The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Robert W. Sidwell - One of the best experts on this subject based on the ideXlab platform.
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Prophylactic and therapeutic intervention of Punta Toro Virus (PhleboVirus, Bunyaviridae) infection in hamsters with interferon alfacon-1
Antiviral research, 2008Co-Authors: Brian B. Gowen, Minhui Wong, Kie-hoon Jung, Lawrence M. Blatt, Robert W. SidwellAbstract:Punta Toro Virus (PTV) is a member of the Bunyaviridae family, genus PhleboVirus, related to the highly pathogenic Rift Valley fever Virus (RVFV). It produces a disease in hamsters that models severe Rift Valley fever (RVF) in humans. The recent outbreak of RVF in Kenya stresses the need to identify prophylactic and therapeutic measures for preventing and treating severe forms of disease. To this end, interferon (IFN) alfacon-1 (consensus IFN-α) was evaluated in cell culture against RVFV and PTV, and in the hamster PTV infection model. Survival outcome following treatment initiated pre- and post-Virus challenge and the suppression of viral burden and liver disease in infected hamsters was determined. Pre-treatment of cell cultures with IFN alfacon-1 induced marked antiviral activity against both Viruses. Intraperitoneal treatment of hamsters initiated 4 h prior to infection with PTV was highly protective and greatly limited liver disease and systemic and liver viral burden. Complete protection from a highly lethal challenge dose was afforded by treatment initiated 36 h following viral inoculation. Although efficacy was much reduced, IFN alfacon-1 therapy was still beneficial when started as late as 3−5 days post-Virus exposure. These studies suggest that IFN alfacon-1 may be an effective treatment for early intervention following infection with RVFV.
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TLR3 is essential for the induction of protective immunity against Punta Toro Virus infection by the double-stranded RNA (dsRNA), poly(I:C12U), but not Poly(I:C): differential recognition of synthetic dsRNA molecules.
Journal of Immunology, 2007Co-Authors: Brian B. Gowen, Minhui Wong, Kie-hoon Jung, Andrew B Sanders, William M Mitchell, Lena Alexopoulou, Richard A Flavell, Robert W. SidwellAbstract:In the wake of RNA Virus infections, dsRNA intermediates are often generated. These viral pathogen-associated molecular patterns can be sensed by a growing number of host cell cytosolic proteins and TLR3, which contribute to the induction of antiviral defenses. Recent evidence indicates that melanoma differentiation-associated gene-5 is the prominent host component mediating IFN production after exposure to the dsRNA analog, poly(I:C). We have previously reported that Punta Toro Virus (PTV) infection in mice is exquisitely sensitive to treatment with poly(I:C(12)U), a dsRNA analog that has a superior safety profile while maintaining the beneficial activity of the parental poly(I:C) in the induction of innate immune responses. The precise host factor(s) mediating protective immunity following its administration remain to be elucidated. To assess the role of TLR3 in this process, mice lacking the receptor were used to investigate the induction of protective immunity, type I IFNs, and IL-6 following treatment. Unlike wild-type mice, those lacking TLR3 were not protected against PTV infection following poly(I:C(12)U) therapy and failed to produce IFN-alpha, IFN-beta, and IL-6. In contrast, poly(I:C) treatment significantly protected TLR3(-/-) mice from lethal challenge despite some deficiencies in cytokine induction. There was no indication that the lack of protection was due to the fact that TLR3-deficient mice had a reduced capacity to fight infection because they were not found to be more susceptible to PTV. We conclude that TLR3 is essential to the induction of antiviral activity elicited by poly(I:C(12)U), which does not appear to be recognized by the cytosolic sensor of poly(I:C), melanoma differentiation-associated gene-5.
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TLR3 deletion limits mortality and disease severity due to PhleboVirus infection.
Journal of Immunology, 2006Co-Authors: Brian B. Gowen, Minhui Wong, Kie-hoon Jung, Lena Alexopoulou, Richard A Flavell, Justin D Hoopes, Kevin C Isakson, Robert W. SidwellAbstract:TLR3 was the first member of the TLR family of pattern recognition receptors found to detect a conserved viral molecular pattern, dsRNA, yet supporting evidence for a major role in host defense against viral pathogens is limited. Punta Toro Virus (PTV) has been shown to produce severe infection in mice, modeling disease caused by the related highly pathogenic Rift Valley fever phleboVirus in humans and domesticated ungulates. Using TLR3-deficient mice, we investigated the involvement of TLR3 in host defense against PTV infection. Compared with wild-type, TLR3(-/-) mice demonstrate increased resistance to lethal infection and have reduced liver disease associated with hepatotropic PTV infection. Infectious challenge produced comparable peak liver and serum viral loads; however, TLR3(-/-) mice were able to clear systemic Virus at a slightly faster rate. Cytokine profiling suggests that TLR3 plays an important role in PTV pathogenesis through the overproduction of inflammatory mediators, which may be central to the observed differences in survival and disease severity. Compared with TLR3-deficient mice, IL-6, MCP-1, IFN-gamma, and RANTES were all present at higher levels in wild-type animals. Most dramatic was the exaggerated levels of IL-6 found systemically and in liver tissue of infected wild-type mice; however, IL-6-deficient animals were found to be more susceptible to lethal PTV infection. Taken together, we conclude that the TLR3-mediated response to PTV infection is detrimental to disease outcome and propose that IL-6, although critical to establishing antiviral defense, contributes to pathogenesis when released in excess, necessitating its controlled production as is seen with TLR3(-/-) mice.
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Protective immunity against acute phleboviral infection elicited through immunostimulatory cationic liposome-DNA complexes.
Antiviral research, 2006Co-Authors: Brian B. Gowen, Donald F Smee, Minhui Wong, Kie-hoon Jung, Jeff Fairman, Anne M. Pace, Matthew Heiner, Kevin W. Bailey, Steven W. Dow, Robert W. SidwellAbstract:Cationic liposome-DNA complexes (CLDC) have been demonstrated to induce potent antitumor activities. The ability of these complexes to elicit protective immunity against viral infections has not been fully explored. Here we report findings on the use of CLDC as an antiviral agent in a mouse model of acute phleboviral (Punta Toro Virus) disease. CLDC treatment of mice challenged with Punta Toro Virus (PTV) resulted in dramatic increases in survival and reduced viral burden and other parameters indicative of protection against disease. CLDC were effective when administered by intraperitoneal and intravenous routes and elicited protective immunity when given within 1 day of Virus challenge. Treatments administered 36 h or longer after challenge, however, were not effective in preventing mortality or disease. CLDC treatment induced release of a number of potential antiviral cytokines including IFN-gamma, IL-12, and IFN-alpha. Taken together, our findings indicate that non-specific immunotherapy with CLDC appears to be an effective treatment for blocking PTV-induced disease and suggests that further exploration in other viral disease models may be warranted.
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Recombinant Eimeria Protozoan Protein Elicits Resistance to Acute PhleboVirus Infection in Mice but Not Hamsters
Antimicrobial agents and chemotherapy, 2006Co-Authors: Brian B. Gowen, Donald F Smee, Minhui Wong, Kie-hoon Jung, John W. Judge, Barnett Rosenberg, Anne M. Pace, Kevin W. Bailey, Robert W. SidwellAbstract:A protein antigen from an Eimeria protozoan has recently been reported to induce antitumor activity in mice. This activity most likely results from the strong induction of interkeukin-12 (IL-12) and gamma interferon (IFN-γ), which are also essential factors in the establishment of protective immunity against viral infection. We evaluated recombinant Eimeria antigen (rEA) as a potential immunotherapeutic agent in mouse and hamster models of acute phleboviral disease. Punta Toro Virus (PTV) was highly sensitive to a single dose of nanogram quantities of rEA in the mouse infection model. Intraperitoneal treatment with rEA also reduced Virus load and liver damage associated with PTV infection. IL-12 was elicited following exposure of uninfected mice to quantities of rEA of 10 ng or greater, and the levels peaked at between 3 and 8 h postexposure. IFN-γ release was induced more slowly and required less rEA (1 ng) to produce a significant rise in systemic levels. The induction of IL-12 and IFN-γ involved in the coordination of innate and adaptive immune responses to microbial pathogens required myeloid differentiation factor 88, a signaling adaptor shared by most members of the Toll-like receptor (TLR) family. Despite encouraging results in the murine system, rEA failed to protect hamsters challenged with PTV. Our findings suggest that hamsters may lack functional TLR11, which has recently been shown to recognize a profilin-like protein homologous to rEA from the protozoan Toxoplasma gondii. Further investigation into the immunostimulatory capacity of rEA in other mammalian systems is necessary.
Brian B. Gowen - One of the best experts on this subject based on the ideXlab platform.
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Extended Protection against PhleboVirus Infection Conferred by Recombinant AdenoVirus Expressing Consensus Interferon (DEF201)
Antimicrobial agents and chemotherapy, 2012Co-Authors: Brian B. Gowen, Minhui Wong, Kie-hoon Jung, Jane Ennis, Eric J. Sefing, Jeffrey D. TurnerAbstract:ABSTRACT Punta Toro Virus (PTV; Bunyaviridae, PhleboVirus) is related to Rift Valley fever Virus (RVFV), a pathogenic agent which causes severe disease in humans and livestock primarily in the sub-Saharan region of Africa. The recent range expansion of RVFV and the potential for its intentional release into naive populations pose a significant threat to public health and agriculture. Studies modeling disease in rodents and nonhuman primates have shown that PTV and RVFV are highly sensitive to the antiviral effects of alpha interferon (IFN-α), an important component of the innate antiviral host response. While recombinant IFN-α has high therapeutic value, its utility for the treatment of neglected tropical diseases is hindered by its short in vivo half-life and costly production of longer-lasting pegylated IFNs. Here, we demonstrate extended preexposure protection against lethal PTV challenge following a single intranasal administration of DEF201, which is a replication-deficient human adenoVirus type 5 vector engineered to constitutively express consensus IFN-α (cIFN-α) from transduced host cells. DEF201 was also efficacious when administered within 24 h as a postexposure countermeasure. Serum concentrations of cIFN-α could be detected as early as 8 h following treatment and persisted for more than 1 week. The prolonged antiphleboVirus prophylactic effect, low production costs, and ease of administration make DEF201 a promising agent for intervention during natural disease outbreaks and for countering possible bioterrorist acts.
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Punta Toro Virus (Bunyaviridae, PhleboVirus) infection in mice: strain differences in pathogenesis and host interferon response.
Virology, 2009Co-Authors: Michelle Mendenhall, Minhui Wong, Ramona T. Skirpstunas, John D. Morrey, Brian B. GowenAbstract:The Adames strain of Punta Toro Virus (PTV-A, Bunyaviridae, PhleboVirus) causes an acute lethal disease in hamsters and mice. The Balliet strain of the Virus (PTV-B) is generally considered to be avirulent. The difference in hamster susceptibility is likely due to the ability of PTV-A to suppress interferon (IFN)-β similarly to that described for Rift Valley fever Virus. Here we investigated strain differences in PTV pathogenesis and the IFN response in mice. Although PTV-B infection in mice did not induce systemic IFN-β release, primary macrophages produced dramatically higher levels when exposed to the Virus in culture. The importance of IFN in resistance to PTV infection was borne out in studies employing STAT-1 knock-out mice. Also, a number of genes specific to IFN response pathways were upregulated in PTV-B-infected macrophages. Our findings provide new insights into the type I IFN response during PTV infection in the mouse model of phleboviral disease.
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A biotechnological product and its potential as a new immunomodulator for treatment of animal phleboVirus infection: Punta Toro Virus
Antiviral research, 2009Co-Authors: Nelson Durán, Brian B. Gowen, Fabio T. M. Costa, Giselle Z. Justo, Marcelo Brocchi, Odilon S. Nunes, Iseu Da Silva NunesAbstract:Intracellular pathogens with widespread drug-resistance contribute substantially to the increasing rates in morbidity and mortality due to emerging and reemerging diseases. Thus, the development of new drugs, including those that can enhance the immune response, is urgently needed. The immunomodulator, P-MAPA, a proteinaceous aggregate of ammonium and magnesium phospholinoleate-palmitoleate anhydride derived from Aspergillus oryzae, have been shown to induce antitumor activities. The ability of this compound to elicit protective immunity against viral infections has not been fully explored. Here, we report findings on the use of P-MAPA as an antiviral agent in a mouse model of acute phleboviral (Punta Toro Virus) disease. A dose administered i.p. 24 h post-infectious challenge (100 mg/kg dose of P-MAPA) was remarkably effective at preventing death due to Punta Toro Virus infection. This dose also reduced systemic viral burden and liver discoloration assayed on day 3 of infection. Taken together, our findings indicate that non-specific immunotherapy with P-MAPA appears to be an effective treatment for blocking Punta Toro Virus-induced disease and suggest that further exploration with other viral disease models is warranted.
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Prophylaxis with cationic liposome–DNA complexes protects hamsters from phleboviral disease: Importance of liposomal delivery and CpG motifs☆
Antiviral research, 2008Co-Authors: Brian B. Gowen, Minhui Wong, Kie-hoon Jung, Peter C. Melby, Jeff Fairman, Steven W. Dow, Ryan M. Troyer, John D. MorreyAbstract:Cationic liposome-DNA complexes (CLDC) are cationic/neutral lipid carriers complexed with plasmid DNA that when administered systemically results in a robust T(H)1 cytokine response. CLDC have been shown to be effective in prophylaxis and therapeutic treatment of animal models of viral disease. To determine the contribution of liposomal delivery and CpG content of the plasmid DNA to the efficacy of CLDC; plasmid, CpG-free plasmid DNA, or CpG-containing oligodeoxynucleotides (ODN) with and without liposomes, as well as poly(I:C(12)U), were evaluated for their ability to elicit protection against lethal Punta Toro Virus (PTV, Bunyaviridae, phleboVirus) challenge in hamsters. CLDC-containing plasmid significantly improved survival, decreased systemic and liver viral loads, and reduced liver damage due to progression of viral infection. Mouse-reactive ODNs complexed with liposomes failed to protect hamsters, whereas ODNs known to cross-react with human and mouse (CpG 2006) or non-liposomal poly(I:C(12)U) showed survival benefit but did not limit liver injury. Liposomes complexed with a non-CpG motif-containing plasmid reduced liver viral load and tissue damage, but did not protect hamsters from death. To evaluate the mechanisms of the enhanced activity of CLDC, microarray experiments examined differences in the gene expression profile. The results suggest a broad T(H)1 response elicited by liposomal delivery of a diverse sequence containing CpG and non-CpG elements may be a more effective antiviral treatment than other nucleic acid based immunotherapeutics.
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Immunoprophylaxis of Punta Toro Virus (PhleboVirus, Bunyaviridae) infection in hamsters with recombinant Eimeria profilin-like antigen.
International immunopharmacology, 2008Co-Authors: Brian B. Gowen, Minhui Wong, Kie-hoon Jung, John W. Judge, Charles F. Aylsworth, Peter C. Melby, Barnett Rosenberg, John D. MorreyAbstract:Recombinant Eimeria antigen (rEA) has been shown to have potent anticancer and antiviral activity in respective mouse disease models, presumably through robust immune stimulation that occurs via TLR11, a pattern recognition receptor that recognizes profilin-like proteins expressed on apicomplexan protozoans. Comparable immunostimulatory activity in other species has yet to be demonstrated. Since rEA is known to be highly effective in treating Punta Toro Virus (PTV) infection in mice, its ability to elicit protective immunity in the hamster PTV infection model was investigated. rEA was given alone, or in combination with IL-18 or IL-2, and virally challenged hamsters were observed for mortality. Cytokine transcript profiles for IL-12p40, IL-21, IFN-γ and TNF-α were assessed to evaluate the induction of these inflammatory mediators known to be induced in mice following exposure to rEA. A dose of 100 μg of rEA, given once 4 h prior to viral challenge, and a second time on day 3 of the infection, was found to be the most effective prophylactic therapy protecting 60% of treated hamsters from mortality, compared to only 5–10% observed in animals receiving placebo. Increased expression of IFN-γ and IL-12p40 was evident following treatment with rEA. The data suggest that rEA does induce host antiviral responses in hamsters that result in significant protection from death, although determining the most appropriate dose for intervention in other species, including humans, will likely be challenging.
Richard W. Compans - One of the best experts on this subject based on the ideXlab platform.
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Molecular Determinants of Golgi Retention in the Punta Toro Virus G1 Protein
Archives of biochemistry and biophysics, 1996Co-Authors: Yumiko Matsuoka, Si-yi Chen, Cherie E. Holland, Richard W. CompansAbstract:Abstract The G1 glycoprotein of Punta Toro Virus, a member of the bunyaVirus family, accumulates in the Golgi complex when it is expressed from cloned cDNA. We previously reported that the information necessary for Golgi retention of the G1 protein is located within the transmembrane domain and a portion of the cytoplasmic domain adjacent to the transmembrane domain (Matsuoka, Y., Chen, S.-Y., and Compans, R. W. (1994) J. Biol. Chem. 269, 22565–22573). To determine the features of the amino acid sequence motif required for Golgi retention, we have introduced mutations including truncations and point mutations in the transmembrane and the cytoplasmic domains and examined the cellular localization of the expressed mutant proteins. The results from truncation mutants indicate that the crucial information appears to be located within the first 10 amino acids of the cytoplasmic domain. Within this region, mutation of a proline residue yielded a protein that was transported to the cell surface. A protein was also expressed on the cell surface when one of the threonine residues in the transmembrane domain was changed to leucine. Thus the transmembrane domain may have a supportive role in Golgi retention, possibly by promoting protein interactions through hydroxylated side chains.
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A signal for Golgi retention in the bunyaVirus G1 glycoprotein.
The Journal of biological chemistry, 1994Co-Authors: Yumiko Matsuoka, Si-yi Chen, Richard W. CompansAbstract:Abstract The G1 and G2 glycoproteins of Punta Toro Virus, a member of the bunyaViruses, are targeted to the Golgi complex, where viral budding occurs. We found that the G1 protein, when expressed in the absence of G2, is also targeted to the Golgi complex. A series of G1 proteins truncated at the carboxyl-terminal region was constructed, and the localization of the expressed proteins was examined. It was found that the proteins expressed from constructs with partial deletions in the cytoplasmic domain were transported to the Golgi complex at a significantly slower rate than G1. Although a major fraction of these proteins was eventually transported to the Golgi complex, they did not exhibit as clearly defined a pattern of accumulation as G1, but rather appeared to be distributed throughout the endoplasmic reticulum as well as the Golgi complex. The proteins expressed from constructs lacking most of the cytoplasmic domain and, in some cases, part of the transmembrane domain sequences as well were transported to the cell surface. We have also constructed chimeric proteins with the envelope protein of a murine leukemia Virus (MCFenv), which is efficiently transported to the plasma membrane. A MCF-G1 chimera that contained the G1 transmembrane and cytoplasmic domains was found to be efficiently retained in the Golgi complex, and a construct that contained only the G1 transmembrane domain was also partially retained in the Golgi complex. Thus, the transmembrane domain as well as a portion of the cytoplasmic domain adjacent to the transmembrane domain are apparently crucial for Golgi retention of the G1 protein.
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Assembly of G1 and G2 glycoprotein oligomers in Punta Toro Virus-infected cells.
Virus research, 1992Co-Authors: Matsuoka Yumiko, Richard W. CompansAbstract:Abstract We have studied the oligomerization of the membrane glycoproteins of Punta Toro Virus (PTV), a member of the PhleboVirus genus of the family Bunyaviridae, and the effect of glycosylation on protein stability and transport. By using sucrose gradient centrifugation, the G1 and G2 glycoproteins in PTV-infected or recombint-transfected cells were found to sediment as dimers after DSP cross-linking, suggesting that the G1 and G2 proteins are associated as dimers by non-covalent interactions. Pulse-chase and two-dimensional gel analysis indicate that dimerization occurs between newly synthesized G1 and G2 proteins, and that a small fraction of the G2 proteins is assembled into G2 homodimers. The amounts of G1 and G2 proteins were substantially decreased, while the amounts of nucleocapsid protein remained nearly unchanged, when PTV-infected cells were treated with the glycosylation inhibitor tunicamycin, indicating that the G1 and G2 proteins are unstable if glycosylation is prevented.
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Assembly and polarized release of Punta Toro Virus and effects of brefeldin A.
Journal of virology, 1991Co-Authors: Si-yi Chen, Yumiko Matsuoka, Richard W. CompansAbstract:Punta Toro Virus (PTV), a member of the sandfly fever group of bunyaViruses, is assembled by budding at intracellular membranes of the Golgi complex. We have examined PTV glycoprotein transport, assembly, and release and the effects of brefeldin A (BFA) on these processes. Both the G1 and G2 proteins were transported out of the endoplasmic reticulum (ER) and retained in the Golgi complex in a stable structure, either during PTV infection or when expressed from a vaccinia Virus recombinant. BFA treatment causes a rapid and dramatic change in the distribution of the G1 and G2 proteins, from a Golgi pattern to an ER pattern. The G1 and G2 proteins were found to be modified by medial but not trans Golgi network enzymes, in the presence or absence of BFA. We found that BFA blocks PTV release from cells but does not interfere with the intracellular assembly of infectious virions. Further, the BFA block of Virus release is fully reversible, with high levels of Virus release occurring upon removal of the inhibitor. It was also found that the release of PTV virions is polarized, occurring exclusively from the basolateral surfaces of the polarized Vero C1008 epithelial cell line.
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Golgi complex localization of the Punta Toro Virus G2 protein requires its association with the G1 protein.
Virology, 1991Co-Authors: Si-yi Chen, Yumiko Matsuoka, Richard W. CompansAbstract:The glycoproteins of bunyaViruses accumulate in membranes of the Golgi complex, where Virus maturation occurs by budding. In this study we have constructed a series of full length or truncated mutants of the G2 glycoprotein of Punta Toro Virus (PTV), a member of the PhleboVirus genus of the Bunyaviridae, and investigated their transport properties. The results indicate that the hydrophobic domain preceding the G2 glycoprotein can function as a translocational signal peptide, and that the hydrophobic domain near the C-terminus serves as a membrane anchor. A G2 glycoprotein construct with an extra hydrophobic sequence derived from the N-terminal NSM region was stably retained in the ER, and was unable to be transported to the Golgi complex. The full-length G2 glycoprotein, when expressed on its own, was transported out of the ER and expressed on the cell surface, whereas the G1 and G2 proteins when expressed together are retained in the Golgi complex. A truncated anchor-minus form of the G2 glycoprotein was found to be secreted into the culture medium, but was retained in the Golgi complex when coexpressed with the G1 glycoprotein. These results indicate that the G2 membrane glycoprotein is a class I membrane protein which does not contain a signal sufficient for Golgi retention, and suggest that its Golgi localization is a result of association with the G1 glycoprotein.
Donald F Smee - One of the best experts on this subject based on the ideXlab platform.
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efficacy of favipiravir t 705 and t 1106 pyrazine derivatives in phleboVirus disease models
Antiviral Research, 2010Co-Authors: Ia Gowe, Donald F Smee, Minhui Wong, Kiehoo Jung, Joh D Morrey, Yousuke FurutaAbstract:Abstract Several studies have reported favipiravir (T-705) to be effective in treating a number of viral diseases modeled in rodent systems. Notably, the related pyrazine derivative, T-1106, was found to be more effective than T-705 in treating yellow fever Virus infection in hamsters. Based on these findings, we hypothesized that T-1106 may be more effective in treating hepatotropic Punta Toro Virus (PTV, PhleboVirus) infection in rodents. In cell culture, the inhibitory concentrations of the compounds against various phleboViruses ranged from 3 to 55 μM for T-705 and from 76 to 743 μM for T-1106. In PTV-challenged hamsters, a model that generally presents with high liver viral loads, T-1106 was more effective at reducing mortality. However, in mice infected with PTV, a model wherein systemic infection is more prominent, the greater efficacy exhibited by T-1106 in the hamster system was not apparent. In contrast, T-705 was superior in preventing mortality in hamsters challenged with Pichinde Virus (PICV, ArenaVirus), an infection characterized as diffuse and pantropic. Remarkably, T-1106 has proven more active in vivo than would have been expected from our cell culture results, and our in vivo findings suggest that it is more effective in infections characterized predominantly by high levels of hepatic viral burden.
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Protective immunity against acute phleboviral infection elicited through immunostimulatory cationic liposome-DNA complexes.
Antiviral research, 2006Co-Authors: Brian B. Gowen, Donald F Smee, Minhui Wong, Kie-hoon Jung, Jeff Fairman, Anne M. Pace, Matthew Heiner, Kevin W. Bailey, Steven W. Dow, Robert W. SidwellAbstract:Cationic liposome-DNA complexes (CLDC) have been demonstrated to induce potent antitumor activities. The ability of these complexes to elicit protective immunity against viral infections has not been fully explored. Here we report findings on the use of CLDC as an antiviral agent in a mouse model of acute phleboviral (Punta Toro Virus) disease. CLDC treatment of mice challenged with Punta Toro Virus (PTV) resulted in dramatic increases in survival and reduced viral burden and other parameters indicative of protection against disease. CLDC were effective when administered by intraperitoneal and intravenous routes and elicited protective immunity when given within 1 day of Virus challenge. Treatments administered 36 h or longer after challenge, however, were not effective in preventing mortality or disease. CLDC treatment induced release of a number of potential antiviral cytokines including IFN-gamma, IL-12, and IFN-alpha. Taken together, our findings indicate that non-specific immunotherapy with CLDC appears to be an effective treatment for blocking PTV-induced disease and suggests that further exploration in other viral disease models may be warranted.
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Recombinant Eimeria Protozoan Protein Elicits Resistance to Acute PhleboVirus Infection in Mice but Not Hamsters
Antimicrobial agents and chemotherapy, 2006Co-Authors: Brian B. Gowen, Donald F Smee, Minhui Wong, Kie-hoon Jung, John W. Judge, Barnett Rosenberg, Anne M. Pace, Kevin W. Bailey, Robert W. SidwellAbstract:A protein antigen from an Eimeria protozoan has recently been reported to induce antitumor activity in mice. This activity most likely results from the strong induction of interkeukin-12 (IL-12) and gamma interferon (IFN-γ), which are also essential factors in the establishment of protective immunity against viral infection. We evaluated recombinant Eimeria antigen (rEA) as a potential immunotherapeutic agent in mouse and hamster models of acute phleboviral disease. Punta Toro Virus (PTV) was highly sensitive to a single dose of nanogram quantities of rEA in the mouse infection model. Intraperitoneal treatment with rEA also reduced Virus load and liver damage associated with PTV infection. IL-12 was elicited following exposure of uninfected mice to quantities of rEA of 10 ng or greater, and the levels peaked at between 3 and 8 h postexposure. IFN-γ release was induced more slowly and required less rEA (1 ng) to produce a significant rise in systemic levels. The induction of IL-12 and IFN-γ involved in the coordination of innate and adaptive immune responses to microbial pathogens required myeloid differentiation factor 88, a signaling adaptor shared by most members of the Toll-like receptor (TLR) family. Despite encouraging results in the murine system, rEA failed to protect hamsters challenged with PTV. Our findings suggest that hamsters may lack functional TLR11, which has recently been shown to recognize a profilin-like protein homologous to rEA from the protozoan Toxoplasma gondii. Further investigation into the immunostimulatory capacity of rEA in other mammalian systems is necessary.
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Antiviral activities of tragacanthin polysaccharides on Punta Toro Virus infections in mice.
Chemotherapy, 1996Co-Authors: Donald F Smee, John H. Huffman, John W. Huggins, Robert W. Sidwell, Meir Kende, Anthony J. VerbiscarAbstract:Tragacanthin polysaccharides from Astragalus brachycentrus (AV208) and Astragalus echidnaeformis (AV212) plants, which are devoid of in vitro antiviral activity, were evaluated in a mouse model of Punta Toro Virus (PTV) infection. The PTV (a phleboVirus member of the Bunyaviridae family of Viruses) is a model for studying the treatment of Rift Valley fever and hantaVirus infections. Single intraperitoneal treatments with 12.5-200 mg/kg/day doses of AV212 given 24 h before or 4 and 24 h after Virus inoculation protected the majority of mice from mortality. Single treatments with AV208 were ineffective when given 24 h before the Virus challenge; however, protection was afforded when treatments were administered at 4 and 24 h following Virus inoculation. In a follow-up study, AV208 treatments of 1.6-50 mg/kg/day given 24 h subsequent to Virus exposure caused reductions in mortality, liver infection scores, liver and spleen Virus titers, and serum transaminases. The polysaccharides did not activate lymphocytes or natural killer cells, nor was interferon induced in treated mice. However, mice pretreated with fumed silica (a macrophage poison) and infected with the PTV were not protected by subsequent administration of AV208 or AV212 at 50 mg/kg, providing evidence that activation of peritoneal macrophages by the polysaccharides affords protection to infected animals. These compounds should be considered for the potential treatment of significant human infections induced by bunyaViruses and hantaViruses.
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Antiviral activity of an immunomodulatory lipophilic desmuramyl dipeptide analog.
Antiviral research, 1995Co-Authors: Robert W. Sidwell, Donald F Smee, John H. Huffman, Roger A. Burger, Reed P. Warren, Kevin W. Bailey, C.l. PenneyAbstract:Abstract BCH-527, the lipophilic hydrochloride salt of octadecyl d -alanyl l -glutamine, was evaluated for efficacy against experimentally induced murine cytomegaloVirus (MCMV), influenza A (H1N1) (IV-A), and Punta Toro Virus (PTV) infections in mice. The compound was administered i.p. every other day for a total of 4 injections commencing 24 h preVirus exposure. Doses ranged from 12.5 to 200 mg/kg per injection in the various experiments. The MCMV infection was significantly inhibited in two experiments by doses of 25–200 mg/kg, as manifested by increased numbers of survivors and decreased titers of Virus recoverable from tissues. The IV-A infection was weakly inhibited, with antiviral activity seen in lowered lung scores and lung weights and less decline in arterial oxygen saturation values. The PTV infection was not inhibited. BCH-527 was stimulatory to cytotoxic T-cells, natural killer (NK) cells, macrophages, and splenic B-cells. The highest dose tested, 200 mg/kg, was inhibitory to cytotoxic T-cell activity and to some extent to NK cell and macrophage activity. These data suggest BCH-527 functions as an immune modulator in exerting the observed antiviral activity.
Tetsuro Ikegami - One of the best experts on this subject based on the ideXlab platform.
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Characterization of Rift Valley fever Virus MP-12 strain encoding NSs of Punta Toro Virus or sandfly fever Sicilian Virus.
PLoS neglected tropical diseases, 2013Co-Authors: Olga Lihoradova, Sabarish V. Indran, Birte Kalveram, Nandadeva Lokugamage, Jennifer A. Head, Bin Gong, Bersabeh Tigabu, Terry L. Juelich, Alexander N. Freiberg, Tetsuro IkegamiAbstract:Rift Valley fever Virus (RVFV; genus PhleboVirus, family Bunyaviridae) is a mosquito-borne zoonotic pathogen which can cause hemorrhagic fever, neurological disorders or blindness in humans, and a high rate of abortion in ruminants. MP-12 strain, a live-attenuated candidate vaccine, is attenuated in the M- and L-segments, but the S-segment retains the virulent phenotype. MP-12 was manufactured as an Investigational New Drug vaccine by using MRC-5 cells and encodes a functional NSs gene, the major virulence factor of RVFV which 1) induces a shutoff of the host transcription, 2) inhibits interferon (IFN)-β promoter activation, and 3) promotes the degradation of dsRNA-dependent protein kinase (PKR). MP-12 lacks a marker for differentiation of infected from vaccinated animals (DIVA). Although MP-12 lacking NSs works for DIVA, it does not replicate efficiently in type-I IFN-competent MRC-5 cells, while the use of type-I IFN-incompetent cells may negatively affect its genetic stability. To generate modified MP-12 vaccine candidates encoding a DIVA marker, while still replicating efficiently in MRC-5 cells, we generated recombinant MP-12 encoding Punta Toro Virus Adames strain NSs (rMP12-PTNSs) or Sandfly fever Sicilian Virus NSs (rMP12-SFSNSs) in place of MP-12 NSs. We have demonstrated that those recombinant MP-12 Viruses inhibit IFN-β mRNA synthesis, yet do not promote the degradation of PKR. The rMP12-PTNSs, but not rMP12-SFSNSs, replicated more efficiently than recombinant MP-12 lacking NSs in MRC-5 cells. Mice vaccinated with rMP12-PTNSs or rMP12-SFSNSs induced neutralizing antibodies at a level equivalent to those vaccinated with MP-12, and were efficiently protected from wild-type RVFV challenge. The rMP12-PTNSs and rMP12-SFSNSs did not induce antibodies cross-reactive to anti-RVFV NSs antibody and are therefore applicable to DIVA. Thus, rMP12-PTNSs is highly efficacious, replicates efficiently in MRC-5 cells, and encodes a DIVA marker, all of which are important for vaccine development for Rift Valley fever.
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Toscana Virus NSs protein promotes degradation of double-stranded RNA-dependent protein kinase.
Journal of virology, 2013Co-Authors: Birte Kalveram, Tetsuro IkegamiAbstract:ABSTRACT Toscana Virus (TOSV), which is transmitted by Phlebotomus spp. sandflies, is a major etiologic agent of aseptic meningitis and encephalitis in the Mediterranean. Like other members of the genus PhleboVirus of the family Bunyaviridae, TOSV encodes a nonstructural protein (NSs) in its small RNA segment. Although the NSs of Rift Valley fever Virus (RVFV) has been identified as an important virulence factor, which suppresses host general transcription, inhibits transcription from the beta interferon promoter, and promotes the proteasomal degradation of double-stranded RNA-dependent protein kinase (PKR), little is known about the functions of NSs proteins encoded by less-pathogenic members of this genus. In this study we report that TOSV is able to downregulate PKR with similar efficiency as RVFV, while infection with the other phleboViruses—i.e., Punta Toro Virus, sandfly fever Sicilian Virus, or Frijoles Virus—has no effect on cellular PKR levels. In contrast to RVFV, however, cellular transcription remains unaffected during TOSV infection. TOSV NSs protein promotes the proteasome-dependent downregulation of PKR and is able to interact with kinase-inactive PKR in infected cells.
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Generation of rMP12-PTNSs and rMP12-SFSNSs.
2013Co-Authors: Olga A. Lihoradova, Sabarish V. Indran, Birte Kalveram, Nandadeva Lokugamage, Jennifer A. Head, Bin Gong, Bersabeh Tigabu, Terry L. Juelich, Alexander N. Freiberg, Tetsuro IkegamiAbstract:(A) Schematics of MP-12 S-segments encoding mutation or foreign gene in place of MP-12 NSs. The rMP12-C13type (C13type) lacks 69% of the NSs ORF as described previously [44]. The rMP12-PTNSs, and rMP12-SFSNSs encode NSs of Punta Toro Virus Adames strain and Sandfly fever Sicilian Virus, respectively. The expected phenotype corresponding to each S-segment is also presented. (B) Plaque phenotypes of MP-12, rMP12-PTNSs and rMP12-SFSNSs at 4 dpi. Plaque assay was performed with VeroE6 cells overlaid with 0.6% noble agar and stained with Neutral red.
