Hepatitis C virus replication in liver and peripheral blood mononuclear cells of interferon-alpha-treated and untreated patients with chronic hepatitis C

Quantitation of hepatitis C virus RNA in peripheral blood mononuclear cells in HCV-monoinfection and HIV/HCV-coinfection

Peripheral blood mononuclear cells (PBMCs) represent an extrahepatic hepatitis C virus (HCV) reservoir, the significance of which is unclear due to limited studies and varying test methodologies. In this study, a commercial viral load assay for measuring cell-associated PBMC HCV RNA was evaluated. HCV RNA was extracted from PBMCs, sorted CD14+, and CD19+ cells and corresponding plasma samples using the Abbott m2000 and Real-Time HCV assay. Test performance and influence of HIV seropositivity on plasma and PBMC HCV RNA were studied. Among 51 patients, 67 and 62 unique patient samples had detectable plasma and PBMC HCV viral load, respectively. The median PBMC viral load was 535 IU/1 M cells (range 29-5,190). CD19+ cells had significantly higher viral load than CD14+ cells (median log(10) HCV viral load 2.63 vs. 1.50 IU/ml; P< 0.001). Stability of PBMC viral load over time was demonstrated in untreated patients; all patients with an undetectable plasma HCV viral load after HCV treatment also demonstrated undetectable PBMC viral load. Repeated testing in nine samples yielded consistent PBMC viral load, differing by only 1.3-fold (range 1.0-1.7-fold). Among samples with detectable plasma HCV RNA, the correlation between PBMC and plasma viral load was moderate (r = 0.66) and was greater among HCV mono-infected compared to HIV/HCV co-infected subjects (r = 0.80 vs. 0.52). Measurement of cell-associated PBMC HCV RNA using a commercial assay demonstrated promising test characteristics. Differences in PBMC HCV viral load based on HIV-coinfection status and the significance of greater copy number in B-cells requires further study.

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

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

Prediction of relapse after interferon therapy in hepatitis C virus-infected patients by the use of triple assay

BACKGROUND AND METHODS

In recent years, several tests have been used as predictive factors for relapse after the end of interferon therapy of chronic hepatitis C carriers. Serum hepatitis C virus (HCV)-RNA has proved insensitive for predicting relapse because more than 50% of patients with undetectable reverse transcription-polymerase chain reaction (RT-PCR) levels of HCV at the end of therapy become positive for viral RNA after interferon withdrawal. The detection of a minus RNA strand of HCV in liver also failed to efficiently predict relapses in chronic hepatitis patients. Furthermore, the use of a whole blood assay of HCV-RNA has been controversial. We used a triple assay comprised of RT-PCR tests for the detection of HCV-RNA plus strand in serum and peripheral blood mononuclear cells (PBMC), together with testing for the minus strand in PBMC for prediction of relapse after interferon + ribavirin combination therapy in 45 patients with chronic hepatitis C.

RESULTS

The only four patients with a negative triple assay had no relapse 1 year after the end of therapy. In contrast, two-thirds of the 12 patients who tested negative for viral RNA in serum at the end of therapy relapsed 1 year later.

CONCLUSION

We concluded that the absence of both minus and plus strands in patients who tested negative for serum PCR may indicate the total eradication of HCV.

A novel strand-specific RT-PCR for detection of hepatitis C virus negative-strand RNA (replicative intermediate): evidence of absence or very low level of HCV replication in peripheral blood mononuclear cells

Hepatitis C virus (HCV) is reported to be lymphotropic under certain circumstances. In order to evaluate viral replication in peripheral blood mononuclear cells (PBMCs), a novel strand-specific RT-PCR was developed for the determination of HCV negative-strand RNA. The detection limit of this strand-specific RT-PCR was 100 copies of HCV negative-strand RNA in the presence of 1 microg liver RNA and 10(7)-10(8) copies of positive-strand RNA. False positive PCR signals occurred only when HCV positive-strand RNA exceeded 10(9) copies. With this RT-PCR, the replicative-intermediates could be detected specifically in eight of ten liver tissues, but not in any samples of serum or plasma (0/65) of patients with chronic hepatitis C. When examining the PBMCs of 46 hepatitis C patients, including 12 patients who had undergone orthotopic liver transplantation, HCV negative-strand RNA was detected in only one patient (1/46). In addition, HCV replicative intermediates were not detected in PBMCs of patients using immunosuppressive agents. It is concluded that the replication of HCV in PBMCs is very unusual.

Combination therapy with ribavirin and alpha interferon for the treatment of chronic hepatitis C refractory to interferon

BACKGROUND

Up to 80% of hepatitis C patients are refractory to treatment with interferon-alpha. These patients are not likely to benefit from higher dosages or longer duration of interferon alone. The addition of ribavirin has been shown to improve the response rate in patients resistant to a previous course of interferon-alpha alone.

AIM

To evaluate whether a sustained hepatitis C virus (HCV) RNA response could be obtained with combination therapy of interferon-alpha and ribavirin in patients who did not respond to or relapsed after a standard interferon-alpha treatment.

METHODS

A total of 73 patients, 59 non-responders and 14 relapsers after interferon-alpha alone, were treated with a combination of ribavirin (1000-1200 mg/day) and interferon-alpha (3 MU three times a week) for 24 weeks. Alanine aminotransferase levels and HCV RNA were checked for 24 weeks after completion of therapy.

RESULTS

At the end of the combination therapy, 36 patients (49%) showed alanine aminotransferase normalization and in 20 patients (27%), HCV RNA was undetectable in serum. At the end of the 24 weeks follow-up period, only 12 patients (16%) had a sustained response with serum negativity of HCV RNA. This response was significantly higher in relapsers than in non-responders: five (36%) vs. seven (12%) patients (P=0.03), respectively. Adverse effects were restricted to flu-like symptoms and moderate haemolytic anaemia.

CONCLUSIONS

Combination of interferon-alpha and ribavirin is quite limited, both in scope and efficacy, in HCV patients who had a non-response to monotherapy with interferon. Better results may be expected in relapsers, but larger studies are necessary.

Interferon versus ribavirin plus interferon in chronic hepatitis C previously resistant to interferon: a randomized trial

BACKGROUND

More than 70% of patients with chronic hepatitis C are resistant to interferon therapy. Ribavirin, in association with interferon, has been demonstrated as effective, at a dose of 800-1200 mg/day, but the efficacy of a lower dose has not been established.

METHODS

We assessed the effectiveness of the combination of 600 mg/day of ribavirin plus 3 MU of interferon over a period of 6 months, in a group of patients previously resistant to interferon. Sixty-two patients with chronic hepatitis C with serum and hepatic HCV RNA relapsers or non-responders to interferon, were randomly divided into two groups: group A received 3 MU of interferon alpha-2b, three times a week for 6 months; group B was given the same dose plus 600 mg per day of ribavirin for 6 months. Two patients from each group dropped from therapy. One patient from group A and two from group B withdrew from treatment because of adverse effects.

RESULTS

Mean alanine aminotransferase levels were similar in both groups throughout the study. A sustained response was observed in 7% and 7.4% of groups A and B with short-term response in 39% and 59%, and no response in 54% and 34% from both groups respectively (non-significant). At 12 months, 4 and 7 patients from groups A and B respectively, cleared serum HCV RNA however, only one sustained responder from each group cleared HCV RNA from peripheral blood mononuclear cells. At 18 months, 3 patients remained serum HCV RNA negative. Adverse effects were similar. Only haemoglobin values were lower in group B in the first month of therapy (p<0.05).

CONCLUSION

In conclusion, the combination of 3 MU of interferon plus 600 mg of ribavirin is not effective in chronic hepatitis C resistant to interferon.

In Vivo Tropism of Hepatitis C Virus Genomic Sequences in Hematopoietic Cells: Influence of Viral Load, Viral Genotype, and Cell Phenotype

Extrahepatic sites capable of supporting hepatitis C virus (HCV) replication have been suggested. We analyzed the influence of virological factors such as viral genotype and viral load, and cellular factors such as cell phenotype, on the detection rate of HCV sequences in hematopoietic cells of infected patients. Thirty-eight chronically infected patients were included in the study: 19 infected by genotype 1 isolates (1a and 1b), 13 by nongenotype 1 isolates (including genotypes 2 a/c, 3a, and 4), and 6 coinfected by genotype 1 and 6 isolates. Polymerase chain reaction (PCR) detection efficiency of viral genomic sequences, both the positive and negative strand RNA, was evaluated using RNA transcripts derived from genotype 1, 2, 3, and 4 cloned sequences and found to be equivalent within one log unit. The serum viral load, ranging from less than 2 × 105 Eq/mL to 161 × 105 Eq/mL, did not influence the detection rate of either strand of RNA in patients' peripheral blood mononuclear cells (PBMCs). Positive and negative strand RNA were found in PBMCs of all 3 cohorts of patients with a detection rate ranging from 15% to 100% and from 8% to 83.3% for the positive and negative strand RNA, respectively. Coinfected patients showed a detection rate in all cases greater than 80%. Patients infected with genotype 1 isolates showed a higher detection rate of either strands of RNA when compared with patients infected with other genotypes (P < .001 andP < .04). Both strands were found restricted to polymorphonuclear leukocytes, monocytes/macrophages, and B (but not T) lymphocytes. These data show that HCV genomic sequences, possibly reflecting viral replication, can be detected in PBMCs of chronically infected patients independent of the viral load and that specific associated cell subsets are implicated in the harboring of such sequences.

In Vivo Tropism of Hepatitis C Virus Genomic Sequences in Hematopoietic Cells: Influence of Viral Load, Viral Genotype, and Cell Phenotype

Extrahepatic sites capable of supporting hepatitis C virus (HCV) replication have been suggested. We analyzed the influence of virological factors such as viral genotype and viral load, and cellular factors such as cell phenotype, on the detection rate of HCV sequences in hematopoietic cells of infected patients. Thirty-eight chronically infected patients were included in the study: 19 infected by genotype 1 isolates (1a and 1b), 13 by nongenotype 1 isolates (including genotypes 2 a/c, 3a, and 4), and 6 coinfected by genotype 1 and 6 isolates. Polymerase chain reaction (PCR) detection efficiency of viral genomic sequences, both the positive and negative strand RNA, was evaluated using RNA transcripts derived from genotype 1, 2, 3, and 4 cloned sequences and found to be equivalent within one log unit. The serum viral load, ranging from less than 2 × 105 Eq/mL to 161 × 105 Eq/mL, did not influence the detection rate of either strand of RNA in patients' peripheral blood mononuclear cells (PBMCs). Positive and negative strand RNA were found in PBMCs of all 3 cohorts of patients with a detection rate ranging from 15% to 100% and from 8% to 83.3% for the positive and negative strand RNA, respectively. Coinfected patients showed a detection rate in all cases greater than 80%. Patients infected with genotype 1 isolates showed a higher detection rate of either strands of RNA when compared with patients infected with other genotypes (P < .001 andP < .04). Both strands were found restricted to polymorphonuclear leukocytes, monocytes/macrophages, and B (but not T) lymphocytes. These data show that HCV genomic sequences, possibly reflecting viral replication, can be detected in PBMCs of chronically infected patients independent of the viral load and that specific associated cell subsets are implicated in the harboring of such sequences.

Hepatitis C virus RNA detection in serum and peripheral blood mononuclear cells of patients with hepatitis C

AIM: To investigate the existence and clinical significance of hepatitis C virus (HCV) RNA in the serum and peripheral blood mononuclear cells (PBMC) of patients with hepatitis C.

METHODS: HCV RNA was detected by nested polymerase chain reaction (Nested PCR) in serum and in PBMC of 46 patients with acute hepatitis C (AHC) and in 42 patients with chronic hepatitis C (CHC).

RESULTS: The positive rate of HCV RNA in PBMC of patients with CHC was markedly higher than that of patients with AHC (P < 0.01). The positive rates of HCV RNA in serum of patients with AHC and CHC and in PBMC of patients with CHC were significantly higher than those of anti-HCV positive patients with normal alanine aminotransferase (ALT) levels (P < 0.01). HCV RNA was negative in the serum of two patients, but could be detected in PBMC. In 12 patients, anti HCV was negative while HCV RNA was positive in serum.

CONCLUSION: (1) detection of serum HCV RNA by nested PCR might be helpful in the early diagnosis of anti-HCV negative hepatitis C; (2) liver damage in patients with hepatitis C might be correlated with HCV-viremia; (3) infection of PBMC by HCV might play an important role in chronic liver damage in patients with HCV and in the chronicity of its clinical course; and (4) PBMC might be considered as a “reservoir” for HCV.

Pathogenesis of chronic hepatitis C and associated clinical manifestations

In 20% of patients exposed to hepatitis C virus, infection is transient but, after a few months, the patient remains susceptible to infection with the same strain. Protective immunity is short-lived. This suggests that recovery is related to the cellular immune response, which presumably lyses infected cells, and that the need during recovery for a virus-neutralizing anti-envelope response, is transient. In 80% of patients the infection is persistent, and it seems that antigenic variation of the envelope proteins allows the virus to escape neutralization by anti-envelope responses. The fact that this antigenic variation occurs at a much lower rate in agammaglobulinaemic subjects suggests that the major immune pressure producing this variation is humoral. How the virus-infected cells avoid lysis by cytotoxic T cells, which can be demonstrated in small numbers in the infected liver, remains unclear. The recent observation, that HCV infects CD8 lymphocytes, raises the possibility that virus infection of CD8 cells may impair their function and contribute to persistent infection. The mechanisms of production of cryoglobulin and of autoantibody formation are both unclear.

Lack of detection of negative-strand hepatitis C virus RNA in peripheral blood mononuclear cells and other extrahepatic tissues by the highly strand-specific rTth reverse transcriptase PCR

To further explore the controversial potential for extrahepatic replication of hepatitis C virus (HCV), the highly strand-specific rTth method of reverse transcriptase PCR was used to examine sera, liver, peripheral blood mononuclear cells, and other extrahepatic tissues from HCV-infected chimpanzees and humans. Positive-strand HCV RNA was present in the liver at approximately 10-fold-higher levels than negative-strand HCV RNA. No negative-strand RNA was detected in peripheral blood mononuclear cells or other extrahepatic tissues despite the presence of abundant positive-strand RNA. These data demonstrate that within the limits of sensitivity of this highly strand-specific reverse transcriptase PCR method, no extrahepatic replication of HCV was detected.

HCV replication in mononuclear cells stimulates anti-HCV-secreting B cells and reflects nonresponsiveness to interferon-alpha

Recently, it was demonstrated in chronic hepatitis C that the release of IgG and IgM anti-HCV antibodies by mononuclear cells (PBMCs) correlated with inflammatory activity, HCV persistence in serum, and negative outcome from antiviral therapy. Thus, persistent antigenic stimulation of the antibody-secreting B cells has been suggested. In this study, PBMCs were derived from 13 patients with chronic hepatitis C. Nucleic acids were extracted by the guanidine-thiocyanate-method, and plus- and minus-stranded HCV-RNAs were determined using primers from the 5'-untranslated region of HCV. Simultaneously, unstimulated PBMCs were cultured for 8 days and anti-HCV antibodies were detected in the supernatants by EIA and RIBA. Seven patients (53.8%) had both plus- and minus-stranded HCV-RNA in PBMCs, while anti-HCV antibodies were secreted in vitro. One of 2 patients with plus- but not minus-stranded HCV-RNA in PBMCs was anti-HCV positive in vitro, whereas 4 patients without HCV-infected PBMCs were anti-HCV negative in vitro. Eight patients received antiviral therapy with interferon-alpha 2b. Four nonresponders and 1 partial responder had plus- and minus-stranded HCV-RNA in PBMCs and anti-HCV secretion in vitro. On the other hand, 2 complete responders and another partial responder showed neither HCV infection of PBMCs nor anti-HCV secretion in vitro.(ABSTRACT TRUNCATED AT 250 WORDS)

Evaluation of cellular immune responses and soluble mediators in patients with chronic hepatitis C virus (cHCV) infection

In 54 patients with cHCV infection, peripheral immune responsiveness and soluble mediator release were evaluated. Results demonstrate that in these patients phagocytosis and killing capacities exerted by polymorphonuclear cells and monocytes were profoundly depressed. At the same time, absolute numbers of CD3+, CD8+ and CD16+ cells were reduced, while the CD4(+)-CD8+ dependent antibacterial activity was also impaired. With special reference to soluble mediators, elevated amounts of both soluble interleukin-2 receptor and soluble intercellular adhesion molecule-1 were detected in sera of patients. By contrast, serum levels of tumor necrosis factor-alpha were within normal ranges, whereas interferon-gamma serum concentrations were decreased. Of note, in 18.5% of cHCV patients circulating levels of bacterial lipopolysaccharides (LPS) were detected by means of Limulus assay. In the Limulus+subset of patients, absolute numbers of CD14+ cells were reduced in a significant manner, this implying a putative monocyte-LPS interaction. In conclusion, the overall results indicate a condition of peripheral immune depression in cHCV patients with an exaggerated shedding of various mediators endowed with noxious effects for the host.

Detection of hepatitis C virus RNA in the cell fraction of saliva before and after oral surgery

The presence of hepatitis C virus (HCV) RNA in serum, whole saliva, and saliva from the submaxillary glands was investigated before and after oral surgery. The presence of HCV RNA (positive and negative-strand RNA) was determined in serum and saliva by a nested polymerase chain reaction in 26 anti-HCV positive patients, of whom 11 were coinfected with human immunodeficiency virus-1. Oral surgery was carried out on five occasions on four of the patients. HCV RNA was detected in the sera of 23 of 26 (88%) patients, and in the saliva of 4 of the 23 (17%) of the viremic patients. In all four cases, HCV RNA was detected only in the cell fraction derived from centrifugation of whole saliva. Negative-stranded HCV RNA was not detected. At one of five occasions of oral surgery, HCV RNA was detected in saliva sampled immediately after surgery, but not before or 24 hours after surgery. The results suggest that HCV is present in saliva in less than 25% of HCV viremic persons. The presence of the virus in saliva is restricted to the cell fraction. Thus, saliva may serve as a possible, but low, nonparenteral transmission route of HCV. Contamination of saliva by blood during and after oral surgery may result in an increased risk of viral exposure. Except for trauma caused by sharp instruments during surgery, this might contribute to the higher HCV seropositivity found among dentists.