Ultracentrifugation of serum samples allows detection of hepatitis C virus RNA in patients with occult hepatitis C

A Simple and Effective Method to Concentrate Hepatitis C Virus: Aqueous Two-Phase System Allows Highly Efficient Enrichment of Enveloped Viruses

To investigate the proliferation cycle of a virus, virus-host interaction, and pathogenesis of a virus, virion particles must be concentrated from the media of virus cell culture or the sera of virus-infected patients. Ultracentrifugation of the culture media is a standard method for concentrating virion particles. However, this method is time-consuming and requires special equipment (ultracentrifuge). Moreover, a large number of infectious viruses are lost during enrichment. We developed a new method of hepatitis C virus (HCV) concentration to overcome the issues associated with traditional methods of virus concentration. We used an aqueous two-phase system (ATPS) to concentrate the virus. HCV, which causes various liver diseases, such as liver fibrosis, cirrhosis, and hepatocellular carcinoma, was used as a model virus to test the efficacy and reliability of the ATPS. The efficiency of HCV concentration by the ATPS was approximately three times higher than that by ultracentrifugation. Moreover, the infectivity of the concentrated HCV, which is a labile virus, remained the same after concentration of the virus by the ATPS. Considering the simplicity and effectiveness of the ATPS, it is the method of choice for concentrating viruses.

Global prevalence of occult hepatitis C virus: A systematic review and meta-analysis

BACKGROUND

Occult hepatitis C infection (OCI) is characterized by the presence of hepatitis C virus (HCV) RNA in the liver, peripheral blood mononuclear cells (PBMC) and/or ultracentrifuged serum in the absence of detectable HCV-RNA in serum. OCI has been described in several categories of populations including hemodialysis patients, patients with a sustained virological response, immunocompromised individuals, patients with abnormal hepatic function, and apparently healthy subjects.

AIM

To highlight the global prevalence of OCI.

METHODS

We performed a systematic and comprehensive literature search in the following 4 electronic databases PubMed, EMBASE, Global Index Medicus, and Web of Science up to 6th May 2021 to retrieve relevant studies published in the field. Included studies were unrestricted population categories with known RNA status in serum, PBMC, liver tissue and/or ultracentrifuged serum. Data were extracted independently by each author and the Hoy et al tool was used to assess the quality of the included studies. We used the random-effect meta-analysis model to estimate the proportions of OCI and their 95% confidence intervals (95%CI). The Cochran's Q-test and the I² test statistics were used to assess heterogeneity between studies. Funnel plot and Egger test were used to examine publication bias. R software version 4.1.0 was used for all analyses.

RESULTS

The electronic search resulted in 3950 articles. We obtained 102 prevalence data from 85 included studies. The pooled prevalence of seronegative OCI was estimated to be 9.61% (95%CI: 6.84-12.73) with substantial heterogeneity [I² = 94.7% (95%CI: 93.8%-95.4%), P < 0.0001]. Seropositive OCI prevalence was estimated to be 13.39% (95%CI: 7.85-19.99) with substantial heterogeneity [I² = 93.0% (90.8%-94.7%)]. Higher seronegative OCI prevalence was found in Southern Europe and Northern Africa, and in patients with abnormal liver function, hematological disorders, and kidney diseases. Higher seropositive OCI prevalence was found in Southern Europe, Northern America, and Northern Africa.

CONCLUSION

In conclusion, in the present study, it appears that the burden of OCI is high and variable across the different regions and population categories. Further studies on OCI are needed to assess the transmissibility, clinical significance, long-term outcome, and need for treatment.

Fatal Hepatitis C after Chemotherapy in a Patient with Malignant Lymphoma: Possible Reactivation of Seronegative Occult Hepatitis C Virus Infection Due to Chemotherapy

A 79-year-old man with lymphoma who tested negative for anti-hepatitis C virus (HCV) antibody received rituximab-containing chemotherapy. Liver dysfunction of unknown cause had persisted since the second cycle of chemotherapy. Ten months after treatment, he rapidly developed massive ascites and atrophy of the liver, and we detected HCV RNA in his serum using real time polymerase chain reaction. Furthermore, medical interviews showed that the patient had no episodes for acute HCV infection, but he did have a history of unspecified liver dysfunction. These findings support the possibility of the reactivation of seronegative occult HCV infection due to chemotherapy in a cancer patient.

Hepatitis C viral RNA in blood mononuclear cells of patients treated with directly acting antivirals

BACKGROUND AND STUDY AIMS

Occult hepatitis C viral infection (OCI) may have serious complications, such as relapse, ongoing histological impairment, hepatic decompensation, hepatocellular carcinoma, and the possible risk of transmission. This study was conducted to assess the occurrence and prevalence of secondary OCI in patients with chronic hepatitis C viral infection (HCV) who received a complete course of directly acting antivirals (DAAs).

PATIENTS AND METHODS

Antiviral therapy consisted of sofosbuvir + daclatasvir ± ribavirin for 12 weeks to 90 treatment-naive, compensated, chronic HCV patients. Plasma and peripheral blood mononuclear cells (PBMCs) were tested for HCV RNA viral load by quantitative, reverse transcription, real-time PCR at 8, 12 (Group I, n = 45), and 24 (Group II, n = 45) weeks after treatment initiation.

RESULTS

By week 8, only 2 and 7 patients were positive for HCV RNA in plasma and PBMCs, respectively. No HCV RNA was detected by weeks 12 or 24 in the PBMCs of Groups I and II, respectively. Older age was significantly associated with HCV RNA positivity in plasma and PBMCs (n = 8) at week 8 compared with HCV RNA negativity (n = 82). No other significant differences were observed for any other variables.

CONCLUSION

The development of secondary OCI among easy-to-treat patients following a full course of DAA treatment doesn't exist, hence, we do not recommend testing the HCV RNA in the PBMCs after complete course of treatment in this patient category. The detection of HCV RNA in PBMCs is recommended as a confirmatory test of cure following a shortened DAA treatment regimen.

Occult hepatitis C virus infection in the Middle East and Eastern Mediterranean countries: A systematic review and meta-analysis

BACKGROUND

The presence of hepatitis C virus (HCV) RNA in liver tissue or peripheral blood mononuclear cells with no identified virus genome in the serum has been reported worldwide among patients with either normal or elevated serum liver enzymes. The characterization of occult HCV infection (OCI) epidemiology in the Middle East and Eastern Mediterranean (M and E) countries, a region with the highest incidence and prevalence rates of HCV infection in the world, would be effective for more appropriate control of the infection.

AIM

To estimate the pooled prevalence of OCI in M and E countries using a systematic review and meta-analysis.

METHODS

A systematic literature search was performed using international, regional and local electronic databases. Some conference proceedings and references from bibliographies were also reviewed manually. The search was carried out during May and June 2020. Original observational surveys were considered if they assessed the prevalence of OCI among the population of M and E countries by examination of HCV nucleic acid in peripheral blood mononuclear cells in at least 30 cases selected by random or non-random sampling methods. The meta-analysis was performed using Comprehensive Meta-analysis software based on heterogeneity assessed by Cochran’s Q test and I-square statistics. Data were considered statistically significant at a P value < 0.05.

RESULTS

A total of 116 non-duplicated citations were found in electronic sources and grey literature. A total of 51 non-overlapping original surveys were appraised, of which 37 met the inclusion criteria and were included in the analysis. Data were available from 5 of 26 countries including Egypt, Iran, Pakistan, Saudi Arabia, and Turkey. The overall prevalence rate of OCI was estimated at 10.04% (95%CI: 7.66%-13.05%). The lowest OCI rate was observed among healthy subjects (4.79%, 95%CI: 2.86%-7.93%). The higher rates were estimated for patients suffering from chronic liver diseases (12.04%, 95%CI: 5.87%-23.10%), and multi-transfused patients (8.71%, 95%CI: 6.05%-12.39%). Subgroup analysis indicated that the OCI rates were probably not associated with the studied subpopulations, country, year of study, the detection method of HCV RNA, sample size, patients’ HCV serostatus, and sex (all P > 0.05). Meta-regression analyses showed no significant time trends in OCI rates among different groups.

CONCLUSION

This review estimated high rates of OCI prevalence in M and E countries, especially among multi-transfused patients as well as patients with chronic liver diseases.

Understanding occult hepatitis C infection

BACKGROUND

Occult hepatitis C infection (OCI) is a type of hepatitis C virus (HCV) infection, defined as the presence of HCV RNA in hepatocytes or peripheral blood mononuclear cells (PBMCs) and the absence of HCV RNA in serum.

STUDY DESIGN AND METHODS

A literature review was conducted to identify articles that characterized OCI as a disease, including its epidemiology, mode of transmission, pattern of infection, progression, and treatment.

RESULTS

OCI patients experience a milder degree of inflammatory and cirrhotic changes than patients with chronic hepatitis C. OCI is transmissible parenterally both in vivo and in vitro, however the duration and outcome of OCI remains unclear. OCI is most consistently found in patients with previous hepatitis C disease and hemodialysis patients. Beyond the at-risk populations, OCI has also been demonstrated among healthy individuals and blood donors.

CONCLUSIONS

This review summarises our current understanding of OCI and suggests areas for further research to improve our understanding of this phenomenon, including a better understanding of its epidemiology and full clinical course. The current understanding of OCI and its clinical implications remain limited. Further standardized detection methods, ongoing surveillance, and investigation of its potential transmissions are required.

[Low concentrations of hepatitis C virus RNA in serologically mild infection.]

Occult HCV infection (OCI) provides significant interest recently. HCV RNA in this case can be detected not in plasma, but in blood cells and/or in liver tissue. In case of antibody genesis impairment anti-HCV detection may lead to negative or "uncertain" result. The aim of the study was to estimate infection type in blood donors and patients with hematological diseases by exploration of samples with uncertain anti-HCV detection results. Blood samples of 30 180 potential blood donors' and 4322 patients with hematological diseases were tested. Comparative analysis of wide pattern of HCV markers was performed. 33 blood donors and 42 patients were enrolled in follow-up examination. Uncertain results of Anti-HCV detection in donors' samples were in 0.18% of cases. Follow-up examination of 33 donors provided discordant results using immunochemiluminescence assay and ELISA. 15.2% donors' samples contained HCV RNA in low concentration. Follow-up observation of 42 patients with incomplete antiviral antibody pattern showed HCV RNA presence in 40.5% cases (21.4% high viremia and 19.0% low viremia). Samples with low RNA concentration contained low titers of anti-core antibodies. Samples with high titers of anti-core antibodies contained high HCV RNA level. Uncertain results of anti-HCV in 15.2% of potential blood donors' samples were confirmed by detection of HCV RNA in low concentration. It proved OCI presence in these individuals and called for testing for wide pattern of HCV markers in addition to routine screening. Patients with hematological diseases showed low level of HCV RNA along with low titers of antibodies against one or two viral antigens.

High prevalence of occult hepatitis C virus infection in injection drug users with HIV infection

One of the pathological forms of chronic hepatitis C is occult HCV infection (OCI), in which there is no detectable HCV RNA in plasma specimens but HCV RNA is present in PBMCs and liver biopsy specimens. The aim of this study is to estimate the prevalence of OCI in HIV-positive people who are injection drug users (IDUs). From April 2015 to August 2018, 161 Iranian IDUs with HIV infection enrolled in the study. Viral RNA was extracted from plasma and PBMC samples of participants, and the presence of HCV RNA was examined using RT nested PCR with primers from two conserved regions (5´-UTR and NS5B). HCV genotyping was performed using RFLP and sequencing methods. Of the 161 patients, 134 (83.2%) were positive for anti-HCV antibodies. All 27 patients who were negative for anti-HCV were also negative for HCV RNA in plasma, but five of them (18.5%) were positive for HCV RNA in PBMCs. Importantly, 9 out of 50 patients (18.0%) who apparently had recovered from HCV infection (i.e., were anti-HCV positive and HCV RNA negative) were positive for HCV RNA in PBMCs. Overall, 18.1% of the patients who had no signs of previous HCV infection or had apparently recovered from the disease had OCI. The HCV genotypes of the cases with OCI were as follows: five patients (35.7%) were infected with subtype 1a, eight patients (57.1%) were infected with subtype 3a, and one patient (7.1%) was infected with genotype 4. Thus, it seems that the prevalence of OCI in HIV-positive IDUs is extremely significant in Iran and is likely to delay the global eradication of HCV infection until 2030.

Occult Hepatitis C Virus Infection: A Review

Occult hepatitis C virus (HCV) infection (OCI), first described in 2004, is defined as the presence of HCV RNA in hepatocytes or peripheral blood mononuclear cells without detectable HCV RNA in the serum. Here, we aimed to review the epidemiology, diagnostic methods, clinical implications and potential management recommendations currently described in the literature, as well as the future directions for investigation of this entity. PubMed and Cochrane databases were searched with combination of the following keywords: "occult", "hepatitis C virus", and "occult HCV infection". There are data to support OCI as a potential culprit in cryptogenic liver disease. There are also consistent data demonstrating the existence of OCI in specific populations, such as dialysis, human immunodeficiency virus-infected and hepatitis B virus-infected patients, and also in the general population. While the gold standard for diagnosis is liver biopsy, examination of peripheral blood mononuclear cells may be a reliable, safer alternative method of diagnosis. Occult HCV infection is likely associated with liver fibrosis and progression of liver disease. Additional studies are required to determine the infectivity of OCI patients, as well as clarify the natural course and specific clinical implications of OCI. Lastly, studies are needed to determine whether treatment of OCI leads to decreased morbidity and/or mortality.

Regulatory polymorphism of CXCL10 rs1439490 in seronegative occult hepatitis C virus infection

AIM

To examine the relationship between the single nucleotide polymorphism CXCL10 rs1439490 and seronegative occult hepatitis C virus (HCV) infection (OCI).

METHODS

One hundred and three cases of seronegative OCI and 155 cases of seropositive chronic HCV infection (CHC) were diagnosed at five Liver Centers in Northeastern China, from 2012 to 2016. CXCL10 rs1439490, rs1440802, and IL-28B rs12979860 were analyzed by sequencing. Serum CXCL10 was measured by ELISA. Intrahepatic CXCL10 was determined by quantitative PCR and immunohistochemical semi-quantitative scoring. Liver necroinflammation and fibrosis were scored according to the METAVIR system.

RESULTS

CXCL10 rs1439490 G/G was more prevalent in OCI patients (n = 93/103; 90.3%) than in CHC patients (n = 116/155; 74.8%; P = 0.008). OCI patients had lower serum CXCL10 levels than CHC patients (192.91 ± 46.50 pg/mL vs 354.78 ± 102.91 pg/mL, P < 0.0001). Of IL-28B rs12979860 C/C patients, OCI patients with rs1439490 G/G had lower serum and liver levels of CXCL10 and lower levels of liver necroinflammation and fibrosis than non-G/G patients. OCI patients had higher alanine aminotransferase normalization rates after Peg-interferon treatment than CHC patients (P < 0.05) and serum CXCL10 decreased significantly (P < 0.0001). Liver necroinflammation and fibrosis were alleviated in 8 OCI patients after treatment. Multivariate analysis indicated that rs1439490 G/G significantly influenced the occurrence of OCI in HCV infection (OR = 0.31, 95%CI: 0.15-0.66, P = 0.002).

CONCLUSION

CXCL10 rs1439490 G/G is positively associated with OCI in HCV infection and antiviral outcome.

Characterisation of liver pathogenesis, human immune responses and drug testing in a humanised mouse model of HCV infection

OBJECTIVE

HCV infection affects millions of people worldwide, and many patients develop chronic infection leading to liver cancers. For decades, the lack of a small animal model that can recapitulate HCV infection, its immunopathogenesis and disease progression has impeded the development of an effective vaccine and therapeutics. We aim to provide a humanised mouse model for the understanding of HCV-specific human immune responses and HCV-associated disease pathologies.

DESIGN

Recently, we have established human liver cells with a matched human immune system in NOD-scid Il2rg(-/-) (NSG) mice (HIL mice). These mice are infected with HCV by intravenous injection, and the pathologies are investigated.

RESULTS

In this study, we demonstrate that HIL mouse is capable of supporting HCV infection and can present some of the clinical symptoms found in HCV-infected patients including hepatitis, robust virus-specific human immune cell and cytokine responses as well as liver fibrosis and cirrhosis. Similar to results obtained from the analysis of patient samples, the human immune cells, particularly T cells and macrophages, play critical roles during the HCV-associated liver disease development in the HIL mice. Furthermore, our model is demonstrated to be able to reproduce the therapeutic effects of human interferon alpha 2a antiviral treatment.

CONCLUSIONS

The HIL mouse provides a model for the understanding of HCV-specific human immune responses and HCV-associated disease pathologies. It could also serve as a platform for antifibrosis and immune-modulatory drug testing.

Lymphomagenesis-related gene expression in B cells from sustained virological responders with occult hepatitis C virus infection

The expression of activation-induced cytidine deaminase, B-aggressive lymphoma, cyclin D1 and serine/threonine kinase 15 genes, among others, is increased in B cells from patients with chronic hepatitis C virus (HCV) infection. It is unknown whether the level of expression of these genes in B cells is increased in patients with hepatitis C who have achieved a sustained virological response (SVR) but who have persistent, detectable HCV RNA, so-called occult infection. Eighty-three patients who achieved and SVR, 27 with detectable HCV and 56 without detectable HCV RNA, 28 chronic hepatitis C patients and 32 healthy controls were studied. RNA was extracted from B cells, and gene expression levels were measured by RT-PCR. Patients with chronic HCV and those who achieved an SVR (with and without persistent low-level HCV RNA) showed a statistically significant higher expression compared to healthy controls, of activation-induced cytidine deaminase (P = 0.004, P < 0.001 and P = 0.002, respectively), B-aggressive lymphoma (P < 0.001, P = 0.001 and P = 0.006) and cyclin D1 (P = 0.026, P = 0.001; P = 0.038). For activation-induced cytidine deaminase patients with an SVR and 'occult infection' had a statistically significantly higher expression level than patients with and SVR without 'occult infection' (P = 0.014). The higher expression levels found for activation-induced cytidine deaminase, together with other genes indicates that these B lymphomagenesis-related genes are upregulated following HCV therapy and this is more marked when HCV can be detected in PBMCs.

Interleukin-28B polymorphisms and interferon gamma inducible protein-10 serum levels in seronegative occult hepatitis C virus infection

Polymorphisms upstream interleukin (IL)-28B gene and serum levels of interferon gamma inducible protein-10 (IP-10) are associated with spontaneous and treatment-induced hepatitis C virus (HCV) clearance. Patients with seronegative occult HCV infection are anti-HCV and serum HCV-RNA negative but have viral RNA in liver and abnormal values of liver enzymes. We examined if the rs12979860 polymorphism of IL-28B and serum IP-10 levels differ between chronic and seronegative occult CV infection. IL-28B polymorphism was determined with allele specific TaqMan probes in total DNA isolated from peripheral blood mononuclear cells and IP-10 by an enzyme-linked immunosorbent assay in serum from 99 patients with seronegative occult HCV infection and 130 untreated patients with chronic hepatitis C. IL-28B genotypes were also determined in 54 healthy volunteers. Prevalence of the IL-28B CC genotype was significantly higher in seronegative occult HCV infection (52/99; 52.5%) than in chronic hepatitis C (32/130; 24.6%, P < 0.0001) or healthy controls (19/54: 32.5%, P = 0.039). Among patients with seronegative occult HCV infection, HCV-RNA load in liver was significantly lower in those with the IL-28B CC genotype than in those with CT + TT genotypes (2.8 × 10(5)  ± 5.8 × 10(4) vs. 4.1 × 10(5)  ± 5.9 × 10(4)  copies/μg of total RNA respectively; P = 0.023). Mean serum IP-10 levels were significantly lower in patients with seronegative occult HCV infection than in patients with chronic hepatitis C (160.8 ± 17.9 vs. 288.7 ± 13.3 pg/ml respectively; P < 0.0001). These findings suggest that the host immune response plays an important role in seronegative occult HCV infection in comparison with chronic hepatitis C.

Occult HCV Infection: The Current State of Knowledge

Context

Occult HCV infection (OCI) is defined as the presence of HCV-RNA in hepatocytes and the absence of HCV in the serum according to usual tests. We aimed to define OCI and provide information about the currently available diagnostic methods. Then we focus on specific groups that are at high risk of OCI and finally investigate immune responses to OCI and the available treatment approaches.

Evidence Acquisition

PubMed, Scopus and Google Scholar were comprehensively searched with combination of following keywords: “occult”, “hepatitis C virus” and “occult HCV infection”. The definition of OCI, diagnostic methods, specific groups that are at high risk and available treatment approaches were extract from literature. An analysis of available articles on OCI also was done based on Scopus search results.

Results

OCI has been reported in several high-risk groups, especially in hemodialysis patients and subjects with cryptogenic liver disease. Furthermore, some studies have proposed a specific immune response for OCI in comparison with chronic hepatitis C (CHC).

Conclusions

With a clinical history of approximately 11 years, occult HCV infection can be considered an occult type of CHC. Evidences suggest that considering OCI in these high-risk groups seems to be necessary. We suggest that alternative diagnostic tests should be applied and that there is a need for the participation of all countries to determine the epidemiology of this type of HCV infection. Additionally, evaluating OCI in blood transfusion centers and in patients who receive large amounts of blood and clotting factors, such as patients with hemophilia, should be performed in future projects.

Persistence of Hepatitis C Virus Traces after Spontaneous Resolution of Hepatitis C

Hepatitis C virus (HCV) frequently causes chronic hepatitis, while spontaneous recovery from infection is infrequent. Persistence of HCV after self-limited (spontaneous) resolution of hepatitis C was rarely investigated. The current study aimed to assess incidence and robustness of HCV persistence after self-resolved hepatitis C in individuals with normal liver enzymes and undetectable virus by conventional tests. Applying high sensitivity HCV RNA detection approaches, we analyzed plasma and peripheral blood mononuclear cells (PBMC) from individuals with previous hepatitis C infection. Parallel plasma and PBMC from 24 such non-viraemic individuals followed for 0.3–14.4 (mean 6.4) years were examined. Additional samples from 9 of them were obtained 4.5–7.2 (mean 5.9) years later. RNA was extracted from 250 μl plasma and, if HCV negative, from ~5 ml after ultracentrifugation, and from ex vivo stimulated PBMC. PBMC with evidence of HCV replication from 4 individuals were treated with HCV protease inhibitor, telaprevir. HCV RNA was detected in 14/24 (58.3%) plasma and 11/23 (47.8%) PBMC obtained during the first collection. HCV RNA replicative strand was evident in 7/11 (63.6%) PBMC. Overall, 17/24 (70.8%) individuals carried HCV RNA at mean follow-up of 5.9 years. Samples collected 4.5–7.2 years later revealed HCV in 4/9 (44.4%) plasma and 5/9 (55.5%) PBMC, while 4 (80%) of these 5 PBMC demonstrated virus replicative strand. Overall, 6/9 (66.7%) individuals remained viraemic for up to 20.7 (mean 12.7) years. Telaprevir entirely eliminated HCV replication in the PBMC examined. In conclusion, our results indicate that HCV can persist long after spontaneous resolution of hepatitis C at levels undetectable by current testing. An apparently effective host immune response curtailing hepatitis appears insufficient to completely eliminate the virus. The long-term morbidity of asymptomatic HCV carriage should be examined even in individuals who achieve undetectable HCV by standard testing and their need for treatment should be assessed.

Occult hepatitis C virus infection in Iranian hemodialysis patients

Background: Occult hepatitis C virus (HCV) infection is defined as the presence of HCV-RNA in liver or peripheral blood mononuclear cells (PBMCs) in the absence of detectable hepatitis C antibody (anti-HCV) or HCV-RNA in the serum. Low concentrations of HCV-RNA may be detected in PBMCs of hemodialysis (HD) patients and this could have a great impact on the management of HD patients.

Objectives: The aim of this study was to detect the occult HCV infection in Iranian HD patients.

Patients and Methods: A total of 70 anti-HCV negative HD patients from three dialysis units in Tehran, Iran were included in this study. In these cases, presence of HCV-RNA in plasma samples was tested by reverse transcriptase-nested polymerase chain reaction (RT-nested PCR). In cases with negative anti-HCV and plasma HCV-RNA, genomic HCV-RNA was checked in PBMC specimens by RT-nested PCR.

Results: Seventy anti-HCV negative HD patients were enrolled in the study. 32.85% and 1.43% of cases had elevated levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) respectively. 7.14% of patients had elevated levels of both ALT and AST. HCV-RNA was negative in plasma samples of all anti-HCV negative HD subjects. The genomic HCV-RNA was not detected in any PBMC samples of HD cases with negative anti-HCV and plasma HCV-RNA.

Conclusions: Occult HCV infection was not detected in our HD patients despite of elevated levels of liver enzymes in some participants. Further studies involving larger number of HD patients are required to elucidate the rate of occult HCV infection in HD cases.

A New Twist to a Chronic HCV Infection: Occult Hepatitis C

Background. The prevalence of occult hepatitis C infection (OCI) in the population of HCV-RNA negative but anti-HCV positive individuals is presently unknown. OCI may be responsible for clinically overt recurrent disease following an apparent sustained viral response (SVR) weeks to years later. Purpose. To review the available current literature regarding OCI, prevalence, pathogenic mechanisms, clinical characteristics, and future directions. Data Sources. Searching MEDLINE, article references, and national and international meeting abstracts for the diagnosis of OCI (1990-2014). Data Synthesis. The long-term followup of individuals with an OCI suggests that the infection can be transient with the loss of detectable HCV-RNA in PPBMCs after 12-18 months or alternatively exist intermittently and potentially long term. The ultimate outcome of HCV infection is decided by interplay between host immune responses, antiviral therapies, and the various well-identified viral evasion mechanisms as well as the presence of HCV infection within extrahepatic tissues. Conclusion. The currently widely held assumption of a HCV-cure in individuals having had "SVR" after 8-12 weeks of a course of DAA therapy as recently defined may not be entirely valid. Careful longitudinal followup utilizing highly sensitive assays and unique approaches to viral isolation are needed.

Seronegative occult hepatitis C virus infection: clinical implications

Occult hepatitis C virus infection (OCI) was first described in anti-HCV and serum HCV-RNA negative patients with abnormal values of liver enzymes but who presented HCV-RNA in liver and in peripheral blood mononuclear cells. Up to now, two types of OCI are recognized: seronegative OCI (anti-HCV and serum HCV-RNA negative) and seropositive OCI (anti-HCV positive and serum HCV-RNA negative). The concept of OCI is still a matter of debate, probably because both types of OCI are not considered as different entities. This review focuses on seronegative OCI. The existence of seronegative OCI has been documented all around the world with the implication of different HCV genotypes (1-4). Seronegative OCI is associated with cryptogenic chronic hepatitis and liver cirrhosis and it may be involved in the appearance of hepatocellular carcinoma. Also seronegative OCI may increase the histological liver damage in chronic hepatitis B and in HIV-infected patients. It may have a negative influence in the natural history of hemodialysis patients and in immune-mediated glomerulonephritis. Seronegative OCI has been detected also in patients with haematological diseases, among healthy subjects and in drug users. Other publications indicate the potential infectivity of seronegative OCI in the setting of family members, sexual partners and liver transplantation. In summary, seronegative OCI may play a role in liver diseases and other human pathologies and may be present in healthy people but larger studies are needed to confirm these findings.

Review: Occult hepatitis C virus infection: still remains a controversy

Occult hepatitis C virus (HCV) infection is characterized by the presence of HCV RNA in the liver cells or peripheral blood mononuclear cells of the patients whose serum samples test negative for HCV RNA, with or without presence of HCV antibodies. The present study reviews the existing literature on the persistence of occult hepatitis C virus infection, with description of the clinical characteristics and methods for identification of occult hepatitis C. Occult hepatitis C virus infection was detected in patients with abnormal results of liver function tests of unknown origin, with HCV antibodies and HCV RNA negativity in serum, and also in patients with spontaneous or treatment-induced recovery from hepatitis C. The viral replication in the liver cells and/or peripheral blood mononuclear cells was present in all clinical presentations of occult hepatitis C. The peripheral blood mononuclear cells represent an extra-hepatic site of HCV replication. The reason why HCV RNA was not detectable in the serum of patients with occult hepatitis C, could be the low number of circulating viral particles not detectable by the diagnostic tests with low sensitivity. It is uncertain whether occult hepatitis C is a different clinical entity or just a form of chronic hepatitis C virus infection. Data accumulated over the last decade demonstrated that an effective approach to the diagnosis of HCV infection would be the implementation of more sensitive HCV RNA diagnostic assays, and also, examination of the presence of viral particles in the cells of the immune system.

Impact of isolated hepatitis C virus (HCV) core-specific antibody detection and viral RNA amplification among HCV-seronegative dialysis patients at risk for infection

Amplification of hepatitis C virus (HCV) RNA from blood detected occult HCV infections in 30.9% of 210 HCV-seronegative dialysis patients with abnormal liver enzyme levels that had evaded standard HCV testing practices. Isolated HCV core-specific antibody detection identified three additional anti-HCV screening-negative patients lacking HCV RNA amplification in blood who were considered potentially infectious. Together, these findings may affect management of the dialysis setting.

High prevalence of occult hepatitis C virus infection in patients with primary and secondary glomerular nephropathies

The association of hepatitis C virus (HCV) infection and glomerulonephritis is well known. However, the relationship between immune-mediated glomerulonephritis and occult HCV, characterized by the presence of HCV-RNA in liver or in peripheral blood mononuclear cells in the absence of serological markers, is unknown. We tested this in 113 anti-HCV-negative patients; 87 with immune-mediated glomerulonephritis and 26 controls with hereditary glomerular nephropathies. All patients were serum HCV-RNA negative by conventional real-time PCR. Significantly, occult HCV-RNA (detectable viral RNA in peripheral blood mononuclear cells or in serum after ultracentrifugation) was found in 34 of 87 patients with immune-mediated glomerulonephritis versus 1 of 26 control patients. The serum creatinine levels were significantly higher in patients with immune-mediated glomerulonephritis with than in those without occult HCV (1.5 versus 1.1 mg/dl, respectively). A multivariate analysis adjusted for gender showed a significantly increased risk of occult HCV in patients with immune-mediated glomerulonephritis versus the controls (odds ratio of 13.29). Progression to end-stage renal disease tended to be faster in patients with immune-mediated glomerulonephritis and occult HCV than in the negative cases. Thus, occult HCV is strongly associated with immune-mediated glomerulonephritis and may have a role in the progression of the disease.

Persistence of hepatitis C virus during and after otherwise clinically successful treatment of chronic hepatitis C with standard pegylated interferon α-2b and ribavirin therapy

Resolution of chronic hepatitis C is considered when serum HCV RNA becomes repeatedly undetectable and liver enzymes normalize. However, long-term persistence of HCV following therapy with pegylated interferon-α/ribavirin (PegIFN/R) was reported when more sensitive assays and testing of serial plasma, lymphoid cells (PBMC) and/or liver biopsies was applied. Our aim was to reassess plasma and PBMCs collected during and after standard PegIFN/R therapy from individuals who became HCV RNA nonreactive by clinical testing. Of particular interest was to determine if HCV genome and its replication remain detectable during ongoing treatment with PegIFN/R when evaluated by more sensitive detection approaches. Plasma acquired before (n = 11), during (n = 25) and up to 12–88 weeks post-treatment (n = 20) from 9 patients and PBMC (n = 23) from 3 of them were reanalyzed for HCV RNA with sensitivity <2 IU/mL. Clone sequencing of the HCV 5′-untranslated region from plasma and PBMCs was done in 2 patients. HCV RNA was detected in 17/25 (68%) plasma and 8/10 (80%) PBMC samples collected from 8 of 9 patients during therapy, although only 5.4% plasma samples were positive by clinical assays. Among post-treatment HCV RNA-negative plasma samples, 9 of 20 (45.3%) were HCV reactive for up to 59 weeks post-treatment. Molecularly evident replication was found in 6/12 (50%) among PBMC reactive for virus RNA positive strand collected during or after treatment. Pre-treatment point mutations persisted in plasma and/or PBMC throughout therapy and follow-up. Therefore, HCV is not completely cleared during ongoing administration of PegIFN/R otherwise capable of ceasing progression of CHC and virus commonly persists at levels not detectable by the current clinical testing. The findings suggest the need for continued evaluation even after patients achieve undetectable HCV RNA post-treatment.

Hepatitis C virus infection in nephrology patients

CONTEXT

Hepatitis C virus (HCV) infection leads to chronic liver disease, but also to extra-hepatic manifestations.

EVIDENCE ACQUISITIONS

Directory of Open Access Journals (DOAJ), Google Scholar, Pubmed (NLM), LISTA (EBSCO) and Web of Science have been searched.

RESULTS

Herein, we provide an overview of renal diseases related to HCV and their therapies, as well as the treatment options available for HCV (+)/RNA (+) dialysis patients. We will not mention, however, HCV infection-related complications in the post-kidney transplantation setting.

CONCLUSIONS

Extra-hepatic manifestations of HCV infection include mixed cryoglobulinemia, lymphoproliferative disorders, and renal disease. HCV infection has been reported in association with distinct histological patterns of glomerulonephritis in native kidneys.

Hepatitis C virus and kidney disease

Hepatitis C virus (HCV) is the most frequently observed viral infection in patients with kidney disease. HCV can cause glomerular disease, which can lead to end-stage renal disease that requires dialysis and/or kidney transplantation. It is recommended to test HCV patients once a year for proteinuria, microscopic hematuria and estimated glomerular filtration rate. Membranoproliferative glomerulonephritis is the most common glomerular disease induced by HCV. Over the past few decades, the prevalence of HCV infection has decreased among dialysis and kidney transplant patients. However, survival is significantly lower in HCV-positive than in HCV-negative dialysis patients whereas survival is significantly better in HCV-positive kidney transplant patients compared with HCV-positive dialysis patients. Thus, dialysis patients without a sustained virological response after anti-HCV therapy should be proposed for kidney transplantation. Recurrence or de novo occurrence of glomerular disease is responsible for the lower kidney allograft survival in HCV-positive compared with HCV-negative kidney transplant patients. Dialysis and kidney transplantation do not appear to negatively affect progression of liver fibrosis in the majority of patients. The available data also suggest that occult HCV infection does not exist in dialysis and kidney transplant patients.

Occupational exposure to hepatitis C virus: early T-cell responses in the absence of seroconversion in a longitudinal cohort study

BACKGROUND

T-cell responses have been described in seronegative patients who test negative for hepatitis C virus (HCV) RNA despite frequent HCV exposure. However, the cross-sectional design of those studies did not clarify whether T cells were indeed induced by low-level HCV exposure without seroconversion or whether they resulted from regular acute infection with subsequent antibody loss.

METHODS

Over a 10-year period, our longitudinal study recruited 72 healthcare workers with documented HCV exposure. We studied viremia and antibody and T-cell responses longitudinally for 6 months.

RESULTS

All healthcare workers remained negative for HCV RNA and antibodies. However, 48% developed proliferative T-cell response and 42% developed responses in interferon-gamma enzyme-linked immunosorbent spot assays, with 29 healthy HCV-unexposed controls used to define assay cutoffs. The response prevalence was associated with the transmission risk score. T-cell responses peaked at week 4 and returned to baseline by week 12 after exposure. They predominantly targeted nonstructural HCV proteins, which are not part of the HCV particle and thus must have been synthesized in infected cells.

CONCLUSIONS

Subclinical transmission of HCV occurs frequently, resulting in infection and synthesis of nonstructural proteins despite undetectable systemic viremia. T-cell responses are more sensitive indicators of this low-level HCV exposure than antibodies.

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 infection in Iranian patients with lymphoproliferative disorders

Occult HCV infection is a form of chronic HCV infection characterized by absence of detectable anti-HCV antibodies or plasma HCV-RNA but presence of HCV-RNA in liver biopsy and/or peripheral blood mononuclear cells (PBMCs). The aim of this study was to determine the presence of HCV-RNA in PBMCs of patients with lymphoproliferative disorders. One hundred and four consecutive patients with lymphoproliferative disorders admitted to Firouzgar Hospital from January 2010 to March 2011 were recruited in this cross-sectional study. A 6-ml sample of whole blood was taken from the patients, the total RNA was extracted from the samples after the separation of plasma and PBMCs. The HCV-RNA of the samples was amplified by reverse transcriptase-nested polymerase chain reaction (RT-nested PCR). The HCV genotypes of the positive samples were tested using the INNO-LiPA™ HCV II kit, and the HCV genotypes were then confirmed by sequencing of the 5'-UTR fragments after the PCR products were cloned into a pJET1.2/blunt cloning vector. The mean age of the patients was 48.3 ± 1.76 years (range: 16-83). HCV-RNA was found in PBMCs from 2 (1.9%) of the 104 patients. Genotyping showed that the patients were infected with HCV subtype 1a. One patient suffered non-Hodgkin's lymphoma and the other suffered chronic lymphocytic leukemia. Patients with lymphoproliferative disorders with negative anti-HCV antibodies and negative plasma HCV-RNA may have occult HCV infection. Therefore, in the absence of a liver biopsy, the testing of PBMCs for the detection of genomic HCV-RNA may be beneficial.

Occult hepatitis C virus infection in Iranian patients with cryptogenic liver disease

The diagnosis of cryptogenic liver disease is made when after extensive evaluations, recognizable etiologies of chronic liver disease are excluded. In this study, the presence of hepatitis C virus (HCV) RNA was tested in peripheral blood mononuclear cells (PBMCs) taken from Iranian patients who although were found negative for plasma HCV RNA and anti-HCV antibodies, suffered from chronic liver disease of unknown etiology. From September 2007 to March 2010, 69 patients from Tehran with chronic liver disease of unknown etiology who were referred to our center were enrolled in the present study. PBMCs were isolated from 10 mL peripheral blood specimens. HCV-RNA status was tested in plasma and PBMCs samples by reverse-transcription polymerase chain reaction (RT-PCR). HCV-RNA was detected in HCV-positive PBMCs specimens by RT-PCR method. HCV genotypes were subsequently analyzed in HCV-positive samples using restriction fragment length polymorphism (RFLP) assay; then HCV genotypes were confirmed by sequencing of 5' non-coding fragments after cloning PCR products into pJET1.2/blunt cloning vector. HCV-RNA was detected in PBMCs specimens belonging to 7 (10%) out of 69 patients. Genotyping of the HCV-RNA isolated from PBMCs showed that 3 (43%) patients with occult HCV infection had genotype 1b, 2 (29%) had genotype 1a, and another 2 (29%) had genotype 3a. The results of this study suggest that patients with chronic liver disease of unknown etiology may have occult HCV infection in the absence of anti-HCV antibodies and plasma HCV-RNA. It has been suggested that in the absence of liver biopsy specimens, analysis of PBMC sample for HCV-RNA would be informative.

Prevalence and follow-up of occult HCV infection in an Italian population free of clinically detectable infectious liver disease

Background

Occult hepatitis C virus infection (OCI) is a recently described phenomenon characterized by undetectable levels of HCV-RNA in serum/plasma by current laboratory assays, with identifiable levels in peripheral blood mononuclear cells (PBMCs) and/or liver tissue by molecular tests with enhanced sensitivity. Previous results from our group showed an OCI prevalence of 3.3% in a population unselected for hepatic disease. The present study aimed to evaluate OCI prevalence in a larger cohort of infectious liver disease-free (ILDF) subjects. Clinical follow-up of OCI subjects was performed to investigate the natural history of the infection.

Methods and Findings

439 subjects referred to a Turin Blood Bank for phlebotomy therapy were recruited. They included 314 ILDF subjects, 40 HCV-positive subjects and 85 HBV-positive subjects, of whom 7 were active HBV carriers. Six subjects (4/314 ILDF subjects [1.27%] and 2/7 active HBV carriers [28%]) were positive for HCV-RNA in PBMCs, but negative for serological and virological markers of HCV, indicating OCI. HCV genotypes were determined in the PBMCs of 3/6 OCI subjects two had type 1b; the other had type 2a/2c. OCI subjects were followed up for at least 2 years. After 12 months only one OCI persisted, showing a low HCV viral load (3.73×10¹ UI/ml). By the end of follow-up all OCI subjects were negative for HCV. No seroconversion, alteration of liver enzyme levels, or reduction of liver synthesis occurred during follow-up.

Conclusions

This study demonstrated the existence of OCI in ILDF subjects, and suggested a high OCI prevalence among active HBV carriers. Follow-up suggested that OCI could be transient, with a trend toward the decrease of HCV viral load to levels undetectable by conventional methods after 12–18 months. Confirmation studies with a longer follow-up period are needed for identification of the OCI clearance or recurrence rates, and to characterize the viruses involved.

New perspectives in occult hepatitis C virus infection

Occult hepatitis C virus (HCV) infection, defined as the presence of HCV RNA in liver and in peripheral blood mononuclear cells (PBMCs) in the absence of detectable viral RNA in serum by standard assays, can be found in anti-HCV positive patients with normal serum levels of liver enzymes and in anti-HCV negative patients with persistently elevated liver enzymes of unknown etiology. Occult HCV infection is distributed worldwide and all HCV genotypes seem to be involved in this infection. Occult hepatitis C has been found not only in anti-HCV positive subjects with normal values of liver enzymes or in chronic hepatitis of unknown origin but also in several groups at risk for HCV infection such as hemodialysis patients or family members of patients with occult HCV. This occult infection has been reported also in healthy populations without evidence of liver disease. Occult HCV infection seems to be less aggressive than chronic hepatitis C although patients affected by occult HCV may develop liver cirrhosis and even hepatocellular carcinoma. Thus, anti-HCV negative patients with occult HCV may benefit from antiviral therapy with pegylated-interferon plus ribavirin. The persistence of very low levels of HCV RNA in serum and in PBMCs, along with the maintenance of specific T-cell responses against HCV-antigens observed during a long-term follow-up of patients with occult hepatitis C, indicate that occult HCV is a persistent infection that is not spontaneously eradicated. This is an updated report on diagnosis, epidemiology and clinical implications of occult HCV with special emphasis on anti-HCV negative cases.

Occult infection with hepatitis C virus: friend or foe?

Hepatitis C virus (HCV) infection is a global pandemic associated with a growing disease burden due to cirrhosis and the consequent morbidity and mortality. Transmission is largely via blood-to-blood contact. Following primary infection, a minority of individuals clear the infection predominantly via cellular immune mechanisms, whereas the majority become chronically infected. Recent data suggest that a third outcome may also be possible, termed 'occult' infection in which subjects who are known, or suspected to have previously been infected with HCV, no longer have viral RNA in their serum at levels detectable by sensitive commercial assays, but do have virus detected by ultra-sensitive techniques. Occult infection has also been detected in peripheral blood mononuclear cells, which may indicate an extra-hepatic reservoir of the virus. Although the clinical significance of occult infection remains unknown, most authors have raised concerns of recrudescent infection. Here we critically review the published literature, suggest further avenues of investigation and propose that occult infection may be beneficial to the host by maintaining immunological memory to protect against reinfection.

Hepatitis C virus persistence after sustained virological response to antiviral therapy in patients with or without past exposure to hepatitis B virus

Hepatitis C virus (HCV) and hepatitis B virus (HBV) frequently coinfect and persist long after clinical resolution. We assessed the incidence of low-level (occult) HCV infection (OCI) after sustained virological response (SVR) to standard anti-HCV therapy in individuals with or without past exposure to HBV to recognize whether HBV could influence the prevalence of OCI, HCV level and hepatic histology. Plasma and peripheral blood mononuclear cells (PBMC) were collected from 24 individuals at 6- to 12-month intervals for up to 72 months after SVR. Liver histology was available for nine patients. HCV and HBV genomes were detected with sensitivity <10 genome copies/mL. In individuals without HBV exposure (n = 15), comprehensive analyses of sequential plasma and PBMC samples revealed HCV RNA in all 15 cases (75% plasma and 61% PBMC). In the group with HBV exposure (n = 9), evidenced by circulating anti-HBc and/or HBV DNA detection by a highly sensitive assay, HCV RNA was identified in all cases (83% plasma and 59% PBMC), at levels similar to those in HBV nonexposed individuals. In both groups of patients, most liver biopsies included those reactive for viral genomes displayed low-grade inflammation (8 of 9) and fibrosis (7 of 9). Sequence polymorphisms at the 5`-UTR between PBMC and liver or plasma, as well as circulating HCV virion-like particles, were observed in patients with or without HBV exposure. In conclusion, the prevalence of OCI after SVR is comparable in individuals with or without past exposure to HBV. HCV loads and liver alterations in OCI appear to be unaffected by low-level HBV DNA carriage.

Long-term virological follow up of patients with occult hepatitis C virus infection

BACKGROUND

Patients with occult hepatitis C virus (HCV) infection (HCV-RNA in liver without detectable anti-HCV and serum HCV-RNA) may have viral RNA in peripheral blood mononuclear cells (PBMCs) and in serum after ultracentrifugation, and may present HCV-specific T-cell responses, but it is unknown whether these markers persist to be detectable over time.

AIM

To perform a prospective virological long-term follow up of patients with occult HCV.

METHODS

Viral markers were tested every 3-4 months during 55.7 ± 20.3 months in 37 patients with occult HCV who were under ursodeoxycholic acid treatment.

RESULTS

Viral RNA was detectable in PBMCs of 31 patients during the follow up. In 23 of them, viral RNA in PBMCs was detected intermittently and in the other eight patients HCV-RNA was positive in a single sample. After ultracentrifugation, serum HCV-RNA was detected in 33 patients, being the viraemia intermittently detectable in 28, whereas in the remaining five patients, serum HCV-RNA was positive only once. Only one patient tested always HCV-RNA negative in PBMCs and in ultracentrifuged serum during follow up. Specific Core, NS3, and/or NS4 T-cell responses were found in 31 of the patients. The patient who was always HCV-RNA negative in PBMCs and in ultracentrifuged serum had specific HCV-T-cell responses.

CONCLUSIONS

Occult HCV infection persists over time with fluctuating viraemia levels that induce and maintain specific T-cell responses against viral proteins.

Clinical variables identify seronegative HCV co-infection in HIV-infected individuals

BACKGROUND

A substantial number of people living with HIV (PLWH) are co-infected with Hepatitis C Virus (HCV) but have a negative screening HCV antibody test (seronegative HCV infection, or SN-HCV).

OBJECTIVE

To identify a concise set of clinical variables that could be used to improve case finding for SN-HCV co-infection among PLWH.

STUDY DESIGN

Two hundred HIV-infected participants of the CHARTER study were selected based on 7 clinical variables associated with HCV infection but were HCV seronegative. Data were analyzed using Fisher's exact tests, receiver-operating characteristic (ROC) curves, and logistic regression.

RESULTS

Twenty-six (13%) participants had detectable HCV RNA. SN-HCV was associated with a history of IDU, elevated ALT and AST, low platelets, black ethnicity, and undetectable HIV RNA in plasma. Each of these clinical variables, except for abnormal AST, remained independently associated with SN-HCV in a multivariate logistic regression analysis. A composite risk score correctly identified SN-HCV with sensitivity up to 85% and specificity up to 88%.

CONCLUSIONS

In a substantial minority of PLWH, seronegative HCV viremia can be predicted by a small number of clinical variables. These findings, after validation in an unselected cohort, could help focus screening in those at highest risk.

Occult HCV or delayed viral clearance from lymphocytes of Chronic HCV genotype 3 patients after interferon therapy

Background

A recently discovered occult HCV entity reported by various investigators seems to be highly controversial. Especially, the clinical significance of these findings remains uncertain. For optimal outcome of antiviral therapy, investigation of occult HCV needs a broad-based probe in order to investigate the results of viral therapy and its host/viral interaction. The current study was aimed at determining the prevalence of occult HCV in peripheral blood lymphocytes of predominantly genotype 3 HCV-infected patients after completion of antiviral therapy and to investigate long term outcomes in the presence or absence of PBMC positivity.

Method

A total of 151 chronic, antiHCV and serum RNA-positive patients were enrolled in the study. Patients with a complete virological response at the end of treatment were screened for the presence of viral RNA in their PBMCs and were followed for up to one year for the presence of serum and PBMC viral genomic RNA.

Results

Out of 151 patients, 104 (70%) responded to the prescribed interferon treatment and showed viral-clearance from serum. These were screened for the presence of genomic RNA in their PBMCs. Sixteen samples were PBMC-positive for viral RNA at the end of treatment (EOT). All these patients had also cleared the virus from peripheral blood cells after the 6-12 month follow-up study.

Conclusion

True occult hepatitis C virus does not exist in our cohort. Residual viremia at the EOT stage merely reflects a difference in viral kinetics in various compartments that remains a target of immune response even after the end of antiviral therapy and is eventually cleared out at the sustained viral response (SVR).

[Occult hepatitis C virus infection]

Occult hepatitis C virus (HCV) infection is characterized by the detection of HCV-RNA in liver in the absence of anti-HCV and serum HCV-RNA determined by conventional techniques. The development of a new enzyme immunoassay for the detection of antibodies against a conserved epitope in the HCV core protein, together with the detection of HCV-RNA in peripheral blood mononuclear cells and in serum after concentrating the viral particles by ultracentrifugation, allow diagnosis of more than 90% of patients with occult HCV without the need to perform a liver biopsy. Histological damage in occult HCV infection ranges from minimal changes to liver cirrhosis and hepatocellular carcinoma, although in general this disease is less severe than classical chronic hepatitis C. A significant prevalence of occult HCV infection has been identified in risk groups such as hemodialysis patients and the family members of patients with occult hepatitis C. This occult HCV infection can also be found in subjects without clinical or biochemical evidence of liver disease.

Human cell types important for hepatitis C virus replication in vivo and in vitro: old assertions and current evidence

Hepatitis C Virus (HCV) is a single stranded RNA virus which produces negative strand RNA as a replicative intermediate. We analyzed 75 RT-PCR studies that tested for negative strand HCV RNA in liver and other human tissues. 85% of the studies that investigated extrahepatic replication of HCV found one or more samples positive for replicative RNA. Studies using in situ hybridization, immunofluorescence, immunohistochemistry, and quasispecies analysis also demonstrated the presence of replicating HCV in various extrahepatic human tissues, and provide evidence that HCV replicates in macrophages, B cells, T cells, and other extrahepatic tissues. We also analyzed both short term and long term in vitro systems used to culture HCV. These systems vary in their purposes and methods, but long term culturing of HCV in B cells, T cells, and other cell types has been used to analyze replication. It is therefore now possible to study HIV-HCV co-infections and HCV replication in vitro.

Spontaneous loss of hepatitis C virus RNA from serum is associated with genotype 1 and younger age at exposure

A variety of factors have been associated with spontaneous loss of hepatitis C virus (HCV)-RNA from serum, including infecting HCV type, although results are conflicting. This study aimed to investigate further whether infecting HCV type was linked to spontaneous loss of HCV-RNA. Serum samples from 321 untreated HCV antibody positive patients presenting at the Hepatology clinic at Addenbrooke's Hospital, Cambridge between 2004 and 2007 were tested. These individuals were classified either as HCV antibody and HCV-RNA positive (viremic, n = 219) or HCV antibody positive and repeatedly HCV-RNA negative (non-viremic, n = 102). Infecting HCV type was identified by genotyping (viremic) or serotyping (non-viremic). Binomial regression analysis investigated the independent effect of HCV type on spontaneous loss of HCV-RNA from serum by comparing the two groups. Ninety-one percent of patients were found to be either genotype 1 or genotype 3. The prevalence of type 1 infection was greater among non-viremic (64.5%) than viremic individuals (45%). After controlling for the effects of potential confounding factors, multivariable analyses showed that individuals with type 1 infections were more likely to be non-viremic than genotype 3 infections (RR = 2.07; 95% CI: 1.25, 3.43; P = 0.005). Individuals infected at an older age were also less likely to become HCV-RNA negative spontaneously (RR = 0.42 comparing those infected at ≥20 years of age against those infected at <20 years of age, 95% CI: 0.25, 0.72; P = 0.002). In conclusion, the results suggest that HCV genotype 1 infections are more likely than genotype 3 infections to become spontaneously non-viremic, as are infections acquired at younger age.

Impact of a sustained virological response on the long-term outcome of hepatitis C

A sustained virological response (SVR), defined as undetectable hepatitis C virus (HCV)-RNA 24 weeks after withdrawal from therapy (SVR-24w), is the primary endpoint of antiviral therapy in chronic hepatitis C. There is solid evidence that patients who reach this target will remain virus free during long-term follow-up, with a risk of late HCV recurrence of <2% in published series using the most stringent criteria for assessing the virological response during and after antiviral therapy. Long-term observational studies indicate that SVR-24w has a profound impact on the natural course of chronic hepatitis C in relation to biochemical and histological remission of liver disease and improvement in quality of life. The effects of successful antiviral therapy on clinical endpoints such as the development of end-stage liver disease, its severe complications and liver-related mortality have been more difficult to ascertain because of the heterogeneity of the initial staging and rate of progression of chronic hepatitis C. However, most available data suggest that SVR following antiviral therapy reduces the risk of progression to cirrhosis and may prevent the development of severe liver complications and improve survival, at least in successfully treated patients who have already progressed to significant liver fibrosis or early cirrhosis. Outcome modelling suggests that these effects might also include HCV patients treated with milder forms of liver damage.

Diagnosis of occult hepatitis C without the need for a liver biopsy

The diagnosis of occult hepatitis C virus (HCV) infection is based on the presence of HCV-RNA in the liver. This study aimed to evaluate the use of combining non-invasive assays to diagnose occult HCV. A total of 122 patients with occult HCV (HCV-RNA in the liver without detectable anti-HCV and serum HCV-RNA) and 45 patients with cryptogenic chronic hepatitis (without HCV-RNA in the liver and negative for anti-HCV and serum HCV-RNA) were included. HCV-RNA was tested in peripheral blood mononuclear cells (PBMCs) and in 2 ml of ultracentrifuged serum. Anti-core HCV was examined by a non-commercial enzyme-linked immunosorbent assay. All controls were negative for the three HCV markers studied. Among patients with occult HCV, 36% were anti-core HCV positive, 57% had serum HCV-RNA after ultracentrifugation, and 61% had HCV-RNA in PBMCs. Combining the results of the assays, 91% of the patients were positive for at least one marker. Intrahepatic HCV-RNA load was significantly higher in patients who were positive simultaneously for the three HCV markers than in patients who were negative for all markers (P = 0.006) and than in those with one or two HCV markers (P = 0.039). Replication of HCV in liver was detected more frequently in patients with three (93%, P = 0.002), two (82%, P = 0.001), and one HCV marker (73%, P = 0.011) than in those without markers (27%). In conclusion, testing for all these markers allows diagnosis of occult HCV without the need for a liver biopsy and these assays may help to elucidate the clinical significance of occult HCV infection.

A highly sensitive and selective viral protein detection method based on RNA oligonucleotide nanoparticle

Globally, approximately 170 million people (representing approximately 3% of the population worldwide), are infected with hepatitis C virus (HCV) and at risk of serious liver disease, including chronic hepatitis. We propose a new quantum dots (QDs)-supported RNA oligonucleotide approach for the specific and sensitive detection of viral protein using a biochip. This method was developed by immobilizing a HCV nonstructural protein 5B (NS5B) on the surface of a glass chip via the formation of a covalent bond between an amine protein group and a ProLinker™ glass chip. The QDs-supported RNA oligonucleotide was conjugated via an amide formation reaction from coupling of a 5′-end-amine-modified RNA oligonucleotide on the surface of QDs displaying carboxyl groups via standard EDC coupling. The QDs-conjugated RNA oligonucleotide was interacted to immobilized viral protein NS5B on the biochip. The detection is based on the variation of signal of QDs-supported RNA oligonucleotide bound on an immobilized biochip. It was demonstrated that the value of the signal has a linear relationship with concentrations of the HCV NS5B viral protein in the 1 μg mL⁻¹ to 1 ng mL⁻¹ range with a detection limit of 1 ng mL⁻¹. The major advantages of this RNA-oligonucleotide nanoparticle assay are its good specificity, ease of performance, and ability to perform one-spot monitoring. The proposed method could be used as a general method of HCV detection and is expected to be applicable to other types of diseases as well.

Real-time quantitative assay for routine testing of HCV RNA in formalin-fixed, paraffin-embedded liver samples

The assessment of hepatitis C virus (HCV) RNA in liver tissues is clinically relevant in cases where histology, liver function tests, and HCV serology are not sufficient for a definitive diagnosis of HCV-related hepatitis. We analyzed 215 formalin-fixed, paraffin-embedded liver needle biopsies from patients infected with HCV genotypes 1b and 2. HCV RNA extracted from paraffin sections were quantified by means of a TaqMan real-time reverse transcription-polymerase chain reaction method. The quantification of HCV RNA in liver tissue was correlated with the amount of HCV detected by immunohistochemistry (IHC) on paired frozen biopsies, the HCV RNA load in the serum, and the main serum tests of liver function and cholestasis. HCV RNA was detected by real-time reverse transcription-polymerase chain reaction in 169 liver biopsies (78.6%) with a mean value of 13.59+/-37.25 IU/ng. Tissue HCV RNA levels strongly correlated with the IHC results (P<0.001, Spearman test), HCV serum load (P<0.001), aspartate aminotransferase (P=0.001), gamma-glutamyl transpeptidase (P=0.012), and aspartate aminotransferase/alanine aminotransferase ratio (P=0.029). HCV RNA was amplified in up to 7-year-old archival tissue samples. Real-time HCV RNA quantification on archival liver tissue may be clinically relevant in case of "occult" HCV infection or for the diagnosis of patients with known HCV infection and hepatic dysfunction but seronegative for HCV RNA. The assessment of the levels of HCV RNA in the liver might also be important for monitoring the effectiveness of antiviral therapy and the progression of disease in patients with chronic HCV hepatitis.