Specific mutations in the C-terminus domain of HBV surface antigen significantly correlate with low level of serum HBV-DNA in patients with chronic HBV infection

• DOI: 10.1016/j.jinf.2014.10.015
• Publication Date: 2014-11-06T16:37:32Z
• Authors: Carmen Mirabelli; Matteo Surdo; Formijn Van Hemert; Zhichao Lian; Romina Salpini; Valeria Cento; Maria Francesca C...; Marianna Aragri; Michela Pollicita; Claudia Alteri; Ada Bertoli; Ben Berkhout; Valeria Micheli; Guido Gubertini; Maria Mercedes Sa...; Sara Romano; Michela Visca; Martina Bernassola; Roberta Longo; Giuseppe Maria De...; Pascal Trimoulet; Hervè Fleury; Nicoletta Marino; Francesco Mazzotta; Giuseppina Cappiello; Alberto Spanò; Cesare Sarrecchia; Jing Maria Zhang; Massimo Andreoni; Mario Angelico; Jens Verheyen; Carlo Federico Perno; Valentina Svicher
• Keywords: Virion maturation; Adult; Male; Models, Molecular; 0301 basic medicine; Hepatitis B virus; HBV; HBsAg; Serum HBV-DNA; Virion maturation; Genotype; Molecular Sequence Data; Medizin; Settore MED/07 - MICROBIOLOGIA E MICROBIOLOGIA CLINICA; 03 medical and health sciences; HBsAg; Hepatitis B, Chronic; HBV; Humans; Virion maturation; HBV; HBsAg; Serum HBV-DNA; Transaminases; Hepatitis B Surface Antigens; Serum HBV-DNA; Bayes Theorem; Middle Aged; 3. Good health; Carrier State; DNA, Viral; Mutation; Mutagenesis, Site-Directed; Female

To define HBsAg-mutations correlated with different serum HBV-DNA levels in HBV chronically-infected drug-naive patients.This study included 187 patients stratified into the following ranges of serum HBV-DNA:12-2000 IU/ml, 2000-100,000 IU/ml, and >100,000 IU/ml. HBsAg-mutations were associated with HBV-DNA levels by applying a Bayesian-Partitional-Model and Fisher-exact test. Mutant and wild-type HBV genotype-D genomes were expressed in Huh7 cells and HBsAg-production was determined in cell-supernatants at 3 days-post-transfection.Specific HBsAg-mutations (M197T,-S204N-Y206C/H-F220L) were significantly correlated with serum HBV-DNA <2000 IU/ml (posterior-probability>90%, P < 0.05). The presence of Y206C/H and/or F220L was also associated with lower median (IQR) HBsAg-levels and lower median (IQR) transaminases (for HBsAg:250[115-840] IU/ml for Y206C/H and/or F220L versus 4300[640-11,838] IU/ml for wild-type, P = 0.023; for ALT:28[21-40] IU/ml versus 53[34-90] IU/ml, P < 0.001). These mutations were localized in the HBsAg C-terminus, known to be involved in virion and/or HBsAg secretion. The co-occurrence of Y206C + F220L was found significant by cluster-analysis, (P = 0.02). In addition, in an in-vitro model Y206C + F220L determined a 2.8-3.3 fold-reduction of HBsAg-amount released in supernatants compared to single mutants and wt (Y206C + F220L = 5,679 IU/ml; Y206H = 16,305 IU/ml; F220L = 18,368 IU/ml; Y206C = 18,680 IU/ml; wt = 14,280 IU/ml, P < 0.05).Specific HBsAg-mutations (compartmentalized in the HBsAg C-terminus) correlated with low-serum HBV-DNA and HBsAg-levels. These findings can be important to understand mechanisms underlying low HBV replicative potential including the inactive-carrier state.