GADD45A was significantly decreased, and cyclin B1 was significantly increased. Colony formation assay showed the survival fraction of circRNA_014511 overexpression cells after irradiation was significantly higher than control group, and the radiosensitivity was decreased. In conclusion，our findings demonstrated that circRNA_014511 could inhibit the expression of P53 by binding miR-29b-2-5p, and decrease the radiosensitivity of bone marrow mesenchymal stem cells by affecting cell cycle and cell apoptosis.

Effects of the (Pro)renin Receptor on Cardiac Remodeling and Function in a Rat Alcoholic Cardiomyopathy Model via the PRR-ERK1/2-NOX4 Pathway

Alcoholic cardiomyopathy (ACM) caused by alcohol consumption manifests mainly as by maladaptive myocardial function, which eventually leads to heart failure and causes serious public health problems. The (pro)renin receptor (PRR) is an important member of the local tissue renin-angiotensin system and plays a vital role in many cardiovascular diseases. However, the mechanism responsible for the effects of PRR on ACM remains unclear. The purpose of this study was to determine the role of PRR in myocardial fibrosis and the deterioration of cardiac function in alcoholic cardiomyopathy. Wistar rats were fed a liquid diet containing 9% v/v alcohol to establish an alcoholic cardiomyopathy model. Eight weeks later, rats were injected with 1 × 10⁹v.g./100 μl of recombinant adenovirus containing EGFP (scramble-shRNA), PRR, and PRR-shRNA via the tail vein. Cardiac function was assessed by echocardiography. Cardiac histopathology was measured by Masson's trichrome staining, immunohistochemical staining, and dihydroethidium staining. In addition, cardiac fibroblasts (CFs) were cultured to evaluate the effects of alcohol stimulation on the production of the extracellular matrix and their underlying mechanisms. Our results indicated that overexpression of PRR in rats with alcoholic cardiomyopathy exacerbates myocardial oxidative stress and myocardial fibrosis. Silencing of PRR expression with short hairpin RNA (shRNA) technology reversed the myocardial damage mediated by PRR. Additionally, PRR activated phosphorylation of ERK1/2 and increased NOX4-derived reactive oxygen species and collagen expression in CFs with alcohol stimulation. Administration of the ERK kinase inhibitor (PD98059) significantly reduced NOX4 protein expression and collagen production, which indicated that PRR increases collagen production primarily through the PRR-ERK1/2-NOX4 pathway in CFs. In conclusion, our study demonstrated that PRR induces myocardial fibrosis and deteriorates cardiac function through ROS from the PRR-ERK1/2-NOX4 pathway during ACM development.

Enhancing Immune Responses to Cancer Vaccines Using Multi-Site Injections

For a vaccine to be effective it must induce a sufficiently robust and specific immune response. Multi-site injection protocols can increase the titers of rabies virus-neutralizing antibodies. Hypothetically, spreading a vaccine dose across multiple lymphatic drainage regions could also potentiate T cell responses. We used a replication-deficient adenovirus serotype 5-vectored cancer vaccine targeting the melanoma-associated antigen dopachrome tautomerase. Clinically, high numbers of tumor-infiltrating CD8⁺ T cells are a positive prognostic indicator. As such, there is interest in maximizing tumor-specific T cell responses. Our findings confirm a positive correlation between the number of tumor-specific T cells and survival. More importantly, we show for the first time that using multiple injection sites could increase the number of vaccine-induced CD8⁺ T cells specific for a self-tumor antigen. Further, the number of tumor antigen-specific antibodies, as well CD8⁺ T cells specific for a foreign antigen could also be enhanced. Our results show that multi-site vaccination induces higher magnitude immune responses than a single-bolus injection. This provides a very simple and almost cost-free strategy to potentially improve the efficacy of any current and future vaccine. Broader clinical adoption of multi-site vaccination protocols for the treatment of cancers and infectious diseases should be given serious consideration.

Effect of adenovirus-mediated RNA interference of IL-1β expression on spinal cord injury in rats

STUDY DESIGN

We introduced an adenoviral vector expressing interleukin-1β (IL-1β) small-hairpin RNA (shRNA) into the injured spinal cords to evaluate the therapeutic potential of IL-1β downregulation in a rat model of spinal cord injury (SCI).

OBJECTIVES

The purpose of this study was to investigate the possible protective effects of the IL-1β downregulation on traumatic SCI in rats.

SETTING

Department of Orthopedic Surgery, The Second Affiliated Hospital, Fujian Medical University, Quanzhou, People's Republic of China.

METHODS

An adenoviral shRNA targeting IL-1β was constructed and injected at the T12 section 7 days before SCI. The rats' motor functions were evaluated by the Basso-Beattie-Bresnahan (BBB) rating scale. Immunofluorescence, enzyme-linked immunosorbent assay, flow-cytometric analysis and western blots were also performed.

RESULTS

Animals downregulating IL-1β had significantly better recovery of locomotor function and less neuronal loss after SCI. In addition, IL-1β downregulation significantly decreased tumor necrosis factor-alpha (TNF-α) level and Bax expression, reduced the activity of caspase-3 and increased Bcl-2 expression after SCI.

CONCLUSION

This study demonstrated that the IL-1β downregulation may have potential therapeutic benefits for both reducing secondary damages and improving the outcomes after traumatic SCI.

Localization of neutralization epitopes on adenovirus fiber knob from species C

Although potential neutralization epitopes on the fiber knob of adenovirus (AdV) serotype 2 (Ad2) and Ad5 have been revealed, few studies have been carried out to identify neutralization epitopes on the knob from a broader panel of AdV serotypes. In this study, based on sequence and structural analysis of knobs from Ad1, Ad2, Ad5 and Ad6 (all from species C), several trimeric chimeric knob proteins were expressed in Escherichia coli to identify the locations of neutralization epitopes on the knobs by analysing their reactivity with mouse and rabbit polyclonal sera raised against AdVs and human sera with natural AdV infection. The dominant neutralization epitopes were located mainly in the N-terminal part of knobs from Ad1, Ad2 and Ad5, but they seemed to be located in the C-terminal part of the Ad6 knob, with some individual differences in rabbit and human populations. Our study adds to our understanding of humoral immune responses to AdVs and will facilitate the construction of more desirable capsid-modified recombinant Ad5 vectors.

Nogo-B protects mice against lipopolysaccharide-induced acute lung injury

Nogo-B, a member of the reticulon 4 protein family, plays a critical role in tissue repair and acute inflammation. Its role in acute lung injury (ALI) remains unclear. Here, we assessed the function of Nogo-B during tissue injury in a lipopolysaccharide (LPS)-induced ALI mouse model. We found that pulmonary Nogo-B was significantly repressed after LPS instillation in C57BL/6 mice. Over-expression of pulmonary Nogo-B using an adenovirus vector carrying the Nogo-B-RFP-3flag gene (Ad-Nogo-B) significantly prolonged the survival of mice challenged with a lethal dose of LPS. The Ad-Nogo-B-treated mice also had less severe lung injury, less alveolar protein exudation, and a higher number of macrophages but less neutrophil infiltration compared with Ad-RFP-treated mice. Interestingly, microarray analysis showed that the Ad-Nogo-B-treated mice had different gene expression profiles compared with the controls and the prominent expression of genes related to wound healing and the humoral immune response after LPS induction. Of the 49 differently expressed genes, we found that the expression of PTX3 was significantly up-regulated following Nogo-B over-expression as observed in lung tissues and RAW264.7 cells. In conclusion, Nogo-B plays a protective role against LPS-induced ALI, and this effect might be exerted through the modulation of alveolar macrophage recruitment and PTX3 production.

Transfer of the IL-37b gene elicits anti-tumor responses in mice bearing 4T1 breast cancer

AIM

IL-37b has shown anti-cancer activities in addition to its anti-inflammatory properties. In this study, we investigated the effects of IL-37b on breast carcinoma growth in mice and to determine the involvement of T cell activation in the effects.

METHODS

IL-37b gene was transferred into mouse breast carcinoma cell line 4T1 (4T1-IL37b cells), the expression of secretory IL-37b by the cells was detected, and the effects of IL-37b expression on the cell proliferation in vitro was evaluated. After injection of 4T1 cells or 4T1-IL37b cells into immunocompetent BALB/c mice, immunodeficient BALB/c nude mice and NOD-SCID mice, the tumor growth and survival rate were measured. The proliferation of T cells in vitro was also detected.

RESULTS

IL-37b was detected in the supernatants of 4T1-IL37b cells with a concentration of 12.02 ± 0.875 ng/mL. IL-37b expression did not affect 4T1 cell proliferation in vitro. BALB/c mice inoculated with 4T1-IL37b cells showed significant retardation of tumor growth. BALB/c mice inoculated with both 4T1 cells and mitomycin C-treated 4T1-IL37b cells also showed significant retardation of tumor growth. But the anti-cancer activity of IL-37b was abrogated in BALB/c nude mice and NOD-SCID mice inoculated with 4T1-IL37b cells. Recombinant IL-37b slightly promoted CD4(+) T cell proliferation without affecting CD8(+) T cell proliferation.

CONCLUSION

IL-37b exerts anti-4T1 breast carcinoma effects in vivo by modulating the tumor microenvironment and influencing T cell activation.

Gene transfer into cardiac myocytes

Traditional methods for DNA transfection are often inefficient and toxic for terminally differentiated cells, such as cardiac myocytes. Vector-based gene transfer is an efficient approach for introducing exogenous cDNA into these types of primary cell cultures. In this chapter, separate protocols for adult rat cardiac myocyte isolation and gene transfer with recombinant adenovirus are provided and are routinely utilized for studying the effects of sarcomeric proteins on myofilament function.

Angiotensin-converting enzyme-2 overexpression attenuates inflammation in rat model of chronic obstructive pulmonary disease

OBJECTIVE

To investigate the anti-inflammatory effects of angiotensin-converting enzyme 2 (ACE2) overexpression on rat model of chronic obstructive pulmonary disease (COPD), and explore underlying mechanism.

METHODS

The rat COPD model was established by cigarette smoking using a total body exposure method. A total of 64 male Wistar rats were randomly divided into four groups: normal, COPD, Ad-ACE2 and Ad-EGFP groups. The COPD model rats (including COPD, Ad-ACE2 and Ad-EGFP groups) received an intratracheal injection of normal saline, Ad-ACE2 and Ad-EGFP, respectively. The normal group underwent the same procedure but received an intratracheal injection of normal saline only. Pulmonary function tests, lung histopathology analysis, malondialdehyde (MDA) and reactive oxygen species (ROS) level, ACE2 mRNA and protein expression level, inflammatory cytokines and related signaling pathway proteins were measured.

RESULTS

COPD rats showed impairment of lung function as evidenced by decreased ratio of forced expiratory volume at 0.3 s and forced vital capacity (FEV0.3/FVC) and dynamic lung compliance (Cldyn), increased resistance inspiration (Ri) and resistance expiration (Re) as compared with the normal group, accompanying with reduced ACE2 mRNA expression, elevated ROS and MDA, elevated inflammatory cytokines levels (tumor necrosis factor α, TNF-α; interleukin-8, IL-8; IL-2 and IL-1β) and activation of nuclear factor-κB (NF-κB) and p38 MAPK (mitogen activated protein kinases) pathway in lung tissues. ACE2 overexpression through Ad-ACE2 infusion significantly attenuated the inflammatory response in lung tissues of COPD model rats.

CONCLUSION

ACE2 could attenuate COPD inflammatory process induced by cigarette smoke through reduction of oxidative stress and inhibition of NF-κB and p38 MAPK pathway activation.

Vaccination with tumor cells expressing IL-15 and IL-15Rα inhibits murine breast and prostate cancer

A number of antitumor vaccines have recently shown promise in upregulating immune responses against tumor antigens and improving patient survival. In this study, we examine the effectiveness of vaccination using interleukin (IL)-15-expressing tumor cells and also examine their ability to upregulate immune responses to tumor antigens. We demonstrated that the coexpression of IL-15 with its receptor, IL-15Rα, increased the cell-surface expression and secretion of IL-15. We show that a gene transfer approach using recombinant adenovirus to express IL-15 and IL-15Rα in murine TRAMP-C2 prostate or TS/A breast tumors induced antitumor immune responses. From this, we developed a vaccine platform, consisting of TRAMP-C2 prostate cancer cells or TS/A breast cancer cells coexpressing IL-15 and IL-15Rα that inhibited tumor formation when mice were challenged with tumor. Inhibition of tumor growth led to improved survival when compared with animals receiving cells expressing IL-15 alone or unmodified tumor cells. Animals vaccinated with tumor cells coexpressing IL-15 and IL-15Rα showed greater tumor infiltration with CD8(+) T and natural killer (NK) cells, as well as increased antitumor CD8(+) T-cell responses. Vaccination with IL-15/IL-15Rα-modified TS/A breast cancer cells provided a survival advantage to mice challenged with unrelated murine TUBO breast cancer cells, indicating the potential for allogeneic IL-15/IL-15Rα-expressing vaccines.

Immunotherapy-induced CD8+ T cells instigate immune suppression in the tumor

Despite clear evidence of immunogenicity, cancer vaccines only provide a modest clinical benefit. To evaluate the mechanisms that limit tumor regression following vaccination, we have investigated the weak efficacy of a highly immunogenic experimental vaccine using a murine melanoma model. We discovered that the tumor adapts rapidly to the immune attack instigated by tumor-specific CD8+ T cells in the first few days following vaccination, resulting in the upregulation of a complex set of biological networks, including multiple immunosuppressive processes. This rapid adaptation acts to prevent sustained local immune attack, despite continued infiltration by increasing numbers of tumor-specific T cells. Combining vaccination with adoptive transfer of tumor-specific T cells produced complete regression of the treated tumors but did not prevent the adaptive immunosuppression. In fact, the adaptive immunosuppressive pathways were more highly induced in regressing tumors, commensurate with the enhanced level of immune attack. Examination of tumor infiltrating T-cell functionality revealed that the adaptive immunosuppression leads to a progressive loss in T-cell function, even in tumors that are regressing. These novel observations that T cells produced by therapeutic intervention can instigate a rapid adaptive immunosuppressive response within the tumor have important implications for clinical implementation of immunotherapies.

The novel replication-defective vaccinia virus (Tiantan strain)-based hepatitis C virus vaccine induces robust immunity in macaques

The induction of a robust neutralizing antibody (nAb) response is likely to be as essential as specific cell-mediated immunity (CMI) against multiple antigens for the development of effective preventive and therapeutic vaccines against hepatitis C virus (HCV) infection in humans. To date, no data on the immunogenicity of the replication-defective vaccinia virus (derived from the Tiantan strain) (rNTV)-based HCV vaccine in primates have been reported. This study describes in detail the immunogenicity of various vaccine candidates in rhesus macaques, including rNTV-based and replication-defective recombinant adenoviral (rAd)-based HCV vaccines, as well as HCV pseudotyped virus-like particles (HCVpp). Our data showed that rAd-HCV vaccine boosting induced robust CMI, while priming or boosting with HCVpp enhanced the antigen-specific nAb response after rAd-HCV vaccination; however, CMI was not enhanced. Vaccination includes rNTV-HCV priming induced robust antigen-specific antibody, particularly nAbs, and CMI responses. Furthermore, more robust and longer-lasting CMI and higher cytokine levels (both Th1 and Th2 types, especially IFN-γ) resulted from boosting with rAd-HCV. We conclude that the rNTV-based HCV vaccine induces robust nAbs and CMI when combined with a heterogeneous primer-booster strategy, which shows promise for development of a human HCV vaccine.

HER3 targeting of adenovirus by fiber modification increases infection of breast cancer cells in vitro, but not following intratumoral injection in mice

Despite the tremendous potential of adenovirus (Ad) as a delivery vector for cancer gene therapy, its use in clinical settings has been limited, mainly as a result of the limited infectivity in many tumors and the wide tissue tropism associated with Ad. To modify the tropism of the virus, we have inserted the epidermal growth factor-like domain of the human heregulin-α (HRG) into the HI loop of Ad5 fiber. This insertion had no adverse effect on fiber trimerization nor did it affect incorporation of the modified fiber into infectious viral particles. Virions bearing modified fiber displayed growth characteristics and viral yields indistinguishable from those of wild-type (wt) virus. Most importantly, HRG-tagged virions showed enhanced infection of cells expressing the cognate receptors HER3/ErbB3 and HER4/ErbB4. This was significantly reduced in the presence of soluble HRG. Furthermore, HER3-expressing Chinese hamster ovary (CHO) cells were transduced by the HRG-modified virus, but not by wt virus. In contrast, CHO cells expressing the coxsackie-Ad receptor were transduced with both viruses. However, infection of an in vivo breast cancer xenograft model after intratumoral injection was similar with both viruses, suggesting that the tumor microenvironment and/or the route of delivery have important roles in infection of target cells with fiber-modified Ads.

Optimizing vaccine-induced CD8(+) T-cell immunity: focus on recombinant adenovirus vectors

Recombinant adenoviruses have emerged as promising viral vectors for CD8(+) T-cell vaccines. Our studies have indicated that unlike most acute infections, the CD8(+) T-cell memory population elicited by recombinant human adenovirus serotype 5 (rHuAd5) displays a dominant effector memory phenotype. Persistent, low-level transgene expression from the rHuAd5 vector sustains the CD8(+) T-cell memory population and a nonhematopoietic cell compartment appears to be involved in long-term presentation of adenoviral antigens. Although we are beginning to learn more about the factors that control the maintenance and functionality of memory CD8(+) T cells, we do not yet fully understand what comprises a protective CD8(+) T-cell response. Results from upcoming Phase II clinical trials will be important for determining whether rHuAd5 T-cell vaccines are effective in humans and should help identify correlates of CD8(+) T-cell protection.

Optimizing adenoviral transduction of endothelial cells under flow conditions

PURPOSE

To target adenoviral vectors to cells of the vasculature and shielding vectors from inactivation by the immune system.

METHODS

Complexes of reporter gene expressing adenoviral vectors with positively charged magnetic nanoparticles were formed by electrostatic interaction in presence or absence of additional negatively charged poly(ethylene glycol)-based polymer. Transduction of HUVEC was analyzed in vitro under flow. Protection from inactivation by the immune system was analyzed by pre-incubation of AdV and complexes with neutralizing antibodies and subsequent reporter protein analysis of infected cells.

RESULTS

Physical association of AdV with MNP and polymers was demonstrated by radioactive labelling of components and co-sedimentation in a magnetic field. Ad-MNP+/-polymer resulted in efficient transduction of HUVEC, depending on MOI and flow rate in presence of magnetic field, whereas no transduction was observed without complex formation with MNP or in absence of magnetic field. Association with MNP did result in protection from neutralizing antibodies, with slightly increased protection provided by the polymer.

CONCLUSIONS

Complex formation of AdV with MNP is a viable means for targeting of vectors to areas of magnetic field gradient. Additional coating with polymer might proof useful in protection from inactivation by the immune system.

Effect of route of delivery on heterologous protection against HCV induced by an adenovirus vector carrying HCV structural genes

Background

An effective vaccine and new therapeutic methods for hepatitis C virus (HCV) are needed, and a potent HCV vaccine must induce robust and sustained cellular-mediated immunity (CMI). Research has indicated that adenoviral and vaccinia vectors may have the ability to elicit strong B and T cell immune responses to target antigens.

Results

A recombinant replication-defective adenovirus serotype 5 (rAd5) vector, rAd5-CE1E2, and a recombinant Tian Tan vaccinia vector, rTTV-CE1E2, were constructed to express the HCV CE1E2 gene (1-746 amino acid HCV 1b subtype). Mice were prime-immunised with rAd5-CE1E2 delivered via intramuscular injection (i.m.), intranasal injection (i.n.), or intradermal injection (i.d.) and boosted using a different combination of injection routes. CMI was evaluated via IFN-γ ELISPOT and ICS 2 weeks after immunisation, or 16 weeks after boost for long-term responses. The humoral response was analysed by ELISA. With the exception of priming by i.n. injection, a robust CMI response against multiple HCV antigens (core, E1, E2) was elicited and remained at a high level for a long period (16 weeks post-vaccination) in mice. However, i.n. priming elicited the highest anti-core antibody levels. Priming with i.d. rAd5-CE1E2 and boosting with i.d. rTTV-CE1E2 carried out simultaneously enhanced CMI and the humoral immune response, compared to the homologous rAd5-CE1E2 immune groups. All regimens demonstrated equivalent cross-protective potency in a heterologous surrogate challenge assay based on a recombinant HCV (JFH1, 2a) vaccinia virus.

Conclusions

Our data suggest that a rAd5-CE1E2-based HCV vaccine would be capable of eliciting an effective immune response and cross-protection. These findings have important implications for the development of T cell-based HCV vaccine candidates.

Adenoviral-transduced dendritic cells are susceptible to suppression by T regulatory cells and promote interleukin 17 production

Dendritic cell (DC) vaccines offer a robust platform for the development of cancer vaccines, but their effectiveness is thought to be limited by T regulatory cells (Tregs). Recombinant adenoviruses (RAdV) have been used successfully to engineer tumor antigen expression in DCs, but the impact of virus transduction on susceptibility to suppression by Tregs is unknown. We investigated the functional consequences of exposure to adenovirus on interactions between human monocyte-derived DCs and Tregs. Since the development of Tregs is linked to that of pro-inflammatory Th17 cells, the role of Th17 cells and IL-17-producing Tregs in the context of DC-based immunotherapies was also investigated. We found that Tregs potently suppressed the co-stimulatory capacity of RAdV-transduced DCs, regardless of whether the DCs were maturated by inflammatory cytokines or by exposure to Th1 or Th17 cells. Furthermore, exposure of Tregs to RAdV-exposed DCs increased IL-17 production and suppressive capacity, and correlated with enhanced secretion of IL-1β and IL-6 by DCs. The findings that DCs exposed to RAdV are suppressed by Tregs, promote Treg plasticity, and enhance Treg suppression indicates that strategies to limit Tregs will be required to enhance the efficacy of such DC-based immunotherapies.

Production of adenovirus vectors and their use as a delivery system for influenza vaccines

IMPORTANCE OF THE FIELD

With the emergence of highly pathogenic avian influenza H5N1 viruses that have crossed species barriers and are responsible for lethal infections in humans in many countries, there is an urgent need for the development of effective vaccines which can be produced in large quantities at a short notice and confer broad protection against these H5N1 variants. In order to meet the potential global vaccine demand in a pandemic scenario, new vaccine-production strategies must be explored in addition to the currently used egg-based technology for seasonal influenza.

AREAS COVERED IN THIS REVIEW

Adenovirus (Ad) based influenza vaccines represent an attractive alternative/supplement to the currently licensed egg-based influenza vaccines. Ad-based vaccines are relatively inexpensive to manufacture, and their production process does not require either chicken eggs or labor-intensive and time-consuming processes necessitating enhanced biosafety facilities. Most importantly, in a pandemic situation, this vaccine strategy could offer a stockpiling option to reduce the response time before a strain-matched vaccine could be developed.

WHAT THE READER WILL GAIN

This review discusses Ad-vector technology and the current progress in the development of Ad-based influenza vaccines.

TAKE HOME MESSAGE

Ad vector-based influenza vaccines for pandemic preparedness are under development to meet global vaccine demand.

Adenovirus-mediated gene transfer

Recombinant adenoviruses are attractive vectors for short-term expression in mouse liver and primary cell lines. Various versatile vector systems have been developed which can be used for the reliable production of recombinant adenoviruses. This protocol describes the entire process for the production of recombinant adenoviruses using the AdEasy system. This protocol will give a practical step-by-step description from the cloning of the gene of interest until the in vivo administration in mice. The entire process will take about 8 weeks to complete.

Mesenchymal stromal cells expressing ErbB-2/neu elicit protective antibreast tumor immunity in vivo, which is paradoxically suppressed by IFN-gamma and tumor necrosis factor-alpha priming

It is unknown whether mesenchymal stromal cells (MSC) can regulate immune responses targeting tumor autoantigens of low immunogenicity. We tested here whether immunization with MSC could break immune tolerance towards the ErbB-2/HER-2/neu tumor antigen and the effects of priming with IFN-γ and tumor necrosis factor-α (TNF-α) on this process. BALB/c- and C57BL/6-derived MSC were lentivirally transduced to express a kinase-inactive rat neu mutant (MSC/Neu). Immunization of BALB/c mice with nontreated or IFN-γ-primed allogeneic or syngeneic MSC/Neu induced similar levels of anti-neu antibody titers; however, only syngeneic MSC/Neu induced protective neu-specific CD8(+) T cell responses. Compared to immunization with nontreated or IFN-γ-primed syngeneic MSC/Neu, the number of circulating neu-specific CD8(+) T cells and titers of anti-neu antibodies were observed to be decreased after immunizations with IFN-γ- plus TNF-α-primed MSC/Neu. In addition, syngeneic MSC/Neu seemed more efficient than IFN-γ-primed MSC/Neu at inducing a protective therapeutic antitumor immune response resulting in the regression of transplanted neu-expressing mammary tumor cells. In vitro antigen-presenting cell assays performed with paraformaldehyde-fixed or live MSC showed that priming with IFN-γ plus TNF-α, compared to priming with IFN-γ alone, increased antigen presentation as well as the production of immunosuppressive factors. These data suggest that whereas MSC could effectively serve as antigen-presenting cells to induce immune responses aimed at tumor autoantigens, these functions are critically regulated by IFN-γ and TNF-α.

Angiotensin-converting enzyme 2 attenuates atherosclerotic lesions by targeting vascular cells

Angiotensin-converting enzyme 2 (ACE2) is a newly discovered homolog of ACE whose actions oppose those of angiotensin II (AngII). However, the underlying mechanisms by which ACE2 effectively suppresses early atherosclerotic lesions remain poorly understood. Here, we show, both in vitro and in vivo, that ACE2 inhibited the development of early atherosclerotic lesions by suppressing the growth of vascular smooth muscle cells (VSMCs) and improving endothelial function. In a relatively large cohort animal study (66 rabbits), aortic segments transfected by Ad-ACE2 showed significantly attenuated fatty streak formation, neointimal macrophage infiltration, and alleviation of impaired endothelial function. Segments also showed decreased expression of monocyte chemoattractant protein 1, lectin-like oxidized low-density lipoprotein receptor 1, and proliferating cell nuclear antigen, which led to the delayed onset of atherosclerotic lesions. At the cellular level, ACE2 significantly modulated AngII-induced growth and migration in human umbilical vein endothelial cells and VSMCs. The antiatherosclerotic effect of ACE2 involved down-regulation of the ERK-p38, JAK-STAT, and AngII-ROS-NF-kappaB signaling pathways and up-regulation of the PI3K-Akt pathway. These findings revealed the molecular mechanisms of the antiatherosclerotic activity of ACE2 and suggested that modulation of ACE2 could offer a therapeutic option for treating atherosclerosis.

Construction and immunogenicity of recombinant adenovirus vaccines expressing the HMW1, HMW2, or Hia adhesion protein of nontypeable Haemophilus influenzae

The objective of the present study was to construct and assess the immunogenicity of recombinant adenovirus vectors expressing the HMW1, HMW2, or Hia protein of nontypeable Haemophilus influenzae (NTHi). These proteins are critical adhesins and potential protective antigens expressed by NTHi. Segments of the hmw1A and hmw2A structural genes that encode the distal one-half of mature HMW1 or HMW2 were cloned into the T7 expression vector pGEMEX-2. These constructs encoded stable HMW1 or HMW2 recombinant fusion protein that expresses B-cell epitopes common to most NTHi strains. A segment of the hia gene that encodes the surface-exposed portion of mature Hia was also cloned into pGEMEX-2. The resulting T7 gene 10 translational fusions were excised from the parent plasmids and cloned into the shuttle plasmid pDC316. Cotransfection of HEK 293 cells with the pDC316 derivatives and pBHGloxΔE1,3Cre resulted in the production of viral plaques from which recombinant adenoviruses expressing fusion proteins were recovered. Chinchillas immunized intraperitoneally with a single 10(8)-PFU dose of either the HMW2 or Hia adenoviral construct developed high anti-HMW2 or anti-Hia serum antibody titers within 4 weeks of immunization. Chinchillas immunized intranasally with a single 10(7)- to 10(9)-PFU dose of the Hia adenoviral construct also developed high anti-Hia serum antibody titers within 8 weeks of immunization. Recombinant adenoviruses represent a promising system to induce mucosal and systemic immunity and protection against mucosal diseases such as otitis media. Recombinant adenoviruses expressing recombinant HMW1, HMW2, or Hia protein will be important new tools in NTHi vaccine development efforts.

Disparate regulation of LPS-induced MAPK signaling and IL-12p40 expression between different myeloid cell types with and without HIV infection

Studies from our laboratory and those of others have implicated lipopolysaccharide (LPS)-induced MAPK signaling as an important pathway in the regulation of cytokine expression. In this article, the regulation of IL-12 expression in two different human myeloid cell populations was evaluated. In primary monocytes, the inhibition of p38 enhanced IL-12 production, whereas it downregulated IL-12 production in THP-1 cells. The role of MAPK signaling in transcription factor binding to the IL-12p40 promoter was subsequently determined. In primary monocytes, ERK and p38 inhibition increased binding of AP-1 and Sp1, respectively, to the IL-12p40 promoter, while JNK inhibition increased NF-kappaB, AP-1, and Sp1 binding. In THP-1 cells, p38, ERK, and JNK inhibition increased NF-kappaB and Sp1 binding to the IL-12p40 promoter, while inhibiting AP-1 binding. In monocytes, mutations in the NF-kappaB, AP-1, Sp1, or Ets-2 binding sites resulted in complete inhibition of LPS-stimulated IL-12p40 promoter activity using a luciferase-based assay. In contrast, promoter activity was abrogated in THP-1 cells only when the Sp1 or Ets-2 binding sites were mutated. Transcription factor binding to the IL-12p40 promoter following in-vitro HIV infection demonstrated several differences between monocytes and THP-1 cells. Infection with HIV produced an increase in NF-kappaB, AP-1, and Sp1 binding in primary monocytes. In contrast, binding of Ets-2 was dramatically impaired following HIV infection of monocytes, but was unaffected in THP-1 cells. These data clearly show that although LPS induces IL-12p40 expression in primary monocytes and THP-1 cells, the signaling pathways involved and the effect of HIV infection differ and can have disparate effects in these two cell types.

Interleukin-15 and its receptor augment dendritic cell vaccination against the neu oncogene through the induction of antibodies partially independent of CD4 help

Interleukin-15 (IL-15) stimulates the diffrentiation and proliferation of T, B, and natural killer cells; enhances CD8(+) cytolytic T-ceII activity; helps maintain CD44(hi)CD8(+) memory T cells; and stimulates immunoglobulin synthesis by B cells. IL-15 is trans-presented to effector cells by its receptor, IL-15Ralpha, expressed on dendritic cells (DC) and monocytes. We examined the antitumor effect of adenoviral-mediated gene transfer of IL-15 and IL-15Ralpha to augment a DC vaccine directed against the NEU (ErbB2) oncoprotein. Transgenic BALB-neuT mice vaccinated in late-stage tumor development with a DC vaccine expressing a truncated NEU antigen, IL-I5, and its receptor (DC(Ad.Neu+Ad_mIL-15+Ad.mlL-15Ralpha)) were protected from mammary carcinomas, with 70% of animals tumor-free at 30 weeks compared with none of the animals vaccinated with NEU alone (DC(Ad.Neu)). The combination of neu, IL-15, and IL-15Ralpha gene transfer leads to a significaintly greater anti-NEU antibody response compared with mice treated with DC(Ad.Neu) or DC(Ad.Neu) combined with either IL-15 (DC(Ad.Neu+Ad.mlL-15)) or lL-15Ralpha (DC(Ad.Neu+Ad.mlL-15Ralpha)). The antitumor effect was antibody mediated and involved modulation of NEU expression and signaIing. Depletion of CD4(+) cells did not abrogate the antitumor effect of the vaccine, nor did it inhibit the induction of anti-NEU aritibodies. Coexpression of IL-15 and IL-15Ralpha in an anticancer vaccine enhanced immune responses against the NEU antigen and may overcome impaired CD4(+) T-helper function.

Persistence of transgene expression influences CD8+ T-cell expansion and maintenance following immunization with recombinant adenovirus

Previous studies determined that the CD8(+) T-cell response elicited by recombinant adenovirus exhibited a protracted contraction phase that was associated with long-term presentation of antigen. To gain further insight into this process, a doxycycline-regulated adenovirus was constructed to enable controlled extinction of transgene expression in vivo. We investigated the impact of premature termination of transgene expression at various time points (day 3 to day 60) following immunization. When transgene expression was terminated before the maximum response had been attained, overall expansion was attenuated, yielding a small memory population. When transgene expression was terminated between day 13 and day 30, the memory population was not sustained, demonstrating that the early memory population was antigen dependent. Extinction of transgene expression at day 60 had no obvious impact on memory maintenance, indicating that maintenance of the memory population may ultimately become independent of transgene expression. Premature termination of antigen expression had significant but modest effects on the phenotype and cytokine profile of the memory population. These results offer new insights into the mechanisms of memory CD8(+) T-cell maintenance following immunization with a recombinant adenovirus.

Vesicular stomatitis virus as a novel cancer vaccine vector to prime antitumor immunity amenable to rapid boosting with adenovirus

Vesicular stomatitis virus (VSV) has proven to be an effective vaccine vector for immunization against viral infection, but its potential to induce an immune response to a self-tumor antigen has not been investigated. We constructed a recombinant VSV expressing human dopachrome tautomerase (hDCT) and evaluated its immunogenicity in a murine melanoma model. Intranasal delivery of VSV-hDCT activated both CD4(+) and CD8(+) DCT-specific T-cell responses. The magnitude of these responses could be significantly increased by booster immunization with recombinant adenovirus (Ad)-hDCT, which led to enhanced efficacy against B16-F10 melanoma in both prophylactic and therapeutic settings. Notably, the interval of VSV/Ad heterologous vaccination could be shortened to as few as 4 days, making it a potential regimen to rapidly expand antigen-specific effector cells. Furthermore, VSV-hDCT could increase DCT-specific T-cell responses primed by Ad-hDCT, suggesting VSV is efficient for both priming and boosting of the immune response against a self-tumor antigen.

A point mutation in the neu1 promoter recruits an ectopic repressor, Nkx3.2 and results in a mouse model of sialidase deficiency

SM/J is an inbred mouse strain with a complex phenotype including small body size, impaired immune response and a tissue-specific sialidase deficiency. We identified a regulatory mutation, (-519G-->A) within the neu1 promoter which in reporter assays resulted in significantly reduced transcription. This mutation generates a consensus binding site for Nkx3 family transcription repressors. Recombinant Nkx3.2 bound strongly to and preferentially repressed transcription of the mutant promoter. This tissue-specific deficiency results in a retarded immune response and modulates leukocyte recruitment. Examination of the hepatic microcirculation in mutant mice revealed increased rolling and decreased adhesion of leukocytes. Our findings support a significant role for lysosomal sialidase in inflammation and highlight the significance of repressor-recruitment in genetic disease.

Neoadjuvant vaccination provides superior protection against tumor relapse following surgery compared with adjuvant vaccination

Tumors that recur following surgical resection of melanoma are typically metastatic and associated with poor prognosis. Using the murine B16F10 melanoma and a robust antimelanoma vaccine, we evaluated immunization as a tool to improve tumor-free survival following surgery. We investigated the utility of vaccination in both neoadjuvant and adjuvant settings. Surprisingly, neoadjuvant vaccination was far superior and provided approximately 100% protection against tumor relapse. Neoadjuvant vaccination was associated with enhanced frequencies of tumor-specific T cells within the tumor and the tumor-draining lymph nodes following resection. We also observed increased infiltration of antigen-specific T cells into the area of surgery. This method should be amenable to any vaccine platform and can be readily extended to the clinic.

Immunization with a bivalent adenovirus-vectored tuberculosis vaccine provides markedly improved protection over its monovalent counterpart against pulmonary tuberculosis

Recombinant virus-vectored vaccines hold great promise for tuberculosis (TB) vaccination strategies. However, there is a lack of side-by-side comparative investigations to dissect the functional differences and support the advantage of multivalent virus-vectored vaccine over its monovalent counterpart. We previously successfully developed a monovalent adenovirus (Ad)-vectored vaccine expressing Ag85a (AdAg85a) and demonstrated its superior protective efficacy in models of pulmonary TB. In this study, we have developed a bivalent Ad TB vaccine expressing Ag85a and TB10.4 antigens as a fusion protein (AdAg85a:TB10.4) and compared its T-cell-activating and immune protective efficacy with that by monovalent AdAg85a. A single intranasal (i.n.) administration of AdAg85a:TB10.4 induced robust T-cell responses toward the respective antigens within the airway lumen and spleen, although the level of Ag85a-specific T-cell responses in the airway lumen triggered by bivalent AdAg85a:TB10.4 was lower than that by its monovalent counterpart at earlier time points. Thus, a single i.n. delivery of AdAg85a:TB10.4 conferred a markedly improved and sustained level of protection in the lung against Mycobacterium tuberculosis (M.tb) challenge over that by AdAg85a or by conventional BCG immunization with similarly induced levels of protection in the spleen. Our results indicate a unique advantage of multivalent viral-vectored TB vaccines for immunization against pulmonary TB.

Re-engineering adenovirus vector systems to enable high-throughput analyses of gene function

With the enhanced capacity of bioinformatics to interrogate extensive banks of sequence data, more efficient technologies are needed to test gene function predictions. Replication-deficient recombinant adenovirus (Ad) vectors are widely used in expression analysis since they provide for extremely efficient expression of transgenes in a wide range of cell types. To facilitate rapid, high-throughput generation of recombinant viruses, we have re-engineered an adenovirus vector (designated AdZ) to allow single-step, directional gene insertion using recombineering technology. Recombineering allows for direct insertion into the Ad vector of PCR products, synthesized sequences, or oligonucleotides encoding shRNAs without requirement for a transfer vector Vectors were optimized for high-throughput applications by making them "self-excising" through incorporating the I-SceI homing endonuclease into the vector removing the need to linearize vectors prior to transfection into packaging cells. AdZ vectors allow genes to be expressed in their native form or with strep, V5, or GFP tags. Insertion of tetracycline operators downstream of the human cytomegalovirus major immediate early (HCMV MIE) promoter permits silencing of transgenes in helper cells expressing the tet repressor thus making the vector compatible with the cloning of toxic gene products. The AdZ vector system is robust, straightforward, and suited to both sporadic and high-throughput applications.

A simplified in vitro ligation approach to clone an E1B55k-deleted double-targeted conditionally-replicative adenovirus

BACKGROUND

Construction of conditionally-replicative Adenovirus (CRAd) is complex and time-consuming. While homologous recombination (HR) using a two-plasmid system in bacteria is commonly used to generate CRAds, alternative methods may be required when HR fails. Previously, in vitro ligation has been suggested to facilitate construction of E1/E3-deleted, replication-incompetent Ad vectors. However, in vitro ligation has only rarely been used to generate CRAds and may be a complex procedure for molecular biologists who are not experts in the field.

METHODS AND RESULTS

A modified in vitro ligation approach was developed to construct a double-targeted, E1B55k-deleted CRAd. The method allowed the incorporation of a tumor-specific promoter, e.g. the heat-shock protein 70 (hsp70) promoter, upstream of E1a, deletion of the E1B55k gene, and HR-free cloning of the recombined E1Delta55k gene into the Ad genome. The genetic structure of the CRAd was confirmed using restriction analysis and PCR. The replication rate of the hsp70E1Delta55k CRAd was 1.5-2% of Ad without E1Delta55k deletion.

CONCLUSION

A 3-step cloning approach can generate a double-targeted, E1B55k-deleted CRAd using a straight-forward, modified in vitro ligation procedure.

High-dose chemotherapy augments the efficacy of recombinant adenovirus vaccines and improves the therapeutic outcome

We have investigated the therapeutic potential of a prototypic melanoma vaccine based on recombinant adenovirus expressing human dopachrome tautomerase in the B16F10 murine melanoma model. We found that in the presence of a tumor, the magnitude of T-cell immunity evoked by the vaccine was significantly reduced. This impairment was compounded by defects in cytokine production and degranulation within the tumor-infiltrating lymphocytes (TILs). We showed that the combination of vaccination with high-dose cyclophosphamide was able to skew the response toward the target antigen and enhanced both the quantity and quality of antigen-specific CD8+ and CD4+ T-cell responses in tumor-bearing mice, which resulted in the inhibition of tumor growth. Furthermore, when tumor-specific antigens were targeted by the vaccine, the combination therapy could actually produce tumor regression, which appeared to result from the high frequency of antigen-specific T cells. These data show that recombinant adenovirus vaccines are compatible with conventional high-dose chemotherapy and that the combined treatment results in improved therapeutic outcomes relative to either agent individually.

Construction of FCU1 recombinant adenovirus vector and its killing effect on colon cancer cells

AIM: To construct a recombinant adenovirus vector containing fusion suicide gene FCU1, and study the cytotoxic effect of prodrug 5-FC on colon cancer cells.

METHODS: Restriction fragment of FCU1 was inserted into pDC316 vector with EcoRⅠ and SalⅠ. Recombinant plasmid pDC316-FCU1 was confirmed by restriction enzyme digestion and sequencing. Thereafter, pDC316-FCU1 was cotransfected with adenovirus backbone pBHG into 293 cells to establish the recombinant adenovirus Ad5-FCU1 by homologous recombination. The cytotoxic effect of prodrug 5-FC on the infected HCT116 cells was determined with MTT assay.

RESULTS: Recombinant plasmid pDC316-FCU1was constructed successfully. After pDC316-FCU1 together with adenovirus backbone pBHG was cotransfected into 293 cells, significant virus plaques were observed, which showed the successful homologous recombination and virus packaging in 293 cells. The titer of the purified Ad-FCU1 was 2 × 10¹² PFU/L. Nontoxic prodrug 5-FC has significant cytotoxic effect on HCT116 cells infected with pAd5-FCU1. The survival of HCT116/FCU1 cells was minimal, while that of the control cells was close to 90%, when 5-FC was used at 100 μmol/L.

CONCLUSION: Recombinant adenovirus Ad5-FCU1 containing fusion suicide gene FCU1 is established successfully, which has significant killing effect on colon cancer cells in vitro.

Overexpression of ACE2 Enhances Plaque Stability in a Rabbit Model of Atherosclerosis

Objective— The purpose of this study was to test the hypothesis that ACE2 overexpression may enhance atherosclerotic plaque stability by antagonizing ACE activity and converting angiotensin II to angiotensin 1–7.

Methods and Results— Atherosclerotic plaques were induced in the abdominal aorta of 114 rabbits by endothelial injury and atherogenic diet. Gene therapy was performed in group A at week 4 and in group B at week 12, respectively. Each group of rabbits were randomly divided into 3 subgroups which received, respectively, a recombinant ACE2 expressing vector (AdACE2), a control vector AdEGFP and AdACE2+A779, an antagonist of angiotensin 1–7 receptor. Local ACE2 overexpression attenuated the progression of lesions from week 4 to week 8, but not progression of plaque size from week 12 to week 16. In group B rabbits, local ACE2 overexpression resulted in stable plaque compositions, ie, fewer macrophages, less lipid deposition and more collagen contents, higher plaque stability scores, decreased angiotensin II levels, and increased angiotensin 1–7 levels in plaque tissues in the AdACE2 subgroup compared with those in the AdEGFP subgroup.

Conclusions— Overexpression of ACE2 results in stabilized atherosclerotic plaques and the mechanism is probably the conversion of vasoconstrictive angiotensin II to vessel protective angiotensin 1–7.

Methods for the production of first generation adenoviral vectors

Adenoviruses (Ads) possess several features that make them attractive mammalian gene transfer vectors. They can efficiently infect a wide variety of quiescent and proliferating cell types from various species to direct high level viral gene expression, their 36 kb double-stranded DNA genome can be manipulated with relative ease by conventional molecular biology techniques, and they can be readily propagated and purified to yield high titer preparations of very stable virus. Consequently, Ads have been extensively used as vectors for recombinant vaccines, for high-level protein production in cultured cells and for gene therapy where high-level, transient transgene expression is desired. This chapter describes in detail methods for the production and characterization of E1-deleted, first generation adenoviral vectors.

Regulated expression of adenoviral vectors-based gene therapies: therapeutic expression of toxins and immune-modulators

Regulatable promoter systems allow gene expression to be tightly controlled in vivo. This is highly desirable for the development of safe, efficacious adenoviral vectors that can be used to treat human diseases in the clinic. Ideally, regulatable cassettes should have minimal gene expression in the "OFF" state, and expression should quickly reach therapeutic levels in the "ON" state. In addition, the components of regulatable cassettes should be non-toxic at physiological concentrations and should not be immunogenic, especially when treating chronic illness that requires long-lasting gene expression. In this chapter, we will describe in detail protocols to develop and validate first generation (Ad) and high-capacity adenoviral (HC-Ad) vectors that express therapeutic genes under the control of the TetON regulatable system. Our laboratory has successfully used these protocols to regulate the expression of marker genes, immune stimulatory genes, and toxins for cancer gene therapeutics, i.e., glioma that is a deadly form of brain cancer. We have shown that this third generation TetON regulatable system, incorporating a doxycycline (DOX)-sensitive rtTA(2)S-M2 inducer and tTS(Kid) silencer, is non-toxic, relatively non-immunogenic, and can tightly regulate reporter transgene expression downstream of a TRE promoter from adenoviral vectors in vitro and also in vivo.