Comparative study on the clinical and virological characteristics among patients with single occult hepatitis B virus (HBV), single occult hepatitis C virus (HCV) and occult HBV and HCV dual infection

Occult Hepatitis B Virus Infection and Its Risks of Cryptic Transmission in Southern Ethiopia

BACKGROUND

The detection of hepatitis B virus surface antigen (HBsAg) in serum remains the mainstay in diagnosing and screening of hepatitis B virus (HBV) in most developing countries. The absence of HBsAg in the blood may not indicate the absence of circulating HBV and might be infectious. Thus, this study aimed to estimate the burden and its cryptic transmission risks of occult hepatitis B infection (OBI) among HBsAg negative healthy individuals in Southern Ethiopia.

METHODS

A community-based cross-sectional study was conducted from September 2020 to January 2021. Serum samples were collected and assayed for HBsAg and HBV core antibody (anti-HBc) seromarkers using enzyme-linked immunosorbent assay (ELISA). In anti-HBc positive samples, HBV DNA was detected using real-time polymerase chain reaction (RT-PCR). Data were entered into Epi-Data version 3.1, cleaned, and analyzed using SPSS version 21.0. Descriptive and logistic regression analyses were employed. Statistical significance was decided at p < 0.05.

RESULTS

A total of 346 were individuals included in this study; 34 (9.8%) were tested positive for HBsAg. The rest 312 (90.2%) negatively tested were further assayed for anti-HBc, and 115 (36.7%) were found positive implying previous exposure to HBV, and 21 (18.3%) out of 115 anti-HBc positives had HBV DNA signifying OBI. The HBV DNA concentration below 200 IU/mL was 85.7%. A high rate of OBI was observed among individuals who had multiple sexual contacts, a family history of hepatitis, and tattooing.

CONCLUSION

In this study, the prevalence of OBI is high. This indicates the burden of HBV is considerable since screening is exclusively dependent on HBsAg which will not eliminate the possibility of residual cryptic transmission through blood donation, organ transplantation, perinatal transmission, and other contacts. Our results demonstrate that nucleic acid-based testing (NAT) should be an essential part of screening to prevent missing OBI.

Prevalence of occult HBV infection in Western countries

Due to a lack of standardized tests, it is difficult to obtain prevalence data and define the real impact of occult HBV infection (OBI) in Western countries. The present review article addresses the prevalence of OBI, defined as presence of hepatitis B virus (HBV) DNA in liver tissue or plasma in HBsAg-negative subjects, in Western countries. This varies in different studies according to the different methodologies used (based on serology vs virology), to the sample analyzed for the diagnosis (liver tissue vs plasma), to the different populations studied, to the different geographical variations in the HBV spread, to the host characteristics (age, gender, risk factors for acquiring HBV infection) and to the presence of other parenteral infections (hepatitis C virus and/or human immunodeficiency virus [HIV] infections). Considering the different liver diseases analyzed, that is in patients with cryptogenic cirrhosis or advanced liver fibrosis, the prevalence of OBI ranges 4% to 38%. Considering the different populations studied, in the case of parenteral blood exposure it is about 45%, in patients with chronic hepatitis C it is estimated at about 52%, in HIV-infected patients it ranges from 0% to 45%, in blood donors from 0% to 22.7% and in hemodialysis patients it ranges from 0% to 54%. In conclusion, OBI is a virological entity to be considered when performing the patient's evaluation for immunosuppressive diseases, liver pathologies, or for blood transfusions. Knowing the prevalence and clinical impact of OBI will allow better patient management.

An estimation of the prevalence of occult HBV infection in Western Europe and in Northern America: A meta-analysis

Data on the prevalence of occult HBV infection (OBI) in Western Europe and in Northern America are few; hence, we conducted a systematic review and meta-analysis. All studies included had to fulfil the following inclusion criteria: (a) they investigated the prevalence of OBI (HBV DNA in liver tissue in HBsAg-negative subjects), (b) were carried out in Western Europe and in Northern America; (c) were available as a full-text manuscript, (d) written in English and (e) published up to December 2018. The exclusion criteria were as follows: (a) meta-analyses, letters, reviews, meeting abstracts or editorial comments; (b) studies investigating HBsAg-positive patients; (c) those investigating OBI outside Western Europe and in Northern America; and (d) to avoid small sample bias in the random-effects model, those enrolling less than five subjects. Thirty-four studies met the inclusion criteria, allowing a meta-analysis on 2729 patients. The overall prevalence of OBI was 34% (95% CI = 26%-42%), 28% (CI 95%: 12%-48%) in 329 subjects without chronic liver disease and 35% (95% CI 26%-44%) in 2400 patients with chronic liver disease. The prevalence of OBI was 51% (95% CI 40%-62%) in the 823 anti-HBc-positive subjects and 19% (95% CI 10%-30%) in the 1,041 anti-HBc-negative subjects. Evaluating the data from 17 studies comparing anti-HBc-positive and negative subjects, the prevalence of OBI was higher in the 641 anti-HBc-positive subjects than in the 1041 anti-HBc-negative (prevalence ratio = 2.29; 95% CI = 1.61-3.26, P < .001). This meta-analysis showed that in HBsAg-negative subjects the prevalence of OBI was high and was associated with anti-HBc positivity.

Viral Biomarkers in Chronic HBeAg Negative HBV Infection

Viral biomarkers are important tools for monitoring chronic hepatitis B virus (HBV) hepatitis B early antigen (HBeAg) negative infection, both in its natural course as well as during and after treatment. The biomarkers consist of antibodies against viral epitopes, viral proteins, and molecular surrogate markers of the quantity and transcriptional activity of the stable episomal HBV covalently closed circular DNA (cccDNA) which is located in the nuclei of the infected hepatocytes. HBV deoxyribonucleic acid (DNA) or else viral load measurement in plasma or serum is a marker of HBV replication of major clinical importance. HBV DNA is used for staging and treatment monitoring as described in international scientific guidelines. Quantification of HBV antigens, mainly hepatitis B surface antigen (HBsAg) as well as Hepatitis B core related antigen (HBcrAg), play an important yet secondary role, especially in cases of low or undetectable HBV DNA and has been evaluated for the classification of the inactive carrier state, as a predictor of subsequent HBsAg clearance, treatment outcome, and development of hepatocellular carcinoma (HCC). The measurement of the replicative intermediate HBV RNA in serum is currently evaluated and may also prove to be a significant biomarker particularly in patients treated with nucleot(s)ide analogs. This review focuses on the viral biomarkers mentioned above and their role in HBV, HBeAg negative, infection.

Occult Hepatitis B Virus Infection and Associated Genotypes among HBsAg-negative Subjects in Burkina Faso

Background

The presence of HBV DNA in the liver (with detectable or undetectable HBV DNA in the serum) of individuals tested HBsAg negative by currently available assays is defined occult B Infection (OBI). It remains a potential transmission threat and risk to HBV chronic infection. The purpose of this study was to determine the OBI prevalence among HBsAg negative subjects and to characterize associated genotypes.

Methods

Blood samples of 219 HBsAg-negative subjects tested by ELISA were collected. HBV DNA was investigated in all samples. Viral loads were determined using quantitative real-time PCR. All samples were screened for HBV markers (anti-HBc, anti-HBe, HBsAg). The Pre-S/S region of the HBV genome was sequenced. The database was analyzed using the SPSS and Epi info software. Phylogenetic analysis was performed using the BioEdit and MEGA software.

Results

Of the 219 samples, 20.1% were anti-HBc positive, 1.8% HBeAg and 22.8% were anti-HBe positive. Fifty-six (56) (25.6%) of the samples had a detectable HBV DNA and viral loads ranging from 4 IU/mL to 13.6 10⁶ IU/mL. Sixteen of them (16/56) had a viral load < 200 IU/mL, resulting in an OBI prevalence of 7.3% (16/219) in our study. The remaining 40 subjects had viral loads > 200 IU/mL, resulting in a “false OBI” prevalence of 18.3% (40/219). HBV genotype E was predominant followed by the quasi-sub-genotype A3. A single “false OBI” strain had the characteristic mutation G145R. Other mutations were observed and all located in the major hydrophilic region (MHR) of the S gene.

Conclusion

The study reported a prevalence of 7.3% of occult hepatitis B infection. It confirms the predominance of genotype E and the existence of a subgroup of quasi-sub-genotype A3 of HBV in Burkina Faso. It further provides information on the presence of “false OBI.” This study has found mutations in the major hydrophilic region (MHR) of the pre-S/S gene of HBV.

Are current screening protocols for chronic hepatitis B virus infection adequate?

Chronic hepatitis B virus (HBV) infection screening usually includes only HBV surface antigen (HBsAg) testing; HBV core and surface antibody (anti-HBc, anti-HBs) assays, indicating resolved infection and immunity, are not routinely performed. Yet, serum HBV DNA is measurable in approximately 10% of HBsAg-negative/anti-HBc-positive cases, representing occult HBV infection (OBI). Patient blood samples from 2 Veterans Affairs medical center look-back investigations were screened for HBV infection using HBsAg enzyme immunoassays. Supplementary testing included anti-HBc and anti-HBs enzyme immunoassays. For anti-HBc-positive samples, HBV DNA testing was performed. Background OBI prevalence was further estimated at these 2 facilities based on HBV serology testing results from 1999-2012. Finally, a literature review was performed to determine OBI prevalence in the published literature. Of 1887 HBsAg-negative cohort patients, 98 (5.2%) were anti-HBc positive/anti-HBs negative; and 175 (9.3%), anti-HBc positive/anti-HBs positive. Six of 273 were HBV DNA positive, representing 0.3% of the total tested and 2.2% who were anti-HBc positive/anti-HBs negative or anti-HBc positive/anti-HBs positive. Among 32,229 general population veterans at these 2 sites who had any HBV testing, 4/108 (3.7%) were HBV DNA positive, none of whom were part of the cohort. In 129 publications with HBsAg-negative patients, 1817/1,209,426 (0.15%) had OBI. However, excluding blood bank studies with greater than 1000 patients, the OBI rate increased to 1800/17,893 (10%). OBI is not rare and has implications for transmission and disease detection. HBsAg testing alone is insufficient for detecting all chronic HBV infections. These findings may impact blood donation, patient HBV screening, follow-up protocols for patients assumed to have cleared the infection, and initiation of immunosuppression in patients with distant or undetected HBV.

Interleukin 27 polymorphisms in HCV RNA positive patients: is there an impact on response to interferon therapy?

Background

Interleukin 27 (IL-27) has pleiotropic properties that can either limit or enhance immune responses. Recent studies revealed that single nucleotide polymorphisms (SNPs) of the IL-27 promoter region modulate the development of infectious diseases and individual's susceptibility to therapeutic response. Little is known about the relationship between IL-27 single nucleotide polymorphisms and therapy response in patients infected by hepatitis C virus (HCV). In this study we have investigated the potential role of SNPs in the promoter region of IL27 p28 gene (alleles rs153109) on the outcome of HCV infected patients.

Methods

rs153109, corresponding to position c.-964A>G of the IL-27 locus, was amplified from genomic DNA extracted from 15 patients with chronic hepatitis C stratified by sustained viral response (SVR), relapser and non-responder, after treatment with peginterferon-α (PegIFN- α) combined with ribavirin (RBV). Amplification products were studied by direct sequencing.

Results

This method has been applied in a preliminary study on patients with chronic hepatitis C to provide information for a standardized assay useful to genotyping of rs153109 SNPs of IL-27p28. The genotype distribution of the c.-964 A>G polymorphism was more present in patients who did not achieve a SVR. By contrast, the genotype G/G was absent in non-responder and relapser patients. Moreover, the analysis of allelic distribution of rs153109 highlighted a predominance of allele A in all genotypes in spite of allele G.

Conclusions

Our work provides preliminary information for a standardized method potentially useful for genotyping rs153109, and suggests its utility as a candidate approach to evaluate IL-27 p28 polymorphisms as additional clinical predictors of response to therapies in HCV infected patients.

Occult hepatitis B virus infection and hepatocellular carcinoma: a systematic review

Occult hepatitis B (OHB) infection has been reported to play an important role in the development of hepatocellular carcinoma (HCC). In this systematic review, a significantly higher prevalence of OHB was observed in patients with HCC in the presence or absence of HCV infection when compared with control populations without HCC. Correspondingly, among adequately designed prospective studies, the cumulative probability of developing HCC was significantly greater among patients with OHB than among HBV DNA-negative patients in the presence or absence of HCV infection. Study design, inclusion criteria, treatment options, methodology and potential confounding variables were evaluated, and immunopathogenic mechanisms that could be involved in OHB as a risk factor in HCC were reviewed. From this analysis, we conclude that although OHB is an independent risk factor in HCC development in anti-HCV-negative patients, a synergistic or additive role in the occurrence of HCC in HCV-coinfected patients is more problematic due to the HCC risk attributable to HCV alone, especially in patients with advanced fibrosis and cirrhosis.

Characterization of the occult hepatitis B virus variants circulating among the blood donors from eastern India

A previous study from West Bengal documented very high rate of occult HBV infection (OBI) among the HBsAg negative blood donors. This study was aimed to characterize the OBI strains circulating among the blood donors and to estimate the risk associated with the prevailing viral variants/mutants. Blood samples from 2195 voluntary blood donors were included in the study. HBsAg, HBeAg, anti-HBc, and anti-HBs statuses of the samples were done by ELISA based detection. PCR amplification and sequencing were done to determine HBV genotypes, basal core promoter (BCP), and precore (Pre-C) mutations. Among the study samples, 268 were anti-HBc positive/HBsAg negative, among which 65 (24.25%) were HBV DNA positive. Phylogenetic analysis revealed the presence of HBV/D (87.23%), HBV/A (8.51%), and HBV/C (4.26%) (P < 0.0001). HBV/D3 (65.85%) was the significantly prevalent subgenotype over HBV/D2 (26.83%) and HBV/D1 (7.31%) (P = 0.0003). Considerable prevalence of differential BCP (1752C, 1753C, 1762T/1764A, 1753C+1762T/1764A, 1773C, and 1814C) and reverse transcriptase (rt) gene (rtI91L, rtL93P, rtS106C, rtR110G, rtN118T, rtS119T, rtY126H, rtG127W/R, rtC136R, and rtY158H) mutations was identified. Association of specific HBV subgenotypes with OBI was interesting and needs further study. Clinically relevant mutations were prevalent among the OBI strains which are of serious concern.

High prevalence of occult hepatitis C virus infection in patients with chronic hepatitis B virus infection

Hepatitis C virus (HCV) infection in the absence of detectable antibodies against HCV and of viral RNA in serum is called occult HCV infection. Its prevalence and clinical significance in chronic hepatitis B virus (HBV) infection is unknown. HCV RNA was tested for in the liver samples of 52 patients with chronic HBV infection and 21 (40 %) of them were positive for viral RNA (occult HCV infection). Liver fibrosis was found more frequently and the fibrosis score was significantly higher in patients with occult HCV than in negative ones, suggesting that occult HCV infection may have an impact on the clinical course of HBV infection.

Prevalence of occult hepatitis C virus in egyptian patients with chronic lymphoproliferative disorders

Background. Occult hepatitis C virus infection (OCI) was identified as a new form of Hepatitis C virus (HCV), characterized by undetectable HCV antibodies and HCV RNA in serum, while HCV RNA is detectable in liver and peripheral blood cells only. Aim. The aim of this study was to investigate the occurrence of OCI in Egyptian patients with lymphoproliferative disorders (LPDs) and to compare its prevalence with that of HCV in those patients. Subjects and Methods. The current study included 100 subjects, 50 of them were newly diagnosed cases having different lymphoproliferative disorders (patients group), and 50 were apparently healthy volunteers (controls group). HCV antibodies were detected by ELISA, HCV RNA was detected in serum and peripheral blood mononuclear cells (PBMCs) by reverse transcription polymerase chain reaction(RT-PCR), and HCV genotype was detected by INNO-LiPA. Results. OCI was detected in 20% of patients group, compared to only 4% OCI in controls group. HCV was detected in 26% of patients group with a slightly higher prevalence. There was a male predominance in both HCV and OCI. All HCV positive patients were genotype 4. Conclusion. Our data revealed occurrence of occult HCV infection in Egyptian LPD patients at a prevalence of 20% compared to 26% of HCV.

Management of occult hepatitis B virus infection: An update for the clinician

Occult hepatitis B virus (HBV) infection (OBI) is defined by the presence of HBV DNA in the liver tissue of individuals who test negative for hepatitis B surface antigen (HBsAg). Patients who have recovered from acute hepatitis B can carry HBV genomes for a long time and show histological patterns of mild necro-inflammation, even fibrosis, years after the resolution of acute hepatitis, without showing any clinical or biochemical evidence of liver disease. At least in conditions of immunocompetence, OBI is inoffensive itself, but when other relevant causes of liver damage are present it might make the course of the liver disease worse. The risk of HBV transmission through transfusion is related to blood donations negative for HBsAg that have been collected during the pre-seroconversion period or during chronic OBI. Use of HBV nucleic acid amplification testing and multivalent anti-HBs antibodies in the HBsAg assays is recommended for detection of true and false OBI, respectively. It is not known if prior hepatitis B immunization with an optimal anti-HBs response in cases of HBV transmission through organ transplantation can effectively modulate or abort the infection. Use of antiviral agents as prophylaxis in patients with serological evidence of past HBV infection prevents reactivation of OBI after transplantation in most cases. Reactivation of OBI has been observed in other conditions that cause immunosuppression, in which antiviral therapy could be delayed until the HBV DNA or HBsAg becomes detectable. OBI might contribute to the progression of liver fibrosis and hepatocellular carcinoma development in patients with chronic liver disease.

Occult hepatitis C virus infection and associated predictive factors: the Pakistan experience

The aim of the present study was to determine the presence of HCV RNA in the liver biopsies of patients with abnormal liver tests but without detectable serum HCV RNA and anti-HCV antibodies in sera. Liver biopsies and whole blood of total 31 patients who were negative for anti-HCV antibodies with elevated liver function tests were received at Division of Molecular Diagnostics, University of the Punjab Pakistan from January 2002 to June 2009 for the detection of HCV RNA. HCV RNA status of the subjects was tested by reverse-transcription PCR and quantified using SmartCycler II real-time PCR. HCV genotyping was carried out in HCV RNA positive samples using molecular genotyping method. HCV RNA was found in liver-biopsy specimens from 23 (74.2%) of the total 31 patients negative for anti-HCV antibodies and undetectable serum HCV RNA. HCV RNA of both negative and positive polarity was found in the livers of 8 (25.8%) patients. Genotyping analysis showed that 65% patients were infected with HCV 3a, 17% with 3b, 13% with 1a and 4% patients were found with untypable genotype. In a multivariate logistic regression model, patients having previous history surgeries, male sex and age above 30 years were significantly associated with the presence of occult HCV infection (p<0.05). In conclusion, patients with elevated liver enzymes and negative HCV antibodies and negative serum RNA may have occult HCV infection and its chance increases with previous history of surgeries, in male sex and above 30 years of age.

Diagnosis and treatment of serum HCV RNA-negative patients with chronic hepatitis C

AIM: To investigate the diagnosis and the treatment of serum HCV RNA-negative patients with chronic hepatitis C (CHC).

METHODS: Eleven consecutive serum HCV RNA-negative CHC patients treated since February 2004 were collected. HCV RNA could be detected in the liver of five patients. There was no evidence of other causes of viral hepatitis. The patients were treated with interferon (IFN) alpha-2b 300 MU, intramuscularly, 1/2 d, in combination with ribavirin 900 mg/d for 12 mo and then followed up regularly.

RESULTS: Of the 11 patients, 10 completed the 12-mo treatment, and 1 discontinued the treatment at 9 mo. The levels of serum ALT and AST in all the patients declined to normal range within 4 wk. No exceptional adverse events occurred. The levels of serum ALT and AST were maintained within the normal range during 17-35 mo of follow-up. HCV-RNA and anti-HCV status remained unchanged during the follow-up.

CONCLUSION: A diagnosis of serum HCV RNA-negative CHC should be considered when a patient has a history of injury and a current or past history of positive serum anti-HCV with incessantly or repeatedly elevated ALT and AST for more than 6 mo after excluding other liver diseases. Anti-HCV treatment with IFN and ribavirin should be promptly given to serum HCV RNA-negative CHC patients.

Occult hepatitis B virus infection: a covert operation

Detection of occult hepatitis B requires assays of the highest sensitivity and specificity with a lower limit of detection of less than 10 IU/mL for hepatitis B virus (HBV) DNA and <0.1 ng/mL for hepatitis B surface antigen (HBsAg). This covert condition is relatively common in patients with chronic hepatitis C virus (HCV) that seems to exert some influence on the replicative capacity and latency of HBV. Detection of virus-specific nucleic acid does not always translate into infectivity, and the occurrence of primer-generated HBV DNA that is of partial genomic length in immunocompetent individuals who have significant levels of hepatitis B surface antibody (anti-HBs) may not be biologically relevant. Acute flares of alanine aminotransferase (ALT) that occur during the early phase of therapy for HCV or ALT levels that remain elevated at the end of therapy in biochemical nonresponders should prompt an assessment for occult hepatitis B. Similarly, the plasma from patients with chronic hepatitis C that is hepatitis B core antibody (anti-HBc) positive (+/-anti-HBs at levels of <100 mIU/mL) should be examined for HBV DNA with the most sensitive assay available. If a liver biopsy is available, immunostaining for hepatitis B surface antigen (HBsAg) and hepatitis B core antigen (HBcAg) should be contemplated and a portion of the sample tested for HBV DNA. This is another reason for optimal collection of a specimen (e.g. two passes with a 16-guage needle under ultrasound guidance). Transmission of HBV to immunosuppressed orthotopic liver transplant recipients by donors with occult hepatitis B (OHB) will continue to occupy the interests of the transplant hepatologist. As patients with OHB may have detectable HBV DNA in serum, peripheral blood mononuclear cells (PBMC) and/or liver that can be reactivated following immunosuppression or intensive cytotoxic chemotherapy, the patient needs to be either monitored or treated depending on the pretreatment serological results such as an isolated anti-HBc reaction or a detectable HBV DNA.

Seroprevalence of hepatitis B virus and hepatitis C virus among blood donors in Nyala, South Dar Fur, Sudan

The objective of this study was to determine the seroprevalence of hepatitis B virus (HBV) and hepatitis C virus (HCV) infections and the possible risk factors among blood donors in Nyala, South Dar Fur State of western Sudan, which has never been studied before. A total of 400 male blood donors were tested for the detection of HBsAg and anti-HCV antibodies, (6.25%) were found reactive for HBsAg and (0.65%) were reactive for anti-HCV antibodies. The highest seroprevalence (30.8%) was found in those between 19-24 and 37-42 years for HBsAg, whereas it was (50%) in those between 31-36 years for anti-HCV antibodies. Unprotected sexual activities (20%) was the most apparent predisposing risk factor for both HBV and HCV seroreactors, followed by razor sharing (13.3%), parenteral drug injections (10%), history of migration to Egypt and alcoholism (6.6%) for each, tattooing and surgical procedures (3.3%) for each and (36.6%) were not aware for their condition. Serum alanine aminotansferase (ALT) was elevated in (30.7%) of HBV seroreactors and in (50%) of HCV seroreactors. Serum albumin was reduced in (23.1%) HBV and in (50%) HCV seroreactors. The study concluded that the seroprevalence of HBV and HCV was in an intermediate and low rates respectively and unprotected sexual activities was the major risk factor for infection in the population studied.

Hepatitis C virus infection in the family setting of patients with occult hepatitis C

Family members of patients with chronic hepatitis C virus (HCV) infection are at increased risk of HCV infection but the prevalence of HCV among family members of patients with occult HCV infection is not known. Anti-HCV, serum HCV RNA and levels of liver enzymes were determined in 102 family members of 50 index patients with occult HCV infection and in 118 family members of 59 chronic hepatitis C index patients. HCV RNA and/or anti-HCV were detected in 10/102 (9.8%) relatives of patients with occult HCV infection and in 4/118 (3.4%) of patients with chronic hepatitis C. Fourteen additional family members (seven were relatives of index patients with occult HCV infection) had abnormal values of liver enzymes without serological markers of HCV infection. Two of these patients (who were relatives of two index patients with occult HCV infection) underwent a liver biopsy and were diagnosed with an occult HCV infection because HCV RNA was detected in the liver cells in the absence of serological HCV markers. In conclusion, the prevalence of HCV infection among family members of patients with occult HCV infection was similar to that found among family members of patients with chronic hepatitis C. This stresses the need to adopt strategies to prevent the transmission of HCV in the family setting of patients with occult HCV infection.

Occult hepatitis B virus and hepatitis C virus infections

Occult HBV infection is a well-recognised clinical entity characterised by the detection of HBV-DNA in serum and/or in liver in the absence of detectable hepatitis B surface antigen (HBsAg). Occult HBV infection has been described not only in patients who have resolved an acute or chronic HBV infection but also in patients without any serological markers of a past HBV infection. Occult HBV infection in patients with chronic HCV infection may induce more severe liver disease and lower response rate to interferon treatment. The existence of occult HCV infections has been also reported more recently. Occult HCV infection is characterised by the presence of HCV-RNA in liver and peripheral blood mononuclear cells in the absence of detectable serum HCV-RNA. Occult HCV infection may occur under two different clinical situations: in hepatitis C antibody-(anti-HCV) negative and serum HCV-RNA-negative patients with abnormal liver function tests and in anti-HCV-positive patients who have no detectable serum HCV-RNA and who have normal liver enzymes. The clinical relevance of occult HCV infections is still under investigation.

Occult hepatitis C virus infection revisited with ultrasensitive real-time PCR assay

Occult hepatitis C infection is regarded as a new entity that should be considered when diagnosing patients with a liver disease of unknown origin. Using an ultrasensitive real-time PCR assay, we demonstrated that occult hepatitis C virus (HCV) infection cannot be found in peripheral blood mononuclear cells of patients with cryptogenic liver diseases, HCV--associated systemic vasculitis, or connective tissue diseases. The significance of such occult infection must be elucidated.

Hepatitis C virus does not infect muscle, the intervertebral disk, or the meniscus in patients with chronic hepatitis C

Chronic infection with hepatitis C virus (HCV) is associated with several extrahepatic manifestations, including neuromuscular and joint disorders, and HCV RNA has been detected in muscle fibers of patients with myosistis and chronic hepatitis C. However, whether HCV infects muscle cells in patients without myosistis is unknown. The presence of HCV in other sites of the musculoskeletal system has not been investigated. In the present study the presence of HCV RNA was sought in muscle (2 cases), intervertebral disk (1 case) and meniscus (1 case) samples from patients with chronic hepatitis C. HCV RNA was not detected by reverse transcription and real-time polymerase chain reaction in any of the samples tested. In conclusion, the results do not support a direct role of HCV in musculoskeletal disorders associated with chronic hepatitis C.