Patent Publication Number: US-9428736-B2

Title: Vesicular stomatitis viruses

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a National Stage application under 35 U.S.C. 371 of International Application No. PCT/US2011/050227, having an International Filing Date of Sep. 1, 2011, which claims the benefit of U.S. Provisional Application No. 61/379,644, filed Sep. 2, 2010. The contents of the foregoing application are hereby incorporated by reference in their entirety. 
    
    
     STATEMENT AS TO FEDERALLY SPONSORED RESEARCH 
     This invention was made with government support under grant number CA129966 awarded by the National Institute of Health. The government has certain rights in the invention. 
    
    
     TECHNICAL FIELD 
     This document relates to methods and materials involved in making and using vesicular stomatitis viruses. For example, this document relates to vesicular stomatitis viruses, nucleic acid molecules, methods for making vesicular stomatitis viruses, and methods for using vesicular stomatitis viruses to treat cancer. 
     BACKGROUND INFORMATION 
     Vesicular stomatitis virus (VSV) is a member of the Rhabdoviridae family. The VSV genome is a single molecule of negative-sense RNA that encodes five major polypeptides: a nucleocapsid (N) polypeptide, a phosphoprotein (P) polypeptide, a matrix (M) polypeptide, a glycoprotein (G) polypeptide, and a viral polymerase (L) polypeptide. 
     SUMMARY 
     This document provides methods and materials related to vesicular stomatitis viruses. For example, this document provides vesicular stomatitis viruses, nucleic acid molecules encoding VSV polypeptides, methods for making vesicular stomatitis viruses, and methods for using vesicular stomatitis viruses to treat cancer. 
     As described herein, vesicular stomatitis viruses can be designed to have a nucleic acid molecule that encodes a VSV N polypeptide, a VSV P polypeptide, a VSV M polypeptide, a VSV G polypeptide, a VSV L polypeptide, an interferon (IFN) polypeptide (e.g., a human IFN-β polypeptide), and a sodium iodide symporter (NIS) polypeptide (e.g., a human NIS polypeptide). The nucleic acid encoding the IFN polypeptide can be positioned between the nucleic acid encoding the VSV M polypeptide and the nucleic acid encoding the VSV G polypeptide. Such a position can allow the viruses to express an amount of the IFN polypeptide that is effective to activate anti-viral innate immune responses in non-cancerous tissues, and thus alleviate potential viral toxicity, without impeding efficient viral replication in cancer cells. The nucleic acid encoding the NIS polypeptide can be positioned between the nucleic acid encoding the VSV G polypeptide and the VSV L polypeptide. Such a position of can allow the viruses to express an amount of the NIS polypeptide that (a) is effective to allow selective accumulation of iodide in infected cells, thereby allowing both imaging of viral distribution using radioisotopes and radiotherapy targeted to infected cancer cells, and (b) is not so high as to be toxic to infected cells. Positioning the nucleic acid encoding an IFN polypeptide between the nucleic acid encoding the VSV M polypeptide and the nucleic acid encoding the VSV G polypeptide and positioning the nucleic acid encoding a NIS polypeptide between the nucleic acid encoding the VSV G polypeptide and the VSV L polypeptide within the genome of a vesicular stomatitis virus can result in vesicular stomatitis viruses that are viable, that have the ability to replicate and spread, that express appropriate levels of functional IFN polypeptides, and that expression appropriate levels of functional NIS polypeptides to take up radio-iodine for both imaging and radio-virotherapy. 
     In some cases, this document features a vesicular stomatitis virus comprising an RNA molecule. The RNA molecule comprises, or consists essentially of, in a 3′ to 5′ direction, a nucleic acid sequence that is a template for a positive sense transcript encoding a VSV N polypeptide, a nucleic acid sequence that is a template for a positive sense transcript encoding a VSV P polypeptide, a nucleic acid sequence that is a template for a positive sense transcript encoding a VSV M polypeptide, a nucleic acid sequence that is a template for a positive sense transcript encoding an IFN polypeptide, a nucleic acid sequence that is a template for a positive sense transcript encoding a VSV G polypeptide, a nucleic acid sequence that is a template for a positive sense transcript encoding a NIS polypeptide, and a nucleic acid sequence that is a template for a positive sense transcript encoding a VSV L polypeptide. The IFN polypeptide can be a human IFN beta polypeptide. The NIS polypeptide can be a human NIS polypeptide. The virus can express the IFN polypeptide when the virus infects a mammalian cell. The virus can express the NIS polypeptide when the virus infects a mammalian cell. 
     In another aspect, this document features a composition comprising, or consisting essentially of, a vesicular stomatitis virus comprising RNA molecule. The RNA molecule comprises, or consists essentially of, in a 3′ to 5′ direction, a nucleic acid sequence that is a template for a positive sense transcript encoding a VSV N polypeptide, a nucleic acid sequence that is a template for a positive sense transcript encoding a VSV P polypeptide, a nucleic acid sequence that is a template for a positive sense transcript encoding a VSV M polypeptide, a nucleic acid sequence that is a template for a positive sense transcript encoding an IFN polypeptide, a nucleic acid sequence that is a template for a positive sense transcript encoding a VSV G polypeptide, a nucleic acid sequence that is a template for a positive sense transcript encoding a NIS polypeptide, and a nucleic acid sequence that is a template for a positive sense transcript encoding a VSV L polypeptide. The IFN polypeptide can be a human IFN beta polypeptide. The NIS polypeptide can be a human NIS polypeptide. The virus can express the IFN polypeptide when the virus infects a mammalian cell. The virus can express the NIS polypeptide when the virus infects a mammalian cell. 
     In another aspect, this document features a nucleic acid molecule comprising a nucleic acid strand comprising, or consisting essentially of, in a 3′ to 5′ direction, a nucleic acid sequence that is a template for a positive sense transcript encoding a VSV N polypeptide, a nucleic acid sequence that is a template for a positive sense transcript encoding a VSV P polypeptide, a nucleic acid sequence that is a template for a positive sense transcript encoding a VSV M polypeptide, a nucleic acid sequence that is a template for a positive sense transcript encoding an IFN polypeptide, a nucleic acid sequence that is a template for a positive sense transcript encoding a VSV G polypeptide, a nucleic acid sequence that is a template for a positive sense transcript encoding a NIS polypeptide, and a nucleic acid sequence that is a template for a positive sense transcript encoding a VSV L polypeptide. The IFN polypeptide can be a human IFN beta polypeptide. The NIS polypeptide can be a human NIS polypeptide. 
     In another aspect, this document features a method for treating cancer. The method comprises, or consists essentially of, administering a composition comprising vesicular stomatitis viruses to a mammal comprising cancer cells. The vesicular stomatitis viruses comprise an RNA molecule comprising, or consisting essentially of, in a 3′ to 5′ direction, a nucleic acid sequence that is a template for a positive sense transcript encoding a VSV N polypeptide, a nucleic acid sequence that is a template for a positive sense transcript encoding a VSV P polypeptide, a nucleic acid sequence that is a template for a positive sense transcript encoding a VSV M polypeptide, a nucleic acid sequence that is a template for a positive sense transcript encoding an IFN polypeptide, a nucleic acid sequence that is a template for a positive sense transcript encoding a VSV G polypeptide, a nucleic acid sequence that is a template for a positive sense transcript encoding a NIS polypeptide, and a nucleic acid sequence that is a template for a positive sense transcript encoding a VSV L polypeptide, wherein administration of the composition to the mammal is under conditions wherein the vesicular stomatitis viruses infect the cancer cells to form infected cancer cells, wherein the infected cancer cells express the IFN polypeptide and the NIS polypeptide, and wherein the number of cancer cells within the mammal is reduced following the administration. The mammal can be a human. The IFN polypeptide can be a human IFN beta polypeptide. The NIS polypeptide can be a human NIS polypeptide. 
     In another aspect, this document features a method for inducing tumor regression in a mammal. The method comprises, or consists essentially of, administering a composition comprising vesicular stomatitis viruses to a mammal comprising a tumor. The vesicular stomatitis viruses comprises an RNA molecule comprising, or consisting essentially of, in a 3′ to 5′ direction, a nucleic acid sequence that is a template for a positive sense transcript encoding a VSV N polypeptide, a nucleic acid sequence that is a template for a positive sense transcript encoding a VSV P polypeptide, a nucleic acid sequence that is a template for a positive sense transcript encoding a VSV M polypeptide, a nucleic acid sequence that is a template for a positive sense transcript encoding an IFN polypeptide, a nucleic acid sequence that is a template for a positive sense transcript encoding a VSV G polypeptide, a nucleic acid sequence that is a template for a positive sense transcript encoding a NIS polypeptide, and a nucleic acid sequence that is a template for a positive sense transcript encoding a VSV L polypeptide, wherein administration of the composition to the mammal is under conditions wherein the vesicular stomatitis viruses infect tumor cells of the tumor to form infected tumor cells, wherein the infected tumor cells express the IFN polypeptide and the NIS polypeptide. The mammal can be a human. The IFN polypeptide can be a human IFN beta polypeptide. The NIS polypeptide can be a human NIS polypeptide. 
     Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. Although methods and materials similar or equivalent to those described herein can be used to practice the invention, suitable methods and materials are described below. All publications, patent applications, patents, and other references mentioned herein are incorporated by reference in their entirety. In case of conflict, the present specification, including definitions, will control. In addition, the materials, methods, and examples are illustrative only and not intended to be limiting. 
     The details of one or more embodiments of the invention are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the invention will be apparent from the description and drawings, and from the claims. 
    
    
     
       DESCRIPTION OF DRAWINGS 
         FIG. 1A  is a schematic diagram of the genome arrangement of an exemplary vesicular stomatitis virus containing nucleic acid encoding an IFN polypeptide (e.g., a human or mouse IFNβ polypeptide) and nucleic acid encoding a NIS polypeptide (e.g., a human NIS polypeptide).  FIG. 1B  is a graph plotting the viral titer of vesicular stomatitis viruses containing nucleic acid encoding a green fluorescent protein (GFP) polypeptide (VSV-GFP; (●)), VSV-mIFN-NIS (▪), or VSV-hIFN-NIS (♦) determined using BHK cells infected at MOI 1.0.  FIG. 1C  is a graph plotting radio-iodide uptake of cells infected with VSV-mIFN-NIS or VSV-hIFN-NIS in the presence or absence of KCLO4, a NIS inhibitor (+inh.). VSV-GFP was used as a control.  FIG. 1D  contains bar graphs plotting the level of secretion of murine or human IFNβ measured by ELISA from mock infected cells or cells infected with VSV-mIFN-NIS (VmN) or VSV-hIFN-NIS (VhN).  FIG. 1E  contains bar graphs plotting IFN responsiveness of 5TGM1 and MPC-11 murine myeloma cells compared to B-16 murine melanoma cells as assessed by pre-treating cells with 100 U/mL murine IFNβ for 12 hours, followed by infection with VSV-GFP (MOI 1.0).  FIG. 1F  contains graphs plotting proliferation of viable cells results assessed by an MTT assay at 48 hours post-infection (plotted as % of untreated cells). 5TGM1 and MPC-11 oncolysis was monitored following infection with VSV-mIFN-NIS or VSV-hIFN-NIS (MOI 1.0) by measuring cell viability at 12 hour intervals by MTT assay. 
         FIG. 2A  is a graph plotting the level of IFN polypeptide release from BHK cells infected with either VSV-mIFN-NIS or VSV-mIFN and monitored over a 48 hour time period. The mouse IFN polypeptide levels were measured in the supernatant using an ELISA designed to detect mouse IFN polypeptides expression levels.  FIG. 2B  is a graph plotting the level of I-125 uptake by BHK cells infected with either VSV-mIFN-NIS or VSV-mIFN at the indicated time (hours). 
         FIG. 3  contains results from monitoring intratumoral spread of intravenously administered VSV-IFN-NIS. Female, 6-10 week old C57B16/KaLwRij mice bearing subcutaneous syngeneic 5TGM1 myeloma tumors were treated with a single intravenous (IV) dose of 100 μL PBS (control) or 1×10 8  TCID 50  VSV-mIFN-NIS. (A) SPECT-CT imaging was carried out at 24 hour intervals post-treatment following administration with 0.5 mCi Tc-99m. Tumor specific Tc-99m uptake was quantified in PBS treated mice (n=2) and VSV-mIFN-NIS treated mice (n=5). (B) Intratumoral viral distribution was monitored by harvesting tumors following SPECT-CT imaging and corollary analysis of adjacent tumor section by autoradiography, and IF was performed. IF was used to detect VSV antigens (which stained red) and cells undergoing cell death by TUNEL staining (which stained green) at 24 hour time periods. (C) Intratumoral VSV and TUNEL were quantified using from 4 images from n=3 tumors (n=2 at 72 hours) using ImageJ software and shown as a percentage of tumor area. There was a significant increase in both VSV(+) and TUNEL(+) between 24 and 48 hours post treatment using t-test (P=0.0455 and P=0.0163, respectively). 
         FIG. 4  contains results of intratumoral viral entry, spread, and oncolysis following intravenous delivery. (A) 5TGM1 tumors were harvested and analyzed by IF at (i) 6 hours, (ii) 12 hours, (iii) 18 hours, and (iv-vi) 24 hours following intravenous VSV-mIFN-NIS administration indicating VSV infected cells (which stained green) and tumor blood vessels by CD31 staining (which stained red). Magnification 100×. (B) High magnification view of treated tumors showing intact tumor blood vessels (which stained red) in proximity of (i) VSV infected tumor cells (which stained green) and (ii) TUNEL positive cells undergoing cells death (which stained green) with Hoescht stained nuclei (which stained blue). (C) Intratumoral foci (n=8) from tumors harvested at 6 hour intervals were measured using ImageJ software, and average diameter was plotted over time. Significance of diameter growth was measured by t-test, and P values are shown along the top of the graph. Diameters were used to measure average foci volume over time. (D) Images of tumor at 48 hours post VSV-mIFN-NIS treatment were used to quantify viable rim of infected cells to obtain an average of ˜10 cells being infected at each round of infection prior to cell death. 
         FIG. 5  contains a set of three images of a tumor from the same mouse, undergoing whole body SPECT-CT imaging to monitor viral distribution (top, left), tumor autoradiography to show specific regions of radio-isotope uptake (top, right), and anti-VSV and DAPI staining to show that regions of NIS expression correspond to intratumoral VSV staining (bottom). 
         FIG. 6  contains results demonstrating a potent therapeutic efficacy of systemically administered VSV-IFN-NIS. Mice bearing subcutaneous 5TGM1 tumors were treated with a single intravenous dose of PBS, VSV-mIFN-NIS, or VSV-hIFN-NIS. (A) Tumor burden was measured by serial caliper measurements to calculate tumor volume over time. (B) Tumor responses were categorized into tumor progression, regression, or regression with relapse. Statistical difference in incidence of relapse as proportion of mice with tumor regression was measured Fischer Exact test indicating significantly higher rate of tumor relapse in VSV-hIFN-NIS treated mice vs. VSV-mIFN-NIS treated mice (P=0.009). (C) Generation of VSV neutralizing antibodies was measured in serum of n=2 (PBS treated) and n=3 (VSV-IFN-NIS treated) mice in the first 5 days post treatment and plotted as the minimum fold dilution that protects from infection with 500 TCID 50  VSV. 
         FIG. 7  contains results demonstrating that immune mediated elimination of tumor cells prevents tumor relapse. (A) Quantification of murine IFNβ in serum of mice bearing subcutaneous 5TGM1 tumors treated intravenously with PBS, VSV-mIFN-NIS, or VSV-hIFN-NIS measured by ELISA. (B) Mice that had complete tumor regression in response to VSV-mIFN-NIS treatment and naïve age-matched syngeneic mice (n=6 each) were challenged with 1×10 7  5TGM1 cells subcutaneously, and tumor occurrence by day 21 post challenge is shown. (C) Immunotherapeutic efficacy of single dose VSV-infected 5TGM1 cells administered subcutaneously (1×10 7  5TGM1 cells infected with VSV-mIFN-NIS at MOI 10 implanted on left flank) at 1 day post or 5 days prior to tumor implantation (5×10 6  subcutaneous 5TGM1 cells on right flank). Log rank survival analysis comparison revealed day (−5) vaccination prolongs survival of mice following tumor implantation compared to unvaccinated mice (P=0.0253). (D) Mice bearing subcutaneous 5TGM1 tumors were treated with single intravenous dose of (i) PBS, (ii) VSV-mIFN-NIS, or (iii) VSV-mIFN-NIS in the presence or absence of antibodies to deplete CD4 +  or CD8 +  T cells. Tumor burden was measured by serial caliper measurements. (E) Tumor responses for the mice described in  FIG. 7D  were categorized into progression, regression, or regression+relapse. Relapse rates were compared by Fischer Exact test indicating that VSV-mIFN-NIS+T-cell depletion exhibited a higher rate of tumor relapse compared to VSV-mIFN-NIS treatment alone (P=0.0498). 
         FIGS. 8A  and B are detailed immunofluorescence images of intratumoral foci of infection. A 5TGM1 tumor was harvested 24 hours post intravenous VSV-mIFN-NIS injection, frozen in OCT, and sectioned. IF was performed to detect VSV (which stained red), dying cells by TUNEL staining (which stained green), and tumor cell nuclei by Hoescht staining (which stained blue). Distinct roughly spherical intratumoral foci of VSV infection contain a central region of VSV infected cells undergoing cell death and a rim of infected, viable cells in the periphery. 
         FIG. 9  contains images demonstrating that functional NIS activity is limited to regions of VSV infected viable cells. 5TGM1 tumors were harvested at 48 hours (A) or 72 hours (B) post intravenous VSV-IFN-NIS injection and sectioned. Adjacent sections were subject to (i) autoradiography, (ii) IF shown at 20× magnification, and (iii) IF shown at 100× magnification to detect VSV (which stained red) and dying cells by TUNEL staining (which stained green). 
         FIG. 10  is a diagram of exemplary intragenic regions of vesicular stomatitis viruses that contain inserted transgenes. The transgenes are flanked by viral start and stop sequences involved in transcription. The IFN nucleic acid is inserted into a NotI cloning site engineered between the VSV M and G nucleic acid sequences. The NIS nucleic acid is inserted into XhoI and NheI restriction sites engineered between the VSV G and L nucleic acid sequences. 
     
    
    
     DETAILED DESCRIPTION 
     This document provides methods and materials related to vesicular stomatitis viruses. For example, this document provides vesicular stomatitis viruses, nucleic acid molecules encoding VSV polypeptides, methods for making vesicular stomatitis viruses, and methods for using vesicular stomatitis viruses to treat cancer. 
     As described herein, a vesicular stomatitis virus can be designed to have a nucleic acid molecule that encodes a VSV N polypeptide, a VSV P polypeptide, a VSV M polypeptide, a VSV G polypeptide, a VSV L polypeptide, an IFN polypeptide, and a NIS polypeptide. It will be appreciated that the sequences described herein with respect to a vesicular stomatitis virus are incorporated into a plasmid coding for the positive sense cDNA of the viral genome allowing generation of the negative sense genome of vesicular stomatitis viruses. Thus, it will be appreciated that a nucleic acid sequence that encodes a VSV polypeptide, for example, can refer to an RNA sequence that is the template for the positive sense transcript that encodes (e.g., via direct translation) that polypeptide. 
     The nucleic acid encoding the IFN polypeptide can be positioned downstream of the nucleic acid encoding the VSV M polypeptide ( FIG. 1A ). For example, nucleic acid encoding the IFN polypeptide can be positioned between the nucleic acid encoding the VSV M polypeptide and the nucleic acid encoding the VSV G polypeptide. Such a position can allow the viruses to express an amount of the IFN polypeptide that is effective to activate anti-viral innate immune responses in non-cancerous tissues, and thus alleviate potential viral toxicity, without impeding efficient viral replication in cancer cells. 
     Any appropriate nucleic acid encoding an IFN polypeptide can be inserted into the genome of a vesicular stomatitis virus. For example, nucleic acid encoding an IFN beta polypeptide can be inserted into the genome of a vesicular stomatitis virus. Examples of nucleic acid encoding IFN beta polypeptides that can be inserted into the genome of a vesicular stomatitis virus include, without limitation, nucleic acid encoding a human IFN beta polypeptide of the nucleic acid sequence set forth in GenBank® Accession No. NM_002176.2 (GI No. 50593016), nucleic acid encoding a mouse IFN beta polypeptide of the nucleic acid sequence set forth in GenBank® Accession Nos. NM_010510.1 (GI No. 6754303), BC119395.1 (GI No. 111601321), or BC119397.1 (GI No. 111601034), and nucleic acid encoding a rat IFN beta polypeptide of the nucleic acid sequence set forth in GenBank® Accession No. NM_019127.1 (GI No. 9506800). 
     The nucleic acid encoding the NIS polypeptide can be positioned downstream of the nucleic acid encoding the VSV G polypeptide ( FIG. 1A ). For example, nucleic acid encoding the NIS polypeptide can be positioned between the nucleic acid encoding the VSV G polypeptide and the nucleic acid encoding the VSV L polypeptide. Such a position of can allow the viruses to express an amount of the NIS polypeptide that (a) is effective to allow selective accumulation of iodide in infected cells, thereby allowing both imaging of viral distribution using radioisotopes and radiotherapy targeted to infected cancer cells, and (b) is not so high as to be toxic to infected cells. 
     Any appropriate nucleic acid encoding a NIS polypeptide can be inserted into the genome of a vesicular stomatitis virus. For example, nucleic acid encoding a human NIS polypeptide can be inserted into the genome of a vesicular stomatitis virus. Examples of nucleic acid encoding NIS polypeptides that can be inserted into the genome of a vesicular stomatitis virus include, without limitation, nucleic acid encoding a human NIS polypeptide of the nucleic acid sequence set forth in GenBank® Accession Nos. NM_000453.2 (GI No. 164663746), BC105049.1 (GI No. 85397913), or BC105047.1 (GI No. 85397519), nucleic acid encoding a mouse NIS polypeptide of the nucleic acid sequence set forth in GenBank® Accession Nos. NM_053248.2 (GI No. 162138896), AF380353.1 (GI No. 14290144), or AF235001.1 (GI No. 12642413), nucleic acid encoding a chimpanzee NIS polypeptide of the nucleic acid sequence set forth in GenBank® Accession No. XM_524154 (GI No. 114676080), nucleic acid encoding a dog NIS polypeptide of the nucleic acid sequence set forth in GenBank® Accession No. XM_541946 (GI No. 73986161), nucleic acid encoding a cow NIS polypeptide of the nucleic acid sequence set forth in GenBank® Accession No. XM_581578 (GI No. 297466916), nucleic acid encoding a pig NIS polypeptide of the nucleic acid sequence set forth in GenBank® Accession No. NM_214410 (GI No. 47523871), and nucleic acid encoding a rat NIS polypeptide of the nucleic acid sequence set forth in GenBank® Accession No. NM_052983 (GI No. 158138504). 
     Nucleic acid inserted into the genome of a vesicular stomatitis virus (e.g., nucleic acid encoding a NIS polypeptide and/or nucleic acid encoding an IFN polypeptide) can be flanked by viral intragenic regions containing the gene transcription start and stop codes required for transcription of the inserted nucleic acid sequences by the viral polymerase. Examples of such viral intragenic regions include, without limitation, those set forth in  FIG. 10 . 
     The nucleic acid sequences of a vesicular stomatitis virus provided herein that encode a VSV N polypeptide, a VSV P polypeptide, a VSV M polypeptide, a VSV G polypeptide, and a VSV L polypeptide can be from a VSV Indiana strain as set forth in GenBank® Accession Nos. NC_001560 (GI No. 9627229) or can be from a VSV New Jersey strain. 
     In one aspect, this document provides vesicular stomatitis viruses containing a nucleic acid molecule (e.g., an RNA molecule) having, in a 3′ to 5′ direction, a nucleic acid sequence that is a template for a positive sense transcript encoding a VSV N polypeptide, a nucleic acid sequence that is a template for a positive sense transcript encoding a VSV P polypeptide, a nucleic acid sequence that is a template for a positive sense transcript encoding a VSV M polypeptide, a nucleic acid sequence that is a template for a positive sense transcript encoding an IFN polypeptide, a nucleic acid sequence that is a template for a positive sense transcript encoding a VSV G polypeptide, a nucleic acid sequence that is a template for a positive sense transcript encoding a NIS polypeptide, and a nucleic acid sequence that is a template for a positive sense transcript encoding a VSV L polypeptide. Such vesicular stomatitis viruses can infect cells (e.g., cancer cells) and direct the expression of the IFN polypeptide and the NIS polypeptide by the infected cells. 
     Any appropriate method can be used to insert nucleic acid (e.g., nucleic acid encoding an IFN polypeptide and/or nucleic acid encoding a NIS polypeptide) into the genome of a vesicular stomatitis virus. For example, the methods described elsewhere (Obuchi et al.,  J. Virol.,  77(16):8843-56 (2003)); Goel et al.,  Blood,  110(7):2342-50 (2007)); and Kelly et al.,  J. Virol.,  84(3):1550-62 (2010)) can be used to insert nucleic acid into the genome of a vesicular stomatitis virus. Any appropriate method can be used to identify vesicular stomatitis viruses containing a nucleic acid molecule described herein. Such methods include, without limitation, PCR and nucleic acid hybridization techniques such as Northern and Southern analysis. In some cases, immunohistochemistry and biochemical techniques can be used to determine if a vesicular stomatitis virus contains a particular nucleic acid molecule by detecting the expression of a polypeptide encoded by that particular nucleic acid molecule. 
     In another aspect, this document provides nucleic acid molecules that encode a VSV N polypeptide, a VSV P polypeptide, a VSV M polypeptide, an IFN polypeptide, a VSV G polypeptide, a NIS polypeptide, and a VSV L polypeptide. For example, a nucleic acid molecule provided herein can be a single nucleic acid molecule that includes a nucleic acid sequence that encodes a VSV N polypeptide, a nucleic acid sequence that encodes a VSV P polypeptide, a nucleic acid sequence that encodes a VSV M polypeptide, a nucleic acid sequence that encodes an IFN polypeptide, a nucleic acid sequence that encodes a VSV G polypeptide, a nucleic acid sequence that encodes a NIS polypeptide, and a nucleic acid sequence that encodes a VSV L polypeptide. 
     The term “nucleic acid” as used herein encompasses both RNA (e.g., viral RNA) and DNA, including cDNA, genomic DNA, and synthetic (e.g., chemically synthesized) DNA. A nucleic acid can be double-stranded or single-stranded. A single-stranded nucleic acid can be the sense strand or the antisense strand. In addition, a nucleic acid can be circular or linear. 
     This document also provides method for treating cancer (e.g., to reduce tumor size, inhibit tumor growth, or reduce the number of viable tumor cells). For example, a vesicular stomatitis virus provided herein can be administered to a mammal having cancer to reduce tumor size, to inhibit cancer cell or tumor growth, and/or to reduce the number of viable cancer cells within the mammal. A vesicular stomatitis virus provided herein can be propagated in host cells in order to increase the available number of copies of that virus, typically by at least 2-fold (e.g., by 5- to 10-fold, by 50- to 100-fold, by 500- to 1.000-fold, or even by as much as 5,000- to 10.000-fold). In some cases, a vesicular stomatitis virus provided herein can be expanded until a desired concentration is obtained in standard cell culture media (e.g., DMEM or RPMI-1640 supplemented with 5-10% fetal bovine serum at 37° C. in 5% CO 2 ). A viral titer typically is assayed by inoculating cells (e.g., BHK-21 cells) in culture. 
     Vesicular stomatitis viruses provided herein can be administered to a cancer patient by, for example, direct injection into a group of cancer cells (e.g., a tumor) or intravenous delivery to cancer cells. A vesicular stomatitis virus provided herein can be used to treat different types of cancer including, without limitation, myeloma (e.g., multiple myeloma), melanoma, glioma, lymphoma, mesothelioma, and cancers of the lung, brain, stomach, colon, rectum, kidney, prostate, ovary, breast, pancreas, liver, and head and neck. 
     Vesicular stomatitis viruses provided herein can be administered to a patient in a biologically compatible solution or a pharmaceutically acceptable delivery vehicle, by administration either directly into a group of cancer cells (e.g., intratumorally) or systemically (e.g., intravenously). Suitable pharmaceutical formulations depend in part upon the use and the route of entry, e.g., transdermal or by injection. Such forms should not prevent the composition or formulation from reaching a target cell (i.e., a cell to which the virus is desired to be delivered to) or from exerting its effect. For example, pharmacological compositions injected into the blood stream should be soluble. 
     While dosages administered will vary from patient to patient (e.g., depending upon the size of a tumor), an effective dose can be determined by setting as a lower limit the concentration of virus proven to be safe and escalating to higher doses of up to 10 12  pfu, while monitoring for a reduction in cancer cell growth along with the presence of any deleterious side effects. A therapeutically effective dose typically provides at least a 10% reduction in the number of cancer cells or in tumor size. Escalating dose studies can be used to obtain a desired effect for a given viral treatment (see, e.g., Nies and Spielberg, “Principles of Therapeutics,” In Goodman &amp; Gilman&#39;s  The Pharmacological Basis of Therapeutics , eds. Hardman, et al., McGraw-Hill, NY, 1996, pp 43-62). 
     Vesicular stomatitis viruses provided herein can be delivered in a dose ranging from, for example, about 10 3  pfu to about 10 12  pfu (e.g., about 10 5  pfu to about 10 12  pfu, about 10 6  pfu to about 10 11  pfu, or about 10 6  pfu to about 10 10  pfu). A therapeutically effective dose can be provided in repeated doses. Repeat dosing is appropriate in cases in which observations of clinical symptoms or tumor size or monitoring assays indicate either that a group of cancer cells or tumor has stopped shrinking or that the degree of viral activity is declining while the tumor is still present. Repeat doses can be administered by the same route as initially used or by another route. A therapeutically effective dose can be delivered in several discrete doses (e.g., days or weeks apart) and in one embodiment, one to about twelve doses are provided. Alternatively, a therapeutically effective dose of vesicular stomatitis viruses provided herein can be delivered by a sustained release formulation. In some cases, a vesicular stomatitis virus provided herein can be delivered in combination with pharmacological agents that facilitate viral replication and spread within cancer cells or agents that protect non-cancer cells from viral toxicity. Examples of such agents are described elsewhere (Alvarez-Breckenridge et al.,  Chem. Rev.,  109(7):3125-40 (2009)). 
     Vesicular stomatitis viruses provided herein can be administered using a device for providing sustained release. A formulation for sustained release of vesicular stomatitis viruses can include, for example, a polymeric excipient (e.g., a swellable or non-swellable gel, or collagen). A therapeutically effective dose of vesicular stomatitis viruses can be provided within a polymeric excipient, wherein the excipient/virus composition is implanted at a site of cancer cells (e.g., in proximity to or within a tumor). The action of body fluids gradually dissolves the excipient and continuously releases the effective dose of virus over a period of time. Alternatively, a sustained release device can contain a series of alternating active and spacer layers. Each active layer of such a device typically contains a dose of virus embedded in excipient, while each spacer layer contains only excipient or low concentrations of virus (i.e., lower than the effective dose). As each successive layer of the device dissolves, pulsed doses of virus are delivered. The size/formulation of the spacer layers determines the time interval between doses and is optimized according to the therapeutic regimen being used. 
     Vesicular stomatitis viruses provided herein can be directly administered. For example, a virus can be injected directly into a tumor (e.g., a breast cancer tumor) that is palpable through the skin. Ultrasound guidance also can be used in such a method. Alternatively, direct administration of a virus can be achieved via a catheter line or other medical access device, and can be used in conjunction with an imaging system to localize a group of cancer cells. By this method, an implantable dosing device typically is placed in proximity to a group of cancer cells using a guidewire inserted into the medical access device. An effective dose of a vesicular stomatitis virus provided herein can be directly administered to a group of cancer cells that is visible in an exposed surgical field. 
     In some cases, vesicular stomatitis viruses provided herein can be delivered systemically. For example, systemic delivery can be achieved intravenously via injection or via an intravenous delivery device designed for administration of multiple doses of a medicament. Such devices include, but are not limited to, winged infusion needles, peripheral intravenous catheters, midline catheters, peripherally inserted central catheters, and surgically placed catheters or ports. 
     The course of therapy with a vesicular stomatitis virus provided herein can be monitored by evaluating changes in clinical symptoms or by direct monitoring of the number of cancer cells or size of a tumor. For a solid tumor, the effectiveness of virus treatment can be assessed by measuring the size or weight of the tumor before and after treatment. Tumor size can be measured either directly (e.g., using calipers), or by using imaging techniques (e.g., X-ray, magnetic resonance imaging, or computerized tomography) or from the assessment of non-imaging optical data (e.g., spectral data). For a group of cancer cells (e.g., leukemia cells), the effectiveness of viral treatment can be determined by measuring the absolute number of leukemia cells in the circulation of a patient before and after treatment. The effectiveness of viral treatment also can be assessed by monitoring the levels of a cancer specific antigen. Cancer specific antigens include, for example, carcinoembryonic antigen (CEA), prostate specific antigen (PSA), prostatic acid phosphatase (PAP), CA 125, alpha-fetoprotein (AFP), carbohydrate antigen 15-3, and carbohydrate antigen 19-4. 
     The invention will be further described in the following examples, which do not limit the scope of the invention described in the claims. 
     EXAMPLES 
     Example 1 
     Single Dose Intravenous Virotherapy Using Vesicular Stomatitis Viruses That Express an IFN Polypeptide and/or a NIS Polypeptide Mediates Oncolytic Tumor Debulking and Immunotherapeutic Eradication of Residual Disease 
     Vesicular stomatitis viruses designed to express a mouse IFN beta polypeptide (VSV-mIFN) and vesicular stomatitis viruses designed to express both a mouse IFN beta polypeptide and a human NIS polypeptide (VSV-mIFN-NIS;  FIG. 1A ) were created using methods similar to those described elsewhere (Obuchi et al.,  J. Virol.,  77(16):8843-56 (2003)); Goel et al.,  Blood,  110(7):2342-50 (2007)); Kelly et al.,  J. Virol.,  84(3):1550-62 (2010); and Lawson et al.,  Proc. Nat&#39;l. Acad. Sci. USA,  92(10):4477-81 (1995) Erratum in:  Proc. Nat&#39;l. Acad. Sci. USA,  92(19):9009 (1995)). Likewise, vesicular stomatitis viruses designed to express a human IFN beta polypeptide and a human NIS polypeptide (VSV-hIFN-NIS;  FIG. 1A ) were created. Briefly, nucleic acid sequences of desired transgenes were generated with specific restriction sites using PCR. The transgenes were inserted at specific insertion sites into a plasmid encoding the positive strand of the VSV genome in a 5′ to 3′ orientation. The modified plasmid was expanded and infective virus was recovered by infection with vaccinia virus coding for required T7 polymerase and transfection of VSV viral proteins N, P, and L. This allowed production of required viral polypeptides allowing generation of the negative sense viral genome that was assembled into infective virions. Recovered virus was amplified, and infective dose was measured on an appropriate cell line in culture (e.g., BHK-21 cells). The nucleic acid sequence of the mouse IFN beta polypeptide used to make these vesicular stomatitis viruses is set forth in GenBank® Accession No. NM_010510.1 (GI No. 6754303). The nucleic acid sequence of the human IFN beta polypeptide used to make these vesicular stomatitis viruses is set forth in GenBank® Accession No. NM_002176.2 (GI No. 50593016). The nucleic acid sequence of the human NIS polypeptide used to make these vesicular stomatitis viruses is set forth in GenBank® Accession No. NM_000453.2 (GI No. 164663746). 
     When nucleic acid encoding the human NIS polypeptide was inserted upstream of the nucleic acid encoding the VSV G polypeptide, functional virions were not generated because the NIS expression levels appear to have been too high for cells to remain viable and allow viral propagation. Inserting nucleic acid encoding the NIS polypeptide downstream of the nucleic acid encoding the VSV G polypeptide resulted in the generation of functional NIS-expressing virions due to lower quantities of NIS polypeptide being produced thereby allowing not only efficient viral propagation, but also sufficient quantities of NIS polypeptide for functional iodide uptake in infected cells ( FIG. 2B ). 
     Inserting nucleic acid encoding an IFN polypeptide between the nucleic acid encoding the VSV M polypeptide and the nucleic acid encoding the VSV G polypeptide resulted in viruses that infected cells and produced a significantly increased level of IFN polypeptide expression that was observed in the supernatant from infected cells ( FIG. 2A ). The VSV-IFN-NIS viruses were able to replicate efficiently in vitro in infected cells and also express high levels of functional NIS as shown by the ability of the infected cells to take up radio-iodide ( FIG. 2B ). 
     Purified stocks of the two VSV-IFN-NIS viruses were titrated on BHK (hamster) cells ( FIG. 1B ), and cell supernatants were harvested to confirm the secretion of virally encoded IFNβ. High concentrations of human or murine IFNβ were detected in supernatants of BHK cells infected with VSV-hIFN-NIS and VSV-mIFN-NIS, respectively ( FIG. 1D ), and radioiodine uptake studies confirmed perchlorate sensitive (i.e., NIS-mediated) concentration of radioactive iodine in virus-infected cells ( FIG. 1C ), maximal at 24 hours after high multiplicity infection. 
     To evaluate the in vivo activity of the VSV-IFN-NIS viruses, the 5TGM1 and MPC-11 murine myeloma cell lines were chosen because they reliably form subcutaneous or orthotopic tumors in immunocompetent syngeneic mice (Lichty et al.,  Hum. Gene Ther.,  15:821-831 (2004) and Turner et al.,  Human Gene Therapy,  9:1121-1130 (1998)). Both lines were confirmed susceptible to VSV-IFN-NIS infection ( FIG. 1E ), resulting in functional NIS expression, IFNβ release, and subsequent cell killing. To determine whether intravenously administered VSV-IFN-NIS viruses could extravasate from tumor blood vessels and spread through the parenchyma of the tumor, subcutaneous 5TGM1 or MPC-11 tumors were grown (˜5 mm diameter) in syngeneic mice, a single intravenous dose of 10 8  TCID 50  VSV-IFN-NIS virus was administered, and the biodistribution of virally encoded NIS expression was noninvasively monitored by daily SPECT/CT imaging using 99 mTcO4 (6 hour half-life) as tracer ( FIG. 3A ). These tracer uptake studies indicated that the virus was efficiently extravasating from tumor blood vessels and suggested that it may be rapidly spreading in the subcutaneous tumors. 
     To confirm that the virus was actually replicating and spreading in the tumor parenchyma, selected tumors were harvested immediately after SPECT/CT imaging at 24, 48, and 72 hours post VSV-IFN-NIS virus administration and subjected to (i) autoradiography to detect viable NIS-expressing tumor cells; (ii) immunofluorescence (IF) to detect VSV antigens, and (iii) TUNEL staining to identify dead or dying cells. Careful analysis of the data shown in  FIG. 3B  indicated the existence of large, approximately spherical zones of VSV infection in which the tumor cells at the center were apoptotic and those at the periphery remained viable (see also  FIG. 8 ), express NIS ( FIG. 5 ), and concentrate 99 mTcO4 ( FIG. 9 ). Quantitative analysis of IF and TUNEL data indicated a significant increase in the number of virus-infected and apoptotic cells between 24 and 48 hours post virus administration ( FIG. 3C ). By 72 hours after infection, the growing zones of VSV infection largely coalesced, resulting in wholesale tumor destruction ( FIG. 3B  and  FIG. 8 ). 
     Additional experiments were conducted to characterize the kinetics of virus spread at very early time-points, during the first 24 hours after virus administration ( FIG. 4A ). Analysis of tumor sections harvested 6 hours after IV virus administration and stained for both VSV and CD31-positive blood vessels revealed individual scattered VSV infected cells, mostly close to tumor blood vessels. By 12 hours, small clusters of virus infected cells were visible and by 18 hours they grew significantly until by 24 hours they exhibited the typical appearance described previously—apoptotic at the center and viable at the periphery. Analysis of these dual CD31/VSV stained sections ( FIG. 4A , panels i-vi) indicated that the endothelial cells lining tumor blood vessels did not succumb to VSV infection, even when completely surrounded by VSV-infected tumor cells, shown at high magnification in  FIG. 4B . By plotting average diameters of infectious centers (measured as number of cells across) at 6, 12, 18, and 24 hour time-points ( FIG. 4C ), it appeared that the virus spread centrifugally at a constant rate, taking approximately 2 hours to infect each successive layer of cells in the expanding sphere. The rate of accrual of new cells into each infectious center therefore increased as the infection progressed, and it was estimated that each center contained approximately 10,000 cells by 24 hours after virus delivery. 
     To determine the approximate time from infection to death of infected tumor cells in vivo, the average diameter of the rim of viable, VSV-infected (i.e. TUNEL-negative, VSV-positive) cells at the advancing edge of intratumoral infection was measured to be approximately 10 cells ( FIG. 4D ). Thus, the virus spread centrifugally, and it took approximately 2 hours to pass the virus on to an adjacent cell ( FIG. 4C ), while cell death did not occur until the rim of infected cells advanced by 10 cell diameters ( FIG. 4D ). Combining these observations, it was concluded that it takes approximately 20 hours for an infected cells to become apoptotic. 
     To determine whether efficient extravasation and rapid intratumoral spread of the virus is associated with tumor regression, additional groups of C57KaLwRij mice with subcutaneous 5TGM1 tumors were treated with a single intravenous dose of 10 8  TCID 50  VSV-IFN-NIS and were followed longer term with daily health status checks and tumor measurements. Tumors regressed rapidly in the majority of VSV-mIFN-NIS and VSV-hIFN-NIS treated animals ( FIG. 6A ). Occasional very early deaths were not associated with neurotoxicity and were presumed due to rapid tumor lysis syndrome, although this was not formally proven. Interestingly, two to three weeks after administration of the viral therapy, tumor recurrence was seen in most of the animals treated with VSV-hIFN-NIS, but not in those treated with VSV-mIFN-NIS ( FIGS. 6A and 6B ), suggesting that the virally encoded mouse IFNβ, but not the human IFNβ, was capable of activating mechanisms that lead to the complete eradication of residual disease in this syngeneic immunocompetent mouse model. Retreatment of relapsing tumors with VSV-IFN-NIS was not attempted since all of the mice had by that time developed high titers of anti-VSV antibodies ( FIG. 6C ). 
     Measurement of serum IFNβ levels in virus treated animals indicated that this virally encoded cytokine was released into the bloodstream by virally infected tumor cells at early time-points after virus administration ( FIG. 7A ). Antitumor actions of interferon beta include the direct inhibition of tumor cell proliferation, natural killer cell activation, anti-angiogenesis, and the enhancement of antitumor T cell responses. However, proliferation of 5TGM1 and MPC11 myeloma cells in vitro was not adversely affected even at high concentrations of IFNβ ( FIG. 1F ). Moreover, analysis of CD31 or CD3 stained sections of virus treated tumors did not reveal any evidence for inhibition of anti-angiogenic activity, nor for tumor infiltration by host T lymphocytes ( FIG. 4B ). However, virus treated animals whose tumors did not recur were found to be resistant to re-challenge with 5TGM1 tumor cells ( FIG. 7B ), indicating that mice had developed 5TGM1 specific antitumor immunity. To determine whether syngeneic VSV-infected myeloma cells could provoke a specific anti-myeloma immune response, syngeneic mice were immunized with a single subcutaneous injection of 10 7  VSV-infected 5TGM1 cells, either one day after or five days prior to subcutaneous tumor cell implantation. Tumor growth was delayed resulting in a significant enhancement of survival in mice that were immunized 5 days prior to tumor challenge ( FIG. 7C ), indicating that the VSV-infected tumor cells provoked a modest antitumor immune response. However, the VSV-infected tumor cell vaccine exhibited no detectable antitumor activity in mice bearing even small, established tumors, suggesting that antitumor immunity was effective only in the context of minimal disease burden. 
     To determine whether the lower tumor relapse rates in VSV-mIFN-NIS treated mice could be attributed to virally encoded IFNβ enhancing the antitumor T-cell response, a cocktail of anti-CD4 and anti-CD8 antibodies was used to deplete T-cells. Tumors responded equally well to the intravenous VSV-mIFN-NIS therapy regardless of T cell depletion status, but the rate of tumor recurrence was significantly higher in T-cell depleted mice ( FIGS. 7D and 7E ). These results indicate that eradication of residual tumor cells after oncolytic debulking by VSV-mIFN-NIS was mediated by tumor-specific T cells whose amplification was stimulated by the virally encoded mouse IFNβ. 
     When compared to the VSV-Δ51-NIS virus described in the Goel et al. reference ( Blood,  110(7):2342-50 (2007)), which exhibited weak oncolytic efficacy in the immune competent 5TGM1 syngeneic multiple myeloma mouse model (C57B1/KalwRijHsd), the VSV-IFN and VSV-IFN-NIS viruses exhibited greatly superior replication kinetics. In addition, compared to the VSV-Δ51-NIS virus, the VSV-IFN-NIS viruses induced higher NIS polypeptide expression in vitro. In vivo therapy studies demonstrated that a single intravenous dose of each of the VSV-IFN and VSV-IFN-NIS viruses promoted tumor regression and significantly prolonged survival of immunocompetent mice bearing subcutaneous or orthotopic 5TGM1 myeloma tumors. Tc-99m imaging studies conducted in mice treated with VSV-IFN-NIS viruses exhibited tumor specific viral NIS polypeptide expression and radio-isotope uptake that increased concurrently with intratumoral viral spread. Further, there were no indications of neurotoxicity following treatment with the VSV-IFN and VSV-IFN-NIS viruses. These results indicate that VSV-IFN-NIS viruses can be used as a therapeutic agent for cancer (e.g., multiple myeloma) that can be combined with radio-isotopes for both non-invasive imaging of viral biodistribution and radiovirotherapy. 
     The results provided herein demonstrate that vesicular stomatitis viruses encoding human IFNβ and human NIS exhibit oncolytic efficacy in vivo in an immune competent mouse model of multiple myeloma. Systemically administered virus was able to replicate in the tumor, express sufficient levels of functional NIS polypeptides, exert an oncolytic activity to induce tumor regression and improve survival, and exhibit superior NIS expression and oncolytic activity as compared to VSV Δ51-NIS virus. 
     Cell Culture and Viruses 
     Cell lines were cultured in media supplemented with 10% fetal bovine serum (FBS), 100 U/mL penicillin and 100 mg/mL streptomycin. BHK-21 and MPC-11 cells, obtained from American Type cell culture (ATCC), were grown in Dulbecco Modified eagles medium (DMEM). 5TGM1 cells were obtained from Dr. Babatunde Oyajobi (UT Health Sciences Center, San Antonio, Tex.) and grown in Iscove&#39;s modified Dulbecco medium (IMDM). B-16 murine melanoma cells were obtained from R. Vile and grown in DMEM. All cell lines tested negative for mycoplasma contamination. 
     Restriction sites were engineered into a pVSV-XN2 plasmid, containing the VSV positive strand antigenome, at the M/G and the G/L gene junctions preceded by the putative VSV intergenic sequence (TATG(A) 7 CTAACAG) required for functional transgene expression (Schnell et al.,  J. Virol.,  70:2318-2323 (1996)). Restriction site flanked cDNA coding for murine IFNβ, human IFNβ, and NIS genes were generated by PCR. Murine or human IFNβ were incorporated into a single NotI site (M/G junction), while NIS was incorporated into XhoI and NheI sites (G/L junction) to generate VSV-IFN-NIS plasmid. VSV-IFN-NIS virus was rescued using methods described elsewhere (Whelan et al.,  Proc. Natl. Acad. Sci. USA,  92:8388-8392 (1995)). Viruses were subsequently amplified in BHK-21 cells, purified by filtration of cell supernatant, and pelleted by centrifugation through 10% w/v sucrose. Viral titer was measured in BHK-21 cells following infection using serially diluted virus stock to measure Tissue culture infective dose (TCID 50 ) determined using the Spearman and Karber equation. 
     In Vitro Viral Characterization 
     Viral titer was measured in supernatant following infection of BHK-21 cells (MOI 1.0, 1 hour at 37° C.). To measure in vitro radio-iodide uptake, cells were incubated in Hanks buffered salt solution (HBSS) with 10 mM HEPES (N-2-hydroxyethylpiperazine-N′-2-ethanesulfonic acid, pH 7.3) in the presence of radio-labeled NaI (I 125  at 1×10 5  cpm) +/−100 μM potassium perchlorate (KClO 4 ). IFNβ secretion in supernatant of infected cells was determined using an enzyme-linked immuno adsorbent assay (ELISA) against murine or human IFN≈ (PBL Interferonsource). To compare IFN responsiveness, cells were pre-incubated with 100 U/mL murine IFNβ for 12 hours, followed by infection with VSV-GFP. Proliferation of viable cells was assessed by MTT assay (ATCC). Killing of 5TGM1 and MPC-11 by VSV-IFN-NIS (MOI 1.0) was similarly monitored at specific time points following infection by MTT assay shown as a percentage of untreated cells. 
     In Vivo Studies 
     5×10 6  5TGM1 or MPC-11 murine myeloma cells were subcutaneously implanted on the right flank of 6-10 week-old syngeneic female C57B16/KaLwRij (Harlan, Netherlands) or Balb/c mice (Taconic), respectively. Tumor burden was measured by serial caliper measurements. Mice were administered with a single, intravenous dose of 1×10 8 /0.1 mL VSV-IFN-NIS or equal volume PBS by tail vein injection. SPECT-CT imaging was carried out following intraperitoneal (IP) administration of 0.5 mCi Tc-99m and quantified as described elsewhere (Penheiter et al.,  AJR Am. J. Roentgenol.,  195:341-349 (2010)). 
     High Resolution Tumor Analysis 
     Tumors harvested at 24 hour intervals were frozen in OCT for sectioning. Tumor sections were analyzed by autoradiography and immunofluorescence (IF) for (i) VSV antigens using polyclonal rabbit anti-VSV generated in-house in the viral vector production labs at the Mayo Clinic, followed by Alexa-labeled anti-rabbit IgG secondary antibody (Invitrogen, Molecular Probes), (ii) cell death by TUNEL staining (DeadEnd™ Fluorometric TUNEL kit, Promega), and (iii) cellular nuclei using Hoescht 33342 (Invitrogen). Image quantification was performed on four random images from n=3 VSV-mIFN-NIS treated tumors (except n=2 tumors at 72 hours post treatment) using ImageJ software to obtain VSV or TUNEL(+) regions as percentage of tumor area. IF analysis of tumors harvested at 6 hour intervals detected VSV antigens and tumor blood vessels using a rat anti-mouse CD31 antibody (BD Pharmingen). Intratumoral foci size was quantified by measuring 7-8 foci from 2 tumors and dividing diameter by average tumor cell size (based on diameter measurements of 50 individual cells) to obtain foci diameter in numbers of cells. Volume of approximately spherical foci was estimated using formula, v=4/3(π*r3). Average width of rim of viable, VSV-infected cells was similarly quantified from IF images from n=3 tumors harvested at 48 hours post VSV-IFN-NIS administration. 
     Immune Studies in Immune Competent Mice 
     To measure generation of antiviral antibodies, serial 2-fold dilutions of heat-inactivated serum were pre-incubated with 500 TCTID 50  VSV-GFP, and subsequently used to infect BHK-21 cells. Minimum serum dilution allowing VSV induced CPE was plotted. In vivo IFNβ secretion was measured in serum by ELISA. 5TGM1 vaccinations were administered by injecting 1×10 7  VSV-mIFN-NIS infected cells (MOI 10.0) subcutaneously in the left flank of syngeneic mice. T-cell depletion studies were performed in C57B16/KaLwRij mice by intraperitoneal administration of anti-CD4 and anti-CD8 antibodies (50 μg each) administered 3 times/week, followed by a weekly maintenance dose. 
     Statistical Methods 
     Visual displays of the data were used to assess for outliers or substantial departures from normality, and t-test was utilized where described. In all cases, two-tail P-values were provided which are not adjusted for multiple comparisons. Comparison of survival differences was performed using Log-rank test from Kaplan meier survival curves. For comparing tumor relapse rates in animal studies, the Fischer exact test was utilized due to small sample size. 
     Other Embodiments 
     It is to be understood that while the invention has been described in conjunction with the detailed description thereof, the foregoing description is intended to illustrate and not limit the scope of the invention, which is defined by the scope of the appended claims. Other aspects, advantages, and modifications are within the scope of the following claims.