In 2008,the European Association for the study of the liver(EASL) defined occult hepatitis B virus infection (OBI) as the"presence of hepatitis B virus(HBV) DNA in the liver(with detectable or undetectable HBV DN...In 2008,the European Association for the study of the liver(EASL) defined occult hepatitis B virus infection (OBI) as the"presence of hepatitis B virus(HBV) DNA in the liver(with detectable or undetectable HBV DNA in the serum) of individuals testing hepatitis B surface antigen(HBsAg) negative by currently available assays".Several aspects of occult HBV infection are still poorly understood,including the definition itself and a standardized approach for laboratory-based detection,which is the purpose of this review.The clinical significance of OBI has not yet been established;however,in terms of public health,the clinical importance arises from the risk of HBV transmission.Consequently,it is important to detect high-risk groups for occult HBV infection to prevent transmission.The main issue is,perhaps,to identify the target population for screening OBI.Viremia is very low or undetectable in occult HBV infection,even when the most sensitive methods are used,and the detection of the viral DNA reservoir in hepatocytes would provide the best evaluation of occult HBV prevalence in a defined set of patients.However,this diagnostic approach is obviously unsuitable:blood detection of occult hepatitis B requires assays of the highest sensitivity and specificity with a lower limit of detection<10 IU/mL for HBV DNA and<0.1 ng/mL for HBsAg.展开更多
Occult hepatitis B infection(OBI) is characterized by hepatitis B virus(HBV) DNA in serum in the absence of hepatitis B surface antigen(HBsAg) presenting HBsAg-negative and anti-HBc positive serological patterns.Occul...Occult hepatitis B infection(OBI) is characterized by hepatitis B virus(HBV) DNA in serum in the absence of hepatitis B surface antigen(HBsAg) presenting HBsAg-negative and anti-HBc positive serological patterns.Occult HBV status is associated in some cases with mutant viruses undetectable by HBsAg assays;but more frequently it is due to a strong suppression of viral replication and gene expression.OBI is an entity with world-wide diffusion.The failure to detect HBsAg,despite the persistence of the viral DNA,is due in most cases to the strong suppression of viral replication and gene expression that characterizes this"occult"HBV infection;although the mechanisms responsible for suppression of HBV are not well understood.The majority of OBI cases are secondary to overt HBV infection and represent a residual low viremia level suppressed by a strong immune response together with histological derangements which occurred during acute or chronic HBV infection.Much evidence suggests that it can favour the progression of liver fibrosis and the development of hepatocellular carcinoma.展开更多
Occult hepatitis B virus(HBV) infection(OBI) is characterized by the persistence of HBV DNA in the liver tissue in individuals negative for the HBV surface antigen.The prevalence of OBI is quite variable depending on ...Occult hepatitis B virus(HBV) infection(OBI) is characterized by the persistence of HBV DNA in the liver tissue in individuals negative for the HBV surface antigen.The prevalence of OBI is quite variable depending on the level of endemic disease in different parts of the world,the different assays utilized in the studies,and the different populations studied.Many studies have been carried out on OBI prevalence in different areas of the world and categories of individuals.The studies show that OBI prevalence seems to be higher among subjects at high risk for HBV infection and with liver disease than among individuals at low risk of infection and without liver disease.展开更多
AIM:To identify blood donors with occult hepatitis B virus(HBV) infection(OBI) to promote safe blood donation.METHODS:Descriptive cross sectional study was conducted on 3167 blood donors negative for hepatitis B surfa...AIM:To identify blood donors with occult hepatitis B virus(HBV) infection(OBI) to promote safe blood donation.METHODS:Descriptive cross sectional study was conducted on 3167 blood donors negative for hepatitis B surface antigen(HBsAg),hepatitis C antibody(HCV Ab) and human immunodeficiency virus Ab.They were subjected to the detection of alanine aminotransferase(ALT) and aspartate transaminase(AST) and screening for anti-HBV core antibodies(total) by two different techniques;[Monoliza antibodies to hepatitis B core(Anti-HBc) Plus-Bio-Rad] and(ARC-HBc total-ABBOT).Positive samples were subjected to quantitative detection of antibodies to hepatitis B surface(anti-HBs)(ETI-AB-AUK-3,Dia Sorin-Italy).Serum anti-HBs titers > 10 IU/L was considered positive.Quantitative HBV DNA by real time polymerase chain reaction(PCR)(QIAGEN-Germany) with 3.8 IU/mL detection limit was estimated for blood units with negative serum anti-HBs and also for 32 whose anti-HBs serum titers were > 1000 IU/L.Also,265 recipients were included,34 of whom were followed up for 3-6 mo.Recipients were investigated for ALT and AST,HBV serological markers:HBsAg(ETI-MAK-4,Dia Sorin-Italy),anti-HBc,quantitative detection of anti-HBs and HBV-DNA.RESULTS:525/3167(16.6%) of blood units were positive for total anti-HBc,64% of those were antiHBs positive.Confirmation by ARCHITECT anti-HBc assay were carried out for 498/525 anti-HBc positive samples,where 451(90.6%) confirmed positive.Reactivity for anti-HBc was considered confirmed only if two positive results were obtained for each sample,giving an overall prevalence of 451/3167(14.2%) for total anti-HBc.HBV DNA was quantified by real time PCR in 52/303(17.2%) of anti-HBc positive blood donors(viral load range:5 to 3.5 x 105 IU/mL) with a median of 200 IU/mL(mean:1.8 x 104 ± 5.1 x 104 IU/mL).AntiHBc was the only marker in 68.6% of donors.Univariate and multivariate logistic analysis for identifying risk factors associated with anti-HBc and HBV-DNA positivity among blood donors showed that age above thirty 展开更多
文摘In 2008,the European Association for the study of the liver(EASL) defined occult hepatitis B virus infection (OBI) as the"presence of hepatitis B virus(HBV) DNA in the liver(with detectable or undetectable HBV DNA in the serum) of individuals testing hepatitis B surface antigen(HBsAg) negative by currently available assays".Several aspects of occult HBV infection are still poorly understood,including the definition itself and a standardized approach for laboratory-based detection,which is the purpose of this review.The clinical significance of OBI has not yet been established;however,in terms of public health,the clinical importance arises from the risk of HBV transmission.Consequently,it is important to detect high-risk groups for occult HBV infection to prevent transmission.The main issue is,perhaps,to identify the target population for screening OBI.Viremia is very low or undetectable in occult HBV infection,even when the most sensitive methods are used,and the detection of the viral DNA reservoir in hepatocytes would provide the best evaluation of occult HBV prevalence in a defined set of patients.However,this diagnostic approach is obviously unsuitable:blood detection of occult hepatitis B requires assays of the highest sensitivity and specificity with a lower limit of detection<10 IU/mL for HBV DNA and<0.1 ng/mL for HBsAg.
文摘Occult hepatitis B infection(OBI) is characterized by hepatitis B virus(HBV) DNA in serum in the absence of hepatitis B surface antigen(HBsAg) presenting HBsAg-negative and anti-HBc positive serological patterns.Occult HBV status is associated in some cases with mutant viruses undetectable by HBsAg assays;but more frequently it is due to a strong suppression of viral replication and gene expression.OBI is an entity with world-wide diffusion.The failure to detect HBsAg,despite the persistence of the viral DNA,is due in most cases to the strong suppression of viral replication and gene expression that characterizes this"occult"HBV infection;although the mechanisms responsible for suppression of HBV are not well understood.The majority of OBI cases are secondary to overt HBV infection and represent a residual low viremia level suppressed by a strong immune response together with histological derangements which occurred during acute or chronic HBV infection.Much evidence suggests that it can favour the progression of liver fibrosis and the development of hepatocellular carcinoma.
文摘Occult hepatitis B virus(HBV) infection(OBI) is characterized by the persistence of HBV DNA in the liver tissue in individuals negative for the HBV surface antigen.The prevalence of OBI is quite variable depending on the level of endemic disease in different parts of the world,the different assays utilized in the studies,and the different populations studied.Many studies have been carried out on OBI prevalence in different areas of the world and categories of individuals.The studies show that OBI prevalence seems to be higher among subjects at high risk for HBV infection and with liver disease than among individuals at low risk of infection and without liver disease.
文摘AIM:To identify blood donors with occult hepatitis B virus(HBV) infection(OBI) to promote safe blood donation.METHODS:Descriptive cross sectional study was conducted on 3167 blood donors negative for hepatitis B surface antigen(HBsAg),hepatitis C antibody(HCV Ab) and human immunodeficiency virus Ab.They were subjected to the detection of alanine aminotransferase(ALT) and aspartate transaminase(AST) and screening for anti-HBV core antibodies(total) by two different techniques;[Monoliza antibodies to hepatitis B core(Anti-HBc) Plus-Bio-Rad] and(ARC-HBc total-ABBOT).Positive samples were subjected to quantitative detection of antibodies to hepatitis B surface(anti-HBs)(ETI-AB-AUK-3,Dia Sorin-Italy).Serum anti-HBs titers > 10 IU/L was considered positive.Quantitative HBV DNA by real time polymerase chain reaction(PCR)(QIAGEN-Germany) with 3.8 IU/mL detection limit was estimated for blood units with negative serum anti-HBs and also for 32 whose anti-HBs serum titers were > 1000 IU/L.Also,265 recipients were included,34 of whom were followed up for 3-6 mo.Recipients were investigated for ALT and AST,HBV serological markers:HBsAg(ETI-MAK-4,Dia Sorin-Italy),anti-HBc,quantitative detection of anti-HBs and HBV-DNA.RESULTS:525/3167(16.6%) of blood units were positive for total anti-HBc,64% of those were antiHBs positive.Confirmation by ARCHITECT anti-HBc assay were carried out for 498/525 anti-HBc positive samples,where 451(90.6%) confirmed positive.Reactivity for anti-HBc was considered confirmed only if two positive results were obtained for each sample,giving an overall prevalence of 451/3167(14.2%) for total anti-HBc.HBV DNA was quantified by real time PCR in 52/303(17.2%) of anti-HBc positive blood donors(viral load range:5 to 3.5 x 105 IU/mL) with a median of 200 IU/mL(mean:1.8 x 104 ± 5.1 x 104 IU/mL).AntiHBc was the only marker in 68.6% of donors.Univariate and multivariate logistic analysis for identifying risk factors associated with anti-HBc and HBV-DNA positivity among blood donors showed that age above thirty
