HBsAg levels <100 IU/mL may herald HBsAg clearance. Disclosures: Cihan Yurdaydin - Advisory Committees or Review Panels: Janssen, Roche, Merck, Gilead The following people have nothing to disclose: Onur Keskin, Mustafa Yakut, Cagdas Kalkan, Senem C. Karatayli, Ersin Karatayli, Ramazan Idilman, A Mithat Bozdayi Background/Aim: The study aimed to
investigate HBV ETV resistance profile of Chinese patients in clinical practice. Methods: Serum samples from 18,419 patients collected from July 2007 to June 2012 in Beijing 302 Hospital were screened. buy Hydroxychloroquine Genotypic resistance was detected by direct PCR sequencing and confirmed by clonal sequencing if necessary. Phenotypic resistance was analyzed by measuring HBV replication capacity under drug pressure in
HepG2 cells. Results: ETV-resistant mutations were detected from 646 samples and the incidence had been increased in the past five years (1.91%, 2.23%, 3.54%, 3.96%, and 4.77%). Mutational pattern analysis showed that concomitant with rtM204V/rtM204I, mutations at rt1 84, rt202, rt250, and two of rt1 84/rt202/rt250 sites were 57.4%, 22.4% and 14.1%, and 6.1%, LBH589 purchase respectively (Figure 1). Nineteen percent (123/646) of ETV-resistant samples harbored rtM204I±L80I/L180M-based pattern rather than rtL180M+M204V-based pattern. Among them 70 samples only harbored two resistant mutations (rtM204I+T184I × 39, rtM204I+M250L × 26, rtM204I+M250I × 5). All ETV-resistant SPTBN5 strains exhibited varied lower natural replication capacity compared to wild-type strains in vitro. ETV susceptibility of rtL180M+M204V-based ETV-resistant mutants
was usually lower than rtM204I-based ETV-resistant mutants. Replication of all tested ETV-resistant strains could be effectively suppressed by tenofovir and adefovir in vitro. In clinical practice, adding-on adefovir was more efficacious than switching-to adefovir as a rescue therapy for ETV-resistant patients. Conclusions: The occurrence of ETV-resistant HBV infection kept growing in the past five years in Chinese patients. ETV-resistant mutational pattern diversified and rtM204I-containing ETV-resistant strains occupied near 1/5 of the patients. ETV-resistant strains could be suppressed by tenofovir or adefovir in vitro; and currently, adding-on adefovir was a practical rescue therapy in clinical practice in China. Disclosures: The following people have nothing to disclose: Yan Liu, Zhihui Xu, Liming Liu, Xiaodong Li, Jiuzeng Dai, Zengtao Yao, Li Chen, Siyu Bai, Shaojie Xin, Dongping Xu Background: Hepatitis B virus (HBV) infection plays a crucial role in the pathogenesis of chronic hepatitis, cirrhosis and hepatocellular carcinoma. Therefore, it is of prime importance to understand the mechanisms of HBV-host interactions during malignant transformation in chronic hepatitis B (CHB) infection to identify novel therapeutic anti-HBV targets.