1. Raimondo G, Pollicino T, Cacciola I, Squadrito G. Occult hepatitis B virus infection. J Hepatol 2007;46:160-170. 17112622.
2. Wong DK, Huang FY, Lai CL, Poon RT, Seto WK, Fung J, et al. Occult hepatitis B infection and HBV replicative activity in patients with cryptogenic cause of hepatocellular carcinoma. Hepatology 2011;54:829-836. 21809355.
4. Chazouilleres O, Mamish D, Kim M, Carey K, Ferrell L, Roberts JP, et al. "Occult" hepatitis B virus as source of infection in liver transplant recipients. Lancet 1994;343:142-146. 7904004.
5. Blackberg J, Kidd-Ljunggren K. Occult hepatitis B virus after acute self-limited infection persisting for 30 years without sequence variation. J Hepatol 2000;33:992-997. 11131464.
6. Brechot C, Thiers V, Kremsdorf D, Nalpas B, Pol S, Paterlini-Brechot P. Persistent hepatitis B virus infection in subjects without hepatitis B surface antigen: clinically significant or purely "occult"? Hepatology 2001;34:194-203. 11431751.
7. Loriot MA, Marcellin P, Walker F, Boyer N, Degott C, Randrianatoavina I, et al. Persistence of hepatitis B virus DNA in serum and liver from patients with chronic hepatitis B after loss of HBsAg. J Hepatol 1997;27:251-258. 9288597.
8. Huang X, Hollinger FB. Occult hepatitis B virus infection and hepatocellular carcinoma: a systematic review. J Viral Hepat 2014;21:153-162. 24438677.
9. Bréchot C, Degos F, Lugassy C, Thiers V, Zafrani S, Franco D, et al. Hepatitis B virus DNA in patients with chronic liver disease and negative tests for hepatitis B surface antigen. N Engl J Med 1985;312:270-276. 2981408.
10. Hou J, Wang Z, Cheng J, Lin Y, Lau GK, Sun J, et al. Prevalence of naturally occurring surface gene variants of hepatitis B virus in nonimmunized surface antigen-negative Chinese carriers. Hepatology 2001;34:1027-1034. 11679975.
12. Kato J, Hasegawa K, Torii N, Yamauchi K, Hayashi N. A molecular analysis of viral persistence in surface antigen-negative chronic hepatitis B. Hepatology 1996;23:389-395. 8617416.
13. Carman WF, Van Deursen FJ, Mimms LT, Hardie D, Coppola R, Decker R, et al. The prevalence of surface antigen variants of hepatitis B virus in Papua New Guinea, South Africa, and Sardinia. Hepatology 1997;26:1658-1666. 9398013.
14. Carman WF, Korula J, Wallace L, MacPhee R, Mimms L, Decker R. Fulminant reactivation of hepatitis B due to envelope protein mutant that escaped detection by monoclonal HBsAg ELISA. Lancet 1995;345:1406-1407. 7539089.
15. Pollicino T, Cacciola I, Saffioti F, Raimondo G. Hepatitis b virus PreS/S gene variants: pathobiology and clinical implications. J Hepatol 2014;61:408-417. 24801416.
16. Cacciola I, Pollicino T, Squadrito G, Cerenzia G, Orlando ME, Raimondo G. Occult hepatitis B virus infection in patients with chronic hepatitis C liver disease. N Engl J Med 1999;341:22-26. 10387938.
18. Hofer M, Joller-Jemelka HI, Grob PJ, Luthy R, Opravil M. Frequent chronic hepatitis B virus infection in HIV-infected patients positive for antibody to hepatitis B core antigen only. Swiss HIV Cohort Study. Eur J Clin Microbiol Infect Dis 1998;17:6-13. 9512175.
19. Tuttleman JS, Pourcel C, Summers J. Formation of the pool of covalently closed circular viral DNA in hepadnavirus-infected cells. Cell 1986;47:451-460. 3768961.
22. He ML, Wu J, Chen Y, Lin MC, Lau GK, Kung HF. A new and sensitive method for the quantification of HBV cccDNA by real-time PCR. Biochem Biophys Res Commun 2002;295:1102-1107. 12135608.
23. Min CH, Kim YW, Cho MK, Hwang BS, Kim HS, Lee JH, et al. Subtypes of hepatitis B surface antigen in Korea in comparison with other Asian nations. J Korean Soc Microbiol 1991;26:289-299.
24. Usuda S, Okamoto H, Iwanari H, Baba K, Tsuda F, Miyakawa Y, et al. Serological detection of hepatitis B virus genotypes by ELISA with monoclonal antibodies to type-specific epitopes in the preS2-region product. J Virol Methods 1999;80:97-112. 10403681.
25. Norder H, Hammas B, Lee SD, Bile K, Courouce AM, Mushahwar IK, et al. Genetic relatedness of hepatitis B viral strains of diverse geographical origin and natural variations in the primary structure of the surface antigen. J Gen Virol 1993;74:1341-1348. 8336122.
26. Furusyo N, Hayashi J, Sawayama Y, Kishihara Y, Kashiwagi S. Hepatitis B surface antigen disappearance and hepatitis B surface antigen subtype: a prospective, long-term, follow-up study of Japanese residents of Okinawa, Japan with chronic hepatitis B virus infection. Am J Trop Med Hyg 1999;60:616-622. 10348237.
27. Bahn A, Gerner P, Martine U, Bortolotti F, Wirth S. Detection of different viral strains of hepatitis B virus in chronically infected children after seroconversion from HBsAg to anti-HBs indicating viral persistence. J Hepatol 1997;27:973-978. 9453421.
28. Mangold CM, Unckell F, Werr M, Streeck RE. Secretion and antigenicity of hepatitis B virus small envelope proteins lacking cysteines in the major antigenic region. Virology 1995;211:535-543. 7645257.
30. Protzer-Knolle U1, Naumann U, Bartenschlager R, Berg T, Hopf U, Meyer zum Büschenfelde KH, et al. Hepatitis B virus with antigenically altered hepatitis B surface antigen is selected by high-dose hepatitis B immune globulin after liver transplantation. Hepatology 1998;27:254-263. 9425945.
31. Ijaz S, Torre F, Tedder RS, Williams R, Naoumov NV. Novel immunoassay for the detection of hepatitis B surface 'escape' mutants and its application in liver transplant recipients. J Med Virol 2001;63:210-216. 11170059.
32. Ghany MG, Ayola B, Villamil FG, Gish RG, Rojter S, Vierling JM, et al. Hepatitis B virus S mutants in liver transplant recipients who were reinfected despite hepatitis B immune globulin prophylaxis. Hepatology 1998;27:213-222. 9425940.
33. Terrault NA, Zhou S, McCory RW, Pruett TL, Lake JR, Roberts JP, et al. Incidence and clinical consequences of surface and polymerase gene mutations in liver transplant recipients on hepatitis B immunoglobulin. Hepatology 1998;28:555-561. 9696024.
34. Kim KH, Lee KH, Chang HY, Ahn SH, Tong S, Yoon YJ, et al. Evolution of hepatitis B virus sequence from a liver transplant recipient with rapid breakthrough despite hepatitis B immune globulin prophylaxis and lamivudine therapy. J Med Virol 2003;71:367-375. 12966541.
35. Kalinina T, Riu A, Fischer L, Will H, Sterneck M. A dominant hepatitis B virus population defective in virus secretion because of several S-gene mutations from a patient with fulminant hepatitis. Hepatology 2001;34:385-394. 11481624.
38. Zanella I, Rossini A, Domenighini D, Albertini A, Cariani E. Real-time quantitation of hepatitis B virus (HBV) DNA in tumorous and surrounding tissue from patients with hepatocellular carcinoma. J Med Virol 2002;68:494-499. 12376956.