RESUMEN
Cytosolic retinoic acid-inducible gene I (RIG-I) is an important innate immune RNA sensor and can induce antiviral cytokines, e.g., interferon-β (IFN-β). Innate immune response to hepatitis B virus (HBV) plays a pivotal role in viral clearance and persistence. However, knowledge of the role that RIG-I plays in HBV infection is limited. The woodchuck is a valuable model for studying HBV infection. To characterize the molecular basis of woodchuck RIG-I (wRIG-I), we analyzed the complete coding sequences (CDSs) of wRIG-I, containing 2778 base pairs that encode 925 amino acids. The deduced wRIG-I protein was 106.847 kD with a theoretical isoelectric point (pI) of 6.07, and contained three important functional structures [caspase activation and recruitment domains (CARDs), DExD/H-box helicases, and a repressor domain (RD)]. In woodchuck fibroblastoma cell line (WH12/6), wRIG-I-targeted small interfering RNA (siRNA) down-regulated RIG-I and its downstrean effector-IFN-β transcripts under RIG-I' ligand, 5'-ppp double stranded RNA (dsRNA) stimulation. We also measured mRNA levels of wRIG-I in different tissues from healthy woodchucks and in the livers from woodchuck hepatitis virus (WHV)-infected woodchucks. The basal expression levels of wRIG-I were abundant in the kidney and liver. Importantly, wRIG-I was significantly up-regulated in acutely infected woodchuck livers, suggesting that RIG-I might be involved in WHV infection. These results may characterize RIG-I in the woodchuck model, providing a strong basis for further study on RIG-I-mediated innate immunity in HBV infection.
Asunto(s)
Animales , Línea Celular Tumoral , Clonación Molecular , Proteína 58 DEAD Box , Genética , Alergia e Inmunología , Fibroblastos , Alergia e Inmunología , Patología , Expresión Génica , Hepatitis B , Genética , Alergia e Inmunología , Patología , Virus de la Hepatitis B de la Marmota , Inmunidad Innata , Interferón beta , Genética , Alergia e Inmunología , Punto Isoeléctrico , Riñón , Alergia e Inmunología , Patología , Virología , Hígado , Alergia e Inmunología , Patología , Virología , Marmota , Genética , Alergia e Inmunología , Virología , Sistemas de Lectura Abierta , Dominios Proteicos , ARN Bicatenario , ARN Interferente Pequeño , Genética , Metabolismo , Enfermedades de los Roedores , Genética , Alergia e Inmunología , Patología , VirologíaRESUMEN
<p><b>OBJECTIVE</b>To search for and verify some common B cell epitopes in the core proteins of woodchuck hepatitis virus and human hepatitis B virus.</p><p><b>METHODS</b>Monoclonal antibodies against both core proteins of woodchuck hepatitis virus (WHV) and human hepatitis B virus (HBV) were prepared by inoculating Balb/c mice with denatured recombination WHV and HBV core proteins. ELISA and immunoblotting assays for WHcAg and HBcAg were carried out by using these antibodies. Immunohistochemistry was carried out with liver tissue sections of both WHV-infected woodchucks and chronic HBV-infected patients. The epitopes were mapped with the mouse mAbs (6D1 and 1H4) by using a panel of 24 16mer overlapping peptides covering the entire WHcAg. The amino acid sequences of WHcAg and HBcAg were compared.</p><p><b>RESULTS</b>Cross-reactions were observed between mAbs (6D1 and 1H4) and WHcAg and between Mabs and HBcAg/HBcAg in ELISA and immunoblotting assay. Liver tissue sections of both WHV-infected woodchucks and chronic HBV-infected patients could be stained specifically by mAbs. The epitopes were mapped at aa1-8 (6D1) and aa125-140 (1H4) of the core proteins of both WHV and HBV by using ELISA assay. WHcAg and HBcAg share similar amino acids sequences at aa1-8 and aa125-140 respectively.</p><p><b>CONCLUSION</b>The core proteins of woodchuck hepatitis virus and human hepatitis B virus share common linear B cell epitopes which span aa1-8 and aa125-140 respectively.</p>
Asunto(s)
Animales , Humanos , Ratones , Anticuerpos Monoclonales , Linfocitos B , Alergia e Inmunología , Línea Celular Tumoral , Reacciones Cruzadas , Epítopos de Linfocito B , Alergia e Inmunología , Antígenos del Núcleo de la Hepatitis B , Alergia e Inmunología , Virus de la Hepatitis B de la Marmota , Genética , Alergia e Inmunología , Virus de la Hepatitis B , Genética , Alergia e Inmunología , Marmota , Proteínas del Núcleo Viral , Alergia e InmunologíaRESUMEN
Histologic and clinicopathologic findings of a woodchuck (Marmota monax) vertically infected with woodchuck hepatitis virus (WHV) are presented. The liver exhibits marked cirrhotic changes, which is characteristic of the pre-transformation phase of WHV. At necropsy, the woodchuck exhibited ascites and the liver had a grossly nodular appearance. Microscopically, focal hepatocyte necrosis and inflammatory cells were observed in midzonal and periportal areas in the liver. In Macchiavellos stained sections, cytoplasmic inclusion bodies appeared reddish granular materials. We believe that this may represent a new suitable and cost-effective cirrhotic model for the disease processes associated with hepadnaviruses in a number of other species, most notably Hepatitis B virus infection in man.