cases had moderate inflammation or significant fibrosis who were recommended to receive antiviral therapy and aspartate amino- transferase (AST) (p = 0.031), AFP (p = 0.044), anti-HBc (p = 0.001) and LSM (p = 0.000) were independent variables. Our novel AAL index [AAL index = exp (Y)/[1+exp (Y), Y = 0.344*AFP (ng/ml) +1.643*log 10 Anti-HBc (IU/ml)+0.526*LSM (kPa)-12.119] showed good performance for diagnosing moderate inflammation or signifi- cant fibrosis with AUROC of 0.889. A high cutoff value (>0.64) with PPV of 96.2% was chosen to diagnose moderate inflammation or significant fibrosis and a low cutoff value (≤ 0.22) with NPV of 87.3% was chosen to exclude. Finally,108 (46.0%) of 235 patients could avoid liver biopsy based on AAL index. Conclusion: AST, AFP, anti-HBc and LSM are related to antiviral therapy decision among CHB patients with normal ALT. The novel AAL index is a more reliable non-invasive model. THU-243 Occult hepatitis B virus infection after haploidentical haematopoietic stem cell transplantation patients: incidence and characterization of HBV pres/s gene mutations Haiying Zhang 1 , Lai Wei 1 , Jianghua Wang 1 , Huiying Rao 1 . 1 Peking University People′s Hospital, Peking University Hepatology Institute, Beijing Key Laboratory for Hepatitis C and Immunotherapy for Liver Disease, Beijing, China Email: weilai@pkuph.edu.cn Background and aims: Occult hepatitis B virus (HBV) infection (OBI) is found in allogeneic haematopoietic stem cell transplantation (HSCT) patients. However, incidence and characterization of HBV preS/S gene mutations in patients with OBI infection receiving haploidentical HSCT (haplo-HSCT) has not been prospectively studied. OBI has been associated with an increased risk for the development of hepatocellular carcinoma and cirrhosis. Method: We retrospectively evaluate the incidence and character- ization of HBV preS/S gene mutantions in haplo-HSCT patients. From January 2014 to September 2018, 227 patients who received haplo- HSCTat Peking University Institute of Haematology were screened for hepatitis B surface antigen (HBsAg), antibodies to HBV core (anti- HBc). Serum samples negative for HBsAg and positive for anti-HBc were subjected to nucleic acid extraction and HBV DNA detection by real-time PCR. PreS/S gene mutants were analyzed by clonal sequencing in cases with occult HBV infection and 30 control chronic carriers. Results: 189/227 patients were HBsAg-negative. The 15/189 (7.94%) HBsAg-negative patients with haplo-HSCT tested positive for HBV- DNA in serum. A total 13 OBI-patients and 30 control patients were analyzed for the the preS gene and S gene through sequencing simultaneously. 45 preS/S gene mutations were cloned from 13 OBI sequential serum samples, including 10 mutations that were not previously documented. 26 preS/S gene mutations significantly correlated with OBI.11/13 OBI-patients (84.6%) carried in median 3 mutations in the three regions labelled here as preS1, preS2, and S were significantly higher in chronically-infected patients. Of 13 OBI sequences, 9 harboured MHR mutations. The populations of variants harbouring the D49V, W56T, L75M, I84T, A90V, P41Q, N51T, P/T78A, M120I, R135K, F141P and T168I mutations in the preS region and the T/I126M/N, P127I, Q129H and P142L mutations in the “a” determin- ant region were detected more frequently in the occult subjects than in the carriers. Conclusion: This is the first report demonstrating OBI after haplo- HSCT confirmed by molecular analysis. We found a high prevalence (7.94%) of OBI in haplo-HSCT patients suggesting that routine screening for HBV-DNA should be considered in haplo-HSCT population in our region. Our data suggest that preS mutations and ‘‘a’’ determinant mutations are associated with OBI. This has implications for HBV diagnosis and vaccine improvement. THU-244 Virological and clinical characteristics of chronic hepatitis delta patients of Mongolia Delgersaikhan Zulkhuu 1 , Bekhbold Dashtseren 2 , Myagmarjav Budeebazar 2 , Maralmaa Enkhbat 2 , Miriam Eichner 3 , Purevjargal Bat-Ulzii 2 , Zulkhuu Genden 2 , Altankhuu Mordorjyn 2 , Dahgwahdorj Yagaanbuyant 3 , Naranbaatar Dashdorj 2,3 , Andreas Bungert 3 , Naranjargal Dashdorj 2,4 . 1 Liver Center, Ulaanbaatar, Mongolia; 2 Liver Center, Ulaanbaatar, Mongolia; 3 Onom foundation, Ulaanbaatar, Mongolia; 4 Onom foundation, Ulaanbaatar, Mongolia Email: z.delgersaikhan@onomfoundation.org Background and aims: Mongolia has the highest prevalence of chronic hepatitis B (HBV) and D (HDV) virus co-infection. HBV-HDV co-infection leads to rapid progression towards liver-related compli- cations and is considered to be the most severe form of chronic viral hepatitis. We here describe virological and clinical characteristics of chronic HDV patients in Mongolia. Method: Data of 2303 HDV patients were collected for this retrospective study. We included individuals who tested positive for HBV surface antigen (HBsAg), HDV antibody (anti-HDV) and HDV- RNA any time between October 2015 toJune 2018. We summarized latest results for HDV-RNA, HBV-DNA, HBV envelope antigen (HBeAg), HBsAg, liver function tests, platelets (PLT) and fibroscan. Patients were divided into groups according to HDV-RNA level (cleared (not detected), low (<10 4 IU/ml), medium (10 4 to 10 5 IU/ml) and high (>10 5 IU/ml)). Differences between this groups with respect to clinical markers and general biomarkers were analyzed by two- tailed t-test. Results: Most individuals were HBeAg-negative (82.1%) and HDV- RNA positive (86.7%). 305 patients had cleared HDV-infection. Advanced liver fibrosis was found in 51.3% of the patients. Table: (abstract: THU-244) patients tested total cleared low (<10 4 IU/ml) medium (10 4 to 10 5 IU/ml) high (>10 5 IU/ml) n = 2303 n = 305 n = 461 n = 336 n = 1201 mean age 2303 44.9 46 45.6 45.7 44.1 male% 2303 47.6 49.1 46.4 43.1 48.5 ALT±SDIU/L 897 71.2 ± 71.8 34.9 ± 27.8 49.5 ± 47.6 76.7 ± 81.7 86.4 ± 78.4 AST±SDIU/L 894 47.8 ± 41.5 27 ± 22.6 34.1 ± 24.4 51.5 ± 4.0 56.8 ± 46.7 ALB±SDmg/dL 891 42.2 ± 3.9 43.6 ± 3.9 43.5 ± 3.4 42.1 ± 4.3 41.4 ± 3.8 PLT±SD10 3 /L 721 189.6 ± 56.9 202 ± 62.4 203.5 ± 64.0 176.3 ± 50.6 186.1 ± 53.4 HbeAg positive at serology% 712 17.9 7.2 7.4 8.5 26.1 HBV-DNAlog 10 IU/ml 1184 275-ND6.5 ± 7.6 6.9 ± 7.9 6.8 ± 7.7 5.3 ± 6.4 5.6 ± 6.6 HDV-RNAlog 10 IU/ml 2303 305-ND7.0 ± 8.1 0 3.2 ± 3.4 4.7 ± 4.4 6.9 ± 8.1 HBsAglog 10 IU/ml 1228 3.9 ± 4.4 3.9 ± 4.8 3.7 ± 4.1 3.8 ± 3.8 4.0 ± 3.9 Fibroscan±SDkPa 720 10.9 ± 7.9 8.2 ± 6 10.1 ± 9.3 11.39 ± 7.19 11.5 ± 7.7 POSTER PRESENTATIONS e272 Journal of Hepatology 2019 vol. 70 | e141–e382