Role of Hepatitis B Virus Surface Antigen Quantification in e Antigen Negative Chronic Hepatitis B Infection
Background/Aim: Hepatitis B surface antigen(HBsAg) is routinely detected qualitatively in Hepatitis B Virus(HBV) infection where its persistence beyond 6 months defines chronic hepatitis B(CHB) infection. Hepatitis B e antigen (HBeAg) usually indicates active HBV replication and risk of transmission of infection. In spite of the emerging use of chemiluminescence based quantitative HBsAg assays for therapeutic monitoring of the patients, we measured HBsAg concentration by sandwich ELISA as a cost effective alternative to ascertain the role of HBsAg levels as surrogate marker of untreated HBeAg negative subjects having CHB infection. Methods : Sixty two subjects were evaluated for serum HBeAg,anti HBe and ALT status by standard ELISA and biochemical procedures.The amount of serum HBV DNA determined by real time TaqMan PCR assay(Roche Diagnostics,USA).Serum HBsAg level(ng/ml) was ascertained by a third generation sandwich ELISA kit(Alpha Diagnostics International,USA)and results expressed upon conversion to IU/ml. Results :The median age of the subjects was 40.5 years(IQR=18;90% male) of which 92% were HBeAg negative and anti-HBe positive.Median ALT value was 35.5 IU/ml(IQR=37).Median viral load(Log copies/ml)and HBsAg(IU/ml) were 4.57(IQR=2.84)and 38002.3 (IQR=23736.8) respectively. When grouped on the basis of viral load(),the median HBsAg concentration seen is 35439.3 (IQR=43093.3) and 44712.7( IQR=25082.4) while median ALT values were 29(IQR=21.2)and 47(IQR=73.2) in lower(2000 IU/ml)viral load groups respectively. Conclusion : Serum HBsAg concentration showed no correlation with serum HBV DNA level in our study subjects which is at par with other studies on CHB patients. Based on the reported correlation between serum HBsAg level and intrahepatic ccc DNA, higher amount of HBsAg in subjects having lower viral load is indicative of the presence of higher amount of intrahepatic HBV DNA in these subjects which warrant further stud
