O-27 impact of hbv genotype f in the diagnosis and evolution of patients with hbeag-negative chronic hbv infection

Background: The quantitative hepatitis B surface antigen (qHBsAg) threshold of 1,000 IU/ml has been proposed to distinguish HBeAg-negative chronic infections from HBeAg-negative chronic hepatitis, to assess risk of liver disease progression, and to predict HBsAg clearance. There is evidence that qHBsAg vary significantly among genotypes, however, there is scarce data on genotype F, the most prevalent in Latin America. Aims: To analyze the impact of HBV genotype F on qHBsAg inpatients with HBeAg-negative chronic infection and to describe clinical and virological outcomes. Methods: HBV-DNA and qHBsAg serum levels of 141 patients with HBeAg-negative chronic infection were correlated with HBV genotype, who were followed for 10.6±7.4 years. Results: The overall genotype distribution was as follows: F 46.8%, D 26.1%, A 25.2%, and B 0.7% and C 0.7%. While no impact of the HBV genotype on HBV DNA levels was observed, qHBsAg differed significantly among genotypes (p<0.001). The highest HBsAg levels were observed in genotype F (4.0±1.1 Log10IU/ml) followed by genotype A (3.9±0.6 Log10IU/ml) and genotype D (2.4±0.9 Log10IU/ml). In genotype A and F, qHBsAg <3.0 Log10IU/ml were only observed in 10.7% and 11.5% respectively.Regardless of the HBV genotype, spontaneous clearance of HBsAg was observed in 17 cases. Of these, 12 patients presented qHBsAg <100 IU/ml one year before clearance. Despite, 101 (71.6%) patients showed qHBsAg >3.0 Log10IU/ml, no cases of advanced liver disease or hepatocellular carcinoma were observed at the end of follow-up. Conclusions: This study provides new insights into the impact of HBV genotypes on serum HBsAg levels, emphasizing the need to implement genotype-specific cut-off to achieve diagnostic certainty in the identification of HBeAg-negative chronic infection and the risk of liver disease progression, particularly on infections with genotypes A and F. Moreover, HBsAg serum levels can became a reliable biomarker to predict HBsAg clearance.