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Supplementary Table 1 from Eradication of Solid Human Breast Tumors in Nude Mice with an Intravenously Injected Light-Emitting Oncolytic Vaccinia Virus

Previously, we reported that a recombinant vaccinia virus (VACV) carrying a light-emitting fusion gene enters, replicates in, and reveals the locations of tumors in mice. A new recombinant VACV, GLV-1h68, as a simultaneous diagnostic and therapeutic agent, was constructed by inserting three expression cassettes (encoding Renilla luciferase–Aequorea green fluorescent protein fusion, β-galactosidase, and β-glucuronidase) into the F14.5L, J2R (encoding thymidine kinase) and A56R (encoding hemagglutinin) loci of the viral genome, respectively. I.v. injections of GLV-1h68 (1 × 107 plaque-forming unit per mouse) into nude mice with established (∼300–500 mm3) s.c. GI-101A human breast tumors were used to evaluate its toxicity, tumor targeting specificity, and oncolytic efficacy. GLV-1h68 showed an enhanced tumor targeting specificity and much reduced toxicity compared with its parental LIVP strains. The tumors colonized by GLV-1h68 exhibited growth, inhibition, and regression phases followed by tumor eradication within 130 days in 95% of the mice tested. Tumor regression in live animals was monitored in real time based on decreasing light emission, hence demonstrating the concept of a combined oncolytic virus–mediated tumor diagnosis and therapy system. Transcriptional profiling of regressing tumors based on a mouse-specific platform revealed gene expression signatures consistent with immune defense activation, inclusive of IFN-stimulated genes (STAT-1 and IRF-7), cytokines, chemokines, and innate immune effector function. These findings suggest that immune activation may combine with viral oncolysis to induce tumor eradication in this model, providing a novel perspective for the design of oncolytic viral therapies for human cancers. [Cancer Res 2007;67(20):10038–46]

Background Oncolytic viral efficacy may be limited by the penetration of the virus into tumors. This may be enhanced by intraoperative application of virus immediately after surgical resection. Methods Oncolytic vaccinia virus GLV-1h68 was delivered in silk-elastin-like protein polymer (SELP) in vitro and in vivo in anaplastic thyroid carcinoma cell line 8505c in nude mice. Results GLV-1h68 in SELP infected and lysed anaplastic thyroid cancer cells in vitro equally as effectively as in phosphate-buffered saline (PBS), and at 1 week retains a thousand fold greater infectious plaque-forming units. In surgical resection models of residual tumor, GLV-1h68 in SELP improves tumor control and shows increased viral β-galactosidase expression as compared to PBS. Conclusion The use of SELP matrix for intraoperative oncolytic viral delivery protects infectious viral particles from degradation, facilitates sustained viral delivery and transgene expression, and improves tumor control. Such optimization of methods of oncolytic viral delivery may enhance therapeutic outcomes. © 2014 Wiley Periodicals, Inc. Head Neck, 2015

Poxviruses produce complement regulatory proteins to subvert the host's immune response. Similar to the human pathogen variola virus, ectromelia virus has a limited host range and provides a mouse model where the virus and the host's immune response have coevolved. We previously demonstrated that multiple components (C3, C4, and factor B) of the classical and alternative pathways are required to survive ectromelia virus infection. Complement's role in the innate and adaptive immune responses likely drove the evolution of a virus-encoded virulence factor that regulates complement activation. In this study, we characterized the ectromelia virus inhibitor of complement enzymes (EMICE). Recombinant EMICE regulated complement activation on the surface of CHO cells, and it protected complement-sensitive intracellular mature virions (IMV) from neutralizationin vitro. It accomplished this by serving as a cofactor for the inactivation of C3b and C4b and by dissociating the catalytic domain of the classical pathway C3 convertase. Infected murine cells initiated synthesis of EMICE within 4 to 6 h postinoculation. The levels were sufficient in the supernatant to protect the IMV, upon release, from complement-mediated neutralization. EMICE on the surface of infected murine cells also reduced complement activation by the alternative pathway. In contrast, classical pathway activation by high-titer antibody overwhelmed EMICE's regulatory capacity. These results suggest that EMICE's role is early during infection when it counteracts the innate immune response. In summary, ectromelia virus produced EMICE within a few hours of an infection, and EMICE in turn decreased complement activation on IMV and infected cells.

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), -galactosidase, and -glucuronidase into the genome of LIVP strain. Infection of 6 ATC cell lines by GLV-1h68 was detected in vitro at 12, 24, and 36 hours. Viral proliferation was measured through viral plaque assays. Cytotoxicity was measured daily at a multiplicity of infection (MOI) of 0.01, 0.1 and 1. Results. Viral infection was detected in all cell lines by 24 hours and increased in intensity at 36 hours. Logarithmic viral replication was detected in all cell lines. At MOI 1, 13% cell survival was measured in 5 cell lines by day 7. At MOI 0.01, 3 cell lines showed 21% cell survival by day 7. Luciferase and -galactosidase activity at 24 hours correlated with cytotoxicity at MOI 0.01 on day 5. Conclusion. A replication-competent vaccinia virus has significant infectious and oncolytic activity against a panel of human ATC. These results encourage future in vivo and clinical studies for this novel agent to treat this fatal cancer. (Surgery 2007;142:976-83.)

Conventional vaccines used for smallpox eradication were often denoted one or another strain of Vaccinia virus (VACV), even though seed virus was sub-cultured multifariously, which rendered the virion population genetically heterogeneous. ACAM2000 cell culture vaccine, recently licensed in the U.S., consists of a biologically vaccine-like VACV homogeneous-sequence clone from the conventional smallpox vaccine Dryvax, which we verified from Dryvax sequence chromatograms is genetically heterogeneous. ACAM2000 VACV and CL3, a mouse-neurovirulent clone from Dryvax, differ by 572 single nucleotide polymorphisms and 53 insertions–deletions of varied size, including a 4.5-kbp deletion in ACAM2000 and a 6.2-kbp deletion in CL3. The sequence diversity between the two clones precludes precisely defining why CL3 is more pathogenic; however, four genes appear significantly dissimilar to account for virulence differences. CL3 encodes intact immunomodulators interferon-α/β and tumor necrosis factor receptors, which are truncated in ACAM2000. CL3 specifies a Cowpox and Variola virus -like ankyrin-repeat protein that might be associated with proteolysis via ubiquitination. And, CL3 shows an elongated thymidylate kinase, similar to the enzyme of the mouse-neurovirulent VACV-WR, a derivative of the New York City Board of Health vaccine, the origin vaccine of Dryvax. Although ACAM2000 encodes most proteins associated with immunization protection, the cloning probably delimited the variant epitopes and other motifs produced by Dryvax due to its VACV genetic heterogeneity. The sequence information for ACAM2000 and CL3 could be significant for resolving the dynamics of their different proteomes and thereby aid development of safer, more effective vaccines.

Ectromelia virus (ECTV), the causative agent of mousepox, expresses an extracellular interferon-gamma binding protein (IFN-gammaBP) with homology to the ligand binding domains of the IFN-gamma high affinity receptor (IFN-gammaR1). Unlike the cellular receptor, the IFN-gammaBP binds IFN-gamma from several species. The IFN-gammaBP is synthesized early after infection, accumulating in the extracellular milieu as dimers composed of two protein species with Mr of 34.6 or 33.0 kDa. Homodimers are covalently linked by an interchain disulphide bond at position 216. The IFN-gammaBP has complex N-linked oligosaccharides at positions 41 and 149 as determined by site-directed mutagenesis and glycosidase treatment. Glycosylation at position 41 is required for secretion from mammalian cells and may play a role in the activity of the IFN-gammaBP. Glycosylation at position 149 is not required for secretion, and the lack of glycosylation at this site does not diminish ligand binding as measured by surface plasmon resonance (SPR) and ELISA.

Cytokines are pivotal to a balanced innate or cell-mediated immune response, can be indicative of disease progression and/or resolution, and are being evaluated as therapeutics. There is a need to purify and/or to measure key cytokines rapidly with accuracy, precision, and sensitivity. The current assay technologies, which are based on RT-PCR, immunoassays, or bioassays, are limited in their use in the clinic, in particular because of the long time (1—3 h) required to carry out the assays. An alternative approach explored here is the use of pathogen-encoded cytokine- binding proteins, which have Kd in the nanomolar range. It is anticipated that pathogens have evolved binding proteins, antagonists, and/or specific neutralizing phenotypes directed against key signaling and effector molecules involved in the multifaceted host defense system. Thus, by screening the genomes of a wide range of microbial agents, we would expect to find coding sequences for binding proteins for the most important cytokines. Consistent with this view is the identification of poxvirus genes encoding binding activities for TNF, type I and type II interferons, interleukin (IL)-1β, IL-18, and β-chemokines. These high-affinity receptors have the potential to act as surrogate antibodies in a number of applications in cytokine quantification and purification and could be potentially useful reagents to complement the existing panel of anti-cytokine, monoclonal, polyclonal, or engineered antibodies that are currently available.

Vascular endothelial growth factor (VEGF) expression is higher in triple-negative breast cancers (TNBC) compared to other subtypes and is reported to predict incidence of distant metastases and shorter overall survival. We investigated the therapeutic impact of a vaccinia virus (VACV) GLV-1h164 (derived from its parent virus GLV-1h100), encoding a single-chain antibody (scAb) against VEGF (GLAF-2) in an orthotopic TNBC murine model. GLV-1h164 was tested against multiple TNBC cell lines. Viral infectivity, cytotoxicity, and replication were determined. Mammary fat pad tumors were generated in athymic nude mice using MDA-MB-231 cells. Xenografts were treated with GLV-1h164, GLV-1h100, or PBS and followed for tumor growth. Viral infectivity was time- and concentration-dependent. GLV-1h164 killed TNBC cell lines in a dose-dependent fashion with greater than 90% cytotoxicity within 4 days at a multiplicity of infection of 5.0. In vitro, cytotoxicity of GLV-1h164 was identical to GLV-1h100. GLV-1h164 replicated efficiently in all cell lines with an over 400-fold increase in copy numbers from the initial viral dose within 4 days. In vivo, mean tumor volumes after 2 weeks of treatment were 73, 191, and 422 mm(3) (GLV-1h164, GLV-1h100, and PBS, respectively) (p < 0.05). Both in vivo Doppler ultrasonography and immuno-staining showed decreased neo-angiogenesis in GLV-1h164-treated tumors compared to both GLV-1h100 and PBS controls (p < 0.05). This is the first study to demonstrate efficient combination of oncolytic and anti-angiogenic activity of a novel VACV on TNBC xenografts. Our results suggest that GLV-1h164 is a promising therapeutic agent that warrants testing for patients with TNBC.

A novel poxvirus gene has been characterized within the genome of ectromelia virus. It has significant similarity to a family of lysophospholipases suggesting that it may function in the degradation of lysophospholipids. Since these molecules are active in the stimulation of inflammation, we hypothesize that this gene may play a role in virus virulence. This gene is expressed early in the ectromelia virus replication cycle, before DNA replication. We have also characterized a human cDNA that encodes a protein which is 49.5% identical to the ectromelia virus protein. By its presence in multiple cDNA libraries, this human gene is known to be expressed in a variety of body tissues and is likely to function in the normal regulation of lysophospholipid levels. This family of proteins have conserved blocks of amino acids that are indicative of a serine-aspartic acid-histidine catalytic triad, similar to those used by true lipases and a number of esterases.

Salivary gland carcinomas are relatively rare malignant tumors, accounting for less than 5% of all cancers of the head and neck.1 They encompass a wide spectrum of histologic abnormalities with varied biologic behavior. Initial therapy of localized disease consists of complete surgical excision. The risk of recurrence and metastasis is significantly higher in patients with locally advanced salivary carcinomas. Individuals with high-grade salivary carcinomas have a 5-year survival of roughly 40%; those with low-and intermediate-grade tumors have a 5-year survival of 85% to 90%.2,3 For these patients, complete surgical resection followed by postoperative radiation therapy is recommended.4 Unfortunately, patients with recurrent and/or unresectable disease have few effective treatment options. Clinical trials exploring the role of chemotherapy in the management of salivary gland carcinomas failed to show survival benefit.1 Chemotherapy, therefore, is generally reserved as a palliative measure for patients with symptoms and/or rapid disease progression. Clearly, novel therapies are needed to improve outcomes for patients with salivary carcinomas. Oncolytic viruses have emerged as versatile therapeutic agents that can selectively infect, replicate within, and ultimately lyse a host cancer cell. A variety of viruses have been reported5–7 to possess on-colytic antitumoral activity, including herpes simplex type 1, adenovirus, reovirus, vesicular stomatitis virus, measles virus, poliovirus, West Nile virus, and New-castle disease virus. Vaccinia virus, which is a double-stranded DNA member of the genus Orthopoxvirus, has many unique characteristics that make it an excellent tool in cancer treatment. In addition to its natural tropism for tumor tissues and its abilities for efficient entry, replication, and lysis, vaccinia virus has a remarkable safety record in its historical widespread human application as a vaccine for smallpox. The vaccinia replication cycle occurs exclusively in the cytoplasm, which eliminates the possibility of chromosomal integration.7 Furthermore, there are many Food and Drug Administration–approved antiviral agents available to limit viral spread and control the unlikely possibility of viral toxicity.8 Consequently, several recombinant vaccinia viruses have been constructed and studied in preclinical and clinical phase 1 settings.8,9 Recombinant, replication-competent vaccinia virus (GLV-1h68) has been reported10–16 as effective in breast cancer, thyroid cancer, mesothelioma, pancreatic cancer, prostate cancer, human hepatocellular carcinoma, and head and neck cancer models. The aim of this study was to assess the usefulness of GLV-1h68 as a therapeutic agent against salivary gland carcinoma in vitro and in vivo. Murine flank and orthotopic parotid tumor models were used.

Background Approximately one fourth of bone and soft-tissue sarcomas recur after prior treatment. GLV-1h68 is a recombinant, replication-competent vaccinia virus that has been shown to have oncolytic effects against many human cancer types. We sought to determine whether GLV-1h68 could selectively target and lyse a panel of human bone and soft-tissue sarcoma cell lines in vitro and in vivo . Methods GLV-1h68 was tested in a panel of four cell lines including: fibrosarcoma HT-1080, osteosarcoma U-2OS, fibrohistiocytoma M-805, and rhabdomyosarcoma HTB-82. Gene expression, infectivity, viral proliferation, and cytotoxicity were characterized in vitro . HT-1080 xenograft flank tumors grown in vivo were injected intratumorally with a single dose of GLV-1h68. Results All four cell lines supported robust viral transgene expression in vitro . At a multiplicity of infection (MOI) of five, GLV-1h68 was cytotoxic to three cell lines, resulting in >80% cytotoxicity over 7 d. In vivo , a single injection of GLV-1h68 into HT-1080 xenografts exhibited localized intratumoral luciferase activity peaking at d 2–4, with gradual resolution over 8 d and no evidence of spread to normal tissues. Treated animals exhibited near-complete tumor regression over a 28-d period without observed toxicity. Conclusion GLV-1h68 has potent direct oncolytic effects against human sarcoma in vitro and in vivo . Recombinant vaccinia oncolytic virotherapy could provide a new platform for the treatment of patients with bone and soft tissue sarcomas. Future clinical trials investigating oncolytic vaccinia as a therapy for sarcomas are warranted.

Context: Anaplastic thyroid carcinoma (ATC) is a fatal disease with a median survival of only 6 months. Novel therapies are needed to improve dismal outcomes. Objective: A mutated, replication-competent, vaccinia virus (GLV-1h68) has oncolytic effects on human ATC cell lines in vitro. We assessed the utility of GLV-1h68 in treating anaplastic thyroid cancer in vivo. Design: Athymic nude mice with xenograft flank tumors of human ATCs (8505C and DRO90–1) were treated with a single intratumoral injection of GLV-1h68 at low dose (5 × 105 plaque-forming unit), high dose (5 × 106 plaque-forming unit), or PBS. Virus-mediated marker gene expression (luciferase, green fluorescent protein, and β-galactosidase), viral biodistribution, and flank tumor volumes were measured. Results: Luciferase expression was detected 2 d after injection. Continuous viral replication within tumors was reflected by increasing luciferase activity to d 9. At d 10, tumor viral recovery was increased more than 50-fold as compared with the injected dose, and minimal virus was recovered from the lung, liver, brain, heart, spleen, and kidneys. High-dose virus directly injected into normal tissues was undetectable at d 10. The mean volume of control 8505C tumors increased 50.8-fold by d 45, in contrast to 10.5-fold (low dose) and 2.1-fold (high dose; P = 0.028) increases for treated tumors. DRO90–1 tumors also showed significant growth inhibition by high-dose virus. No virus-related toxicity was observed throughout the study. Conclusions: GLV-1h68 efficiently infects, expresses transgenes within, and inhibits the growth of ATC in vivo. These promising findings support future clinical trials for patients with ATC.

INTRODUCTION Vaccinia virus (VV) is the prototypic member of the genus Orthopoxvirus of the family Poxviridae, which was used worldwide as a live vaccine against smallpox virus that was declared eradicated by the World Health Organization in 1980. Since the early 1980s when the first genetically engineered W s were created, VV has been widely used for high-level expression of foreign genes in mammalian cells and as a vector for vaccines against other infectious diseases and cancer.' Recently, VV has also been explored in tumor-directed oncolytic virotherapy and imaging of tumors and meta~tases.~'~ As an oncolytic agent, the capability of a virus to replicate in vitro in cultured tumor cells is a must. To facilitate evaluation of virus replication in vitro and monitoring virus therapeutic effects and spread in vivo we have created two recombinant vaccinia viruses that express click beetle luciferase-mRFP1 (CBG99-mRFPI) and Renilla luciferase-GFP (RUC-GFP) fusion genes, respectively. We have shown that vaccinia virus replication in cultured cells and in living mice can be monitored by both fluorescence and bioluminescence imaging.

Ectromelia virus (ECTV), a natural mouse pathogen and the causative agent of mousepox, is closely related to variola virus (VARV), which causes smallpox in humans. Mousepox is an excellent surrogate small-animal model for smallpox. Both ECTV and VARV encode a multitude of host response modifiers that target components of the immune system and that are thought to contribute to the high mortality rates associated with infection. Like VARV, ECTV encodes a protein homologous to the ectodomain of the host gamma interferon (IFN-γ) receptor 1. We generated an IFN-γ binding protein (IFN-γbp) deletion mutant of ECTV to study the role of viral IFN-γbp (vIFN-γbp) in host-virus interaction and also to elucidate the contribution of this molecule to the outcome of infection. Our data show that the absence of vIFN-γbp does not affect virus replication per se but does have a profound effect on virus replication and pathogenesis in mice. BALB/c mice, which are normally susceptible to infection with ECTV, were able to control replication of the mutant virus and survive infection. Absence of vIFN-γbp from ECTV allowed the generation of an effective host immune response that was otherwise diminished by this viral protein. Mice infected with a vIFN-γbp deletion mutant virus, designated ECTV-IFN-γbpΔ, produced increased levels of IFN-γ and generated robust cell-mediated and antibody responses. Using several strains of mice that exhibit differential degrees of resistance to mousepox, we show that recovery or death from ECTV infection is determined by a balance between the host's ability to produce IFN-γ and the virus' ability to dampen its effects.

Background Vaccinia virus (VACV)-DUKE was isolated from a lesion on a 54 year old female who presented to a doctor at the Duke University Medical Center. She was diagnosed with progressive vaccinia and treated with vaccinia immune globulin. The availability of the VACV-DUKE genome sequence permits a first time genomic comparison of a VACV isolate associated with a smallpox vaccine complication with the sequence of culture-derived clonal isolates of the Dryvax vaccine. Results This study showed that VACV-DUKE is most similar to VACV-ACAM2000 and CLONE3, two VACV clones isolated from the Dryvax® vaccine stock confirming VACV-DUKE as an isolate from Dryvax®. However, VACV-DUKE is unique because it is, to date, the only Dryvax® clone isolated from a patient experiencing a vaccine-associated complication. The 199,960 bp VACV-DUKE genome encodes 225 open reading frames, including 178 intact genes and 47 gene fragments. Between VACV-DUKE and the other Dryvax® isolates, the major genomic differences are in fragmentation of the ankyrin-like, and kelch-like genes, presence of a full-length Interferon-α/β receptor gene, and the absence of a duplication of 12 ORFs in the inverted terminal repeat. Excluding this region, the DNA sequence of VACV-DUKE differs from the other two Dryvax® isolates by less than 0.4%. DNA sequencing also indicated that there was little heterogeneity in the sample, supporting the hypothesis that virus from an individual lesion is clonal in origin despite the fact that the vaccine is a mixed population. Conclusion Virus in lesions that result from progressive vaccinia following vaccination with Dryvax are likely clonal in origin. The genomic sequence of VACV-DUKE is overall very similar to that of Dryvax® cell culture-derived clonal isolates. Furthermore, with the sequences of multiple clones from Dryvax® we can begin to appreciate the diversity of the viral population in the smallpox vaccine.

Studies indicate that West African and Congo basin isolates of monkeypox virus (MPXV) are genetically distinct. Here, we show Congo basin MPXV-ZAI-V79 is more virulent for cynomolgus monkeys as compared to presumed West African MPXV-COP-58. This finding may explain the lack of case-fatalities in the U.S. 2003 monkeypox outbreak, which was caused by a West African virus. Virulence differences between West African and Congo basin MPXV are further supported by epidemiological analyses that observed a similar prevalence of antibodies in non-vaccinated humans in both regions, while >90% of reported cases occurred in the Congo basin, and no fatal cases were observed outside of this region. To determine the basis for this difference in virulence, we sequenced the genomes of one human West African isolate, and two presumed West African isolates and compared the sequences to Congo basin MPXV-ZAI-96-I-16. The analysis identified D10L, D14L, B10R, B14R, and B19R as possible virulence genes, with D14L (ortholog of vaccinia complement protein) as a leading candidate.

The hepadnavirus reverse transcriptase binds cotranslationally to the viral pregenomic RNA. This ribonucleoprotein complex is then encapsidated into nascent viral core particles, where the reverse transcriptase copies the viral RNA into DNA. Here we report that 75% of the duck hepatitis B virus reverse transcriptase present in transfected LMH cells does not follow this well-known pathway but rather exists in the cell separate from the core protein or nucleocapsids. The nonencapsidated reverse transcriptase is also abundant in infected duck liver. The nonencapsidated reverse transcriptase exists as a complex set of isoforms that are most likely produced by posttranslational modification. Interestingly, only the smallest of these isoforms is encapsidated into viral core particles. The nonencapsidated reverse transcriptase is bound to a large cellular cytoplasmic structure(s) in a detergent-sensitive complex. The cellular distribution of the reverse transcriptase only partially overlaps that of the core protein, and this distribution is unaffected by blocking encapsidation. These observations raise the possibilities that the metabolic fate of the reverse transcriptase may be posttranscriptionally regulated and that the reverse transcriptase may have roles in the viral replication cycle beyond its well-known function in copying the viral genome.

IL-18 induces IFN-γ and NK cell cytotoxicity, making it a logical target for viral antagonism of host defense. We demonstrate that the ectromelia poxvirus p13 protein, bearing homology to the mammalian IL-18 binding protein, binds IL-18, and inhibits its activity in vitro. Binding of IL-18 to the viral p13 protein was compared with binding to the cellular IL-18R. The dissociation constant of p13 for murine IL-18 is 5 nM, compared with 0.2 nM for the cellular receptor heterodimer. Mice infected with a p13 deletion mutant of ectromelia virus had elevated cytotoxicity for YAC-1 tumor cell targets compared with control animals. Additionally, the p13 deletion mutant virus exhibited decreased levels of infectivity. Our data suggest that inactivation of IL-18, and subsequent impairment of NK cell cytotoxicity, may be one mechanism by which ectromelia evades the host immune response.

Ectromelia virus is the causative agent of mousepox, an acute exanthematous disease of mouse colonies in Europe, Japan, China, and the U.S. The Moscow, Hampstead, and NIH79 strains are the most thoroughly studied with the Moscow strain being the most infectious and virulent for the mouse. In the late 1940s mousepox was proposed as a model for the study of the pathogenesis of smallpox and generalized vaccinia in humans. Studies in the last five decades from a succession of investigators have resulted in a detailed description of the virologic and pathologic disease course in genetically susceptible and resistant inbred and out-bred mice. We report the DNA sequence of the left-hand end, the predicted right-hand terminal repeat, and central regions of the genome of the Moscow strain of ectromelia virus (approximately 177,500 bp), which together with the previously sequenced right-hand end, yields a genome of 209,771 bp. We identified 175 potential genes specifying proteins of between 53 and 1924 amino acids, and 29 regions containing sequences related to genes predicted in other poxviruses, but unlikely to encode for functional proteins in ectromelia virus. The translated protein sequences were compared with the protein database for structure/function relationships, and these analyses were used to investigate poxvirus evolution and to attempt to explain at the cellular and molecular level the well-characterized features of the ectromelia virus natural life cycle.

The poxvirus molluscum contagiosum (MC) has a worldwide distribution and its prevalence is on the rise. Here we report that the MCV MC013L protein inhibits glucocorticoid and vitamin D, but not retinoid or estrogen, nuclear receptor transactivation. A direct interaction of MC013L with glucocorticoid and vitamin D receptor is supported by yeast two-hybrid, GST pull-down, and far Western blot analyses. Glucocorticoids act as potent inhibitors of keratinocyte proliferation, while vitamin D and retinoids promote and block terminal differentiation, respectively. Therefore, MC013L may promote efficient virus replication by blocking the differentiation of infected keratinocytes. MC013L may be the first member of a new class of poxvirus proteins that directly modulate nuclear receptor-mediated transcription.

Background Novel therapies are necessary to improve outcomes for patients with squamous cell carcinomas (SCC) of the head and neck. Historically, vaccinia virus was administered widely to humans as a vaccine and led to the eradication of smallpox. We examined the therapeutic effects of an attenuated, replication-competent vaccinia virus (GLV-1h68) as an oncolytic agent against a panel of six human head and neck SCC cell lines. Results All six cell lines supported viral transgene expression (β-galactosidase, green fluorescent protein, and luciferase) as early as 6 hours after viral exposure. Efficient transgene expression and viral replication (>150-fold titer increase over 72 hrs) were observed in four of the cell lines. At a multiplicity of infection (MOI) of 1, GLV-1h68 was highly cytotoxic to the four cell lines, resulting in ≥ 90% cytotoxicity over 6 days, and the remaining two cell lines exhibited >45% cytotoxicity. Even at a very low MOI of 0.01, three cell lines still demonstrated >60% cell death over 6 days. A single injection of GLV-1h68 (5 × 106 pfu) intratumorally into MSKQLL2 xenografts in mice exhibited localized intratumoral luciferase activity peaking at days 2–4, with gradual resolution over 10 days and no evidence of spread to normal organs. Treated animals exhibited near-complete tumor regression over a 24-day period without any observed toxicity, while control animals demonstrated rapid tumor progression. Conclusion These results demonstrate significant oncolytic efficacy by an attenuated vaccinia virus for infecting and lysing head and neck SCC both in vitro and in vivo, and support its continued investigation in future clinical trials.