OBI is a worldwide diffused entity, although its distribution may reflect the general prevalence of the HBV in the various geographic areas and in the various populations 12. Carriers of occult infection may be a source of HBV transmission in the case of blood transfusion 13.
The possibility of persistent HBV infection in anti-HBc-positive individuals has been supported by the fact that traces of HBV are often detectable in the blood for many years after clinical recovery from acute hepatitis 16.
Detection of HBV-DNA from serum or liver samples is considered the gold standard for the diagnosis of OBI. Experts have recommended the use of highly sensitive nested PCR or real-time PCR assays that can detect fewer than 10 copies of HBV-DNA for the diagnosis of OBI. In addition, testing for multiple targets on the HBV genome increases the HBV-DNA detection rates in patients with OBI 15,17.
Because viral DNA levels in OBI are very low, the identification of OBI is strongly dependent on both the sensitivity and the specificity of the assay 18.
Moreover, the technical procedures used so far have differed considerably from one study to another in terms of both specificity and sensitivity and, as a consequence, the results obtained have frequently been contradictory 12,19. The current technologies used for DNA detection are nested PCR, real-time PCR, and transcription mediated amplification. Primers must be specific for different HBV genomic regions and complementary to highly conserved (genotype shared) nucleotide sequences 9,20.
We used a commercial kit (Artus-Biotech) for the quantitative detection of the HBV-DNA viral load using the Taqman probe technique, but HBV-DNA could not be detected using this method. This may be attributed to the small region amplified by the kit (134 bp) with the possibility of the presence of mutations in the primers or probe sequences. Occult HBV strain populations harbor a genetic heterogeneity in viral regions (Pre-S/S, Pre-Core/Core; X, Polymerase) and regulatory elements (Core promoter, Enhancer I and II) potentially involved in viral replication and/or gene expression 18–21.
The studies of prevalence in Europe have shown that HBV-DNA was detected in 0–1.59% of those who were HBsAg negative and anti-HBc positive (with or without anti-HBs) 31.
Studies of prevalence in the Middle East and Asia have shown that HBV-DNA was detected in 1.09–3% of those who were HBsAg negative and anti-HBc positive (with or without anti-HBs) and that HBV-DNA was detected in 8.1% in the anti-HBc-only category (no anti-HBs) 32–34.
Increasing attention has recently been focused on the impact of viral load on the evolution of chronic liver disease. The serum viral load correlates with the risk of progression to cirrhosis, and high HBV viremia may favor the development of HCC through a sustained inflammatory activity 21,35.
Occult HBV maintains several of the oncogenic mechanisms of HBV such as the capacity to be integrated in the host’s genome and production of transforming proteins. Therefore, it is conceivable that occult HBV increases the risk for development of HCC. Integration of HBV-DNA could also induce carcinogenesis through transactivation of other oncogenes. Both HBx protein and the truncated pre-S/S protein are potent transactivators and are commonly found in HCC tissue 21,22,35,36. In the present study, the X gene has been be detected in 71.4% of the 42 anti-HBc-positive blood donors.
The usefulness of monitoring liver enzymes and HBV-DNA levels in monitoring OBI has been reported 23,37. This was not the case in the present study as the majority of ALT, AST were in the normal range. Only two blood donors showed slightly elevated levels of AST and one showed elevated ALT.
Our data confirm the possibility of post-transfusion HBV infection as the prevalence of the anti-HBc among our blood donors was 42%, with the presence of HBV-DNA in 38 (90.5%) of these donors.
With the use of HBsAg as the sole detection marker for HBV, there is a danger of HBV transmission through blood transfusion. Anti-HBc testing should be added to the routine blood donor screening test if OBI is to be diagnosed.
There are no conflicts of interest.
2. Lok AS. Chronic hepatitis B. N Engl J Med. 2002;346:1682–1683
3. Liu Y, Li P, Li C, Zhou J, Wu C, Zhou Y-H. Detection of hepatitis B virus DNA among accepted blood donors
in Nanjing, China. Virol J. 2010;7:193 . doi: 10.1186/1743-422X-7-193
4. Raimondo G/, Allain J-P, Brunetto MR, Buendia M-A, Chen D-S, Colombo M, et al. Statements from the Taormina expert meeting on occult hepatitis B virus
infection. J Hepatol. 2008;49:652–657
5. Mudawi HM. Epidemiology of viral hepatitis in Sudan. Clin Exp Gastroenterol. 2008;1:9–13
6. Norder H, Hammas B, Larsen J, Skaug K, Magnius LO. Detection of HBV DNA by PCR in serum from an HBsAg negative blood donor implicated in cases of post-transfusion hepatitis B. Arch Virol Suppl. 1992;4:116–118
7. Said ZNA. An overview of occult hepatitis B virus
infection. World J Gastroenterol. 2011;17:1927–1938
8. Hollinger FB. Hepatitis B virus infection and transfusion medicine: science and the occult. Transfusion. 2008;48:1001–1026
9. Hollinger FB, Sood G. Occult hepatitis B virus
infection: a covert operation. J Viral Hepat. 2010;17:1–15
10. Wood B Essentials of medical statistics. 1988 London Blackwell Scientific Publications:191–194 Ch 26
11. Kao J-H, Chen P-J, Lai M-Y, Chen D-S. Occult hepatitis B virus
infection and clinical outcomes of patients with chronic hepatitis C. J Clin Microbiol. 2002;40:4068–4071
12. Raimondo G, Pollicino T, Cacciola I, Squadrito G. Occult hepatitis B virus
infection. J Hepatol. 2007;46:160–170
13. Chazouillères 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
14. Grob P, Jilg W, Bornhak H, Gerken G, Gerlich W, Günther S, et al. Serological pattern’anti-HBc alone’: report on a workshop. J Med Virol. 2000;62:450–455
15. De Almeida Neto C, Strauss E, Sabino EC, Sucupira MCA, Chamone DDAF. Significance of isolated hepatitis B core antibody in blood donors
from São Paulo. Rev Inst Med Trop Sao Paulo. 2001;43:203–208
16. Rehermann B, Ferrari C, Pasquinelli C, Chisari FV. The hepatitis B virus persists for decades after patients’ recovery from acute viral hepatitis despite active maintenance of a cytotoxic T-lymphocyte response. Nat Med. 1996;2:1104–1108
17. Hassan ZK, Hafez MM, Mansor TM, Zekri ARN. Occult HBV infection among Egyptian hepatocellular carcinoma patients. Virol J. 2011;8:90 . doi: 10.1186/1743-422X-8-90
18. Ramia S, Sharara AI, El-Zaatari M, Ramlawi F, Mahfoud Z. Occult hepatitis B virus
infection in Lebanese patients with chronic hepatitis C liver disease. Eur J Clin Microbiol Infect Dis. 2008;27:217–221
19. 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
20. Ocana S, Casas ML, Buhigas I, Lledo JL. Diagnostic strategy for occult hepatitis B virus
infection. World J Gastroenterol. 2011;17:1553–1557
21. Squadrito G, Orlando ME, Pollicino T, Raffa G, Restuccia T, Cacciola I, et al. Virological profiles in patients with chronic hepatitis C and overt or occult HBV infection. Am J Gastroenterol. 2002;97:1518–1523
22. Allice T, Cerutti F, Pittaluga F, Varetto S, Gabella S, Marzano A, et al. COBAS AmpliPrep-COBAS TaqMan hepatitis B virus (HBV) test: a novel automated real-time PCR assay for quantification of HBV DNA in plasma. J Clin Microbiol. 2007;45:828–834
23. Levast M, Larrat S, Thelu M-A, Nicod S, Plages A, Cheveau A, et al. Prevalence and impact of occult hepatitis B infection in chronic hepatitis C patients treated with pegylated interferon and ribavirin. J Med Virol. 2010;82:747–754
24. Sagnelli E, Imparato M, Coppola N, Pisapia R, Sagnelli C, Messina V, et al. Diagnosis and clinical impact of occult hepatitis B infection in patients with biopsy proven chronic hepatitis C: a multicenter study. J Med Virol. 2008;80:1547–1553
25. Shetty K, Hussain M, Nei L, Reddy KR, Lok ASF. Prevalence and significance of occult hepatitis B in a liver transplant population with chronic hepatitis C. Liver Transpl. 2008;14:534–540
26. Kleinman SH, Kuhns MC, Todd DS, Glynn SA, McNamara A, DiMarco A, Busch MP. Frequency of HBV DNA detection in US blood donors
testing positive for the presence of anti-HBc: implications for transfusion transmission and donor screening. Transfusion. 2003;43:696–704
27. Kleinman SH, Strong DM, Tegtmeier GGE, Holland PV, Gorlin JB, Cousins CR, et al. Hepatitis B virus (HBV) DNA screening of blood donations in minipools with the COBAS AmpliScreen HBV test. Transfusion. 2005;45:1247–1257
28. Linauts S, Saldanha J, Strong DM. PRISM hepatitis B surface antigen detection of hepatits B virus minipool nucleic acid testing yield samples. Transfusion. 2008;48:1376–1382
29. Chevrier M-C, St-Louis M, Perreault J, Caron B, Castilloux C, Laroche J, Delage G. Detection and characterization of hepatitis B virus of anti-hepatitis B core antigen-reactive blood donors
in Quebec with an in-house nucleic acid testing assay. Transfusion. 2007;47:1794–1802
30. O’Brien SF, Fearon MA, Yi Q-L, Fan W, Scalia V, Muntz IR, Vamvakas E. Hepatitis B virus DNA-positive, hepatitis B surface antigen-negative blood donations intercepted by anti-hepatitis B core antigen testing: the Canadian Blood Services experience. Transfusion. 2007;47:1809–1815
31. Hourfar MK, Jork C, Schottstedt V, Weber-Schehl M, Brixner V, Busch MP, et al. Experience of German Red Cross blood donor services with nucleic acid testing: results of screening more than 30 million blood donations for human immunodeficiency virus-1, hepatitis C virus, and hepatitis B virus. Transfusion. 2008;48:1558–1566
32. Bhatti FA, Ullah Z, Salamat N, Ayub M, Ghani E. Anti-hepatits B core antigen testing, viral markers, and occult hepatitis B virus
infection in Pakistani blood donors
: implications for transfusion practice. Transfusion. 2007;47:74–79
33. Nantachit N, Thaikruea L, Thongsawat S, Leetrakool N, Fongsatikul L, Sompan P, et al. Evaluation of a multiplex human immunodeficiency virus-1, hepatitis C virus, and hepatitis B virus nucleic acid testing assay to detect viremic blood donors
in northern Thailand. Transfusion. 2007;47:1803–1808
34. Satake M, Taira R, Yugi H, Hino S, Kanemitsu K, Ikeda H, Tadokoro K. Infectivity of blood components with low hepatitis B virus DNA levels identified in a lookback program. Transfusion. 2007;47:1197–1205
35. Tamori A, Yamanishi Y, Kawashima S, Kanehisa M, Enomoto M, Tanaka H, et al. Alteration of gene expression in human hepatocellular carcinoma with integrated hepatitis B virus DNA. Clin Cancer Res. 2005;11:5821–5826
36. Peng Z, Zhang Y, Gu W, Wang Z, Li D, Zhang F, et al. Integration of the hepatitis B virus X fragment in hepatocellular carcinoma and its effects on the expression of multiple molecules: a key to the cell cycle and apoptosis. Int J Oncol. 2005;26:467–473
37. Kleinman SH, Busch MP. Hbv: amplified and back in the blood safety spotlight. Transfusion. 2001;41:1081–1085