CASL Symposium Hepatitis B Co-chairs: Carla Coffin and Mang Ma

Transcription

1 CASL Symposium Hepatitis B Co-chairs: Carla Coffin and Mang Ma Occult HBV Infection: Assessment and Clinical Significance D. Lorne Tyrrell Director, Li Ka Shing Institute of Virology University of Alberta March 2, 2013

2 Disclosure KMT Hepatech Inc. Founder and Director Chief Scientific Officer Shareholder Merck Research funding GlaxoSmithKline Research funding

3 Occult HBV-Outline HBV Definition of Occult HBV Milestones in History of Occult HBV Mechanisms of Occult HBV Clinical Impact of Occult HBV

4 Hepatitis B Virus Non-cytopathic, enveloped, partially dsdna virus 350 million carriers worldwide HBsAg is the mainstay of diagnosis 15-40% will develop cirrhosis, liver failure, Hepatocellular carcinoma 600,000-1,000,000 deaths/yr Many unaware of status Vertical Transmission (Endemic Countries) At birth Horizontal Transmission (Low prevalence) IV Drug abuse Sexual transmission Occupational Exposure

5 Hepatitis B disease burden is most prevalent in Africa and Asia Lavanchy D J Viral Hepat

6 Duck vs Human HBV

7 HBV life cycle: anti-viral drugs do not target cccdna- need immune cell activation! Chan et al. J Hepatol 2011

8 CD8 T cell (and NK cell) secretion of IFNg acts with TNFa and IFNa/b = non-cytolytic clearance Almost 100% of hepatocytes can be infected,

9 Occult HBV- Recent Reviews G. Raimondo et al Semin Immunopathol (2013) 35: J Samal M Kandpal and P Vivekanandan Clin Micro Reviews (2012) 25: G Raimondo et al Expert Opinion Statements-J Hepatology (2008) 49:

10 Occult HBV - definition HBV DNA detectable HBsAg not detectable

11 Occult HBV HBV-DNA positive HBsAg - negative 80% 20% seropositive (anti HBs+, Anti HBc+) seronegative (anti HBs-, anti HBc-)

12 Schematic representation of HBV profile in OBI and false OBI. Statements from the Taormina expert meeting on occult hepatitis B virus infection Giovanni Raimondo, Jean-Pierre Allain, Maurizia R. Brunetto, Marie-Annick Buendia, Ding-Shinn Chen, Massimo C. et al. Journal of Hepatology Volume 49, Issue

13 False Occult HBV Serum DNA levels comparable to levels in overt HBV infection. HBV has mutations in HBsAg not recognized by commercially available kits. Escape mutations in S gene.

14 Milestones in the progression of knowledge of occult HBV infection 1975 Gastroenterology Wands et al. [4] OBI reactivation in patients undergoing chemotherapy 1978 N Engl J Med Hoofnagle et al. [13] HBV transmission by blood transfusion from an OBI donor 1981 N Engl J Med Shafritz et al. [7] HBV DNA integration in the hepatocyte genome of HBsAg-negative individuals 1981 Proc Natl Acad Sci Brechot et al. [15] 1988 Lancet Thiers et al. [6] Acute hepatitis B in chimpanzees injected with HBV isolates from blood of OBI carriers 1989 Proc Natl Acad Sci Kaneko et al. [12] Polymerase chain reaction detection of HBV DNA in serum of HBsAgnegative individuals

15 Milestones in the progression of knowledge of occult HBV infection (continued) 1994 Lancet Chazouillères et al. [14] Liver transplant from OBI donors may induce hepatitis B in recipients 1994 J Clin Invest Michalak et al. [11] OBI in patients recovered from acute hepatitis B 1996 Nature Medicine Rehermann et al. [8] A strong CTL-specific anti-hbv response persists over time in patients who recovered from acute hepatitis B 1996 J Clin Invest Penna et al. [10] 1999 N Engl J Med Cacciola et al. [3] OBI is associated with cirrhosis in patients with chronic hepatitis C and the virus is wild-type 2002 Lancet Inf Dis Torbenson and Thomas [5] First systematic review of the OBI field 2004 Gastroenterology Pollicino et al. [9] Molecular analyses of a large series of liver tumor tissues confirm the association between OBI and HCC 2008 J Hepatol Raimondo et al. [2] Statements on OBI by an international, large panel of experts

16 G. Raimondo et al (2013) Publications on occult HBV infection over time Semin Immunopathol (2013) 35:30-52

17 Diagnosis of Occult B Infection Measure HBV-DNA - carefully collected and stored for PCR Anti-HBc is a less than ideal surrogate marker when HBV-DNA measurement is not feasible Gold standard analysis of liver as well as blood for HBV-DNA - two rounds of nested PCR Rarely possible to get liver tissue for this assay

18 Basis of Occult HBV Long-lasting persistence of HBV-ccc DNA Strong suppression of HBV replication decreased yields of HBV-DNA Loss of HBsAg Occult B infection often have long-lasting T-cell immunity suggesting low level long-term immune stimulation by viral antigens

19 Schematic representation of the various conditions leading to different OBI serological profiles Semin Immunopathol (2013) 35:39-52

20 Overview of mechanisms leading to occult hepatitis B virus (HBV) infection. Samal J et al. Clin. Microbiol. Rev. 2012;25:

21 Mechanism of occult HBV infection via methylation of HBV DNA. HBV induces expression of cellular DNA methyltransferases (DNMTs), leading to methylation of CpG dinucleotides in the HBV genome. Samal J et al. Clin. Microbiol. Rev. 2012;25:

22 Model of HBV infection and its relationship to methylation. Vivekanandan P et al. J. Virol. 2010;84:

23 Immunohistochemical analysis of hepatitis B virus (HBV) protein (HBV core antigen [HBcAg] [A and B] and HBV surface antigen [HBsAg] [C and D]) accumulation in HepG2 cells harvested 48 h after transfection with HBV DNA. After transfection with unmethylated HBV DNA, HBcAg was detectable in the nuclei of a small proportion of HepG2 cells (A; arrows indicate examples of positive cells), but no HBcAg was detected after transfection with fully methylated HBV DNA (B). Vivekanandan P et al. J Infect Dis. 2009;199: by the Infectious Diseases Society of America

24 HCV co-infection in occult HBV infection. Samal J et al. Clin. Microbiol. Rev. 2012;25:

25 Role of APOBEC deaminases in occult HBV infection. Samal J et al. Clin. Microbiol. Rev. 2012;25:

26 Host immunological responses leading to occult HBV infection. Samal J et al. Clin. Microbiol. Rev. 2012;25:

27 Key Clinical Implications of Occult HBV 1. Transmission of HBV - blood transfusion 2. Transmission of HBV orthotopic liver transplantation 3. Reactivation of HBV with chemotherapy and potent immunological drugs 1. Occult HBV and chronic liver disease 2. Occult HBV and HCC

28 Clinical Impact of Occult HBV 1. Blood transfusion HBsAg testing not enough even with multivalent HBsAb AntiHBc better than HBsAg HBV-DNA PCR gold standard

29 Occult HBV-Transfusion Risk HBV in transfusion- Window Period or OBI low anti HBc, low anti HBs -1.94% HBV DNA pos Sensitive HBV-DNA testing Detection rate increased 3.9 to 15.2 per million Transfusion Hepatitis-1.5/million. R Taira et al-transfusion-in press

30 Occult HBV-Transfusion 1:1000 to1:50,000 OBI In European Blood donations. Transmission OBI- anti HBs neg into unvaccinated recipients 28 of 44 (63%). Transmission OBI-anti HBs positive into unvaccinated-4 of 26 (15.4%) Depends on volume of plasma-200ml %: 50 ml-51%: 20ml- 24% JP Allain et al Transfusion in press

31 Clinical Impact of Occult HBV (continued) 2. In liver transplantation Occult HBV seropositive donor to a recipient that is negative for HBV serum markers can transmit HBV Prophylaxis with antivirals indicated Occult HBV seronegative no evidence to date of HBV transmission

32 Occult HBV -Cancer >10,000 cancer patients on chemotherapy -one quarter of HBsAg neg but antihbcag pos had HBV reactivation. HBV prophylaxis over all mortality-22% Treatment of HBV after reactivation-over all mortality was 72% J Hwang et al Hepatology (2011):445A

33 Occult HBV and Chemotherapy, radiotherapy, or immunotherapy All patients should be tested for anti HBc antibodies Possibly HBV-DNA by PCR Antiviral therapy prophylaxis if positive

34 Occult HBV and HIV/AIDS HBV reactivation in HIV-positive well documented Changing therapy may lead to reactivation

35 Occult HBV role in cirrhosis May accelerate cirrhosis development May accelerate HCV-induced cirrhosis These observations require more study

36 Occult HBV and HCC Integration of HBV - oncogenesis Production of transforming protein Interference with tumor suppressor genes No doubt about HBV role, but role of Occult HBV requires more study

37 Conclusions HBV-a simple virus, but complex biology. cccdna-generation and mechanisms to maintain it are not fully understood. 2 billion infected-350 million carrierspotential for occult HBV is large. Clinical significance is still evolving Clearly occult HBV is important in a number of clinical settings.

38 Thanks to our collaborators!