ABSTRACT
Hepatitis C virus (HCV) is a cause of chronic liver disease, with more than 170 million persistently infected individuals worldwide. Although the combination therapy of alpha interferon (IFN-alpha) and ribavirin is effective for chronic HCV infection, around half of all patients infected with HCV genotype 1 fail to show sustained virologic responses and remain chronically infected. Previously, we demonstrated that bile acids were essential for growth of porcine enteric calicivirus in cell culture in association with down-regulation of IFN responses. Because hepatocytes are exposed to high concentrations of bile acids in the liver, we hypothesized that bile acids have similar effects on HCV replication. We incubated HCV replicon-harboring cells (genotype 1b, Con1) in the presence of various bile acids and monitored the expression of HCV RNA and protein (NS5B). The addition of an individual bile acid (deoxycholic acid, chenodeoxycholic acid, ursodeoxycholic acid, or glycochenodeoxycholic acid) in the medium increased the levels of HCV RNA and proteins up to fivefold at 48 h of incubation. An antagonist of bile acid receptor farnesoid X receptor (FXR), Z-guggulsterone, reduced the bile acid-mediated increase of HCV RNA. When IFN (alpha or gamma) and each bile acid were incubated together, we observed that bile acid significantly reduced the anti-HCV effect of IFN. These results indicated that bile acids are factors in the failure of IFN treatment for certain patients infected with HCV genotype 1. Our finding may also contribute to the establishment of better regimens for treatment of chronic HCV infections by including agents altering the bile acid-mediated FXR pathway.
Subject(s)
Antiviral Agents/pharmacology , Bile Acids and Salts/pharmacology , Hepacivirus/metabolism , Hepatitis C, Chronic/metabolism , Hepatocytes/virology , Interferon-alpha/pharmacology , Virus Replication/drug effects , Animals , Antiviral Agents/antagonists & inhibitors , Antiviral Agents/therapeutic use , Bile Acids and Salts/antagonists & inhibitors , Bile Acids and Salts/metabolism , Cell Line , DNA-Binding Proteins/antagonists & inhibitors , DNA-Binding Proteins/metabolism , Dose-Response Relationship, Drug , Down-Regulation/drug effects , Drug Antagonism , Drug Therapy, Combination , Genotype , Hepatitis C, Chronic/drug therapy , Hepatocytes/metabolism , Humans , Interferon-alpha/antagonists & inhibitors , Interferon-alpha/therapeutic use , Interferon-gamma/pharmacology , Pregnenediones/pharmacology , Receptors, Cytoplasmic and Nuclear/antagonists & inhibitors , Receptors, Cytoplasmic and Nuclear/metabolism , Replicon/physiology , Ribavirin/antagonists & inhibitors , Ribavirin/pharmacology , Ribavirin/therapeutic use , Swine , Transcription Factors/antagonists & inhibitors , Transcription Factors/metabolism , Vesicular Exanthema of Swine/metabolism , Vesicular exanthema of swine virus/metabolism , Virus Replication/physiologyABSTRACT
Sensitive methods are required to study the early pathogenesis of swine vesicular diseases (SVD). Therefore, two new methods, immunohistochemistry (IHC) and in-situ hybridization (ISH), were developed and tested for their specificity and sensitivity. With these methods the SVD virus (SVDV) infection in cytospins of primary porcine kidney cells and in frozen skin sections was investigated. Both IHC and the ISH showed a specific cytoplasmic staining, but the IHC detected more infected cells than the ISH. Furthermore, both IHC and ISH were able to detect SVDV in skin sections 4.5 h after infection. It is concluded that IHC is the most suitable and simplest method to identify cells and tissues that support the initial replication of swine vesicular disease virus. However, IHC can only be applied to frozen sections, whereas ISH can also be used in paraformaldehyde-fixed tissues.
