The Experts below are selected from a list of 60 Experts worldwide ranked by ideXlab platform
Grant Mcfadden - One of the best experts on this subject based on the ideXlab platform.
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The complete genome sequence of shope (Rabbit) Fibroma Virus.
Virology, 1999Co-Authors: David O. Willer, Grant Mcfadden, David H. EvansAbstract:Abstract We have determined the complete DNA sequence of the LeporipoxVirus Shope Fibroma Virus (SFV). The SFV genome spans 159.8 kb and encodes 165 putative genes of which 13 are duplicated in the 12.4-kb terminal inverted repeats. Although most SFV genes have homologs encoded by other Chordopoxvirinae , the SFV genome lacks a key gene required for the production of extracellular enveloped Virus. SFV also encodes only the smaller ribonucleotide reductase subunit and has a limited nucleotide biosynthetic capacity. SFV preserves the Chordopoxvirinae gene order from S012L near the left end of the chromosome through to S142R (homologs of vaccinia F2L and B1R, respectively). The unique right end of SFV appears to be genetically unstable because when the sequence is compared with that of myxoma Virus, five myxoma homologs have been deleted (C. Cameron, S. Hota-Mitchell, L. Chen, J. Barrett, J.-X. Cao, C. Macaulay, D. Willer, D. Evans, and G. McFadden, 1999, Virology 264, 298–318). Most other differences between these two LeporipoxViruses are located in the telomeres. LeporipoxViruses encode several genes not found in other poxViruses including four small hydrophobic proteins of unknown function (S023R, S119L, S125R, and S132L), an α 2,3-sialyltransferase (S143R), a protein belonging to the Ig-like protein superfamily (S141R), and a protein resembling the DNA-binding domain of proteins belonging to the HIN-200 protein family S013L). SFV also encodes a type II DNA photolyase (S127L). Melanoplus sanguinipes entomopoxVirus encodes a similar protein, but SFV is the first mammalian Virus potentially capable of photoreactivating ultraviolet DNA damage.
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Transforming Growth Factor Alpha, Shope Fibroma Growth Factor, and Vaccinia Growth Factor Can Replace Myxoma Growth Factor in the Induction of Myxomatosis in Rabbits
Virology, 1993Co-Authors: Andrea Opgenorth, Nick Nation, Kathryn Graham, Grant McfaddenAbstract:Abstract The epidermal growth factor (EGF) homologues encoded by vaccinia Virus, myxoma Virus, and malignant Rabbit Fibroma Virus have been shown to contribute to the pathogenicity of Virus infection upon inoculation of susceptible hosts. However, since the primary structures of these growth factors and the disease profiles induced by different poxVirus genera vary substantially, the degree to which the various EGF homologues perform similar roles in viral pathogenesis remains unclear. In order to determine whether different EGF-like growth factors can perform qualitatively similar functions in the induction of myxomatosis in Rabbits, we created recombinant myxoma Virus variants in which the native growth factor, myxoma growth factor (MGF), was disrupted and replaced with either vaccinia Virus growth factor, Shope Fibroma growth factor, or rat transforming growth factor alpha. Unlike the control Virus containing an inactivated MGF gene, which caused marked attenuation of the disease syndrome and substantially less proliferation of the epithelial cell layers in the conjunctiva and respiratory tract, the recombinant myxoma Virus strains expressing heterologous growth factors produced infections which were both clinically and histopathologically indistinguishable from wild-type myxomatosis. We conclude that these poxviral and cellular EGF-like growth factors, which are diverse with respect to primary structure and origin, have similar biological functions in the context of myxoma Virus pathogenesis and are mitogenic for the same target cells.
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Inhibition of plasmin, urokinase, tissue plasminogen activator, and C1S by a myxoma Virus serine proteinase inhibitor.
Journal of Biological Chemistry, 1993Co-Authors: David A. Lomas, Chris Upton, Grant Mcfadden, Dyfed L.i. Evans, Robin W. CarrellAbstract:Abstract The myxoma and malignant Rabbit Fibroma poxViruses are lethal tumorigenic Viruses of Rabbits whose virulence is modulated by the production of a Virus-encoded secreted serine proteinase inhibitor, SERP-1. This viral protein was detected in medium harvested from myxoma and malignant Rabbit Fibroma Virus-infected cells, and its inhibitory profile has been characterized by gel and kinetic analysis. SERP-1 forms complexes with and inhibits the human fibrinolytic enzymes plasmin, urokinase, and two-chain tissue-type plasminogen activator (association rate constants 3.4 x 10(4), 4.3 x 10(4), and 3.6 x 10(4) M-1 s-1 respectively). It is also able to inhibit C1S, the first enzyme in the complement cascade with an association rate constant which was unaffected by the addition of heparin (1.3 x 10(3) M-1 s-1). SERP-1 acts as a substrate for and is cleaved by thrombin, porcine trypsin, human neutrophil elastase, porcine pancreatic elastase, thermolysin, subtilisin, bovine alpha-chymotrypsin, and factor Xa. Incubation with kallikrein and cathepsin G had no effect. The structure of SERP-1 has been modeled on other members of the serpin family which revealed the characteristic serpin architecture apart from the absence of the D-helix. Structural analysis and kinetic assays demonstrate that the absence of this region does not prevent inhibitory activity and furthermore allow the identification of cysteine residues involved in internal and intermolecular disulfide bonding.
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Virus-induced loss of class I MHC antigens from the surface of cells infected with myxoma Virus and malignant Rabbit Fibroma Virus.
Journal of Immunology, 1992Co-Authors: Lynn Boshkov, Joanne L. Macen, Grant McfaddenAbstract:Shope Fibroma Virus (SFV) is a leporipoxVirus that causes localized benign Fibromas in immunocompetent adult Rabbits that spontaneously regress due, in part, to a cell-mediated immune response. Myxoma Virus (MYX) and malignant Rabbit Fibroma Virus (MRV) are related leporipoxViruses that induce rapidly lethal generalized infections accompanied by tumors and immunosuppression. Because only these latter two Viruses are known to compromise cell-mediated antiviral responses, cell surface levels of class I MHC molecules in SFV-, MRV-, and MYX-infected cells were investigated by fluorescent activated cell sorting analysis using a variety of different anti-HLA mAb. After infection with MYX or MRV there is a rapid decrease in the levels of detectable surface class I epitopes as detected by each antibody and by 24 h postinfection class I MHC Ag levels at the cell surface approach the level of background fluorescence observed with control antibodies. In contrast, only a moderate class I decrease is seen during infection with either SFV or vaccinia Virus, an orthopoxVirus that is neither tumorigenic nor immunosuppressive. Surface class I marker loss induced by MYX and MRV is not simply due to nonspecific inhibition of total cellular protein synthesis by the Viruses because class I levels decrease much further than the extent measured by estimating surface marker turnover in the presence of the protein synthesis inhibitor cycloheximide. Thus the loss of cellular surface class I molecules greatly exceeds the drop in level caused by complete blockage of host cell gene expression, and must involve removal or masking of preexisting class I epitopes from the cell surface by MRV/MYX. Cell surface levels of the transferrin receptor are unaffected by MYX and MRV infection, suggesting the observed class I decrease is not a nonspecific effect on total cell surface glycoproteins. Analysis of cells infected with MRV/MYX in the presence of cycloheximide or of cytosine arabinoside, an inhibitor of poxviral DNA replication, indicates that the class I marker loss is mediated in part by one or more viral late gene products. A probable explanation is that MRV/MYX late protein(s) interact with the class I MHC complex to either physically sequester these away from the cell surface and inhibit their recycling or else induce a conformational change that precludes recognition by all class I antibodies tested. In either event, we propose that such a major perturbation of the class I MHC complex would likely downregulate the class I-mediated presentation of viral Ag required to initiate cell-mediated immunity to these Viruses.
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deletion of the growth factor gene related to egf and tgfα reduces virulence of malignant Rabbit Fibroma Virus
Virology, 1992Co-Authors: Andrea Opgenorth, Chris Upton, D S Strayer, Grant McfaddenAbstract:Abstract The role of the epidermal growth factor homologue in malignant Rabbit Fibroma Virus (MRV) pathogenicity was investigated by constructing a viral growth factor deletion mutant (MRV-GF − ). Since MRV is a recombinant Virus with a myxoma Virus background but possesses some terminal sequences derived from Shope Fibroma Virus, the growth factor gene in MRV is in fact identical to Shope Fibroma growth factor (SFGF). Although no significant differences were detected in the in vitro characteristics of MRV and MRV-GF − , a pronounced attenuation was observed after inoculation of the test Rabbits with MRV-GF − , Animals infected with wild-type MRV uniformly developed a fatal syndrome involving disseminated tumors accompanied by purulent conjunctivitis and rhinitis. In contrast, although MRV-GF − recipients developed similar initial signs of the MRV disease syndrome, 75% of these animals completely recovered from the viral and secondary bacterial infections and became immune to subsequent MRV challenge. Tumors in MRV-GF − recipients displayed earlier and more prominent inflammatory reactions than their wild-type MRV counterparts and contained fewer proliferating cells. Squamous metaplasia and hyperplasia of target epithelia were less pronounced in MRV-GF − than in MRV infection. We conclude that SFGF is a major virulence factor in MRV infection and is responsible for at least some of the cellular proliferation observed at tumor sites. In addition, the diminished ability of MRV-GF − to cause hyperplasia in nasal and conjunctival epithelia may decrease the extent of gram negative bacterial overgrowth as compared to the parental Virus and hence contribute to the dramatic reduction in the lethality of MRV-GF − infection.
Chris Upton - One of the best experts on this subject based on the ideXlab platform.
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Inhibition of plasmin, urokinase, tissue plasminogen activator, and C1S by a myxoma Virus serine proteinase inhibitor.
Journal of Biological Chemistry, 1993Co-Authors: David A. Lomas, Chris Upton, Grant Mcfadden, Dyfed L.i. Evans, Robin W. CarrellAbstract:Abstract The myxoma and malignant Rabbit Fibroma poxViruses are lethal tumorigenic Viruses of Rabbits whose virulence is modulated by the production of a Virus-encoded secreted serine proteinase inhibitor, SERP-1. This viral protein was detected in medium harvested from myxoma and malignant Rabbit Fibroma Virus-infected cells, and its inhibitory profile has been characterized by gel and kinetic analysis. SERP-1 forms complexes with and inhibits the human fibrinolytic enzymes plasmin, urokinase, and two-chain tissue-type plasminogen activator (association rate constants 3.4 x 10(4), 4.3 x 10(4), and 3.6 x 10(4) M-1 s-1 respectively). It is also able to inhibit C1S, the first enzyme in the complement cascade with an association rate constant which was unaffected by the addition of heparin (1.3 x 10(3) M-1 s-1). SERP-1 acts as a substrate for and is cleaved by thrombin, porcine trypsin, human neutrophil elastase, porcine pancreatic elastase, thermolysin, subtilisin, bovine alpha-chymotrypsin, and factor Xa. Incubation with kallikrein and cathepsin G had no effect. The structure of SERP-1 has been modeled on other members of the serpin family which revealed the characteristic serpin architecture apart from the absence of the D-helix. Structural analysis and kinetic assays demonstrate that the absence of this region does not prevent inhibitory activity and furthermore allow the identification of cysteine residues involved in internal and intermolecular disulfide bonding.
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deletion of the growth factor gene related to egf and tgfα reduces virulence of malignant Rabbit Fibroma Virus
Virology, 1992Co-Authors: Andrea Opgenorth, Chris Upton, D S Strayer, Grant McfaddenAbstract:Abstract The role of the epidermal growth factor homologue in malignant Rabbit Fibroma Virus (MRV) pathogenicity was investigated by constructing a viral growth factor deletion mutant (MRV-GF − ). Since MRV is a recombinant Virus with a myxoma Virus background but possesses some terminal sequences derived from Shope Fibroma Virus, the growth factor gene in MRV is in fact identical to Shope Fibroma growth factor (SFGF). Although no significant differences were detected in the in vitro characteristics of MRV and MRV-GF − , a pronounced attenuation was observed after inoculation of the test Rabbits with MRV-GF − , Animals infected with wild-type MRV uniformly developed a fatal syndrome involving disseminated tumors accompanied by purulent conjunctivitis and rhinitis. In contrast, although MRV-GF − recipients developed similar initial signs of the MRV disease syndrome, 75% of these animals completely recovered from the viral and secondary bacterial infections and became immune to subsequent MRV challenge. Tumors in MRV-GF − recipients displayed earlier and more prominent inflammatory reactions than their wild-type MRV counterparts and contained fewer proliferating cells. Squamous metaplasia and hyperplasia of target epithelia were less pronounced in MRV-GF − than in MRV infection. We conclude that SFGF is a major virulence factor in MRV infection and is responsible for at least some of the cellular proliferation observed at tumor sites. In addition, the diminished ability of MRV-GF − to cause hyperplasia in nasal and conjunctival epithelia may decrease the extent of gram negative bacterial overgrowth as compared to the parental Virus and hence contribute to the dramatic reduction in the lethality of MRV-GF − infection.
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myxoma Virus expresses a secreted protein with homology to the tumor necrosis factor receptor gene family that contributes to viral virulence
Virology, 1991Co-Authors: Chris Upton, Joanne L. Macen, Martha Schreiber, G McfaddeniAbstract:Abstract PoxViruses are known to contain a large number of open reading frames, particularly near the termini of the viral genome, that are not required for growth in tissue culture. However, many of these these gene products are believed to play important roles in determining the virulence of the Virus by modulating the host immune response to the infection. Recently it has been shown that Shope Fibroma Virus encodes, within the terminal inverted repeats, a protein (T2) related to the cellular tumor necrosis factor receptor (TNFR) and which specifically binds both TNFa and TNFβ We have sequenced the terminal regions of two otherLeporipoxViruses (myxoma Virus and malignant Rabbit Fibroma Virus) that are extremely invasive and capable of inducing extensive immunosuppression in Rabbits and demonstrate that they also encode a closely related T2 homolog with all the structural motifs predicted for a secreted TNF binding protein. To investigate the biological role of the T2 protein, we have inactivated the myxoma Virus T2 gene within each copy of the viral TIR by the insertion of a dominant selectable marker (Escherichia coli guanosine phosphoribosyltransferase) and selection of the recombinant Virus in the presence of mycophenolic acid. The success of the inactivation of both copies of T2 was confirmed by the loss a broad protein band (52–56 kDa) of the predicted size for T2 from the profile of proteins secreted from mutant Virus-infected BGMK cells at earlytimes after infection. Although the T2-minus recombinant myxoma Virus grew normally in tissue culture, upon infection of susceptible Rabbits the viral disease was observed to be significantly attenuated. The majority of infected Rabbits were able to mount an effective immune response to the infection and completely recovered. These survivor Rabbits became immune to subsequent challenge with wild type myxoma Virus. We conclude that the T2 viral protein is an important secreted virulence factor and that it in all likelihood functions by compromising the antiviral effects of TNF. We propose the term “viroceptor” to describe viral-encoded homologs of cellular lymphokine receptors whose function is to intercept the activity of the cognate lymphokine in order to short circuit the host immune response to the viral infection.
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myxoma Virus and malignant Rabbit Fibroma Virus encode a serpin like protein important for Virus virulence
Virology, 1990Co-Authors: Chris Upton, Joanne L. Macen, David S Wishart, Grant McfaddenAbstract:Abstract The leporipoxViruses Shope Fibroma Virus (SFV), the myxoma Virus (MYX), and the SFV/MYX recombinant malignant Rabbit Fibroma Virus (MRV) are closely related yet induce profoundly different diseases in the European Rabbit. SFV, which produces a benign tumor at the site of inoculation, is cleared by the immune system after approximately 2 weeks whereas MYX and MRV induce a rapidly lethal systemic infection characterized by generalized suppression of host immune functions. DNA sequencing studies reveal that MRV and MYX possess homologous gene members of the T6/T8/T9 family originally described in the terminal inverted repeat (TIR) of SFV. We also describe a gene present in both MYX and MRV genomes, but which has apparently evolved in the SFV genome into a fragmented pseudogene that appears to contribute to the aggressive nature of MYX and MRV infections. Translation of this open reading frame, designated MYXOMA SERPIN 1 (SERP1), reveals a protein sequence with highly significant homology to the super-family of serine protease inhibitors (serpins) which also includes a number of other poxviral proteins. In the MYX genome the SERP1 gene lies entirely within the TIR sequences and is thus present as two copies, while in the MRV genome SERP1 is present in the unique sequences adjacent to the TIR boundary and hence is a single copy. The amino acid homology between the putative active site of SERP1 and those of other serpins predicts that the target enzyme will be different from the known catalog of serine antiprotease substrates. Deletion of this gene from MRV significantly attenuates the disease spectrum induced by the normally lethal Virus. Although the MRV-S1 deletion construct (MRV with SERP1 gene deleted) grows in all tissue culture cells tested in a fashion identical to the MRV parent, the majority of Rabbits infected with MRV-S1 are able to mount an effective immune response and totally recover from the Virus infection to become resistant to subsequent challenge by MRV or MYX.
Joanne L. Macen - One of the best experts on this subject based on the ideXlab platform.
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Virus-induced loss of class I MHC antigens from the surface of cells infected with myxoma Virus and malignant Rabbit Fibroma Virus.
Journal of Immunology, 1992Co-Authors: Lynn Boshkov, Joanne L. Macen, Grant McfaddenAbstract:Shope Fibroma Virus (SFV) is a leporipoxVirus that causes localized benign Fibromas in immunocompetent adult Rabbits that spontaneously regress due, in part, to a cell-mediated immune response. Myxoma Virus (MYX) and malignant Rabbit Fibroma Virus (MRV) are related leporipoxViruses that induce rapidly lethal generalized infections accompanied by tumors and immunosuppression. Because only these latter two Viruses are known to compromise cell-mediated antiviral responses, cell surface levels of class I MHC molecules in SFV-, MRV-, and MYX-infected cells were investigated by fluorescent activated cell sorting analysis using a variety of different anti-HLA mAb. After infection with MYX or MRV there is a rapid decrease in the levels of detectable surface class I epitopes as detected by each antibody and by 24 h postinfection class I MHC Ag levels at the cell surface approach the level of background fluorescence observed with control antibodies. In contrast, only a moderate class I decrease is seen during infection with either SFV or vaccinia Virus, an orthopoxVirus that is neither tumorigenic nor immunosuppressive. Surface class I marker loss induced by MYX and MRV is not simply due to nonspecific inhibition of total cellular protein synthesis by the Viruses because class I levels decrease much further than the extent measured by estimating surface marker turnover in the presence of the protein synthesis inhibitor cycloheximide. Thus the loss of cellular surface class I molecules greatly exceeds the drop in level caused by complete blockage of host cell gene expression, and must involve removal or masking of preexisting class I epitopes from the cell surface by MRV/MYX. Cell surface levels of the transferrin receptor are unaffected by MYX and MRV infection, suggesting the observed class I decrease is not a nonspecific effect on total cell surface glycoproteins. Analysis of cells infected with MRV/MYX in the presence of cycloheximide or of cytosine arabinoside, an inhibitor of poxviral DNA replication, indicates that the class I marker loss is mediated in part by one or more viral late gene products. A probable explanation is that MRV/MYX late protein(s) interact with the class I MHC complex to either physically sequester these away from the cell surface and inhibit their recycling or else induce a conformational change that precludes recognition by all class I antibodies tested. In either event, we propose that such a major perturbation of the class I MHC complex would likely downregulate the class I-mediated presentation of viral Ag required to initiate cell-mediated immunity to these Viruses.
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myxoma Virus expresses a secreted protein with homology to the tumor necrosis factor receptor gene family that contributes to viral virulence
Virology, 1991Co-Authors: Chris Upton, Joanne L. Macen, Martha Schreiber, G McfaddeniAbstract:Abstract PoxViruses are known to contain a large number of open reading frames, particularly near the termini of the viral genome, that are not required for growth in tissue culture. However, many of these these gene products are believed to play important roles in determining the virulence of the Virus by modulating the host immune response to the infection. Recently it has been shown that Shope Fibroma Virus encodes, within the terminal inverted repeats, a protein (T2) related to the cellular tumor necrosis factor receptor (TNFR) and which specifically binds both TNFa and TNFβ We have sequenced the terminal regions of two otherLeporipoxViruses (myxoma Virus and malignant Rabbit Fibroma Virus) that are extremely invasive and capable of inducing extensive immunosuppression in Rabbits and demonstrate that they also encode a closely related T2 homolog with all the structural motifs predicted for a secreted TNF binding protein. To investigate the biological role of the T2 protein, we have inactivated the myxoma Virus T2 gene within each copy of the viral TIR by the insertion of a dominant selectable marker (Escherichia coli guanosine phosphoribosyltransferase) and selection of the recombinant Virus in the presence of mycophenolic acid. The success of the inactivation of both copies of T2 was confirmed by the loss a broad protein band (52–56 kDa) of the predicted size for T2 from the profile of proteins secreted from mutant Virus-infected BGMK cells at earlytimes after infection. Although the T2-minus recombinant myxoma Virus grew normally in tissue culture, upon infection of susceptible Rabbits the viral disease was observed to be significantly attenuated. The majority of infected Rabbits were able to mount an effective immune response to the infection and completely recovered. These survivor Rabbits became immune to subsequent challenge with wild type myxoma Virus. We conclude that the T2 viral protein is an important secreted virulence factor and that it in all likelihood functions by compromising the antiviral effects of TNF. We propose the term “viroceptor” to describe viral-encoded homologs of cellular lymphokine receptors whose function is to intercept the activity of the cognate lymphokine in order to short circuit the host immune response to the viral infection.
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myxoma Virus and malignant Rabbit Fibroma Virus encode a serpin like protein important for Virus virulence
Virology, 1990Co-Authors: Chris Upton, Joanne L. Macen, David S Wishart, Grant McfaddenAbstract:Abstract The leporipoxViruses Shope Fibroma Virus (SFV), the myxoma Virus (MYX), and the SFV/MYX recombinant malignant Rabbit Fibroma Virus (MRV) are closely related yet induce profoundly different diseases in the European Rabbit. SFV, which produces a benign tumor at the site of inoculation, is cleared by the immune system after approximately 2 weeks whereas MYX and MRV induce a rapidly lethal systemic infection characterized by generalized suppression of host immune functions. DNA sequencing studies reveal that MRV and MYX possess homologous gene members of the T6/T8/T9 family originally described in the terminal inverted repeat (TIR) of SFV. We also describe a gene present in both MYX and MRV genomes, but which has apparently evolved in the SFV genome into a fragmented pseudogene that appears to contribute to the aggressive nature of MYX and MRV infections. Translation of this open reading frame, designated MYXOMA SERPIN 1 (SERP1), reveals a protein sequence with highly significant homology to the super-family of serine protease inhibitors (serpins) which also includes a number of other poxviral proteins. In the MYX genome the SERP1 gene lies entirely within the TIR sequences and is thus present as two copies, while in the MRV genome SERP1 is present in the unique sequences adjacent to the TIR boundary and hence is a single copy. The amino acid homology between the putative active site of SERP1 and those of other serpins predicts that the target enzyme will be different from the known catalog of serine antiprotease substrates. Deletion of this gene from MRV significantly attenuates the disease spectrum induced by the normally lethal Virus. Although the MRV-S1 deletion construct (MRV with SERP1 gene deleted) grows in all tissue culture cells tested in a fashion identical to the MRV parent, the majority of Rabbits infected with MRV-S1 are able to mount an effective immune response and totally recover from the Virus infection to become resistant to subsequent challenge by MRV or MYX.
Andrea Opgenorth - One of the best experts on this subject based on the ideXlab platform.
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Transforming Growth Factor Alpha, Shope Fibroma Growth Factor, and Vaccinia Growth Factor Can Replace Myxoma Growth Factor in the Induction of Myxomatosis in Rabbits
Virology, 1993Co-Authors: Andrea Opgenorth, Nick Nation, Kathryn Graham, Grant McfaddenAbstract:Abstract The epidermal growth factor (EGF) homologues encoded by vaccinia Virus, myxoma Virus, and malignant Rabbit Fibroma Virus have been shown to contribute to the pathogenicity of Virus infection upon inoculation of susceptible hosts. However, since the primary structures of these growth factors and the disease profiles induced by different poxVirus genera vary substantially, the degree to which the various EGF homologues perform similar roles in viral pathogenesis remains unclear. In order to determine whether different EGF-like growth factors can perform qualitatively similar functions in the induction of myxomatosis in Rabbits, we created recombinant myxoma Virus variants in which the native growth factor, myxoma growth factor (MGF), was disrupted and replaced with either vaccinia Virus growth factor, Shope Fibroma growth factor, or rat transforming growth factor alpha. Unlike the control Virus containing an inactivated MGF gene, which caused marked attenuation of the disease syndrome and substantially less proliferation of the epithelial cell layers in the conjunctiva and respiratory tract, the recombinant myxoma Virus strains expressing heterologous growth factors produced infections which were both clinically and histopathologically indistinguishable from wild-type myxomatosis. We conclude that these poxviral and cellular EGF-like growth factors, which are diverse with respect to primary structure and origin, have similar biological functions in the context of myxoma Virus pathogenesis and are mitogenic for the same target cells.
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deletion of the growth factor gene related to egf and tgfα reduces virulence of malignant Rabbit Fibroma Virus
Virology, 1992Co-Authors: Andrea Opgenorth, Chris Upton, D S Strayer, Grant McfaddenAbstract:Abstract The role of the epidermal growth factor homologue in malignant Rabbit Fibroma Virus (MRV) pathogenicity was investigated by constructing a viral growth factor deletion mutant (MRV-GF − ). Since MRV is a recombinant Virus with a myxoma Virus background but possesses some terminal sequences derived from Shope Fibroma Virus, the growth factor gene in MRV is in fact identical to Shope Fibroma growth factor (SFGF). Although no significant differences were detected in the in vitro characteristics of MRV and MRV-GF − , a pronounced attenuation was observed after inoculation of the test Rabbits with MRV-GF − , Animals infected with wild-type MRV uniformly developed a fatal syndrome involving disseminated tumors accompanied by purulent conjunctivitis and rhinitis. In contrast, although MRV-GF − recipients developed similar initial signs of the MRV disease syndrome, 75% of these animals completely recovered from the viral and secondary bacterial infections and became immune to subsequent MRV challenge. Tumors in MRV-GF − recipients displayed earlier and more prominent inflammatory reactions than their wild-type MRV counterparts and contained fewer proliferating cells. Squamous metaplasia and hyperplasia of target epithelia were less pronounced in MRV-GF − than in MRV infection. We conclude that SFGF is a major virulence factor in MRV infection and is responsible for at least some of the cellular proliferation observed at tumor sites. In addition, the diminished ability of MRV-GF − to cause hyperplasia in nasal and conjunctival epithelia may decrease the extent of gram negative bacterial overgrowth as compared to the parental Virus and hence contribute to the dramatic reduction in the lethality of MRV-GF − infection.
Hassan Moeini - One of the best experts on this subject based on the ideXlab platform.
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Generation of recombinant MVA-noroVirus: a comparison study of bacterial artificial chromosome- and marker-based systems
Virology Journal, 2019Co-Authors: Franziska Kugler, Ingo Drexler, Ulrike Protzer, Dieter Hoffmann, Hassan MoeiniAbstract:Background Recombinant Modified Vaccinia Virus Ankara has been employed as a safe and potent viral vector vaccine against infectious diseases and cancer. We generated recMVAs encoding noroVirus GII.4 genotype capsid protein by using a marker-based approach and a BAC-based system. In the marker-based approach, the capsid gene together with a reporter gene was introduced into the MVA genome in DF-1 cells. Several rounds of plaque purification were carried out to get rid of the WT-MVA. In the BAC-based approach, recMVA-BAC was produced by en passant recombineering in E. coli . Subsequently, the recMVAs were rescued in DF-1 cells using a helper Rabbit Fibroma Virus. The BAC backbone and the helper Virus were eliminated by passaging in DF-1 cells. Biochemical characteristics of the recMVAs were studied. Results We found the purification of the rare spontaneous recombinants time-consuming in the marker-based system. In contrast, the BAC-based system rapidly inserted the gene of interest in E. coli by en passant recombineering before virion production in DF-1 cells. The elimination of the reporter gene was found to be faster and more efficient in the BAC-based approach. With Western blotting and electron microscopy, we could prove successful capsid protein expression and proper Virus-assembly, respectively. The MVA-BAC produced higher recombinant Virus titers and infected DF-1 cells more efficiently. Conclusions Comparing both methods, we conclude that, in contrast to the tedious and time-consuming traditional method, the MVA-BAC system allows us to quickly generate high titer recMVAs.
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Generation of recombinant MVA-noroVirus: a comparison study of bacterial artificial chromosome- and marker-based systems.
Virology Journal, 2019Co-Authors: Franziska Kugler, Ingo Drexler, Ulrike Protzer, Dieter Hoffmann, Hassan MoeiniAbstract:Recombinant Modified Vaccinia Virus Ankara has been employed as a safe and potent viral vector vaccine against infectious diseases and cancer. We generated recMVAs encoding noroVirus GII.4 genotype capsid protein by using a marker-based approach and a BAC-based system. In the marker-based approach, the capsid gene together with a reporter gene was introduced into the MVA genome in DF-1 cells. Several rounds of plaque purification were carried out to get rid of the WT-MVA. In the BAC-based approach, recMVA-BAC was produced by en passant recombineering in E. coli. Subsequently, the recMVAs were rescued in DF-1 cells using a helper Rabbit Fibroma Virus. The BAC backbone and the helper Virus were eliminated by passaging in DF-1 cells. Biochemical characteristics of the recMVAs were studied. We found the purification of the rare spontaneous recombinants time-consuming in the marker-based system. In contrast, the BAC-based system rapidly inserted the gene of interest in E. coli by en passant recombineering before virion production in DF-1 cells. The elimination of the reporter gene was found to be faster and more efficient in the BAC-based approach. With Western blotting and electron microscopy, we could prove successful capsid protein expression and proper Virus-assembly, respectively. The MVA-BAC produced higher recombinant Virus titers and infected DF-1 cells more efficiently. Comparing both methods, we conclude that, in contrast to the tedious and time-consuming traditional method, the MVA-BAC system allows us to quickly generate high titer recMVAs.
