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

Occurrence and clinical characteristics of occult hepatitis C virus infection in hemodialysis units at Ismailia, Egypt

BACKGROUND AND AIMS

Occult hepatitis C infection is defined as the presence of hepatitis C virus RNA in peripheral blood mononuclear cells (PBMC) ± hepatocytes in the absence of HCV-RNA in serum. It has been a lot of debate and controversy in recent years and not discussed well. This issue has not been discussed or investigated in Egypt, especially in patients on hemodialysis in Ismailia. This study is the first one to investigate the prevalence of occult HCV infection in large populations of chronic hemodialysis (CHD) patients in Ismailia, Egypt.

METHODS

Our study is cross-sectional analytic and included 204 CHD patients; who are negative for HCV infection. Sensitive commercial real-time assay was used to detect HCV-RNA in PBMC. In our study, the presence of genomic HCV-RNA in PBMCs of all these patients was detected by real-time PCR. On the other hand, 22 patients on hemodialysis with an established diagnosis of chronic hepatitis C virus infection were included as a control group and examined by real-time PCR was used to evaluate HCV infection.

RESULTS

Occult HCV infection is defined as the presence of HCV-RNA in PBMNCs in patients on chronic hemodialysis, and it was found in 14/204 (7%) of the patients. Patients who were on CHD for a longer time are susceptible to occult HCV infection, and their mean alanine aminotransferase levels are significantly higher during the last 3 months before study entry. In comparison, chronic HCV patients have elevated bilirubin, aspartate transferase and alanine transferase than occult HCV infection.

CONCLUSIONS

The prevalence of occult HCV infection was 7% in our CHD patients. No available data are showing the virulence of this form of virus. However, further studies in other geographic populations with high HCV endemicity are needed to clarify the significance of occult HCV infection in these patient groups, in addition to test for the presence of negative antigenomic strand to confirm or disconfirm the reliability of occult HCV.

Detection of residual HCV-RNA in patients who have achieved sustained virological response is associated with persistent histological abnormality

BACKGROUND

Whether achieving sustained virological response (SVR) in patients with hepatitis C attains complete elimination of hepatitis C virus (HCV) is unknown, because occult HCV infection (OCI), defined as the detection of HCV-RNA in hepatocytes or peripheral blood mononuclear cells (PBMC) in absence of serum HCV-RNA, may occur. We thus investigated the prevalence and clinical relevance of OCI.

METHODS

Subjects from three hospitals who had achieved serum HCV clearance, including 60 of Direct-acting antiviral agents (DAAs) induced SVR, 50 of pegylated interferon plus ribavirin (PR) induced SVR, and 30 of spontaneous resolution, were subjected to detect HCV-RNA in liver by robust RNAscope assay and PBMC by qPCR. Paired liver biopsies at baseline and at SVR24 were analyzed.

RESULTS

OCI was detected in 16 of 140 subjects (11.4%), with 15.0% in DAA-based group, 10.0% in PR group and 6.7% in spontaneously resolved group. In DAA-based subgroups, the incidence of OCI was gradually increased in group of solely DAA(s) therapy, combining DAA and PR therapy and combining DAA and ribavirin therapy. OCI is more frequent in patients with genotype 3. No correlation between baseline viral load, interleukin-28B genotype, baseline transaminases, post-SVR transaminases and OCI were found. However, OCI was significantly linked with severity of fibrosis and active inflammation at post-SVR, even considering basal fibrosis status. In addition, both the magnitude and the frequency of fibrosis regression were lower in patients with OCI than in those without OCI. In the multivariate analysis, PR therapy was identified an independent negative prognostic factor for both hepatic inflammation (P = .022) and fibrosis regression (P = .015). Importantly, we found HCV relapse in one of the OCI patients at 48 weeks after the end of PR treatment.

CONCLUSIONS

HCV-RNA can persist in hepatocytes and/or PBMC in a certain of patients who achieved spontaneous or treatment-induced HCV RNA clearance from serum and associated with persistent histological abnormality. Our findings provide new insights into cure of HCV and could influence the following-up scenario after SVR.

Prevalence of occult hepatitis C virus among hemodialysis patients in Tanta university hospitals: a single-center study

Occult hepatitis C virus infection (OCI) is a newly defined type of infection by the chronic hepatitis virus (HCV) distinguished by the existence of HCV RNA in liver tissue and/or peripheral blood mononuclear cells (PBMCs) in patients whose plasma are devoid of both positive serology and RNA. Patients on maintenance hemodialysis evince a higher HCV prevalence than the general population due to high nosocomial transmission by the dialysis units. We investigated the prevalence of occult HCV infection in patients attending our university hemodialysis centers for maintenance hemodialysis. Sixty-two CHD patients negative for serum HCV tests were enrolled in the study. PMNCs were tested by real-time PCR for the presence of HCV RNA. For the 62 patients, the average duration since starting dialysis was 32.7 months and the mean (SD) alanine transaminase and aspartate transaminase were 25.74 ± 9.75 and 28.81 ± 11.32 IU/l, respectively. Out of the 62 CHD patients negative for serum anti-HCV and HCV RNA patients, only three (4.84%) were shown to have HCV RNA in their PBMCs implying the diagnosis of OCI; their viral load range was 1.24-4.15 IU/ml. All three OCI-proven patients gave no history of hepatic disease. In this study, we found that patients considered to be free of HCV can have HCV replicating in their PBMCs. This awareness points to the possibility of HCV being transmitted from apparently uninfected persons. A positive HCV RNA detection in PBMCs is dependable in determining OCI among high-risk subjects particularly when a liver biopsy is not an option. HCV transmission can occur through hemodialysis units signaling incorrect application of infection control measures in our Egyptian dialysis units. Additional studies on hemodialysis patients are necessary to realize the true magnitude of OCI among this patient group and to highlight the importance of incorporating HCV viral assays in PBMCs into the diagnostic algorithm.

Authentic Patient-Derived Hepatitis C Virus Infects and Productively Replicates in Primary CD4+ and CD8+ T Lymphocytes In Vitro

Accumulated evidence indicates that immune cells can support the replication of hepatitis C virus (HCV) in infected patients and in culture. However, there is a scarcity of data on the degree to which individual immune cell types support HCV propagation and on characteristics of virus assembly. We investigated the ability of authentic, patient-derived HCV to infect in vitro two closely related but functionally distinct immune cell types, CD4⁺ and CD8⁺ T lymphocytes, and assessed the properties of the virus produced by these cells. The HCV replication system in intermittently mitogen-stimulated T cells was adapted to infect primary human CD4⁺ or CD8⁺ T lymphocytes. HCV replicated in both cell types although at significantly higher levels in CD4⁺ than in CD8⁺ T cells. Thus, the HCV RNA replicative (negative) strand was detected in CD4⁺ and CD8⁺ cells at estimated mean levels ± standard errors of the means of 6.7 × 10² ± 3.8 × 10² and 1.2 × 10² ± 0.8 × 10² copies/μg RNA, respectively (P < 0.0001). Intracellular HCV NS5a and/or core proteins were identified in 0.9% of CD4⁺ and in 1.2% of CD8⁺ T cells. Double staining for NS5a and T cell type-specific markers confirmed that transcriptionally competent virus replicated in both cell types. Furthermore, an HCV-specific protease inhibitor, telaprevir, inhibited infection in both CD4⁺ and CD8⁺ cells. The emergence of unique HCV variants and the release of HCV RNA-reactive particles with biophysical properties different from those of virions in plasma inocula suggested that distinct viral particles were assembled, and therefore, they may contribute to the pool of circulating virus in infected patients.IMPORTANCE Although the liver is the main site of HCV replication, infection of the immune system is an intrinsic characteristic of this virus independent of whether infection is symptomatic or clinically silent. Many fundamental aspects of HCV lymphotropism remain uncertain, including the degree to which different immune cells support infection and contribute to virus diversity. We show that authentic, patient-derived HCV productively replicates in vitro in two closely related but functionally distinct types of T lymphocytes, CD4⁺ and CD8⁺ cells. The display of viral proteins and unique variants, the production of virions with biophysical properties distinct from those in plasma serving as inocula, and inhibition of replication by an antiviral agent led us to ascertain that both T cell subtypes supported virus propagation. Infection of CD4⁺ and CD8⁺ T cells, which are central to adaptive antiviral immune responses, can directly affect HCV clearance, favor virus persistence, and decisively influence the development and progression of 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.

Evolution of the Humoral Response during HCV Infection: Theories on the Origin of Broadly Neutralizing Antibodies and Implications for Vaccine Design

Similar to human immunodeficiency virus (HIV)-1, vaccine-induced elicitation of broadly neutralizing (bNt) antibodies (Abs) is gaining traction as a key goal toward the eradication of the hepatitis C virus (HCV) pandemic. Previously, the significance of the Ab response against HCV was underappreciated given the prevailing evidence advancing the role of the cellular immune response in clearance and overall control of the infection. However, recent findings have driven growing interest in the humoral arm of the immune response and in particular the role of bNt responses due to their ability to confer protective immunity upon passive transfer in animal models. Nevertheless, the origin and development of bNt Abs is poorly understood and their occurrence is rare as well as delayed with emergence only observed in the chronic phase of infection. In this review, we characterize the interplay between the host immune response and HCV as it progresses from the acute to chronic phase of infection. In addition, we place these events in the context of current hypotheses on the origin of bNt Abs against the HIV-1, whose humoral immune response is better characterized. Based on the increasing significance of the humoral immune response against HCV, characterization of these events may be critical in understanding the development of the bNt responses and, thus, provide strategies toward effective vaccine design.

Peripheral Blood Mononuclear Cell Gene Expression Remains Broadly Altered Years after Successful Interferon-Based Hepatitis C Virus Treatment

Background. Inflammatory gene expression in peripheral blood mononuclear cells (PBMCs) is altered in chronic Hepatitis C Virus (HCV) infection. Duration of changes after pegylated interferon- (peg-IFN-) based HCV treatment is unclear. Methods. PBMC mRNA expression of 184 inflammatory response genes was analyzed (nCounter GX Human Inflammation Kit, Nanostring) from peg-IFN treatment nonresponders (NR, n = 18), sustained virologic responders (SVR, n = 22), and spontaneous clearers (SC, n = 15). Logistic regression was used for comparison. Results. Median time from last treatment was 2 and 2.7 years in SVR and NR, respectively (p = NS). Mean mRNA counts were significantly different for 42 and 29 genes comparing SVR to SC patients and NR to SC, respectively, and no genes comparing SVR to NR. Differential expression of 24 genes was significantly different in both SVR and NR groups compared to SC. Among these 24 acute and chronic inflammatory cascade genes, significant upregulation was noted for proinflammatory transcription regulators Fos, CEBPB, and MyD88 in SVR and NR compared to SC. HDAC4 was significantly downregulated in SVR and NR compared to the SC group. Conclusions. PBMC inflammatory gene expression patterns in SVR resemble NR more than SC patients. A generalized inflammatory response persists in PBMCs long after successful peg-IFN treatment for HCV infection.

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.

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.

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.

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.

Differential expression of candidate virus receptors in human T lymphocytes prone or resistant to infection with patient-derived hepatitis C virus

Accumulated evidence implies that hepatitis C virus (HCV) infects not only the liver but also the immune system. A lymphocyte-specific CD5 molecule was recently identified as essential for infection of T cells with native, patient-derived HCV. To assess whether the proposed hepatocyte receptors may also contribute to HCV lymphotropism, expression of scavenger receptor-class B type 1 (SR-B1), claudin-1 (CLDN-1), claudin-6 (CLDN-6), occludin (OCLN), CD5 and CD81 was examined by real-time RT-PCR and the respective proteins quantified by immunoblotting in HCV-prone and resistant T cell lines, peripheral blood mononuclear cells (PBMC), primary T cells and their subsets, and compared to hepatoma Huh7.5 and HepG2 cells. SR-B1 protein was found in T and hepatoma cell lines but not in PBMC or primary T lymphocytes, CLDN-1 in HCV-resistant PM1 T cell line and hepatoma cells only, while CLDN-6 equally in the cells investigated. OCLN protein occurred in HCV-susceptible Molt4 and Jurkat T cells and its traces in primary T cells, but not in PBMC. CD5 was displayed by HCV-prone T cell lines, primary T cells and PBMC, but not by non-susceptible T and hepatoma cell lines, while CD81 in all cell types except HepG2. Knocking-down OCLN in virus-prone T cell line inhibited HCV infection, while de novo infection downregulated OCLN and CD81, and upregulated CD5 without modifying SR-B1 expression. Overall, while no association between SR-B1, CLDN-1 or CLDN-6 and the susceptibility to HCV was found, CD5 and CD81 expression coincided with virus lymphotropism and that of OCLN with permissiveness of T cell lines but unlikely primary T cells. This study narrowed the range of factors potentially utilized by HCV to infect T lymphocytes amongst those uncovered using laboratory HCV and Huh7.5 cells. Together with the demonstrated role for CD5 in HCV lymphotropism, the findings indicate that virus utilizes different molecules to enter hepatocytes and lymphocytes.

Genetic variations in host IL28B links to the detection of peripheral blood mononuclear cells-associated hepatitis C virus RNA in chronically infected patients

Hepatitis C virus (HCV) is mainly hepatotropic; however, several reports document the presence of genomic viral RNA in extrahepatic sites including peripheral blood mononuclear cells (PBMCs). In this study, the presence of HCV RNA was initially evaluated in the plasma and peripheral blood mononuclear cells (PBMCs) of 53 HCV-infected patients who were treated per protocol. PBMC-associated HCV RNA was detectable in 79% of patients. Early virological response to combined pegylated interferon-α (PegIFN) and ribavirin (RBV) therapy in patients with undetectable levels of PBMCs-associated HCV RNA was 100%, while it was 60% (P = 0.003) in those who had detectable levels of PBMC-associated HCV RNA. A sustained virological response was observed in 35% of patients with detectable PBMC-associated HCV RNA, but was 70% in patients with undetectable levels of PBMC-associated HCV RNA (P = 0.07). In a multivariate analysis incorporating parameters such as HCV genotype, viral load, presence of cirrhosis and absence of PBMC-associated HCV RNA, a significant relationship was observed between the detection of PBMC-associated HCV RNA and the sustained virological response (OR 19.4, 95% CI: 2.1-486.2, P = 0.0061). The association between single nucleotide polymorphism (SNP) in IL28B, known predictor of antiviral therapy outcome, and the occurrence of HCV RNA in PBMC in 84 chronically infected patients was then evaluated. Results suggest that the presence of a G allele in rs8099917, known to associate to a poor response to PegIFN/RBV therapy, also predicts an increased association of HCV RNA with PBMC (OR: 3.564; 95% CI: 1.114-11.40, P = 0.0437).

Clinical associations and potential novel antigenic targets of autoantibodies directed against rods and rings in chronic hepatitis C infection

Background

Chronic hepatitis C virus (HCV) infection is frequently associated with extrahepatic autoimmune disorders while interferon (IFN) and ribavirin treatment may exacerbate these conditions. Autoantibodies from HCV patients identify a novel indirect immunofluorescence (IIF) pattern on HEp-2 cells characterized by cytoplasmic rods and rings (RR). Our objectives were to determine the prevalence and clinical associations of RR autoantibodies in HCV patients, and identify related novel autoantibody targets.

Methods

Sera from 315 patients with HCV (301 treatment naive, 14 treated with interferon and/or ribavirin) were analyzed for the presence of RR antibodies by IIF on commercially available HEp-2 cell substrates. Antibodies to inosine monophosphate dehydrogenase 2 (IMPDH2) and cytidine triphosphate synthase 1 (CTPS1) were detected by addressable laser bead assay and other potential targets were identified by immunoscreening a protein microarray. Clinical and demographic data including HCV genotype, mode of infection, prior antiviral therapy, and histological findings were compared between RR antibody positive (RR+) and negative (RR-) patients.

Results

The median age of the HCV cohort was 51 years, 61% were male, and 76% were infected with HCV genotype 1 (G1). Four percent (n=14) had been treated with IFN-based therapy (IFN monotherapy, n=3; IFN/ribavirin, n=11); all had a sustained virologic response. In total, 15 patients (5% of the cohort) were RR+. RR+ and RR- patients had similar demographic and clinical characteristics including age, sex, mode of HCV infection, prevalence of the G1 HCV genotype, and moderate to severe fibrosis. Nevertheless, RR+ patients were significantly more likely than RR- cases to have been treated with IFN-based therapy (33% vs. 3%; adjusted odds ratio 20.5 [95% confidence interval 5.1-83.2]; P<0.0005). Only 1/10 RR positive sera had detectable antibodies to IMPHD2 and none had antibodies to CTPS1. Potentially important autoantibody targets identified on protein arrays included Myc-associated zinc finger protein (MAZI) and ankyrin repeat motif.

Conclusion

The majority of HCV patients with RR autoantibodies previously received IFN/ribavirin antiviral therapy. Further studies are necessary to determine the genesis of intracellular RR and elucidate the clinically relevant autoantigens as well as the clinical and prognostic significance of their cognate autoantibodies.

Patient-derived hepatitis C virus and JFH-1 clones differ in their ability to infect human hepatoma cells and lymphocytes

Hepatitis C virus (HCV) is a hepatotropic virus that also infects cells of the immune system. HCV clones cultivated in human hepatoma Huh-7.5 cells have significantly advanced our understanding of HCV replication and candidate hepatocyte receptors. However, naturally occurring patient-derived HCV, in contrast to the HCV JFH-1 clone, is unable to infect Huh-7.5 cells, while it can replicate in human primary T-cells and selected T-cell lines. To better understand this incongruity, we examined the susceptibility of primary T-cells, PBMCs and T-cell lines to infection with patient-derived HCV, the classical HCV JFH-1 and a cell culture-adapted JFH1T known to be highly infectious to Huh-7.5 cells. We also tested whether Huh-7.5 cells are prone to virus readily infecting T-lymphocytes. The results revealed that while primary T-cells and Molt4 and Jurkat T-cell lines were susceptible to patient-derived HCV, they were resistant to infection with either JFH1T or JFH-1. However, the JFH1T clone interacted more firmly, although non-productively, with the cells than JFH-1. Further, Huh-7.5 cells robustly supported replication of JFH1T but not patient-derived, wild-type virus, despite using highly sensitive detection assays. In conclusion, JFH-1 and JFH1T clones were unable to establish productive infection in human primary T-cells, PBMCs and T-cell lines known to be prone to infection by patient-derived HCV, while Huh-7.5 cells were resistant to infection with naturally occurring virus infecting immune cells. The data showed that the ability to infect lymphocytes is a characteristic of native virus but not laboratory HCV clones.

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.

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.