Abstract
BackgroundHepatitis B virus (HBV) occult infection (OBI) is a risk factor to be taken into account in transfusion, hemodialysis and organ transplantation. The aim of this study was to identify and characterize at the molecular level OBI cases in patients with end-stage liver disease.MethodsSixty-six liver samples were obtained from patients with diagnosis of end-stage liver disease submitted to liver transplantation in Medellin (North West, Colombia). Samples obtained from patients who were negative for the surface antigen of HBV (n = 50) were tested for viral DNA detection by nested PCR for ORFs S, C, and X and confirmed by Southern-Blot. OBI cases were analyzed by sequencing the viral genome to determine the genotype and mutations; additionally, viral genome integration events were examined by the Alu-PCR technique.ResultsIn five cases out of 50 patients (10%) the criteria for OBI was confirmed. HBV genotype F (subgenotypes F1 and F3), genotype A and genotype D were characterized in liver samples. Three integration events in chromosomes 5q14.1, 16p13 and 20q12 affecting Receptor-type tyrosine-protein phosphatase T, Ras Protein Specific Guanine Nucleotide Releasing Factor 2, and the zinc finger 263 genes were identified in two OBI cases. Sequence analysis of the viral genome of the 5 OBI cases showed several punctual missense and nonsense mutations affecting ORFs S, P, Core and X.ConclusionsThis is the first characterization of OBI in patients with end-stage liver disease in Colombia. The OBI cases were identified in patients with HCV infection or cryptogenic cirrhosis. The integration events (5q14.1, 16p13 and 20q12) described in this study have not been previously reported. Further studies are required to validate the role of mutations and integration events in OBI pathogenesis.
Highlights
Hepatitis B virus (HBV) is responsible for significant morbidity and mortality worldwide
Hepatitis B virus (HBV) occult infection (OBI) is a risk factor to be taken into account in transfusion, hemodialysis and organ transplantation
Three integration events in chromosomes 5q14.1, 16p13 and 20q12 affecting Receptortype tyrosine-protein phosphatase T, Ras Protein Specific Guanine Nucleotide Releasing Factor 2, and the zinc finger 263 genes were identified in two occult HBV infection (OBI) cases
Summary
Hepatitis B virus (HBV) is responsible for significant morbidity and mortality worldwide. More than 780.000 people die each year due to liver diseases associated with HBV infection including cirrhosis and hepatocellular carcinoma (HCC) [1, 2]. HBV infection is diagnosed by detecting the HBV surface antigen (HBsAg) in serum samples using immunoassays; other serological markers are necessary to identify the type and/or stage of HBV infection including the E antigen (HBeAg), anti-Core protein (anti-HBc), anti-HBsAg (anti-HBs) and anti-HBeAg (anti-HBe) antibodies and viral load [3, 4]. Patients with OBI could develop HBV reactivation, cirrhosis and HCC [8, 9]. Hepatitis B virus (HBV) occult infection (OBI) is a risk factor to be taken into account in transfusion, hemodialysis and organ transplantation. The aim of this study was to identify and characterize at the molecular level OBI cases in patients with end-stage liver disease
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