Tobias Goeser

Peripheral blood leukocytes serve as a possible extrahepatic site for hepatitis C virus replication

To study possible extrahepatic sites for the replication of hepatitis C virus (HCV), we examined fresh and cultured peripheral blood mononuclear leukocytes (PBML), as well as different subpopulations of PBML of HCV-infected patients, for the presence of viral genomic and antigenomic RNA. Sense and antisense oligonucleotide primers derived from HCV sequences were used for reverse transcription (RT) followed by an amplification with the polymerase chain reaction assay (PCR). Using antisense primers for RT, genomic viral RNA could be detected in serum, liver, total PBML and B lymphocytes of chronically infected patients. However, only liver tissue and PBML specimens were positive when a sense primer was used. To demonstrate further the specificity of these findings, total PBML were stimulated using pokeweed mitogen and synthesis of HCV RNA was determined by incorporation of [3H]uridine into nascent viral RNA molecules using a hybrid release assay. Additionally, total PBML from an uninfected person could be infected in vitro using an HCV RNA-positive serum. The PCR products obtained from serum, liver and PBML specimens of an HCV-positive individual were found to have nearly identical sequences. Our findings suggest that PBML could be a site for viral replication of HCV during the natural course of infection and may represent a reservoir for hepatitis C virions.

Establishment of persistent hepatitis C virus infection and replication in vitro.

Hepatitis C virus (HCV) is a major cause of chronic viral hepatitis. Development of anti-viral strategies has been hampered by the lack of efficient cell systems to propagate HCV in vitro. To establish a long-term culture system, we tested human hepatoma (HuH7, HepG2) and porcine non-hepatoma (PK15, STE) cell lines, as well as several culture and infection conditions. As a marker for virus replication, minus-strand HCV RNA in infected cells was detected by an enhanced detection system using nested RT-PCR followed by hybridization analysis. Short-term efficiency of HCV infection (10 days) was slightly increased by addition of polyethylene glycol (PEG) and/or dimethyl sulfoxide (DMSO) to culture media during inoculation of HuH7, PK15 and STE cells, but no augmentation in long-term culture was achieved, suggesting enhanced attachment of HCV to cells rather than more efficient infection. A stabilizing effect on HCV propagation was observed for 50 days in a serum-free medium with stimulation of the low-density lipoprotein (LDL) receptor expression by lovastatin. Using partially serum-free culture conditions, long-term persistence of HCV in cells and release of virions into supernatant was achieved for up to 130 days. Infectivity of released virions in supernatants after long-term culturing (day 30-80) was shown by successful infection of fresh cells. In conclusion, supplementation with PEG, DMSO and lovastatin during inoculation did not enhance virus replication substantially, but continued stimulation of LDL-receptor expression resulted in infections which persisted for over 4 months. These data support the hypothesis of an LDL-receptor mediated uptake of HCV into cells in vitro.

Hepatotropism of GB virus C (GBV-C): GBV-C replication in human hepatocytes and cells of human hepatoma cell lines

BACKGROUND/AIMS Recently, GB virus C (GBV-C) has been identified as another virus potentially causing viral hepatitis. However, its hepatotropism and pattern of infection in humans is still unknown. To elucidate the presence and replication of GBV-C in the human liver, we investigated tissue samples of six explanted livers from five GBV-C mono- or GBV-C/HCV co-infected patients for GBV-C RNA plus- and minus-strand RNA. METHODS These tissues were examined using nested RT-PCR followed by Southern blot hybridization as well as fluorescence in situ hybridization on liver cryosections. To further substantiate susceptibility of liver cells for GBV-C, in vitro infection of human hepatoma cells (HuH7, HepG2) with GBV-C mono-infected serum was performed. RESULTS By reverse transcription followed by nested PCR (RT-PCR), 5 of 6 liver specimens (4/5 patients) were positive for GBV-C plus-strand RNA, and viral minus-strand RNA could be detected in 4 of 6 liver specimens (4/5 patients). One liver sample was negative for GBV-C RNA. In two specimens we could identify GBV-C infection by in situ hybridization. Virus infection appeared to be restricted to hepatocytes and detection of minus-strand RNA showed viral replication in a few highly infected liver cells. In vitro infection of HepG2 or HuH7 cells confirmed these findings by a release of virions into supernatant. CONCLUSION In conclusion, our results establish GBV-C as a hepatotropic virus infecting human cells of hepatic origin in vivo and in vitro.

B-lymphocytes are predominantely involved in viral propagation of hepatitis C virus (HCV)

Recent reports have shown that HCV infection is not only restricted to hepatocytes. Like hepatitis B virus (HBV), which also was thought to be strictly hepatotropic in early molecular and cellular investigations, infection of lymphoid cells by HCV in vivo has been demonstrated. We showed that total peripheral blood leukocytes of chronically HCV-infected patients are infected by detection of plus- and minus-stranded HCV RNA using strand-specific oligonucleotide primers in the RT-PCR. These cells also represent extrahepatic sites for the viral replication, as demonstrated by incorporation of [3H]-uridine into nascent RNA after stimulation of the cells with a mitogen. Furthermore, total PBML from an uninfected person could be infected in vitro using an HCV-positive serum. It could be shown that replication of HCV RNA takes place in these cells. Examination of different subsets of PBML showed predominant infection of B-lymphocytes during HCV disease. Additionally, infection of T-lymphocytes was detected in about 50% of all chronically HCV-infected patients.

Clinical presentation of GB-C virus infection in drug abusers with chronic hepatitis C

BACKGROUND/AIMS Recently, the hepatitis GB-C virus (GBV-C) has been identified as another virus potentially causing chronic hepatitis. Although high rates of coinfection are emerging in drug addicts with chronic hepatitis C virus infection, no detailed data on clinical presentation are available. Therefore, co-infection was sought in hepatitis C virus patients to determine the impact of GB-C virus on clinical presentation. METHODS GBV-C was determined by nested reverse transcriptase-polymerase chain reaction in serum of 70 HIV negative intravenous drug abusers with chronic hepatitis C. Biochemical, histological and virological parameters were compared between patients with or without GBV-C coinfection. RESULTS Hepatitis C virus and GBV-C coinfection was found in 18 of 70 (25.7%) patients. Cases with coinfection were younger and had shorter duration of disease (31.4+/-6.2 vs. 35.3+/-7.3 (p=0.09) and 9.9+/-6.8 vs. 12.9+/-7.7 (p=0.17) years) than those without coinfection. Neither hepatitis C virus genotype distribution and HCV RNA levels nor serum liver function tests, titers of immunoglobulins or autoantibodies differed between the two groups. Histologically, chronic active hepatitis (16.7 vs. 46.4%, p=0.07), fibrosis (8.3% vs. 21.4%, p=0.3), and cirrhosis (0% vs. 8.2%, p=0.31) were less prevalent in coinfected patients. After interferon treatment, 5/6 coinfected and 11/19 patients with hepatitis C virus infection alone had cleared HCV RNA and 4/6 lost GBV-C RNA from serum. The two patients with GBV-C/HCV infection who persistently cleared hepatitis C virus but not GBV-C from serum had normal transaminases during follow-up despite persistence of GBV-C. CONCLUSIONS Coinfection of chronic hepatitis C patients with GBV-C does not lead to a significant change in clinical presentation, severity of liver disease, hepatitis C viremia, or response to interferon treatment.

Case Report: Primary Hepatic High-Grade Non-Hodgkin's Lymphoma and Chronic Hepatitis C Infection

Little is known about the coincidence of hepatitis C virus infection (HCV) and non-Hodgkins lymphoma, although there is an increased incidence of chronic HCV infection with cryoglobulinemia type II and, interestingly, low-grade non-Hodgkins lymphoma (NHL) in a few patients. We therefore report on a 74-year-old white male with known chronic hepatitis C virus infection who was admitted to the clinic due to weight loss and pain in the right upper quadrant. Ultrasound examination was performed for suspected hepatocellular carcinoma since a lesion in the left lobe of the liver was seen. X-ray of the lungs showed a few scattered lesions, suggestive of metastases. The ultrasound-guided fine-needle puncture revealed a high-grade malignant B-cell NHL While alpha-fetoprotein was normal, both cryoglobulin type II and the polymerase chain reaction (PCR) for HCV were positive. After six cycles of chemotherapy consisting of CHOP, the patient showed complete remission over three years. Ultimately, he died due to a sudden myeloic blast crisis. In summary, we discuss the possible etiopathologic role of the hepatitis viruses in the occurrence of non-Hodgkins lymphoma. As we and others showed that HCV infects peripheral mononuclear blood cells (PBML), the infected PBML not only may be a source for reinfection after orthotopic liver transplantation, but also could be the cause for transformation and monoclonal propagation of lymphomatous tissue.

SEQUENCE ANALYSIS OF HEPATITIS GB VIRUS C (GBV-C) ISOLATES FROM 14 PATIENTS

In 1995, a new human hepatitis virus belonging to the family Flaviviridae was described and designated hepatitis GBV-C. To investigate variations within the genome of GBV-C and to study the relationship of GBV-C to GBV-A/B or hepatitis C virus (HCV), we established a detection system using reverse transcriptase polymerase chain reaction (RT-PCR) of the putative helicase region (NS3). So far, isolates derived from 14 different GBV-C-positive sera were analyzed (GBV-C/S3-36), showing 80.1-89.4% (mean: 85%) identical nucleotides. The deduced amino acid sequences revealed 97.3% homology. Nucleotide sequences of GBV-C/S3-36 revealed about 60% identity to GBV-A as well as to HCV, but only 56% identity to GBV-B. Amino acid sequences revealed 73.4 and 68.6% similarity to GBV-A and GBV-B, respectively, but a slightly higher percentage of 78.5% to HCV sequences. Thus, according to the putative GBV-C helicase sequence, a subtyping of GBV-C into different genotypes may be necessary.