Occult hepatitis C: how convincing are the current data?

Expanding the liver donor pool worldwide with hepatitis C infected livers, is it the time?

Liver transplantation (LT) provides a life-saving option for cirrhotic patients with complications and hepatocellular carcinoma. Despite the increasing number of liver transplants performed each year, the number of LT candidates on the waitlist remains unchanged due to an imbalance between donor organ supply and the demand which increases the waitlist time and mortality. Living donor liver transplant had a great role in increasing the donor pool and shortened waitlist time for LT candidates. Nevertheless, further strategies can be implemented to increase the pool of potential donors in deceased donor LT, such as reducing the rate of organ discards. Utilizing hepatitis C virus (HCV) seropositive liver grafts is one of the expanded donor organ criteria. A yearly increase of hundreds of transplants is anticipated as a result of maximizing the utilization of HCV-positive organs for HCV-negative recipients. Direct-acting antiviral therapy's efficacy has revolutionized the treatment of HCV infection and the use of HCV-seropositive donors in transplantation. The American Society of Transplantation advises against performing transplants from HCV-infected liver donors (D+) into HCV-negative recipient (R-) unless under Institutional Review Board-approved study rules and with full informed consent of the knowledge gaps associated with such transplants. Proper selection of patients to be transplanted with HCV-infected grafts and confirming their access to direct-acting antivirals if needed is important. National and international consensuses are needed to regulate this process to ensure the maximum benefit and the least adverse events.

Evaluation of Long-Term Outcomes of Direct Acting Antiviral Agents in Chronic Kidney Disease Subjects: A Single Center Cohort Study

BACKGROUND

The chronic kidney disease (CKD) population, including kidney transplant recipients (KTRs) and subjects on renal replacement therapy, is particularly vulnerable to unfavorable outcomes from chronic hepatitis C (CHC). Currently, there are oral direct-acting antiviral agents (DAAs) available to eradicate the virus with favorable short-term outcomes; however, their long-term effects are lacking. The aim of the study is to assess the long-term efficacy and safety of DAA therapy in the CKD population.

METHODS

An observational, cohort single-center study was performed. Fifty-nine CHC subjects with CKD, treated with DAAs between 2016 and 2018, were enrolled in the study. Safety and efficacy profiles were assessed, including sustained virologic response (SVR), occult hepatitis C infection (OCI) incidence, and liver fibrosis.

RESULTS

SVR was achieved in 96% of cases (n = 57). OCI was diagnosed only in one subject following SVR. Significant liver stiffness regression was observed 4 years after SVR compared to baseline values (Mdn = 6.1 kPa, IQR = 3.75 kPa; 4.9 kPa, IQR = 2.9 kPa), p < 0.001. The most common adverse events were anemia, weakness, and urinary tract infection.

CONCLUSION

DAAs provide a safe and effective cure for CHC in both CKD patients and KTRs with a favorable safety profile in the long-term follow-up.

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.

Hepatitis C virus relapse after successful treatment with direct-acting antivirals, followed by sarcomatous changes in hepatocellular carcinoma: a case report

Background

Combination therapy of interferon and ribavirin has traditionally been used to eradicate hepatitis C virus. The sustained virologic response achieved with interferon-related therapy is persistent, and late relapses after achieving sustained virologic response at 24 weeks using this therapy are reportedly rare (< 1%). In 2014, interferon-free therapy with direct-acting antivirals was developed, and the rate of sustained virologic response was improved. However, the persistence thereof remains uncertain, and the appropriate follow-up period for hepatitis C virus-positive patients is under discussion.

Case presentation

A 74-year-old Japanese man who had hepatitis C virus–related hepatocellular carcinoma and was successfully treated with radiofrequency ablation four times underwent direct-acting antiviral therapy with daclatasvir and asunaprevir; sustained virologic response at 24 weeks was confirmed. However, although he had no high risk factors for reinfection, hepatitis C virus ribonucleic acid was detected again 6 months after achieving sustained virologic response at 24 weeks. Moreover, he developed active hepatitis with an increased viral load. Five months after development of hepatitis, recurrent hepatocellular carcinoma emerged in segment II, where we had performed radiofrequency ablation 17 months previously. The recurrent hepatocellular carcinoma enlarged quite rapidly and induced multiple peritoneal disseminations and lung metastases. He died 3 months after the abrupt recurrence. A sarcomatous change in the hepatocellular carcinoma was identified during the autopsy.

Conclusions

Although sustained virologic response at 24 weeks has generally been regarded to denote complete eradication of hepatitis C virus, we present a patient in whom hepatitis C virus recurred 6 months after achieving sustained virologic response at 24 weeks with direct-acting antiviral therapy. In addition, a sarcomatous change in hepatocellular carcinoma emerged 5 months after active hepatitis developed due to late hepatitis C virus relapse in this case. The sarcomatous change in hepatocellular carcinoma is generally thought to be related to anticancer therapies, such as radiofrequency ablation. However, in this case, late viral relapse and active hepatitis in addition to the previous radiofrequency ablation could have been the trigger. There may be a need for follow-up of hepatitis C virus ribonucleic acid beyond sustained virologic response at 24 weeks with direct-acting antiviral therapy, owing to the possibility of late viral relapse and tumorigenesis.

Occult hepatitis C virus infection in hemophilia patients and its correlation with interferon lambda 3 and 4 polymorphisms

Occult HCV infection (OCI) is described as the presence of HCV RNA in the liver and peripheral blood mononuclear cells (PBMCs), with no HCV RNA in the serum. Single-nucleotide polymorphisms (SNPs) near interferon lambda 3/4 (IFNL3/4) gene are associated with spontaneous clearance and treatment response in patients with hepatitis C virus (HCV) infection. In this study, we evaluated the frequency of OCI in hemophilia patients and determined the association of three IFNL3 SNPs (rs12979860, rs12980275, and rs8099917) and IFNL4 ss469415590 with OCI positivity. A total of 450 hemophilia patients with HCV negative markers were included in this study. Positive- and negative-stranded HCV-RNA was determined in peripheral blood mononuclear cells (PBMCs) samples by reverse-transcription polymerase chain reaction (RT-PCR) method. IFNL3 SNPs and IFNL4 ss469415590 were genotyped by PCR-RFLP and TaqMan® Real-Time PCR methods, respectively. The frequency of OCI was estimated at 10.2%. Among 46 OCI patients, 56.5%, 23.9%, and 19.6% were infected with HCV-1b, HCV-1a, and HCV-3a, respectively. Compared to patients without OCI, unfavorable IFNL3 rs12979860 TT, IFNL3 rs8099917 GG, IFNL3 rs12980275 GG, and IFNL4 ss469415590 ∆G/∆G genotypes were more frequently reported in OCI patients. The multivariate logistic regression analysis showed that alanine aminotransferase (ALT), cholesterol, triglyceride, IFNL3 rs12979860 (TT), IFNL3 rs8099917 (GG), IFNL3 rs12980275 (GG), and IFNL4 ss469415590 (∆G/∆G) were associated with OCI positivity. In conclusion, we studied the incidence of OCI in Iranian patients with hemophilia for the first time. Our results demonstrated that unfavorable genotypes of IFNL3 SNPs and IFNL4 ss469415590 have a strong relationship with OCI positivity. It seems that the host immune response plays a vital role in OCI positivity.

Evaluation of hepatitis C viral RNA persistence in HIV-infected patients with long-term sustained virological response by droplet digital PCR

Several studies have reported the persistence of HCV RNA in liver and/or peripheral blood mononuclear cells (PBMCs) in spite of undetectable viremia in patients who have achieved sustained virological response (SVR). This event, defined as occult HCV infection, remains controversial and low titers of persistent virus may be underestimated because it has not yet been analyzed by a highly sensitive test such as droplet digital PCR (ddPCR). This method provides an alternate ultra-sensitive detection technique for very low numbers of copies of viral RNA or DNA. The aim of this study was to evaluate the persistence of HCV in HIV-coinfected patients with long-term SVR using ddPCR. For each patient, the presence of HCV RNA in serum and PBMCs at baseline was determined by nested RT-ddPCR. Patients with HCV RNA in PBMCs at baseline were followed until the end of the study. One hundred and twenty-three patients were analyzed for persistence of HCV RNA in serum and PBMCs. Persistence of HCV was not found in serum in any patient. HCV RNA was detected in PBMCs in one patient (0.81%; 95% CI: 0.04–3.94) and resolved spontaneously during follow-up. Persistence of HCV RNA in PBMCs is not a common event in HIV/HCV co-infected patients with long-term SVR evaluated by RT-ddPCR.

Long-term follow-up after cure from chronic hepatitis C virus infection shows occult hepatitis and a risk of hepatocellular carcinoma in noncirrhotic patients

OBJECTIVES

Curing of hepatitis C virus (HCV) infection primarily aims to prevent severe liver complications. Our objectives were to investigate the long-term presence and impact of occult HCV infection (OCI) and to study the outcomes in terms of liver disease after virological cure.

PATIENTS AND METHODS

A total of 97 patients with achieved sustained virological response (SVR) during 1990-2005 were followed either by a clinical follow-up (FU) visit with blood sampling and liver elastography (n=54) or through national registries for outcomes (n=43). To diagnose OCI among patients with SVR, a highly sensitive method was used to detect HCV-RNA traces in whole blood. The FU duration was a median of 10.5 years, with samples up to 21.5 years after the end of treatment (EOT).

RESULTS

The majority of patients [52 (96%)] were HCV-RNA negative at FU, and regression of fibrosis was statistically significant. OCI was found in two (4%) of them at 8 and 9 years after EOT. These patients had F1 and F2 fibrosis before treatment and F2 at FU, but no other abnormal findings. Three previously noncirrhotic men were diagnosed with hepatocellular carcinoma 8-11 years after EOT.

CONCLUSION

Occult infection could be detected many years after the achievement of SVR but was not associated with serious liver disease. The majority had persistent viral eradication and regression of fibrosis after SVR. However, an increased risk of hepatocellular carcinoma may persist in the long term after SVR even in noncirrhotic patients. Further studies with FU after direct-acting antiviral therapy and on the long-term impact after cure are needed.

Insights From Antiviral Therapy Into Immune Responses to Hepatitis B and C Virus Infection

There are 257 million persons worldwide with chronic hepatitis B virus (HBV) infection, a leading causes of liver cancer. Almost all adults with acute HBV infection have a rapid immune response to the virus, resulting in life-long immunity, but there is no cure for individuals with chronic HBV infection, which they acquire during early life. The mechanisms that drive the progression of HBV through distinct clinical phases to end-stage liver disease are poorly understood. Likewise, it is not clear whether and how immune responses can be modulated to allow control and/or clearance of intrahepatic HBV DNA. We review the innate and adaptive immune responses to acute and chronic HBV infections and responses to antiviral therapy. Comparisons with hepatitis C virus infection provide insights into the reversibility of innate inflammatory responses and the potential for successful therapy to recover virus-specific memory immune responses.

Molecular diagnosis of occult hepatitis C virus infection in Iranian injection drug users

Occult HCV infection (OCI) has been described as the presence of hepatitis C virus (HCV) genomic RNA in hepatocytes and/or peripheral blood mononuclear cell (PBMC) specimens and the lack of HCV genomic RNA and anti-HCV antibodies (Abs) in plasma samples. Injection drug users (IDUs) are the most important high-risk group for infection with blood-borne viruses, particularly HCV. The purpose of this study was to determine the presence of OCI in IDUs. A prospective cross-sectional study of 126 consecutive Iranian IDUs was performed from March 2017 to January 2018. PBMCs were separated from blood samples from the participants, and after extraction of the viral RNA from the plasma and PBMC specimens, HCV RNA was detected in the samples using RT-nested PCR by amplification of the 5'-NTR of HCV. HCV genotyping was carried out using restriction a fragment length polymorphism (RFLP) assay. The viral RNA was amplified using RT-nested PCR with specific primers for the NS5B gene, and the PCR products were sequenced to confirm the results obtained by HCV RNA detection and HCV genotyping. Out of the 126 IDUs studied, 105 (83.3%) were negative for anti-HCV Abs and HCV RNA in plasma samples, whereas HCV RNA was detected in the PBMC samples of six (5.7%) participants, indicating that these individuals had OCI. Moreover, HCV genomic RNA was detected in PBMC samples from five (23.8%) of the 21 IDUs studied who were positive for anti-HCV Abs and negative for HCV genomic RNA in plasma specimens. These IDUs also had OCI. The HCV genotypes in the PBMC samples from the subjects with OCI were determined. Six (54.5%) subjects were infected with HCV subtype 3a, and five (45.5%) were infected with HCV subtype 1a. This study showed that 8.7% of the Iranian IDUs had OCI, and therefore, a study focusing on the diagnosis of OCI in these individuals can be valuable and informative.

Hepatitis C transmission from seropositive, nonviremic donors to non-hepatitis C liver transplant recipients

Breakthroughs in hepatitis C virus (HCV) treatment and rising rates of intravenous drug use have led to an increase in the number of organ donors who are HCV antibody-positive but serum nucleic acid test (NAT)-negative. The risk of HCV transmission from the liver grafts of these donors to recipients is unknown. To estimate the incidence of HCV transmission, we prospectively followed 26 consecutive HCV antibody-negative (n = 25) or NAT-negative (n = 1) transplant recipients who received a liver graft from donors who were HCV antibody-positive but serum NAT-negative between March 2016 and March 2017. HCV transmission was considered to have occurred if recipients exhibited a positive HCV PCR test by 3 months following transplantation. Drug overdose was listed as the cause of death in 15 (60%) of the donors. One recipient died 18 days after transplantation from primary graft nonfunction and was excluded. Of the remaining 25 recipients, HCV transmission occurred in 4 (16%), at a median follow-up of 11 months, all from donors who died of drug overdose. Three of these patients were treated with direct-acting antiviral therapy, with two achieving a sustained virologic response and one an end-of-treatment response. One patient with HCV transmission died after a complicated postoperative course and did not receive antiviral therapy.

CONCLUSION

In this prospective cohort of non-HCV liver recipients receiving grafts from HCV antibody-positive/NAT-negative donors, the incidence of HCV transmission was 16%, with the highest risk conferred by donors who died of drug overdose; given the availability of safe and highly effective antiviral therapies, use of such organs could be considered to expand the donor pool. (Hepatology 2018;67:1673-1682).

Prevalence of Occult Hepatitis C Virus Infection among Blood Donors in Jiangsu, China

OBJECTIVE

In 2010, only 1 donor blood sample was found to be anti-hepatitis C virus (HCV) negative and HCV RNA positive, as detected by nucleic acid testing. In occult HCV infection (OCI), HCV RNA is found in peripheral blood mononuclear cells (PBMCs). We investigated the prevalence of OCI among blood donors.

METHODS

We collected 513 samples from 334 eligible and 179 deferred donors, including 55 anti-HCV-positive, 113 alanine aminotransferase (ALT)-elevated, and 11 hepatitis B virus surface antigen (HBsAg)-positive blood donors. PBMCs were isolated, the 5'-untranslated region of HCV RNA was amplified by reverse transcription nested PCR, and the genotype of the core region was determined.

RESULTS

No HCV RNA was detected among the eligible samples. Among the deferred donors, 15 (27.2%) had detectable HCV RNA in 55 anti-HCV PBMC specimens. HCV RNA was detected in 1 (9.1%) HBsAg-positive and 9 (8%) ALT-elevated samples. The prevalence of OCI in the blood donors was 2.2% (10/458). HCV genotypes were determined in 10 subjects, indicating that 2 (20.0%) were subtype 2a, 7 (70.0%) were 1b, and 1 (10%) was 6a.

CONCLUSIONS

This study showed that OCI does exist among Chinese blood donors. However, to determine the epidemiology and outcome of this HCV infection, further follow-up with more participants and patients receiving blood components with OCI is needed.

Detection of Occult Hepatitis C Virus Infection in Patients Who Achieved a Sustained Virologic Response to Direct-Acting Antiviral Agents for Recurrent Infection After Liver Transplantation

Occult infection with hepatitis C virus (HCV) is defined as the presence of the HCV genome in either liver tissue or peripheral blood monocytes, despite constant negative results from tests for HCV RNA in serum. We investigated whether patients who maintained a sustained virologic response 12 weeks after therapy (SVR12) with direct-acting antiviral (DAA) agents for recurrent HCV infection after liver transplantation had occult HCV infections. We performed a prospective study of 134 patients with recurrent HCV infection after liver transplantation who were treated with DAAs, with or without ribavirin, from 2014 through 2016 (129 patients achieved an SVR12). In >10% of the patients who achieved SVR12 (n = 14), serum levels of aminotransferases did not normalize during or after DAA therapy, or they normalized transiently but then increased sharply after DAA therapy. Of these 14 patients, 9 were assessed for occult HCV infection by reverse transcription quantitative polymerase chain reaction. This analysis revealed that 55% of these patients (n = 5) had an occult infection, with the detection of negative strand viral genome, indicating viral replication. These findings indicate the presence of occult HCV infection in some patients with abnormal levels of serum aminotransferases, despite SVR12 to DAAs for HCV infection after liver transplantation.

Preferential association of hepatitis C virus with CD19+ B cells is mediated by complement system

Extrahepatic disease manifestations are common in chronic hepatitis C virus (HCV) infection. The mechanism of HCV-related lymphoproliferative disorders is not fully understood. Recent studies have found that HCV in peripheral blood mononuclear cells from chronically infected patients is mainly associated with cluster of differentiation 19-positive (CD19+ ) B cells. To further elucidate this preferential association of HCV with B cells, we used in vitro cultured virus and uninfected peripheral blood mononuclear cells from healthy blood donors to investigate the necessary serum components that activate the binding of HCV to B cells. First, we found that the active serum components were present not only in HCV carriers but also in HCV recovered patients and HCV-negative, healthy blood donors and that the serum components were heat-labile. Second, the preferential binding activity of HCV to B cells could be blocked by anti-complement C3 antibodies. In experiments with complement-depleted serum and purified complement proteins, we demonstrated that complement proteins C1, C2, and C3 were required to activate such binding activity. Complement protein C4 was partially involved in this process. Third, using antibodies against cell surface markers, we showed that the binding complex mainly involved CD21 (complement receptor 2), CD19, CD20, and CD81; CD35 (complement receptor 1) was involved but had lower binding activity. Fourth, both anti-CD21 and anti-CD35 antibodies could block the binding of patient-derived HCV to B cells. Fifth, complement also mediated HCV binding to Raji cells, a cultured B-cell line derived from Burkitt's lymphoma.

CONCLUSION

In chronic HCV infection, the preferential association of HCV with B cells is mediated by the complement system, mainly through complement receptor 2 (CD21), in conjunction with the CD19 and CD81 complex. (Hepatology 2016;64:1900-1910).

Persistent replication of a hepatitis C virus genotype 1b-based chimeric clone carrying E1, E2 and p6 regions from GB virus B in a New World monkey

The development of effective hepatitis C virus (HCV) vaccines is essential for the prevention of further HCV dissemination, especially in developing countries. Therefore the aim of this study is to establish a feasible and immunocompetent surrogate animal model of HCV infection that will help in evaluation of the protective efficacy of newly developing HCV vaccine candidates. To circumvent the narrow host range of HCV, an HCV genotype 1b-based chimeric clone carrying E1, E2 and p6 regions from GB virus B (GBV-B), which is closely related to HCV, was generated. The chimera between HCV and GBV-B, named HCV/G, replicated more efficiently as compared with the HCV clone in primary marmoset hepatocytes. Furthermore, it was found that the chimera persistently replicated in a tamarin for more than 2 years after intrahepatic inoculation of the chimeric RNA. Although relatively low (<200 copies/mL), the viral RNA loads in plasma were detectable intermittently during the observation period. Of note, the chimeric RNA was found in the pellet fraction obtained by ultracentrifugation of the plasma at 73 weeks, indicating production of the chimeric virus. Our results will help establish a novel non-human primate model for HCV infection on the basis of the HCV/G chimera in the major framework of the HCV genome.

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.

Is psychosocial and cognitive dysfunction misattributed to the virus in hepatitis C infection? Select psychosocial contributors identified

Chronic hepatitis C is associated with health-related quality of life and cognitive impairments, even in mild disease. Recent evidence demonstrating hepatitis C virus (HCV) neurotropism has strengthened a neuropathophysiological hypothesis. However, sample heterogeneity confounds study outcomes. A uniquely homogeneous cohort of Irish women, following an iatrogenic HCV outbreak, offers a rare opportunity to control for HCV chronicity and the virus' purported impact on quality of life and cognition. A multi site, three-group, cross-sectional design was employed. Noncirrhotic, iatrogenically infected women, developing either acute or chronic infection, were recruited from prospective tertiary-care liver clinics and the community. Well-matched healthy controls were also recruited. All participants completed a psychosocial survey and were invited to undergo a comprehensive neuropsychological test battery. Significantly distressed psychosocial symptom profiles were observed in those with an iatrogenic HCV exposure history, which was independent of viral chronicity. Chronic and cleared HCV cohorts were not differentiated from each other. Two distinct subgroups, demarcated along 'impaired' vs 'nonimpaired' quality-of-life reports, were clearly identified and logistic regression analysis identified depressed mood and cognitive fatigue, rather than viral status, as statistically significant predictors of group membership. Compared with matched controls, significant cognitive impairments were not observed in either HCV cohort. Our findings provide strong evidence of nonviral factors accounting for quality of life impairment in chronic HCV and they also appear to question existing reports of cognitive dysfunction in mild disease. Depressed mood and cognitive fatigue appear to be critical psychosocial mediators of reduced quality-of-life and we hypothesize that metabolite abnormalities reported in HCV samples may also be confounded by these factors, given the associated literature.

Prevalence of occult hepatitis C virus infection in the Iranian patients with human immunodeficiency virus infection

Occult hepatitis C virus (HCV) infection is a new form of chronic HCV infection described by the presence of the genomic HCV-RNA in liver biopsy and/or peripheral blood mononuclear cell (PBMC) samples, and undetectable levels or absence of HCV-RNA and in the absence or presence of anti HCV antibodies in the plasma specimens. The aim of the present study was to evaluate the occurrence of occult HCV infection (OCI) among Iranian subjects infected with human immunodeficiency virus (HIV) using RT-nested PCR. From March 2014 until April 2015, 109 Iranian patients with established HIV infection were enrolled in this cross-sectional study. After extraction of viral RNA from the plasma and PBMC samples, HCV-RNA status was examined by RT-nested PCR using primers from the 5'-NTR. HCV genotyping was conducted using RFLP analysis. For the confirmation of HCV genotyping by RFLP method, the PCR products were sequenced. Of the 109 patients, 50 were positive for antibodies against HCV. The HCV-RNA was detected in PBMC specimens in 6 (10.2%) out of the total 59 patients negative for anti-HCV Abs and undetectable plasma HCV-RNA and also from 4 (8.0%) out of the total 50 patients positive for anti-HCV Abs and undetectable plasma HCV-RNA. HCV genotyping analysis showed that 6 (60.0%) patients were infected with HCV subtype 3a, 3 (30.0%) were infected with HCV subtype 1a and 1 (10.0%) patient was infected with HCV subtype 1b. This study revealed the incidence of OCI (9.2%) in HIV-infected Iranian patients. Hence, designing prospective studies focusing on the detection of OCI in these patients would provide more information. J. Med. Virol. 88:1960-1966, 2016. © 2016 Wiley Periodicals, Inc.

Prevalence of occult hepatitis C virus infection in Iranian patients with beta thalassemia major

Occult hepatitis C virus infection (OCI) is a new pathological form of chronic hepatitis virus (HCV) infection characterized by the presence of HCV RNA in liver biopsy and/or peripheral blood mononuclear cell (PBMC) specimens and the absence of HCV RNA and anti-HCV antibodies (Abs) in plasma samples. β-thalassemia major is a hereditary recessive blood disease with deficiency in the hemoglobin beta chain. Thalassemic patients need blood transfusion therapy; repeated blood transfusion increases the risk of viral blood-borne infection. The aim of this study was to determine the prevalence of OCI in Iranian patients with β-thalassemia major. From February 2015 to November 2015, a total of 147 Iranian patients with β-thalassemia major were enrolled in this cross-sectional study. After extraction of viral RNA from the plasma and PBMC samples, HCV genomic RNA in the specimens was amplified by RT-nested PCR using primers from the 5'-UTR. The HCV genotypes of the positive specimens were tested using the RFLP assay. To confirm the HCV genotypes, the 5'-UTR fragment was amplified and cloned into the pJET1.2/blunt cloning vector and then sequenced. Out of 147 patients, 106 (72.1 %) were negative for anti-HCV Abs and HCV RNA. HCV RNA was found in PBMC specimens of six (5.7 %) patients, from a total of 106 patients with undetectable plasma HCV RNA and anti-HCV Abs. Therefore, six out of 106 patients had OCI. HCV genotyping revealed that three patients were infected with HCV subtype 1b, two patients were infected with HCV subtype 3a, and one patient was infected with HCV subtype 1a. These results revealed that Iranian patients with beta-thalassemia major might have OCI. Therefore, it seems that the design of a study to identify this infection in patients with β-thalassemia major would provide valuable information.

Cellular immune response to hepatitis-C-virus in subjects without viremia or seroconversion: is it important?

Hepatitis C Virus (HCV) causes chronic infection and represents a global health burden. To date, there is no licensed vaccine for HCV. The high viral replication rate and the existence of several HCV genotypes and quasispecies hamper the development of an effective universal vaccine. In this regard, the current HCV vaccine candidates show genotype-specific protection or narrow cross reactivity against other genotypes. Importantly, HCV spontaneous clearance occurs in 15-50 % of infected subjects, indicating that natural resistance to chronic infection exists. This phenomenon was demonstrated among humans and chimpanzees and continues to motivate researchers attempting to develop an effective HCV vaccine. However, what constitutes a protective immune response or correlate of protection against HCV infection is still vague. Additionally, the mechanisms behind successful HCV clearance suggest the coordination of several arms of the immune system, with cell-mediated immunity (CMI) playing a crucial role in this process. By contrast, although neutralizing antibodies have been identified, they are isolate-specific and poorly correlate with viral clearance. Antigen-specific CD4 T cells, instead, correlate with transient decline in HCV viremia and long-lasting control of the infection. Unfortunately, HCV has been very successful in evading host immune mechanisms, leading to complications such as liver fibrosis, cirrhosis and hepatocellular carcinoma. Interestingly, CMI to HCV antigens were shown among exposed individuals without viremia or seroconversion, suggesting the clearance of prior HCV infection(s). These individuals include family members living with HCV-infected subjects, healthcare workers, IV drug users, and sexual contacts. The correlates of protection could be closely monitored among these individuals. This review provides a summary of HCV-specific immune responses in general and of CMI in particular in these cohorts. The importance of these CMI responses are discussed.

Occult Hepatitis C Virus Infection in Hemodialysis Patients; Single Center Study

INTRODUCTION

A new form of hepatitis C virus infection, known as occult hepatitis C virus (HCV) infection, is characterized by the presence of HCV_RNA in the liver or peripheral blood mononuclear cells (PBMCs). However, no serological markers of infection occur and there is not as much damage to the liver damage as is produced by chronic hepatitis C. There is a high incidence of HCV infection among hemodialysis patients, there is significant concern about viral transmission. HCV infection is a major problem in hemodialysis (HD) units even though blood products are screened for anti-HCV antibodies and other precautions are taken. The aim of this study was to determine the prevalence of occult HCV infection in PBMC in chronic hemodialysis (CHD) patients in the dialysis unit at Theodor Bilharz Research Institute (TBRI) with HCV antibodies and HCV RNA negativity irrespective of their liver function tests.

METHODS

Fifty-three patients who were repeatedly were anti-HCV negative and serum HCV-RNA negative and on regular hemodialysis for > six months were enrolled in the study, which was conducted in the dialysis unit of Nephrology Department at TBRI; there were 10 healthy matched controls. The patients were classified into two groups according to the result HCV RNA in their PBMCs. Serological markers of HCV infection, including anti-HCV antibody and serum HCV-RNA, were repeatedly negative for all patients included in the study. We collected serum and PBMC samples from the patients on the day they entered the study. The test of all serum samples for anti-HCV antibodies and HCV-RNA was repeated by RT-PCR to ensure that the patients did not have these HCV serologic markers, We also measured their ALT and GGT levels.

RESULTS

Occult hepatitis C virus infection (OCI) was detected in 15.1% of our CHD patients without any evidence of chronic liver disease.

CONCLUSION

Occult HCV infection was present among the hemodialysis patients irrespective of whether they had persistent abnormal values of liver enzymes for which no cause had been identified. Further study is required to determine the clinical significance of occult HCV infections in these patients.

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.

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.

Detection of Hepatitis C virus RNA in peripheral blood mononuclear cells of patients with abnormal alanine transaminase in Ahvaz

PURPOSE

Hepatitis C virus (HCV) is an important agent for chronic and acute hepatitis. Occult hepatitis C remains a major health problem worldwide. Patients with chronic occult HCV may progress to cirrhosis and hepatocellular carcinoma. The aim of this study was to determine prevalence of occult hepatitis C by IS-PCR-ISH (in situ PCR in situ hybridisation) in the patients with abnormal ALT.

MATERIALS AND METHODS

The blood samples were taken from 53 patients including 17 females (32.1%) and 36 (67.9%) males who had abnormal alanine transaminase (ALT) for more than 1 year. The mean ALT and aspartate transaminase (AST) level were 41.02±9.3 and 24.17±7.3, respectively. The patients' age were between 4 and 70-years old with mean age 38±13. All the patients were negative for HCV antibody, HCV RNA and HBs Ag. The peripheral blood mononuclear cells (PBMC) were separated with ficoll gradient from each blood sample, then the cells were fixed on slides by cold acetone and followed by IS-PCR-ISH for HCV RNA detection.

RESULTS

Seventeen (32%) patients including 6 (11.3%) females and 11 (20.7%) males showed positive results for HCV RNA by in situ-PCR in situ hybridisation. Ten (18.8%) positive cases were between 20 and 40-years old and 6 (11.3%) positive patients were between 40 and 60 years old. Ten (19.6%) patients who were positive for IS-PCR-ISH also had positive anti-HBc IgG and 7 (13.2%) patients were negative for HBc-IgG.

CONCLUSION

In the present study high rate of 32% occult hepatitis C were found among the patients with elevated ALT.

Immunological aspects of antiviral therapy of chronic hepatitis B virus and hepatitis C virus infections

Hepatitis B virus (HBV) and hepatitis C virus (HCV) cause a large proportion of acute and chronic liver disease worldwide. Over the past decades many immunological studies defined host immune responses that mediate spontaneous clearance of acute HBV and HCV infection. However, host immune responses are also relevant in the context of treatment-induced clearance of chronic HBV and HCV infection. First, the pretreatment level of interferon-stimulated genes as well as genetic determinants of innate immune responses, such as single nucleotide polymorphisms near the IFNL3 gene, are strong predictors of the response to interferon-alpha (IFN-α)-based therapy. Second, IFN-α, which has been a mainstay of HBV and HCV therapy over decades, and ribavirin, which has also been included in interferon-free direct antiviral therapy for HCV, modulate host immune responses. Third, both IFN-α-based and IFN-α-free treatment regimens of HBV and HCV infection alter the short-term and long-term adaptive immune response against these viruses. Finally, treatment studies have not just improved the clinical outcomes, but also provided opportunities to study virus-host interaction. This review summarizes our current knowledge on how a patient's immune response affects the treatment outcome of HBV and HCV infection and how innate and adaptive immune responses themselves are altered by the different treatment regimens.

Hepatitis C virus infection and kidney transplantation in 2014: what's new?

Chronic hepatitis C virus (HCV) infection remains an important health problem, which is associated with deleterious consequences in kidney transplant recipients. Besides hepatic complications, several extrahepatic complications contribute to reduced patient and allograft survival in HCV-infected kidney recipients. However, HCV infection should not be considered as a contraindication for kidney transplantation because patient survival is better with transplantation than on dialysis. Treatment of HCV infection is currently interferon-alpha (IFN-α) based, which has been associated with higher renal allograft rejection rates. Therefore, antiviral treatment before transplantation is preferable. As in the nontransplant setting, IFN-free treatment regimens, because of their greater efficacy and reduced toxicity, currently represent promising and attractive therapeutic options after kidney transplantation as well. However, clinical trials will be required to closely evaluate these regimens in kidney recipients. There is also a need for prospective controlled studies to determine the optimal immunosuppressive regimens after transplantation in HCV-infected recipients. Combined kidney and liver transplantation is required in patients with advanced liver cirrhosis. However, in patients with cleared HCV infection and early cirrhosis without portal hypertension, kidney transplantation alone may be considered. There is some agreement about the use of HCV-positive donors in HCV-infected recipients, although data regarding posttransplant survival rates are controversial.

Trace amounts of sporadically reappearing HCV RNA can cause infection

Successful hepatitis C virus (HCV) treatment is defined as the absence of viremia 6 months after therapy cessation. We previously reported that trace amounts of HCV RNA, below the sensitivity of the standard clinical assay, can reappear sporadically in treatment responders. Here, we assessed the infectivity of this RNA and infused 3 chimpanzees sequentially at 9-week intervals with plasma or PBMCs from patients who tested positive for trace amounts of HCV RNA more than 6 months after completing pegylated IFN-α/ribavirin therapy. A fourth chimpanzee received HCV RNA-negative plasma and PBMCs from healthy blood donors. The 3 experimental chimpanzees, but not the control chimpanzee, generated HCV-specific T cell responses against nonstructural and structural HCV sequences 6-10 weeks after the first infusion of patient plasma and during subsequent infusions. In 1 chimpanzee, T cell responses declined, and this animal developed high-level viremia at week 27. Deep sequencing of HCV demonstrated transmission of a minor HCV variant from the first infusion donor that persisted in the chimpanzee for more than 6 months despite undetectable systemic viremia. Collectively, these results demonstrate that trace amounts of HCV RNA, which appear sporadically in successfully treated patients, can be infectious; furthermore, transmission can be masked in the recipient by an extended eclipse phase prior to establishing high-level viremia.

Hepatitis C virus-specific cellular immune responses in sustained virological responders with viral persistence in peripheral blood mononuclear cells

BACKGROUND & AIMS

Hepatitis C virus (HCV)-RNA detection in peripheral blood mononuclear cells (PBMCs) after recovery from HCV infection, is a type of occult HCV infection although is unclear how the viral persistence in PBMCs affects HCV-specific T-cell responses. The aim of this study was to investigate if cellular immune responses are modified by HCV persistence in PBMCs.

METHODS

HCV-specific CD4(+) and CD8(+) T-cell responses against six HCV peptides, situated within the non-structural (NS) proteins NS3, NS4b and NS5b, were measured by flow cytometry-through intracellular detection of gamma interferon (IFN-γ) or interleukin 4 (IL-4) and CD69 expression- in 27 sustained virological responders (SVR): 13 with and 14 without occult HCV infection in PBMCs, detected by strand-specific real-time PCR. Ten healthy individuals and 14 chronically infected patients with viraemia, were included as controls.

RESULTS

SVR without occult infection showed a higher percentage of activated CD4(+) cells against peptides belonging to NS3 (p124, p153) and NS5b (p257, p294), activated CD8(+) cells against NS3 (p124, p153, p158) and NS5b-p294, as well as an elevated percentage of CD4(+) cells releasing IFN-γ + IL-4 against NS3-p153, and by CD8(+) cells against NS3 (p124, p153). SVR without occult infection showed a higher percentage of activation and release of IFN-γ + IL-4 by both cell subpopulations than the two group of controls, in contrast to SVR with occult infection.

CONCLUSION

The lower HCV-specific T-cell response found in SVR with occult infection indicates that the immune response may be impaired when the virus persists in PBMCs.

Does chemotherapy cause viral relapse in cancer patients with hepatitis C infection successfully treated with antivirals?

Authors have reported conflicting results on the persistence of hepatitis C virus (HCV) infection in patients having sustained virologic response (SVR) to treatment. Therefore, we sought to determine whether chemotherapy leads to viral relapse in 30 HCV-infected patients who had SVR before cancer diagnosis. Half of them had hematologic malignancies. Most (60%) received HCV therapy with interferon and ribavirin. Chemotherapy was started at a median of 72 months after SVR and included rituximab (27%), cyclophosphamide (23%), cisplatin (17%), or corticosteroids (37%). No patient had post-SVR viral relapse. Therapeutically induced resolution of HCV appears to be permanent and not affected by chemotherapy.

Prevalence of occult hepatitis C infection in chronic hemodialysis and kidney transplant patients

BACKGROUND & AIMS

Detection of hepatitis C virus (HCV) RNA in peripheral blood mononuclear cells (PBMC) and/or hepatocytes in absence of HCV RNA in serum, designated as 'occult HCV infection', has been a matter of controversy in recent years. We investigated for the first time the prevalence of occult HCV infection in large cohorts of chronic hemodialysis (CHD) and kidney transplant (KTx) patients.

METHODS

We enrolled 417 CHD patients, 417 KTx recipients and 2 control groups - 25 anti-HCV (antibody against HCV)-positive and HCV RNA-positive patients with chronic hepatitis C, and 40 anti-HCV-, HCV RNA-, and HBsAg-negative healthy subjects. HCV RNA was tested in serum and PBMC using a sensitive commercial assay.

RESULTS

In CHD patients, the prevalence of anti-HCV was 3.6% (15/417) and of positive serum HCV RNA 2.4% (10/417). HCV RNA was detected in PBMC in 1/407 (0.25%) HCV serum RNA-negative patients ("occult HCV infection"). In KTx recipients, prevalence of anti-HCV was 4.8% (20/417) and of positive serum HCV RNA 4.6% (19/417). Occult HCV infection was found in 2/398 (0.5%) serum HCV RNA-negative patients. On a mean longitudinal follow-up of 30months of the 3 patients with occult HCV infection, there was no clinical or virological evidence of HCV infection.

CONCLUSIONS

The prevalence of occult HCV infection was very low in our CHD and KTx patients, and it did not appear to be clinically relevant. Further studies in geographic populations with high HCV endemicity are required to clarify the significance of occult HCV infection in these patient groups.

Hepatitis C virus late relapse after sustained virologic response from interferon and ribavirin treatment as confirmed by RNA sequencing

Hepatitis C virus (HCV) viremia is unusual (<5%) after successful treatment, defined as sustained virologic response (SVR) or undetectable HCV PCR 12 to 24 weeks after therapy. We present a case of late virologic relapse (de novo infection was excluded by RNA sequencing) after SVR followed by spontaneous viral clearance.

Sequence analysis of hepatitis C virus from patients with relapse after a sustained virological response: relapse or reinfection?

BACKGROUND

A sustained virological response (SVR) is the major end point of therapy for chronic hepatitis C virus (HCV) infection. Late relapse of infection is rare and poorly characterized. Three of 103 patients with a SVR treated at the National Institutes of Health had late relapse. We evaluated HCV RNA sequences in serum and liver tissue to distinguish relapse from reinfection.

METHODS

Per patient, 10-22 clones of amplified 5' untranslated region were evaluated in pretreatment and relapse serum specimens and in liver biopsy specimens obtained during SVR. Genotypes and sequence diversity were evaluated. Four patients whose infection relapsed before they reached a SVR (ie, the early relapse group) were used as a comparison.

RESULTS

Results of tests for detection of serum HCV RNA in all patients with late relapse were repeatedly negative during the first 24 weeks after therapy but became positive 8, 75, and 78 months after SVR. Reinfection risk factors were absent in 2 of 3 patients. In all patients with early or late relapse, apart from minor variations, the original HCV sequence was present before treatment and after relapse. All liver biopsy specimens from patients with late relapse were HCV RNA positive at SVR, with sequences nearly identical to those of specimens obtained at other time points.

CONCLUSIONS

Sequence comparisons suggest that reappearance of HCV RNA years after a SVR can be from relapse of the initial viral infection rather than reinfection from a different virus.

Extinction of hepatitis C virus by ribavirin in hepatoma cells involves lethal mutagenesis

Lethal mutagenesis, or virus extinction produced by enhanced mutation rates, is under investigation as an antiviral strategy that aims at counteracting the adaptive capacity of viral quasispecies, and avoiding selection of antiviral-escape mutants. To explore lethal mutagenesis of hepatitis C virus (HCV), it is important to establish whether ribavirin, the purine nucleoside analogue used in anti-HCV therapy, acts as a mutagenic agent during virus replication in cell culture. Here we report the effect of ribavirin during serial passages of HCV in human hepatoma Huh-7.5 cells, regarding viral progeny production and complexity of mutant spectra. Ribavirin produced an increase of mutant spectrum complexity and of the transition types associated with ribavirin mutagenesis, resulting in HCV extinction. Ribavirin-mediated depletion of intracellular GTP was not the major contributory factor to mutagenesis since mycophenolic acid evoked a similar decrease in GTP without an increase in mutant spectrum complexity. The intracellular concentration of the other nucleoside-triphosphates was elevated as a result of ribavirin treatment. Mycophenolic acid extinguished HCV without an intervening mutagenic activity. Ribavirin-mediated, but not mycophenolic acid-mediated, extinction of HCV occurred via a decrease of specific infectivity, a feature typical of lethal mutagenesis. We discuss some possibilities to explain disparate results on ribavirin mutagenesis of HCV.

Occult hepatitis C virus infection in candidates for liver transplant with cryptogenic cirrhosis

BACKGROUND

Occult hepatitis C virus (HCV) infection is a new entity described by the presence of HCV-RNA in liver biopsy and/or peripheral blood mononuclear cell (PBMC) specimens, and undetectable levels or absence of HCV-RNA and in the absence or presence of anti HCV antibodies in plasma by current laboratory methods.

OBJECTIVES

To evaluate the detection of HCV-RNA in PBMC specimens of the liver transplant candidates with cryptogenic cirrhosis by reverse transcriptase-nested polymerase chain reaction (RT-nested PCR).

PATIENTS AND METHODS

From November 2007 to March 2013, 45 patients from Liver Transplant Center of Imam Khomeini Hospital, Tehran, were enrolled in this cross sectional study. PBMC specimens were separated from the peripheral blood sample. After extraction of RNA from plasma and PBMC specimens, HCV-RNA status was tested by RT-nested PCR. The 5'-untranslated region (5'-UTR) genotyping of HCV-RNA amplified from PBMC specimens was performed by a standard methodology with the INNO-LiPA(TM) HCV II kit. The PCR products of 5'-UTR were sequenced after cloning into the pJET1.2 / blunt cloning vector.

RESULTS

Of 45 patients, 4 (8.9% [95% CI: 4.4-15.6]) had detectable genomic HCV-RNA in their PBMC specimens. HCV genotypes were determined in the PBMCs of these subjects showed that 2 (50.0%) subjects with occult HCV infection had HCV subtype 3a, and 2 (50.0%) had HCV subtype 1b.

CONCLUSIONS

This study found that 8.9 % of the Iranian candidates for liver transplant with cryptogenic cirrhosis had occult HCV infection. Therefore, designing prospective studies focusing on the diagnosis of occult HCV infection in these subjects prior to liver transplantation could be valuable.

Deep sequencing analysis of HCV NS3 resistance-associated variants and mutation linkage in liver transplant recipients

Viral variants with decreased susceptibility to HCV protease inhibitors (PIs) occur naturally and preexist at low levels within HCV populations. In patients failing PI monotherapy, single and double mutants conferring intermediate to high-level resistance to PIs have been selected in vivo. The abundance, temporal dynamics and linkage of naturally occurring resistance-associated variants (RAVs), however, have not been characterized in detail. Here, using high-density pyrosequencing, we analyzed HCV NS3 gene segments from 20 subjects with chronic HCV infection, including 12 subjects before and after liver transplantation. Bioinformatics analysis revealed that Q80 substitution was a dominant variant in 40% of the subjects, whereas other RAVs circulate at low levels within quasispecies populations. Low frequency mutation linkage was detectable by Illumina paired-end sequencing in as low as 0.5% of the mock populations constructed from in vitro RNA transcripts but were uncommon in vivo. We show that naturally occurring RAVs are common and can persist long term following liver transplant at low levels not readily detectable by conventional sequencing. Our results indicate that mutation linkage at low levels could be identified using the Illumina paired-end approach. The methods described here should facilitate the analysis of low frequency HCV drug resistance, mutation linkage and evolution, which may inform future therapeutic strategies in patients undergoing direct acting antiviral therapies.

Two distinct functional patterns of hepatitis C Virus (HCV)-specific T cell responses in seronegative, aviremic patients

In hepatitis C Virus (HCV) high-risk groups, HCV-specific T cell responses have been detected in seronegative, aviremic persons who have no evidence of HCV infection. Herein, we investigated functional profiles of HCV-specific T-cell responses in seronegative, aviremic patients of a HCV high-risk group. Seventy seven hemodialysis patients with chronic renal disease were analyzed by IFN-γ ELISpot assays, and eight of 71 (11.3%) seronegative, aviremic patients displayed HCV-specific T-cell responses. Their HCV-specific memory T cells were characterized by assessing cytokine polyfunctionality, known to provide antiviral protection. By intracellular staining of IFN-γ, TNF-α, IL-2 and MIP-1β, we identified two distinct populations in the seronegative, aviremic patients: polyfunctional responders and TNF-α-predominant responders. In further analysis, occult HCV infection was excluded as a cause of the HCV-specific T cell response via secondary nested RT-PCR of HCV RNA in peripheral blood mononuclear cell samples. HCV-specific T cells targeted multiple epitopes including non-structural proteins in a single patient, implying that their T cells might have been primed by HCV proteins synthesized within the host. We conclude that HCV-specific memory T cells of seronegative, aviremic patients arise from authentic HCV replication in the host, but not from current occult HCV infection. By functional pattern of HCV-specific T cells, there are two distinct populations in these patients: polyfunctional responders and TNF-α-predominant responders.

Investigation of residual hepatitis C virus in presumed recovered subjects

Recent studies have found hepatitis C virus (HCV) RNA in peripheral blood mononuclear cells (PBMCs) of the majority of presumed recovered subjects. We investigated this unexpected finding using samples from patients whose HCV RNA and anti-HCV status had been serially confirmed. HCV RNA was detected in PBMCs from 66 of 67 chronic HCV carriers. Subpopulation analysis revealed that the viral load (log copies/10(6) cells) in B cells (4.14 ± 0.71) was higher than in total PBMCs (3.62 ± 0.71; P < 0.05), T cells (1.67 ± 0.88; P < 0.05), and non-B/T cells (2.48 ± 1.15; P < 0.05). HCV negative-strand RNA was not detected in PBMCs from any of 25 chronically infected patients. No residual viral RNA was detected in total PBMCs or plasma of 59 presumed recovered subjects (11 spontaneous and 48 treatment induced) using nested real-time polymerase chain reaction with a detection limit of 2 copies/μg RNA (from ≈ 1 × 10(6) cells). PBMCs from 2 healthy HCV-negative blood donors became HCV RNA positive, with B-cell predominance, when mixed in vitro with HCV RNA-positive plasma, thus passively mimicking cells from chronic HCV carriers. No residual HCV was detected in liver or other tissues from 2 spontaneously recovered chimpanzees.

CONCLUSION

(1) HCV RNA was detected in PBMCs of most chronic HCV carriers and was predominant in the B-cell subpopulation; (2) HCV detected in PBMCs was in a nonreplicative form; (3) HCV passively adsorbed to PBMCs of healthy controls in vitro, becoming indistinguishable from PBMCs of chronic HCV carriers; and (4) residual HCV was not detected in plasma or PBMCs of any spontaneous or treatment-recovered subjects or in chimpanzee liver, suggesting that the classic pattern of recovery from HCV infection is generally equivalent to viral eradication.