Underestimation of occult hepatitis C virus infection in chronic haemodialysis and kidney transplant patients
Authors: Javier Bartolomé, Inmaculada Castillo, Juan Antonio Quiroga, Vicente Carreño
Journal: Journal of Hepatology (2014)

Prevalence of occult hepatitis C infection in chronic hemodialysis and kidney transplant patientsJournal of HepatologyVol. 60Issue 5PreviewDetection of hepatitis C virus (HCV) RNA in peripheral blood mononuclear cells (PBMC) and/or hepatocytes in absence of HCV RNA in serum, designated as ‘occult HCV infection’, has been a matter of controversy in recent years. We investigated for the first time the prevalence of occult HCV infection in large cohorts of chronic hemodialysis (CHD) and kidney transplant (KTx) patients. Full-Text PDF Reply to: “Underestimation of occult hepatitis C virus infection in chronic haemodialysis and kidney transplant patients”Journal of HepatologyVol. 61Issue 5PreviewWe thank Carreno et al. for their interest in our study regarding occult hepatitis C virus (HCV) infection in haemodialysis and kidney transplant patients and appreciate their comments as they reflect the complexity and controversy of data available on the topic of occult HCV infection [1]. Their group has provided evidence on the presence of occult HCV infection in patients on chronic haemodialysis in Spain [2]. However, it must be noted that several studies have failed to confirm occult HCV infection under various circumstances using particularly sensitive tests [3–5]. Full-Text PDF Open Access We have read with interest the article by Baid-Agrawal et al. [[1]Baid-Agrawal S. Schindler R. Reinke P. Staedtler A. Rimpler S. Malik B. et al.Prevalence of occult hepatitis C infection in chronic hemodialysis and kidney transplant patients.J Hepatol. 2014; 60: 928-933Abstract Full Text Full Text PDF PubMed Scopus (45) Google Scholar]. The authors define occult hepatitis C virus (HCV) infection “as presence of HCV RNA in peripheral blood mononuclear cells (PBMC) in the absence of HCV RNA in serum, irrespective of the anti-HCV status”. This definition includes two different types of patients: those who have presumably recovered of an HCV infection (anti-HCV positive) and those without serological evidences of a prior exposure to HCV (anti-HCV negative) and thus, they should be studied separately. The concept of occult HCV infection is still a matter of debate, and in our opinion, this is because both types of occult HCV infection are not considered as separate entities. In this regard, when authors affirm that several studies have failed to detect HCV RNA in PBMC in various clinical settings, most of the cited articles deal with anti-HCV positive cases and only three analyzed anti-HCV negative patients. By contrast, occult HCV infection has been detected by different investigators in anti-HCV negative patients with cryptogenic liver disease, hepatocellular carcinoma or onco-hematological disorders [2Idrees M. Lal A. Malik F.A. Hussain A. Rehman I.U. Akbar H. et al.Occult hepatitis C virus infection and associated predictive factors: the Pakistan experience.Infect Genet Evol. 2011; 11: 442-445Crossref PubMed Scopus (29) Google Scholar, 3Bokharaei-Salim F. Keyvani H. Monavari S.H. Alavian S.M. Madjd Z. Toosi M.N. et al.Occult hepatitis C virus infection in Iranian patients with cryptogenic liver disease.J Med Virol. 2011; 83: 989-995Crossref PubMed Scopus (58) Google Scholar, 4Saad Y. Zakaria S. Ramzy I. El Raziky M. Shaker O. Elakel W. et al.Prevalence of occult hepatitis C in Egyptian patients with non alcoholic fatty liver disease.Open J Int Med. 2011; 1: 33-37Crossref Google Scholar, 5Farahani M. Bokharaei-Salim F. Ghane M. Basi A. Meysami P. Keyvani H. Prevalence of occult hepatitis C virus infection in Iranian patients with lymphoproliferative disorders.J Med Virol. 2013; 85: 235-240Crossref PubMed Scopus (25) Google Scholar, 6Hernandez B.Y. Zhu X. Kwee S. Chan O.T. Tsai N. Okimoto G. et al.Viral hepatitis markers in liver tissue in relation to serostatus in hepatocellular carcinoma.Cancer Epidemiol Biomarkers Prev. 2013; 22: 2016-2023Crossref PubMed Scopus (6) Google Scholar]. The authors have found a low prevalence of HCV infection in the study population (3.6% in hemodialysis and 4.8% in kidney transplant). Furthermore, the authors indicate that the reported overall HCV prevalence in Germany is 0.3%. Taking into account this low incidence of HCV, the prevalence of occult HCV infection found in this study (0.25% in haemodialysis and 0.5% in kidney transplant) cannot be considered negligible. For HCV RNA detection in PBMC, integrity of the isolated RNA and the amount used for viral RNA detection are crucial parameters especially when very low amounts of intracellular HCV RNA are expected. This information has not been provided by the authors and it is important to be sure that no false negative results have been obtained due to poor quality of the total RNA used in HCV RNA detection. Furthermore, although TMA is the most sensitive commercial assay for HCV RNA detection, it has been shown that ultracentrifugation of 2 ml of serum to concentrate viral particles prior to RT-PCR, allows HCV RNA detection in TMA negative samples [[7]Bartolomé J. López-Alcorocho J.M. Castillo I. Rodriguez-Iñigo E. Quiroga J.A. Palacios R. et al.Ultracentrifugation of serum samples allows detection of hepatitis C virus RNA in patients with occult hepatitis C.J Virol. 2007; 81: 7710-7715Crossref PubMed Scopus (83) Google Scholar]. So, in the absence of a liver biopsy, to discard the existence of occult HCV infection, testing for HCV RNA in serum after ultracentrifugation and detection of anti-HCV core antibodies [[8]Castillo I. Bartolomé J. Quiroga J.A. Barril G. Carreño V. Diagnosis of occult hepatitis C without the need for a liver biopsy.J Med Virol. 2010; 82: 1554-1559Crossref PubMed Scopus (46) Google Scholar] must be performed as these are the only detectable serum markers in some patients who are HCV RNA negative in PBMC but who have an occult HCV infection in the liver. As this has not been performed, prevalence of occult HCV infection in the studied patients may be underestimated. In the discussion section, the authors argue against the existence of occult HCV infection stating that in renal or liver transplants of anti-HCV positive patients, clearance of the virus before transplantation is associated with a lack of reinfection after transplantation. However, reinfection of liver graft in occult HCV infection has been demonstrated [[9]Cortés-Mancera F.M. Restrepo J.C. Osorio G. Hoyos S. Correa G. Navas M.C. Occult hepatitis C virus infection in a re-transplanted patients with liver failure of unknown etiology.Rev Colomb Gastroenterol. 2010; 25: 72-80Google Scholar]. On the other hand, the fact that patients with occult HCV in this study present normal liver function tests in the follow-up does not imply that they do not have liver disease, as this type of patients usually have normal ALT levels due to their immunological status. Thus, it cannot be assumed that occult HCV infection has no clinical relevance in these patients unless absence of liver damage is demonstrated by transient elastography (as liver biopsy may not be performed in this type of patients due to possible complications). The authors suggest that the high prevalence of occult HCV infection documented in other studies may be due to cross-contamination during HCV RNA detection. However, in these studies, cross-contamination was discarded because positivity to HCV RNA in liver or peripheral blood mononuclear cells was confirmed by amplifying a different region of the HCV genome and by cloning, sequencing and phylogenetic analysis of the PCR products. Finally, we completely disagree with the assertion that presence of HCV RNA in PBMC in the absence of anti HCV should be called “occult detection of HCV RNA” rather than “occult HCV infection”, because these patients have both positive and negative HCV RNA strands in liver and in PBMC and have circulating viral particles with the same physicochemical characteristics than those found in patients with chronic HCV infection [[7]Bartolomé J. López-Alcorocho J.M. Castillo I. Rodriguez-Iñigo E. Quiroga J.A. Palacios R. et al.Ultracentrifugation of serum samples allows detection of hepatitis C virus RNA in patients with occult hepatitis C.J Virol. 2007; 81: 7710-7715Crossref PubMed Scopus (83) Google Scholar]. Furthermore, HCV RNA persists a long time in serum and PBMC of patients with occult HCV infection [[10]Castillo I. Bartolomé J. Quiroga J.A. Barril G. Carreño V. Long-term virological follow-up of patients with occult hepatitis C virus infection.Liver Int. 2011; 31: 1519-1524Crossref PubMed Scopus (22) Google Scholar], indicating an ongoing HCV infection. The authors declared that they do not have anything to disclose regarding funding or conflict of interest with respect to this manuscript.