(1/1584) Inhibition of vaccinia virus growth by the nucleoside analogue 1-beta-D-ribofuranosyl-1,2,4-triazole-3-carboxamide (virazole, ribavirin).
Virazole or Ribavirin (1-beta-D-ribofuranosyl-1,2,4-triazole-3-carboxamide) inhibits the growth of vaccinia virus at a concentration ode to a certain extent in the presence of Virazole, the DNA fails to acquire resistance to deoxyribonuclease and virus particles are not formed. Reversibility of the antiviral effect occurs when the drug is washed out from the infected cultures or when guanosine at an equimolar concentration is added. (+info)
(2/1584) SVMPA, a mutant of sindbis virus resistant to mycophenolic acid and ribavirin, shows an increased sensitivity to chick interferon.
SVMPA is a mutant of Sindbis virus, selected for its ability to replicate in mycophenolic acid (MPA)-treated mosquito cells. SVMPA has another phenotype: although able to replicate normally in primary cultures of chick embryo fibroblasts (CEF), its replication is restricted in secondary cultures prepared from aged primary CEF cultures. The mutations responsible for these phenotypes mapped to the region of the viral genome that codes for nsP1. We report here that SVMPA has yet another phenotype. Relative to our standard Sindbis virus (SVSTD) from which it was derived, SVMPA shows an increased sensitivity to chick interferon, both crude interferon prepared from virus-infected cells and recombinant interferon. Characterization of viral mutants obtained after site-directed mutagenesis indicated that the same mutations responsible for the host restriction of SVMPA in secondary cultures of CEF were also responsible for its increased sensitivity to chick interferon. (+info)
(3/1584) Fulminant adenovirus hepatitis following unrelated bone marrow transplantation: failure of intravenous ribavirin therapy.
Fulminant hepatic failure due to adenovirus infection is a rare complication following stem cell transplantation. We report this complication in an unrelated bone marrow transplant recipient 30 weeks post-transplant. Treatment with intravenous ribavirin was started within 36 h of admission, but he succumbed to unusually fulminant hepatic failure. Adenovirus type 2 was isolated from stool surveillance samples and from post-mortem liver samples. Adenovirus DNA was detected by PCR in blood and sputum samples at admission and was identified in post-mortem liver tissue by electron microscopy. Implications of the failure of ribavirin therapy are discussed. (+info)
(4/1584) Effect of retreatment with interferon alone or interferon plus ribavirin on hepatitis C virus quasispecies diversification in nonresponder patients with chronic hepatitis C.
Alpha interferon (IFN-alpha) treatment is effective on a long-term basis in only 15 to 25% of patients with chronic hepatitis C. The results of recent trials indicate that response rates can be significantly increased when IFN-alpha is given in combination with ribavirin. However, a large number of patients do not respond even to combination therapy. Nonresponsiveness to IFN is characterized by evolution of the hepatitis C virus (HCV) quasispecies. Little is known about the changes occurring within the HCV genomes when nonresponder patients are retreated with IFN or with IFN plus ribavirin. In the present study we have examined the genetic divergence of HCV quasispecies during unsuccessful retreatment with IFN or IFN plus ribavirin. Fifteen nonresponder patients with HCV-1 (4 patients with HCV-1a and 11 patients with HCV-1b) infection were studied while being retreated for 2 months (phase 1) with IFN-alpha (6 MU given three times a week), followed by IFN plus ribavirin or IFN alone for an additional 6 months (phase 2). HCV quasispecies diversification in the E2 hypervariable region-1 (HVR1) and in the putative NS5A IFN sensitivity determining region (ISDR) were analyzed for phase 1 and phase 2 by using the heteroduplex tracking assay and clonal frequency analysis techniques. A major finding of this study was the relatively rapid evolution of the HCV quasispecies observed in both treatment groups during the early phase 1 compared to the late phase 2 of treatment. The rate of quasispecies diversification in HVR1 was significantly higher during phase 1 versus phase 2 both in patients who received IFN plus ribavirin (P = 0.017) and in patients who received IFN alone (P = 0. 05). A trend toward higher rates of quasispecies evolution in the ISDR was also observed during phase 1 in both groups, although the results did not reach statistical significance. However, the NS5A quasispecies appeared to be rather homogeneous and stable in most nonresponder patients, suggesting the presence of a single well-fit major variant, resistant to antiviral treatment, in agreement with published data which have identified an IFN sensitivity determinant region within the NS5A. During the entire 8 months of retreatment, there was no difference in the rate of fixation of mutation between patients who received combination therapy and patients who were treated with IFN alone, suggesting that ribavirin had no major effects on the evolution of the HCV quasispecies after the initial 2 months of IFN therapy. (+info)
(5/1584) Inhibition of Borna disease virus replication by ribavirin.
The guanosine analogue ribavirin was tested for antiviral activity in two neural cell lines, human oligodendrocytes and rat glia, against Borna disease virus (BDV) strains V and He/80. Ribavirin treatment resulted in lower levels of virus and viral transcripts within 12 h. Addition of guanosine but not adenosine resulted in a profound reduction of the ribavirin effect. Ribavirin appears to be an effective antiviral agent for treatment of BDV infection in vitro. A likely mechanism for its activity is reduction of the intracellular GTP pool, resulting in inhibition of transcription and capping of BDV mRNAs. (+info)
(6/1584) Hepatitis C: epidemiology and review of complementary/alternative medicine treatments.
Hepatitis C is emerging as a serious worldwide problem. In the United States the current mortality figures may triple in the next ten years, rivaling HIV. The disease has a latency of 10-30 years and symptoms or signs may not appear until cirrhosis is evident. Adequate diagnosis, including liver biopsy, is essential in assessing the current stage of the viral infection and the need for treatment. Hepatitis C may manifest as hepatic fibrosis, cirrhosis, hepatocellular carcinoma, lichen planus, glomerulonephritis, mixed cryoglobulinemia, or porphyria. The hepatic damage is due both to the cytopathic effect of the virus and the inflammatory changes secondary to immune activation. The use of the botanical components glycyrrhizin, catechin, silymarin and phytosterols, and the antioxidants N-acetylcysteine and vitamin E are reviewed for their efficacy in treating chronic hepatitis and affecting liver damage. (+info)
(7/1584) Sustained response to interferon-alpha or to interferon-alpha plus ribavirin in hepatitis C virus-associated symptomatic mixed cryoglobulinaemia.
BACKGROUND: Hepatitis C virus (HCV) infection has been associated with mixed cryoglobulinaemia. AIM: To investigate the efficacy of anti-viral therapy on the eradication of HCV and its clinical manifestations in patients with HCV-associated symptomatic mixed cryoglobulinaemia. PATIENTS AND METHODS: 18 out of 32 patients with symptomatic mixed cryoglobulinaemia (MC group) received a 12-month course of interferon (3 MU three times a week, subcutaneously). Nonresponders or relapsers to this therapy were treated with interferon plus ribavirin (1200 mg/day, orally) for 12-months. 226 patients with HCV infection and without cryoglobulins were studied in comparison (Hepatitis C group). Serial quantification of serum HCV-RNA and cryoglobulins were performed. RESULTS: In the MC group, 10 out of 18 patients (55%) receiving interferon showed an end of treatment response, but at the end of follow-up, only five (28%) patients had a sustained response. In the hepatitis C group, 91 patients (47%) showed an end of treatment response but only 42 (20%) a sustained response. In the MC group alanine transaminase, cryocrit and rheumatoid factor decreased significantly in responders, with an improvement or disappearance of the MC-associated clinical manifestations. Alanine transaminase, cryocrit and rheumatoid factor increased in the relapsers and the clinical manifestations reappeared. Nonresponders and relapsers to interferon in the MC group were retreated with interferon plus ribavirin. Five out of eight nonresponders showed a end of treatment response but it was sustained in three of them. In the relapsers, treatment with combined therapy achieved a sustained response in four out of the five patients (80%). CONCLUSIONS: Interferon as monotherapy or combined with ribavirin is a safe and effective treatment in patients with HCV-associated MC. The presence of cryoglobulins does not affect the response to anti-viral treatment in patients with HCV infection. The eradication of HCV is associated with an improvement or disappearance of MC-associated clinical manifestations. (+info)
(8/1584) Patients with multiple myeloma may safely undergo autologous transplantation despite ongoing RSV infection and no ribavirin therapy.
Respiratory syncytial virus (RSV) has been reported as a cause of death among autologous peripheral blood stem cell (ASCT) and marrow recipients and recommendations for therapy with aerosolized ribavirin plus intravenous immunoglobulin (IVIG) made. This therapy is expensive, may be toxic, and causes a significant disruption of patient care. The purpose of this study was to evaluate the morbidity and mortality of RSV infections in patients with multiple myeloma undergoing ASCT without ribavirin therapy. During the months of February-April 1997, 10 consecutive patients (median age 57 years, seven males) with advanced and heavily pretreated myeloma underwent ASCT while having active RSV upper respiratory tract infection. After melphalan (200 mg/m2), all patients became neutropenic (<1000 cells/mm3) for a median of 7 days. Ribavirin was not given to any patient. No patient developed lower respiratory tract infection, required transfer to intensive care or died at a median follow-up of 8 months. One patient developed tracheobronchitis requiring oxygenation by nasal cannula. No delay in the treatment of the underlying myeloma was incurred. RSV infection may not necessarily be a contraindication for ASCT or an indication for therapy with aerosolized ribavirin. Additional studies are needed to confirm our preliminary findings. (+info)