Preparation and qualification of internal rabies reference standards for use in the rabies rapid fluorescent focus inhibition test.

The World Health Organization (WHO) international standard rabies immune globulins (SRIGs) allow the standardisation of the cell-based rapid fluorescent-focus inhibition test (RFFIT) for rabies virus neutralising antibody measurement. SRIG stocks have been depleted. We describe the preparation and qualification of two internal rabies reference standards (IRRSs), calibrated against WHO SRIGs.

Rapid fluorescent focus inhibition test optimization and validation: Improved detection of neutralizing antibodies to rabies virus.

The rabies rapid fluorescent focus inhibition test (RFFIT) is the most widely used cell-based assay for detecting and quantitating rabies virus neutralizing antibodies (RVNA) in human serum. However, it is a complex, labor intensive, and somewhat subjective manual assay, the performance of which may be affected by a number of factors including the quality of cells and virus, variability of assay reagents and the skill and expertise of analysts. This study sought to identify and evaluate conditions that may impact RFFIT performance and RVNA detection by evaluating assay parameters including: different serial dilution scheme of serum samples in a 96-well microplate using semi-automated pipetting systems, the range of dose of challenge virus standard (CVS-11) strain of rabies virus, the effect of complement (C'), the effect of cell seeding density and passage number, the effect of diethylaminoethyl (DEAE) dextran concentration on virus infectivity, and the assay incubation period prior to immunostaining.

Influence of FcγRIIa-Expressing Cells on the Assessment of Neutralizing and Enhancing Serum Antibodies Elicited by a Live-Attenuated Tetravalent Dengue Vaccine.

Background.  Recent trials of recombinant, live-attenuated chimeric yellow fever-dengue tetravalent dengue vaccine (CYD-TDV) demonstrated efficacy against symptomatic, virologically confirmed dengue disease with higher point estimates of efficacy toward dengue virus (DENV)3 and DENV4 and moderate levels toward DENV1 and DENV2. It is interesting to note that serotype-specific efficacy did not correlate with absolute neutralizing antibody (nAb) geometric mean titer (GMT) values measured in a Vero-based plaque reduction neutralization test assay.

Optimization and validation of a plaque reduction neutralization test for the detection of neutralizing antibodies to four serotypes of dengue virus used in support of dengue vaccine development.

A dengue plaque reduction neutralization test (PRNT) to measure dengue serotype-specific neutralizing antibodies for all four virus serotypes was developed, optimized, and validated in accordance with guidelines for validation of bioanalytical test methods using human serum samples from dengue-infected persons and persons receiving a dengue vaccine candidate. Production and characterization of dengue challenge viruses used in the assay was standardized. Once virus stocks were characterized, the dengue PRNT(50) for each of the four serotypes was optimized according to a factorial design of experiments approach for critical test parameters, including days of cell seeding before testing, percentage of overlay carboxymethylcellulose medium, and days of incubation post-infection to generate a robust assay.

Lister strain of vaccinia virus armed with endostatin-angiostatin fusion gene as a novel therapeutic agent for human pancreatic cancer.

Survival after pancreatic cancer remains poor despite incremental advances in surgical and adjuvant therapy, and new strategies for treatment are needed. Oncolytic virotherapy is an attractive approach for cancer treatment. In this study, we have evaluated the effectiveness of the Lister vaccine strain of vaccinia virus armed with the endostatin-angiostatin fusion gene (VVhEA) as a novel therapeutic approach for pancreatic cancer.

Treatment of anaplastic thyroid carcinoma in vitro with a mutant vaccinia virus.

Background: Anaplastic thyroid carcinoma (ATC) is a fatal disease resistant to all conventional treatments. Novel therapies are needed to improve dismal outcomes.

Methods: A replication-competent vaccinia virus (GLV-1h68) was engineered by inserting expression cassettes encoding Renilla luciferase-green fluorescent protein (GFP), beta-galactosidase, and beta-glucuronidase into the genome of LIVP strain.

Attenuation of a vaccine strain of vaccinia virus via inactivation of interferon viroceptor.

Background: Interferons (IFNs) play an important role in host antiviral responses, but viruses, including vaccinia viruses (VV), employ mechanisms to disrupt IFN activities, and these viral mechanisms are often associated with their virulence. Here, we explore an attenuation strategy with a vaccine strain of VV lacking a virus-encoded IFN-gamma receptor homolog (viroceptor).

Methods: To facilitate the monitoring of virus properties, first we constructed a Lister vaccine strain derivative VV-RG expressing optical reporters.

Protection of NOD mice from type 1 diabetes after oral inoculation with vaccinia viruses expressing adjuvanted islet autoantigens.

Oral administration of autoantigens and allergens can delay or suppress clinical disease in experimental autoimmune and allergic disorders. However, repeated feeding of large amounts of the tolerogens is required over long periods and is only partially effective in animals systemically sensitized to the ingested antigen. Enhanced suppression of type 1 autoimmune diabetes insulitis and hyperglycemia was demonstrated in both naive and immune animals following oral inoculation with plant-based antigens coupled to the cholera toxin B subunit (CTB).

Radiation-enhanced endostatin gene expression and effects of combination treatment.

Targeting cells that support tumor growth by administering potent angiogenesis inhibitors is currently an area of intense interest. In the present study, a unique plasmid vector for the mouse endostatin gene, pXLG-mEndo, was constructed and evaluated with and without radiation using the Lewis lung carcinoma (LLC) cell line. The physical properties of the expressed endostatin protein were validated by PCR, gel electrophoresis, and Western blot.

Vaccinia virus mediated p53 gene therapy for bladder cancer in an orthotopic murine model.

Purpose: We determined if vaccinia virus (VV) mediated delivery of human tumor suppressor p53 is safe and effective for bladder tumor therapy in an orthotopic murine model.

Materials And Methods: We used recombinant VV (rVV) vectors to express transgenes in murine bladder cancer MB-49 cells in culture and those growing orthotopically in syngeneic mice. Cultured MB-49 cells were infected with rVV expressing reporter genes (rVV-L15) or p53 (rVV-TK-53) to measure virus infection and apoptosis induction.

Proton radiation and TNF-alpha/Bax gene therapy for orthotopic C6 brain tumor in Wistar rats.

High-grade tumors of the brain remain virtually incurable with current therapeutic regimens, new approaches to augment existing therapies need to be explored. The major goal of this pilot study was to evaluate the feasibility of gene therapy using plasmid DNA encoding tumor necrosis factor-alpha and bax together with proton radiation in an immunocompetent animal model with orthotopic brain tumor. C6 glioma cells were stereotactically implanted into the left hemibrain of Wistar rats (day 0).

Visualization of tumors and metastases in live animals with bacteria and vaccinia virus encoding light-emitting proteins.

We have shown that bacteria injected intravenously into live animals entered and replicated in solid tumors and metastases. The tumor-specific amplification process was visualized in real time using luciferase-catalyzed luminescence and green fluorescent protein fluorescence, which revealed the locations of the tumors and metastases. Escherichia coli and three attenuated pathogens (Vibrio cholerae, Salmonella typhimurium, and Listeria monocytogenes) all entered tumors and replicated.

Optical imaging: bacteria, viruses, and mammalian cells encoding light-emitting proteins reveal the locations of primary tumors and metastases in animals.

Early detection of tumors and their metastases is crucial for the prognosis of cancer treatment. Traditionally, tumor detection is achieved by various methods, including magnetic resonance imaging and computerized tomography. With the recent cloning, cellular expression, and real-time imaging of light-emitting proteins, such as Renilla luciferase (Ruc), bacterial luciferase (Lux), firefly luciferase (Luc), green fluorescent protein (GFP), or Ruc-GFP fusion protein, significant efforts have been focused on using these marker proteins for tumor detection.

Radiation enhances the anti-tumor effects of vaccinia-p53 gene therapy in glioma.

The overall goal of this study was to analyze the effect and mechanism of radiation in combination with vaccinia viruses (VV) carrying the p53 gene against glioma. Comparison of two alternative treatments of cultured C6 (p53(+)) and 9L (p53(-)) rat glioma cells showed significantly reduced survival for both cell lines, especially 9L, when radiation was applied prior to virus versus radiation alone. High p53 protein expression mediated by VV-TK-p53 was measured in infected cells.

Evaluation of TNF-alpha/Bax gene therapy and radiation against C6 glioma xenografts.

Successful therapy of high-grade tumors of the brain is likely to require a combination of new therapeutic approaches. The major goal of the present study was to construct a plasmid-based bax gene vector (pGL1-Bax) and evaluate its expression in vitro and in vivo using athymic mice with subcutaneously growing C6 glioma. Preliminary experiments of efficacy and safety were also performed using pGL1-Bax alone and in combination with previously constructed pGL1-TNF-alpha, as well as with radiation.

Lymphocyte activation with localized pGL1-TNF-alpha gene therapy in a glioma model.

The major goal of this study was to evaluate the effects of tumor necrosis factor-alpha (TNF-alpha), delivered as pGL1-TNF-alpha, on hematological variables, as well as C6 tumor growth in athymic mice treated with and without radiation. pGL1-TNF-alpha was administered intratumorally at low to high doses (15, 150 and 450 microg) in all three phases of this study. In phase A, pGL1-TNF-alpha expression within tumors was dose dependent and transient, with highest levels seen at 18 h after injection, whereas no TNF-alpha protein was detected in plasma.

Evaluation of cytokine toxicity induced by vaccinia virus-mediated IL-2 and IL-12 antitumour immunotherapy.

Single intratumoural treatment of nude mice with a vaccinia virus (VV)-expressing interleukin-1 (IL-2) or IL-12 induced significant tumour growth inhibition associated with clear signs of toxicity. At a low virus dose, only some treated animals showed signs of toxicity. We characterized and compared the activity of NK and B cells and major pro-inflammatory factors (IFN-gamma, TNF-alpha) in treated animals with and without toxicity.

Construction of recombinant vaccinia viruses using PUV-inactivated virus as a helper.

Recombinant vaccinia viruses (VVs) are widely used as expression vectors in molecular biology and immunology and are now under evaluation for gene therapy. The current techniques for inserting foreign DNA into the large VV genome are based on either homologous recombination between transfer plasmids and VVgenomes or direct DNA ligation and packaging using replication-deficient poxviruses. Here, we describe efficient new versions of both methods that produce 90%-100% of the recombinant viruses.

Low-dose vaccinia virus-mediated cytokine gene therapy of glioma.

Recombinant viruses can produce cytokines in tumors mobilizing an immune response to tumor cells. In this study, the authors investigated gene expression, in vivo antitumor efficacy, and safety of attenuated recombinant vaccinia virus (rVV) carrying murine cytokine genes interleukin (IL)-2 (rVV-mIL-2), IL-12 (rVV-mIL-12), and both IL-2 and IL-12 (rVV-2-12) in an athymic nude mice model. Significant tumor inhibition (p < 0.

Evaluation of combined vaccinia virus-mediated antitumor gene therapy with p53, IL-2, and IL-12 in a glioma model.

Our previous studies have shown that vaccinia virus (VV) expressing p53, interleukin-2 (IL-2), and interleukin-12 (IL-12) results in an effective inhibition of subcutaneous glioma growth in mice. We propose that combination therapy of tumors with virus-mediated p53 and cytokine genes offers the prospect of synergistic antitumor response. In this work, the antitumor efficacy of VV-mediated combination of p53, IL-2, and IL-12 genes was evaluated in a nude mouse model.

Antitumor effect of IL-2, p53, and bax gene transfer in C6 glioma cells.

The use of interleukin-2 (IL-2) and p53 for immunotherapy and gene therapy for cancer has shown promising results. In this study, we examined the efficacy of plasmid gene therapy utilizing murine IL-2, the wild-type (wt) human p53 gene, the combination of these genes, and the murine bax gene, which are under the control of the cytomegalovirus (CMV) immediate-early promoter, in nude mice bearing established subcutaneous C6 glioma. In vitro assays and immunocytochemical analysis for therapeutic genes demonstrated expression of the proteins in C6 transfected cells.

Antitumor effect of vaccinia virus in glioma model.

The ability of certain viruses to lyse cancer cells suggests that they may have potential as oncolytic agents. We investigated the effect of vaccinia virus (VV) and its recombinant derivatives (recVV2, rVV-p53) on growth of C6 rat glioma cells that form fast growing tumors in athymic nude mice. VV effectively infected C6 cells in vitro, inducing high level of foreign gene expression.

Vaccinia virus-mediated expression of wild-type p53 suppresses glioma cell growth and induces apoptosis.

The use of vaccinia virus vectors for cancer gene therapy may become a powerful method to achieve efficient anti-tumor effects. We used recombinant vaccinia virus expressing wild-type p53 (rVV-p53) to examine the biological effects of exogenous tumor suppressor p53 in human (U-373MG, U-87MG, LN-Z308) and rat glioma cells (9L, C6) in vitro. All glioma cell lines infected with rVV-p53 exhibited growth inhibition and underwent apoptosis as demonstrated by morphological studies using nuclear staining and flow cytometry.