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Infectious Virus (infectious + virus)
Selected AbstractsGenotype-dependent sensitivity of hepatitis C virus to inhibitors of the p7 ion channel,HEPATOLOGY, Issue 6 2008Stephen Griffin The hepatitis C virus (HCV) p7 protein plays a critical role during particle formation in cell culture and is required for virus replication in chimpanzees. The discovery that it displayed cation channel activity in vitro led to its classification within the "viroporin" family of virus-coded ion channel proteins, which includes the influenza A virus (IAV) M2 protein. Like M2, p7 was proposed as a potential target for much needed new HCV therapies, and this was supported by our finding that the M2 inhibitor, amantadine, blocked its activity in vitro. Since then, further compounds have been shown to inhibit p7 function but the relationship between inhibitory effects in vitro and efficacy against infectious virus is controversial. Here, we have sought to validate multiple p7 inhibitor compounds using a parallel approach combining the HCV infectious culture system and a rapid throughput in vitro assay for p7 function. We identify a genotype-dependent and subtype-dependent sensitivity of HCV to p7 inhibitors, in which results in cell culture largely mirror the sensitivity of recombinant protein in vitro; thus building separate sensitivity profiles for different p7 sequences. Inhibition of virus entry also occurred, suggesting that p7 may be a virion component. Second site effects on both cellular and viral processes were identified for several compounds in addition to their efficacy against p7 in vitro. Nevertheless, for some compounds antiviral effects were specific to a block of ion channel function. Conclusion: These data validate p7 inhibitors as prototype therapies for chronic HCV disease. (HEPATOLOGY 2008;48:1779-1790.) [source] Effects of age and viral determinants on chronicity as an outcome of experimental woodchuck hepatitis virus infectionHEPATOLOGY, Issue 1 2000Paul J. Cote Ph.D. Acute hepadnavirus infections either resolve or progress to chronicity. Factors that influence chronicity as an outcome of hepatitis B virus (HBV) infection in humans can be studied experimentally in the woodchuck model. Accordingly, several woodchuck hepatitis virus (WHV) inocula were characterized. Representative inocula had high titers of infectious virus (approximately 107.7 -109.5 woodchuck 50% infectious doses per milliliter [WID50% /mL] by subcutaneous inoculation), with 1 WID50% ranging between 21 and 357 physical virion particles. WHV7P1 (standard high dose, 5 × 106WID50%) produced a 72% chronicity rate (i.e., percent chronic of total infected) in neonatal woodchucks (1-3 days old). Comparable doses of WHV8P1 resulted in a lower chronicity rate in neonates (34% chronic) indicating that it represented a strain different from WHV7P1. Neonatal woodchucks were more susceptible to chronic infection by high doses of WHV7P1 (range, 65%-75% chronic) compared with 8-week-old weanlings (33% chronic) and adult woodchucks (0% chronic; i.e., all resolved). High doses of cloned wild-type viruses also induced high rates of chronicity in neonates (70%-80% chronic). Chronicity rates in neonates were decreased for low doses of WHV7P1 (500 WID50% , 9% chronic) and for high doses of a precore WHeAg-minus mutant WHV8 clone (17% chronic). Thus, both age and viral determinants can influence chronicity as an outcome of experimental WHV infection. Standardized inocula will enable the study of mechanisms that initiate and maintain chronic hepadnavirus infection and also provide a means for developing WHV carriers for therapeutic studies. [source] Asymptomatic reactivation and shed of infectious varicella zoster virus in astronautsJOURNAL OF MEDICAL VIROLOGY, Issue 6 2008Randall J. Cohrs Abstract Varicella zoster virus (VZV) causes varicella (chickenpox), after which virus becomes latent in ganglia along the entire neuraxis. Virus reactivation produces zoster (shingles). Infectious VZV is found in vesicles of patients with zoster and varicella, but virus shed in the absence of disease has not been documented. VZV DNA was previously detected in saliva of astronauts during and after spaceflight, a uniquely stressful environment in which cell mediated immunity (CMI) is temporally dampened. The decline in CMI to VZV associated with zoster led to the hypothesis that infectious VZV would also be present in the saliva of astronauts subjected to stress of spaceflight. Herein, not only was the detection of salivary VZV DNA associated with spaceflight validated, but also infectious virus was detected in saliva from 2 of 3 astronauts. This is the first demonstration of shed of infectious VZV in the absence of disease. J. Med. Virol. 80:1116,1122, 2008. © 2008 Wiley-Liss, Inc. [source] Experimental hepatitis A virus infection in guinea pigsJOURNAL OF MEDICAL VIROLOGY, Issue 4 2001Britt Hornei Abstract Although many of the properties of hepatitis A virus (HAV) are known, several aspects of HAV pathogenesis are still not understood, such as the mechanism underlying the hepatotropism or HAV replication in extrahepatic sites. Detailed studies of these aspects were hampered mostly by the lack of accessible animal models, since only nonhuman primates are susceptible to experimental infections. An alternative animal model would also be of interest to assess the primary replication site and for the evaluation of the safety and efficacy of vaccines. A study was undertaken to determine whether HAV can infect guinea pigs and whether they are useful as a model for studying aspects of HAV pathogenesis and for the evaluation of vaccines. HAV variants adapted to primate or guinea pig tissue culture were used to inoculate guinea pigs intraperitoneally and by the oral route. The animals were observed for clinical disease, shedding of HAV in stools, viremia, seroconversion, evidence for liver damage by biochemical liver function tests, virus presence in the liver, development of hepatic histopathological changes, and occurrence of HAV in extrahepatic organs. The animals developed an active, clinically inapparent infection with specific histopathological changes in the liver. Although virus replication occurred, as shown by RT-PCR and isolation of infectious virus from feces and serum, it seems unlikely that guinea pigs are suitable for studying the clinical features of hepatitis A, because the clinical and laboratory parameters remained normal. However, guinea pigs appear useful for studying some aspects of HAV pathogenesis and for testing the safety of vaccines. J. Med. Virol. 64:402,409, 2001. © 2001 Wiley-Liss, Inc. [source] Phenotypic analysis of the sensitivity of HIV-1 to inhibitors of the reverse transcriptase, protease, and integrase using a self-inactivating virus vector systemJOURNAL OF MEDICAL VIROLOGY, Issue 3 2001Gergely Jįrmy Abstract Conventional phenotypic analysis of resistance of the human immunodeficiency virus (HIV) to antiviral therapy is time-consuming and requires culture of infectious virus. Although phenotypic analyses may be desirable, rapid generation of test results and decentralized availability of the test system will be important to achieve utility in the clinical practice. This study describes the design of an alternative phenotypic resistance test using replication incompetent viral vectors. Chimeric HIV vectors containing a marker gene were generated. The env and most of the regulatory and accessory genes of HIV were removed. In addition, the 3,U3 region was deleted to obtain a self-inactivating construct. Cotransfection of the plasmid with a plasmid that provided the vesicular stomatitis virus glycoprotein resulted in the production of replication-incompetent virus vectors. Infection of susceptible cells with the vectors led to marker gene expression. Vector production in the presence of protease (PR) inhibitors, or infection in the presence of reverse transcriptase (RT) or integrase (IN) inhibitors reduced marker gene expression in a dose-dependent manner. Marker gene activity was preserved at higher drug levels if vectors contained RT and PR genes from resistant virus isolates. Sensitivity to nucleoside and non-nucleoside RT inhibitors, protease and integrase inhibitors could be determined in 10 working days. The phenotypic drug resistance test using replication-incompetent HIV vectors significantly speeds up drug resistance measurements and allows testing at reduced biosafety levels. This will make clinical use of phenotypic assessment of antiviral resistance more feasible. J. Med. Virol. 64:223,231, 2001. © 2001 Wiley-Liss, Inc. [source] Mosquito cells bind and replicate hepatitis C virusJOURNAL OF MEDICAL VIROLOGY, Issue 1 2001Raphaėle Germi Abstract Several studies have demonstrated some hepatitis C virus (HCV) replication in lymphocyte and hepatocyte cell lines such as in African green monkey Vero cells. The aim of the present study was to select other cell lines able to bind and replicate HCV. Human hepatoma PLC/PRF/5 cells, human lymphoma Namalwa cells, Vero and mosquito AP61 cells were inoculated with HCV-positive plasma, washed six times and examined for the presence of the viral genome at different times post infection, using an RT-PCR method. Binding of HCV to cells was estimated by HCV RNA detection in cells 2 hr after inoculation and in the last wash of these cells. Successive virus passages in cells were carried out. All the cells studied were able to bind HCV but only AP61 and Vero cells provided evidence of replication and production of infectious virus: virus RNA was detected during 28 days post-infection in four successive virus passages. CD81 molecules, a putative HCV receptor, were detected by cytofluorometric analysis. Vero cells express CD81 molecules whereas these molecules were not detected on AP61 cells. It is suggested that other receptors are involved in HCV binding to Vero and AP61 cells. J. Med. Virol. 64:6,12, 2001. © 2001 Wiley-Liss, Inc. [source] Transient detection of E1-containing adenovirus in saliva after the delivery of a first-generation adenoviral vector to human parotid gland,THE JOURNAL OF GENE MEDICINE, Issue 1 2010Changyu Zheng Abstract Background Radiation-induced salivary hypofunction is a common side-effect of treatment for head and neck cancers. Patients suffer significant morbidity and there is no suitable conventional therapy. We are conducting a Phase I clinical trial, using a first-generation serotype 5 adenoviral (Ad5) vector encoding human aquaporin-1 (AdhAQP1) to treat such patients. One week after the administration of AdhAQP1 to an enrolled, generally healthy patient, E1-containing adenovirus was detected in parotid saliva. Methods The real-time quantitative polymerase chain reactuion (PCR) was used to measure the Ad5 E1 gene and AdhAQP1 in saliva and serum. PCR and sequencing were used to characterize viral/vector DNA extracted from saliva. The presence of infectious adenovirus was assessed by the inoculation of A549 cells with aliquots of saliva. Serum Ad5 neutralizing antibodies were measured by the inhibition of 293-cell transduction with an Ad5 vector encoding luciferase. Multiple clinical evaluations were performed. Results On day 7 after AdhAQP1 delivery, low levels of the Ad5 E1 gene were detected in parotid saliva (82 copies/µl). In addition, significant levels of AdhAQP1 were also detected (1.5 × 103 copies/µl). The patient was asymptomatic and subsequent analysis of parotid saliva samples prior to day 7 and after day 7 until day 42 was negative for both virus and vector. No virus or vector was detected in serum at any time. Detailed PCR analyses of DNA extracted from the day 7 parotid saliva sample suggested the absence of a recombination event, and no infectious virus was found. Conclusions The patient most likely had a latent Ad5 infection in the targeted parotid gland that was activated after gene transfer and was without clinical consequence. Published in 2009 by John Wiley & Sons, Ltd. [source] | ||||||||||