Consensus oligonucleotide primers for the detection of GB virus C in human cryptogenic hepatitis

Viral metagenomics

Characterisation of new viruses is often hindered by difficulties in amplifying them in cell culture, limited antigenic/serological cross-reactivity or the lack of nucleic acid hybridisation to known viral sequences. Numerous molecular methods have been used to genetically characterise new viruses without prior in vitro replication or the use of virus-specific reagents. In the recent metagenomic studies viral particles from uncultured environmental and clinical samples have been purified and their nucleic acids randomly amplified prior to subcloning and sequencing. Already known and novel viruses were then identified by comparing their translated sequence to those of viral proteins in public sequence databases. Metagenomic approaches to viral characterisation have been applied to seawater, near shore sediments, faeces, serum, plasma and respiratory secretions and have broadened the range of known viral diversity. Selection of samples with high viral loads, purification of viral particles, removal of cellular nucleic acids, efficient sequence-independent amplification of viral RNA and DNA, recognisable sequence similarities to known viral sequences and deep sampling of the nucleic acid populations through large scale sequencing can all improve the yield of new viruses. This review lists some of the animal viruses recently identified using sequence-independent methods, current laboratory and bioinformatics methods, together with their limitations and potential improvements. Viral metagenomic approaches provide novel opportunities to generate an unbiased characterisation of the viral populations in various organisms and environments.

HEV, TTV and GBV-C/HGV markers in patients with acute viral hepatitis

The aim of the present study was to evaluate the prevalence of HEV, TTV and GBV-C/GBV-C/HGV in patients with acute viral hepatitis A, B and non-A-C. We evaluated sera of 94 patients from a sentinel program who had acute hepatitis A (N = 40), B (N = 42) and non-A-C (N = 12); 71 blood donors served as controls. IgM and anti-HEV IgG antibodies were detected by enzyme immunoassay using commercial kits. TTV and GBV-C/HGV were detected by nested PCR; genotyping was done by sequencing and phylogenetic analysis. Anti-HEV IgG was present in 38, 10 and 17% of patients with hepatitis A, B and non-A-C. Four patients with hepatitis A and 1 with non-A-C hepatitis also had anti-HEV IgM detected in serum. TTV was detected in 21% of patients with acute hepatitis and in 31% of donors. GBV-C/HGV was detected in 9% of patients with hepatitis, and in 10% of donors. We found TTV isolates of genotypes 1, 2, 3, and 4 and GBV-C/HGV isolates of genotypes 1 and 2. Mean aminotransferase levels were lower in patients who were TTV or GBV-C/HGV positive. In conclusion, the detection of anti-HEV IgM in some acute hepatitis A cases suggests co-infection with HEV and hepatitis E could be the etiology of a few cases of sporadic non-A-C hepatitis in Salvador, Brazil. TTV genotype 1, 2, 3 and 4 isolates and GBV-C/HGV genotype 1 and 2 strains are frequent in the studied population. TTV and GBV-C/HGV infection does not appear to have a role in the etiology of acute hepatitis.

The occupational hazards of emergency physicians

Emergency physicians are exposed to a variety of occupational hazards. Among these are infectious diseases, such the human immunodeficiency virus, hepatitis B and C viruses, and tuberculosis. Hepatitis G virus is transmissible but may not be a cause of illness. The likelihood of being exposed to these agents appears to be higher in the ED than other medical settings but estimates of the prevalence of these diseases in the ED vary, depending on the patient population served. Estimates of risk for contracting these infections are reviewed. Measures to prevent these exposures can reduce risk, but compliance is low, particularly for those involving changes in the behavior of emergency physicians (such as not recapping needles). Latex allergy is a hazard of health care workers. Its prevalence is reported to be quite high, but these findings are difficult to interpret in the absence of a universally accepted definition of the condition. Its prevalence in emergency physicians is not known. Other noninfectious hazards include workplace violence and exposure to nitrous oxide. The health effects of rotating shift work may put emergency physicians at increased risk of coronary artery disease and impaired reproductive health. Emotional stress is another hazard of emergency physicians, and may lead to burnout.

Reappraisal of biochemical hepatitis C activity in hemodialysis patients

We reappraised biochemical hepatitis C activity in hemodialysis patients in comparison with normal controls. A total of 111 hemodialysis patients and 66 healthy volunteer blood donors with hepatitis C virus (HCV) infection were consecutively enrolled. Serum alanine aminotransferase (ALT) levels were normal (< or =45 U/L) in 103 (93%) hemodialysis patients and 34 (52%) donors (p < 0.001). HCV viremic levels were lower in the hemodialysis group (p = 0.044), with no difference in the HCV genotype prevalence. During two-year follow-up, 60 (67%) of 90 hemodialysis patients and 13 (26%) of 50 donors showed persistently normal ALT levels (p < 0.001). For hemodialysis patients, however, the upper normal limit of ALT activity was reset at 25 U/L corresponding to the mean + 2 x SD for the normalized ALT distribution in 400 control patients. The adjusted ALT levels were initially normal in 73 (66%) hemodialysis patients and persistently normal in 19 (21%). Thus, ALT levels were the same for the two groups. GB virus C (GBV-C)/hepatitis G virus (HGV) coinfection found only in the hemodialysis group (10/111) had no influence on the disease. A relationship was noted between low disease activity and female gender in both groups. These findings indicate that biochemical hepatitis C activity in hemodialysis patients is similar to that in normal controls and should be monitored based on adjusted ALT levels.

Lessons from a multicentre study of the detectability of viral genomes based on a two-round quality control of GB virus C (GBV-C)/hepatitis G virus (HGV) polymerase chain reaction assay

The aim of this study was to determine whether multicentre quality controls for the detectability of viral genomes could contribute to the improvement of diagnostic performance in the participating laboratories. The study was carried out during two successive rounds, during which 18 laboratories specialized in nucleic acid testing analyzed, through a polymerase chain reaction (PCR) assay, a common panel of GB virus C (GBV-C)/hepatitis G virus (HGV) RNA-positive and -negative samples. During the first round, the laboratories used either an 'in-house' PCR procedure or a partly standardized commercial test. After decoding the results of the first round, the procedures of the participating laboratories were compared in order to establish a consensus procedure deduced from those of the laboratories which provided the best results. During the second round, each participating laboratory could use the resulting consensus procedure, or its own procedure, or both. The results of this quality control study indicated that, whatever method used, even specialized and trained laboratories may give false-negative or false-positive results. The commercial assay did not guarantee a systematic high quality level of results. The striking heterogeneity of results observed among laboratories using the same commercial assay confirm that molecular biology methods need skilled technicians. The results of this quality control study suggest that full standardization of viral genome detection, including all steps of the procedure, is necessary and that the laboratories performing PCR should participate in repeated quality control studies, whatever technique is being used.

Hepatitis G virus: molecular organization, methods of detection, prevalence, and disease association

This article reviews data on hepatitis G virus (HGV) prevalence and possible disease associations in various groups of patients. An important fraction of acute or chronic hepatitis cases probably have a viral etiology and are not attributable to known hepatitis viruses. Therefore, researchers continually are looking for new hepatitis viruses. Among the agents found are members of GB hepatitis viruses, including GB-C virus, or HGV. This review presents the history of the discovery of HGV, its molecular biology and some methods of detection; results of clinical and molecular studies of HGV infection also are discussed.

High prevalence of GB virus C in Brazil and molecular evidence for intrafamilial transmission

The prevalence of GB virus C (GBV-C) in candidate Brazilian blood donors with normal and elevated alanine aminotransferase levels was found to be 5.2% (5 of 95) and 6.5% (5 of 76), respectively. Among Brazilian patients, GBV-C was found in 9.5% (13 of 137) of cases of hepatitis not caused by hepatitis A virus (HAV), HBV, HCV, HDV, or HEV (non-A-E hepatitis) and in 18.2% (8 of 44) of individuals infected with HCV. Molecular characterization of GBV-C by partial sequencing of the NS3 region showed clustering between members of a single family, implying intrafamilial transmission. In conclusion, these results together suggest that contagion mechanisms which facilitate intrafamilial transmission of GBV-C may partially explain the high prevalence of viremic carriers worldwide.

No association between hepatitis C and B-cell lymphoma

Chronic viral infection has been implicated in the pathogenesis of B-cell lymphoma, and hepatitis C virus (HCV) infects lymphocytes. Chronic infection with HCV may result in B-cell proliferation. Individuals infected with hepatitis C are often co-infected with the RNA virus GB virus type C. Studies from Europe where hepatitis C infection is more common than in North America have shown a high prevalence of hepatitis C infection in patients with B-cell lymphoma. The aim of this study was to establish the prevalence of HCV and GBV-C infection in patients with B-cell lymphoma in an area of low HCV prevalence. One hundred patients with B-cell lymphoma (10 high grade, 46 intermediate grade, and 44 low grade) and 100 controls with nonhematological malignancies were studied. Serum was analyzed for HCV antibodies by third generation enzyme-linked immunosorbant assay, and HCV RNA and GBV-C RNA was analyzed by reverse transcriptase PCR. None of the controls or lymphoma patients had antibodies to HCV. HCV RNA was undetected in 60 out of 100 lymphoma patients tested. GBV-C RNA was detected in the serum of 5 out of 100 (5%) of lymphoma patients and in 3 out of 100 (3%) controls. Hepatitis C and GBV-C are, therefore, unlikely to play a major role in the pathogenesis of B-cell lymphoma in North America.

Hepatitis G virus infection in renal transplant recipients

To determine the prevalence and clinical significance of hepatitis G virus (HGV)/GB virus C (GBV-C) infection in renal transplant recipients, prospectively collected serum samples from a cohort of cadaveric renal transplant patients were studied for the presence of HGV RNA using a sensitive reverse transcription 'nested'-polymerase chain reaction (RT-PCR) based on primers derived from the 5' untranslated region. All positive PCR amplicons were sequenced bidirectionally and aligned. The nucleotide substitution rate was estimated by the 6-parameter method, and a phylogenetic tree was constructed using the Neighbour-joining method. HGV RNA was detected in 11/93 (12%) patients pretransplant and in 15/90 (17%) patients 1-4 years post-transplant. All PCR amplicons were confirmed to be specific for HGV by sequencing. Phylogenetic tree construction revealed that 17 PCR amplicons had sequences related to HGV and one had a sequence related to GBV-C. Two HGV RNA-positive patients pretransplant became HGV RNA negative post-transplant, and seven HGV RNA-negative patients pretransplant became HGV RNA positive post-transplant. There was no relationship between hepatitis C virus (HCV) and HGV infection. There were also no differences in age, gender distribution, ethnic origin, the total number of blood units transfused and either graft or patient survival between patients who were positive or negative for HGV RNA. We conclude that HGV infection is common among renal transplant candidates and recipients. Most of the isolates had sequences related to the HGV prototype. HGV infection does not appear to adversely affect clinical outcome in renal transplant recipients during early follow-up.

Absence of the negative strand of GBV-C/HGV RNA from the liver

BACKGROUND/AIMS

The pathogenic role of the human virus GBV-C/HGV remains unclear as information on tissue specific tropism and sites of replication of GBV-C/HGV is limited and controversial. The aim of this study was to determine whether the liver is the site of GBV-C/HGV replication.

METHODS

We utilized the strand-specific Tth RT-PCR assay to investigate the presence of the positive- and negative-strand of GBV-C/HGV RNA in liver and serum samples from 12 patients with chronic GBV-C/HGV infection; four were infected with GBV-C/HGV alone, six were coinfected with HCV and two with HBV. A control group of six patients infected with HCV alone was included. The presence of the positive- and negative-strand of HCV RNA was also investigated in the same samples.

RESULTS

All liver specimens were negative for the presence of the replicating negative-strand of GBV-C/HGV RNA. Positive-strand GBV-C/HGV RNA was found in 6 of the 12 liver samples and was detectable only at low levels, most probably reflecting serum contamination. By contrast, the negative strand of HCV RNA was detected in high titers in the liver of all HCV-infected and -coinfected subjects with less than a 100-fold difference from the positive strand. In serum samples only the positive strands of GBV-C/HGV and HCV RNA were detected in comparable titers.

CONCLUSIONS

The results of this study suggest that GBV-C/HGV is not replicating in the liver and, taken together with the bulk of evidence against hepatopathogenicity, they argue against the new agent being a hepatotropic virus. We suggest that the acronymic term of this agent GBV-C/HGV is used with the understanding that it is not a hepatitis virus.

Detection of GB virus C RNA by GBV-C LCx and two PCR assays with primers from the 5' non-coding and NS5B region

The objective of this study was to compare the sensitivity of three different reverse transcriptase-polymerase chain reaction (RT-PCR) based tests, for detection of GB virus C (GBV-C) RNA. One commercial and two 'in house' RT-PCR assays were employed in the testing of serum samples from 114 chronic hepatitis C infected individuals. A part of the 5' non-coding region (5'NCR) of the GBV-C genome was amplified by the GBV-C LCx assay (Abbott) and one of the 'in house' RT-PCR tests. In the other 'in house' RT-PCR a segment of the NS5B region was amplified. The 'in house' assays included the use of internal controls that were co-amplified with use of the same outer PCR primers as the virus targets. The GBV-C LCx from Abbott and 5'NCR 'in house' PCR tests detected 28 and 27 GBV-C positive individuals, respectively. The sample positive only in the LCx test was confirmed by the 'in house' 5'NCR RT PCR using an increased virus input. In comparison, the NS5B 'in house' PCR test detected 24 of the GBV-C positive samples. One sample showed no amplification of internal controls/virus target in the 5'NCR 'in house' PCR and another samples was amplification negative in the NS5B PCR. The PCR assays with primers from the 5'NCR of the virus genome e.g. the GBV-C LCx, were more sensitive compared with RT-PCR using primers from the NS5B region. The GBV-C LCx seemed to be the most sensitive and robust assay. Internal controls included in the 'in house' assays identified two samples with failure of the amplification.

Detection of GB virus C by the RT-PCR LCx system

The recent publication of representative genomic sequences of GBV-C has permitted the selection of PCR primers for detection of GBV-C in clinical samples by PCR techniques. Traditional amplification methodologies which couple reverse transcription polymerase chain reaction (RT-PCR) and Southern blot detection are slow, cumbersome, and can be technique dependent. This has hampered studies to determine the clinical significance of GBV-C. We report the selection of highly conserved PCR primers and a probe useful for semi-automated RT-PCR using the Abbott LCx system. This adaptation of the LCx system expands its capabilities to include the detection of RNA by RT-PCR, in addition to DNA detection by ligase chain reaction (LCR).

Elevated alanine aminotransferase (ALT) in blood donors: an assessment of the main associated conditions and its relationship to the development of hepatitis C

The determination of aminotranferases levels is very useful in the diagnosis of hepatopathies. In recent years, an elevated serum ALT level in blood donors has been associated with an increased risk of post-transfusion hepatitis (PTH). The purpose of the study was to research the factors associated with elevated ALT levels in a cohort of voluntary blood donors and to evaluate the relationship between increased ALT levels and the development of hepatitis C (HCV) infection. 166 volunteer blood donors with elevated ALT at the time of their first donation were studied. All of the donors were questioned about previous hepatopathies, exposure to hepatitis, exposure to chemicals, use of medication or drugs, sexual behaviour, contact with blood or secretions and their intake of alcohol. Every three months, the serum levels of AST, ALT, alkaline phosphatase, gamma glutamyl transpeptidase, cholesterol, triglyceride and glycemia are assessed over a two year follow-up. The serum thyroid hormone levels as well as the presence of auto-antibodies were also measured. Abdominal ultrasound was performed in all patients with persistently elevated ALT or AST levels. A needle biopsy of liver was performed in 9 donors without definite diagnostic after medical investigation. The presence of anti-HCV antibodies in 116 donors were assayed again the first clinical evaluation. At the end of follow-up period (2 years later) 71 donors were tested again for the presence of anti-HCV antibodies. None of donors resulted positive for hepatitis B or hepatitis C markers during the follow-up. Of the 116 donors, 101 (87%) had persistently elevated ALT serum levels during the follow-up. Obesity and alcoholism were the principal conditions related to elevated ALT serum levels in 91/101 (90.1%) donors. Hypertriglyceridemia, hypercholesterolemia, hypothyroidism and diabetes mellitus also were associated with increased ALT levels. Only 1/101 (0.9%) had mild chronic active non A-G viral hepatitis and 3/101 (2.9%) had liver biopsy with non-specific reactive hepatitis. The determination of ALT levels was not useful to detect donors infected with HCV at donation in Brazil, including the initial seronegative anti-HCV phase.

HGV: the identification, biology and prevalence of an orphan virus

Hepatitis G virus (HGV) and GB virus C (GBV-C) (both hereinafter referred to as HGV) were independently identified in patients with hepatitis of unknown aetiology. HGV is a positive-sense RNA virus of the family Flaviviridae. The virus can establish both acute and chronic infection and appears to be sensitive to interferon. Horizontal transmission is mainly parenteral, although other routes such as vertical have been well documented. High risk groups include intravenous drug users (i.v.DUs), the multiply transfused, haemodialysis patients and haemophiliacs. Up to 90% of i.v.DUs are positive for either HGV-RNA or antibodies to HGV envelope-2 protein (anti-E2). HGV is frequently detected in patients with HBV and HCV infection. Its link to hepatitis has now become less certain. Only around 3-6% of non-A E hepatitis cases are HGV viraemic, clearly showing that HGV is not the major cause of idiopathic hepatitis as originally hoped. Around 1-5% of volunteer blood donors in developed countries are HGV viraemic, but the prevalence is 10-20% in the general population in some developing countries. At present, it is not known whether HGV is associated with other diseases in humans, is a passenger virus, or only becomes virulent under certain conditions.

Detection of hepatitis G virus RNA in patients with acute non-A-E hepatitis

We investigated the possible role of hepatitis G virus (HGV or GBV-C) in the aetiology of acute non-A-E hepatitis in Argentina by detecting viral RNA in sera by reverse transcriptase-polymerase chain reaction (RT-PCR) using primers specific for the putative NS3 helicase region of HGV. Sixty two patients with acute hepatitis were included in this study. The absence of hepatitis A-E was confirmed by serological testing, and all patients were negative for HCV RNA and autoimmune markers. All patients denied alcohol intake and the use of hepatotoxic drugs. Their mean age was 35.3 years and 37 were males. HGV RNA was present in 19/62 (30.6%) of the patients with non-A-E acute hepatitis. Among HGV-positive patients, three had parenteral risk factors within 3 months of onset, one was a health care worker, one was sexually promiscuous, one had travelled to the Middle East and 13 (68.4%) had no history of parenteral exposure. Epidemiological, clinical and biochemical features between HGV-positive and negative patients did not achieve statistical significance. Hence, HGV appears to play a role in the pathogenesis of acute viral hepatitis; however, the etiology of a significant number of hepatitis cases remains unclear, suggesting the existence of an additional agent(s). The absence of parenteral exposure in most of the HGV RNA-positive patients in this study shows that routes of community-acquired HGV infection are not yet completely understood.

Simple one-tube reverse transcription-polymerase chain reaction protocol containing anticontamination procedure for detection of GB virus C/hepatitis G virus RNA

A simple one-tube reverse transcription-polymerase chain reaction protocol for detection of GB virus C/hepatitis G virus (GBV-C/HGV) RNA in serum samples containing anticontamination uracil-N-glycosylase procedure was developed. Amplification products were detected in a standard microtiter plate format using a commercial PCR ELISA kit (Boehringer Mannheim, Germany). Complete agreement between the results of a novel method and the previously determined GBV-C/HGV RNA status was obtained on 131 serum samples (76 GBV-C/HGV RNA positive and 55 GBV-C/HGV RNA negative samples). The novel method provides the potential for automated, simple, rapid and accurate routine detection of GBV-C/HGV RNA in diagnostic virological laboratories.

GB virus C (GBV-C) infection in patients with chronic hepatitis C. Influence on liver disease and on hepatitis virus behaviour: effect of interferon alfa therapy

The aim of this study was to evaluate, in patients with chronic hepatitis C, 1) the prevalence and the epidemiological characteristics of GB virus C (GBV-C) infection, 2) the influence of GBV-C on hepatitis C virus (HCV) infection, 3) the pathogenicity of GBV-C in the absence of treatment and under interferon therapy, and 4) the effect of interferon alfa on GBV-C and HCV replications. One hundred fifteen patients with chronic hepatitis C were studied. Before treatment, they were tested for GBV-C RNA by PCR and GBV-C genotype was determined for positive samples. Pretreatment information was collected, including age, gender, source of HCV, estimated duration of HCV infection, alanine aminotransferase and gamma-glutamyl transpeptidase activities, cirrhosis and Knodell's score on liver biopsy, HCV genotype, HCV viral burden and anti-HCV core IgM antibodies. The genetic complexity of the hypervariable region 1 (HVR1) of HCV was studied by PCR-Single Strand Conformation Polymorphism. All patients were treated with 3 to 9 mega units of interferon alfa-2a three times per week for 3 to 6 months. The influence of GBV-C on the evolution of ALT and HCV replication during and after treatment was studied, and GBV-C and HCV RNA were monitored monthly by PCR during this period. Eighteen patients (16%) were GBV-C RNA-positive. Among 11 samples studied, GBV-C genotype 2a was present in 9 cases, 2b in one case and type 3 in one case. GBV-C RNA-positive patients were significantly younger than GBV-C RNA-negative ones (38.4 +/- 11.5 vs. 47.4 +/- 14.0, P = 0.012), a result independent of the route of transmission and the disease duration. No difference between GBV-C RNA-positive and -negative patients was found for other epidemiological parameters (e.g. gender, risk factor for parenteral viral infections, disease duration and HCV genotypes), or for the characteristics of HCV infection and related liver disease (e.g. HCV RNA level, genetic complexity of the HVR1, anti-HCV core IgM, alanine aminotransferase and gamma-glutamyl transpeptidase activities, cirrhosis and Knodell's score). GBV-C did not influence the rates of ALT normalization at months 3, 6 and 12 and of sustained hepatitis C virological response at month 12 of treatment follow-up. During treatment, GBV-C viremia became undetectable in 12 patients (67%) but relapse occurred after treatment withdrawal in all the nine patients with sufficient follow-up. In the remaining six patients (33%), GBV-C resisted interferon. Whatever the effect of interferon on GBV-C replication, the ALT levels correlated with the presence of HCV RNA. In conclusion, GBV-C infection is frequent in patients with chronic hepatitis C, who are mainly, but not exclusively, infected by GBV-C genotype 2a. GBV-C positive patients are significantly younger than GBV-C negative ones. GBV-C does not seem to affect HCV replication, liver disease and responses of HCV infection and liver disease to interferon therapy. GBV-C is sensitive to 3 mega units of interferon alfa administered three times per week in two-thirds of the patients, but relapse is constant with this dosage after treatment withdrawal.

Rapid detection of GB virus C RNA by reverse transcription-polymerase chain reaction (RT-PCR) using primers derived from the 5'nontranslated region

A simple reverse transcription-polymerase chain reaction (RT-PCR) procedure for the detection of GB virus C (GBV-C) RNA in serum or plasma is described. In this method, total nucleic acid, extracted from a small volume of human plasma, is reverse transcribed using random hexamers. An aliquot of cDNA is then utilized in PCR employing GBV-C specific primers designed to highly conserved regions of the 5'nontranslated region (NTR). For additional sensitivity, a second round of nested amplification is performed. Reactions are analyzed on an agarose gel and samples showing an ethidium bromide stained band of the appropriate size in the first and second amplification, or in the second amplification only, are designated to be positive. This protocol allows for the rapid and sensitive detection of GBV-C infection in human plasma or serum.

Detection of HCV and GBV-C/HGV infection by multiplex PCR in plasma samples of transfused subjects

A multiplex polymerase chain reaction (PCR) was applied to clinical samples for simultaneous detection of hepatitis C virus (HCV) and GBV-C/HGV genome. With both RNA viruses, the amplification was performed with primers of the 5' UTR region starting from the single viral RNA reverse transcripted (cDNA) with random hexanucleotide primer mix. GBV-C/HGV RNA was detected in plasma sample of seven out of 50 transfused patients (14%). The multiplex PCR demonstrated a sensitivity up to 7.8 x 10(2) copies/ml respectively for GBV-C/HGV and HCV RNA in plasma samples of 5/50 patients with GBV-C/HGV/HCV co-infection and in patients with HCV (27/50) or GBV-C/HGV infection alone (2/50).

GEMHEP multicenter quality control study of PCR detection of GB virus C/hepatitis G virus RNA in serum

PCR is, to date, the only available tool for the detection of GB virus C (GBV-C) and hepatitis G virus (HGV) RNAs. Twenty-two French laboratories participated in a quality control study to assess the sensitivity and specificity of their procedures. The panel included 13 positive controls and 7 negative controls. The laboratories used either in-house PCR techniques adapted from the literature or partly standardized commercial tests. Three laboratories performed faultlessly with the entire panel. Most laboratories had excellent specificity (100% in 20 of 22 laboratories). Sensitivity was acceptable (85 to 100%) in 15 centers and insufficient (38 to 77%) in 7. As with nonstandardized in-house PCR, the commercial assays gave discrepant performances in different laboratories. These results suggest that laboratories willing to use PCR for detection of GBV-C/HGV RNA for research or diagnostic purposes should participate in multicenter quality control trials.

High prevalence of hepatitis G viremia among kidney transplant patients in Thailand

Patients receiving kidney transplants (KT) are at high risk for blood borne viral infections. To determine the prevalence of a recently discovered hepatitis G virus (HGV) in this patient group, reverse transcription-polymerase chain reaction (RT-PCR) employing primers derived from the NS5 region of the viral genome was utilized. HGV RNA was detected in 40 of 94 KT patients (43%), as compared to 3 of 69 healthy subjects (4.3%). Cocirculation of HGV and hepatitis C virus (HCV) RNA was detected in 12 patients (13%). Comparison of patients with and without HGV revealed that the former had received hemodialysis before transplantation for a significantly longer duration than the latter (28 vs. 17 months, respectively; P < 0.05). The amount of blood transfused and mean levels of liver enzymes, including alkaline phosphatase, alanine transaminase, and aspartate transaminase, were the same in both groups. Sequence analysis of 275-base pair DNA clones obtained from 2 patients revealed approximately 92% sequence homology to the published HGV and GB virus C sequences. These results suggested that HGV infection among Thai KT patients was high and the role of HGV in causing liver disease remains to be determined.

Seroprevalence of GB virus C and persistence of RNA and antibody

Exposure to GB virus C (GBV-C) was determined in several U.S. populations by both reverse-transcription-polymerase chain reaction (RT-PCR) and by an enzyme linked immunosorbent assay (ELISA) for antibodies to mammalian cell-expressed GBV-C envelope protein, E2 (GBV-C E2). Most individuals exposed to GBV-C were either RNA positive/ELISA negative or ELISA positive/RNA negative. Exposure, therefore, was measured as the sum of GBV-C RNA positive and GBV-C E2 antibody positive specimens, and was higher in commercial plasmapheresis donors (40.5%) than in volunteer blood donors (5.5%). In intravenous drug users (IVDUs), GBV-C exposure was 89.2%. Serial bleed specimens tested for GBV-C RNA indicate that some patients remain viremic for at least 3 years and fail to produce detectable antibodies to GBV-C E2. In other exposed individuals who tested negative for GBV-C RNA, antibodies to E2 appear to be similarly long-lived (greater than 3 years) with a fairly constant titer (ranging in reciprocal endpoint dilution from 336 to 21,504). Since the detection of GBV-C RNA and GBV-C E2 antibody are mutually exclusive in most exposed individuals, studies pertaining to incidence and prevalence of GBV-C infection require both antibody and nucleic acid detection.

Immunoassays to study prevalence of antibody against GB virus C in blood donors

Immunoassays were developed to determine the seroprevalence of antibody against human GB virus C (GBV-C). The antigenic target in each assay was a 44.6-kDa glycosylated protein representing the first 315 amino acids encoded by the GBV-C E2 gene. Sera or plasma were assayed for E2 antibody using an anti-human EIA format in which antigen-coated polystyrene beads were reacted with sample, and bound antibody was detected by addition of enzyme labelled goat anti-human IgG. The presence of anti-E2 antibody was confirmed using a sandwich EIA format in which samples were reacted with antigen coated polystyrene beads, followed by addition of solution phase biotinylated antigen. Detection of antibody captured biotinylated E2 was accomplished by addition of enzyme-conjugated anti-biotin antibody. Antibody against the E2 antigen was detected in 7.4 and 7.8% of 500 sera and 500 plasma, respectively, from US volunteers donating to a Wisconsin blood center, and in approximately 10.7% of hepatitis and retrovirus marker-negative volunteer blood donors from a Missouri blood center. The rate in 1018 sera from US commercial donors at multiple US blood centers was 36.7%. These results indicated a relatively high prevalence of GBV-C exposure in US volunteer donors, and particularly in commercial donors. The clinical implication of the high exposure rate is unclear. These immunoassays are being combined with nucleic acid detection to assess prevalence of GBV-C world wide and to determine if GBV-C plays a role as an etiologic agent.

GB virus-C RNA in Japanese patients with hepatocellular carcinoma and cirrhosis

BACKGROUND/AIMS

The involvement of non-B, non-C virus in the incidence of hepatocellular carcinoma (HCC) is not yet known. We have therefore examined the occurrence of GBV-C RNA in such patients.

METHODS

One hundred and eleven patients diagnosed as having HCC and 67 patients with cirrhosis without HCC were examined for the prevalence of GBV-C RNA by nested reverse transcription polymerase chain reaction with primers located at the helicase region. Sera were obtained and kept at -20 degrees C until analysis.

RESULTS

GBV-C RNA was positive in 11/111 (9.9%) cases with HCC, in 10/74 (13.5%) anti-HCV positive cases, in 1/25 (4%) HBsAg positive cases, and in 0/8 (0%) anti-HCV and HBsAg negative cases. GBV-C RNA was also positive in 7/67 (10.4%) cases with cirrhosis, in only 1/18 (5.6%) anti-HCV and HBsAg negative cases, in 4/33 (12.1%) anti-HCV positive, and in 2/14 (14.3%) HBsAg positive cases. The clinical background of patients with anti-HCV positive HCC who were also positive for GBV-C RNA did not differ from the background of those negative for GBV-C RNA.

CONCLUSIONS

GBV-C is unlikely to be a major etiologic agent of non-B, non-C chronic liver diseases and HCC in Japan.

Identification of GB virus C variants by phylogenetic analysis of 5'-untranslated and coding region sequences

Phylogenetic analysis of 44 GB virus C (GBV-C) 5'-untranslated region (5'-UTR) sequences from 37 individuals suggested the presence of GBV-C genotypes (A. S. Muerhoff, J. N. Simons, T. P. Leary, J. C. Erker, M. L. Chalmers, T. J. Pilot-Matias, G. J. Dawson, S. M. Desai, and I. K. Mushahwar, J. Hepatol. 25:379-384, 1996) that correlated with geographic origin: type 1, 2a and 2b, and 3 isolates are found predominantly in West Africa, the United States and Europe, and Japan, respectively. We have extended our analysis to include 5'-UTR sequences from 129 globally distributed GBV-C isolates and sequences from the second envelope protein (E2) gene and nonstructural (NS) regions 3 and 5b from a subset of these isolates. Bootstrap analysis of a 157-nucleotide segment of the 5'-UTR from 129 sequences provided weak support for the existence of the four major groups of GBV-C isolates previously described, although phylogenetic analysis of a 374-nucleotide segment of the 5'-UTR from 83 isolates provided stronger support. Thus, the groups of GBV-C variants previously identified upon analysis of the entire 5'-UTR can be distinguished by analysis of the shorter, 374-nucleotide region from the 5'-UTR. In contrast, independent analysis of the E2, NS3, or NS5b region sequences does not identify groups of GBV-C variants that correlate with geographic origin. However, bootstrap analysis of these coding sequences, when linked to form colinear sequences, demonstrates that longer coding regions can produce GBV-C groupings that are similar to that determined from 5'-UTR sequence analysis. The inability to distinguish between GBV-C variants by using small segments of coding sequence suggests that the GBV-C genome is constrained. As a result of these constraints, there is a high degree of nucleotide and amino acid sequence conservation between isolates from widely separated geographic areas. Hence, substitutions at many nucleotide positions are not tolerated, so that substitutions at the positions which can change are saturated, thereby obscuring the evolutionary relationships.

High prevalence of GB virus-C/hepatitis G virus infection in liver transplant recipients

BACKGROUND

To determine the prevalence of GB virus-C/hepatitis G virus (GBV-C/HGV) infection in liver transplant recipients transplanted for non-hepatitis C virus indications, 44 patients transplanted for cryptogenic, autoimmune, hepatitis B, or cholestatic liver disease and 91 non-liver transplantation (LT) patients with similar diagnoses seen in the same study period (control group) were studied.

METHODS

HGV RNA was detected by reverse transcription polymerase chain reaction with primers from the 5'-untranslated region.

RESULTS

GBV-C/HGV RNA was commonly detected in post-LT patients compared with the control group (28/44 [64%] vs. 13/91 [14%]; P<0.001). GBV-C/HGV infection was not related to the number of blood products transfused, a particular surgeon, or a specific liver disease. GBV-C/HGV infection also had no significant impact on the post-LT clinical profile.

CONCLUSIONS

We conclude that GBV-C/HGV infection is very common in LT recipients, but that it has minimal clinical impact in this population.

Infection with GB virus C/hepatitis G virus in Brazilian hemodialysis and hepatitis patients and asymptomatic individuals

Recently, sequences from a novel human flavivirus, termed GB virus C (GBV-C) or hepatitis G virus (HGV), have been identified in serum from patients with cryptogenic hepatitis and others. Sera from 116 patients with different clinical backgrounds were tested for the presence of GBV-C/HGV RNA by a reverse transcription-polymerase chain reaction with primers from the nonstructural (NS) 5 region. Ten (15%) patients on maintenance hemodialysis and 5 (19%) non A-C hepatitis patients were GBV-C/HGV RNA positive, along with one patient with chronic hepatitis B, one patient with chronic hepatitis C, and two asymptomatic individuals. Sequence comparison within 354 base pairs in the NS5 region showed homology rates varying from 87% to 97% among five Brazilian isolates, and from 86% to 93% between Brazilian strains and GBV-C/HGV isolates from other countries previously sequenced. Homology rates were higher at the amino acid level since most substitutions occurred at the third nucleotide position of codons without changing the codon meaning.

Detection of GB virus-C/hepatitis G virus RNA in serum by reverse transcription polymerase chain reaction

Three PCR methods based on the GB virus-C/hepatitis G virus (GBV-C/HGV) 5'UTR and NS3 genomic region were used for the detection of GBV-C/HGV RNA in serum of 62 patients with chronic hepatitis C virus (HCV) infection. Ten of 62 (16%) patients were found to have GBV-C/HGV RNA, which was confirmed by sequence analysis of the 5'UTR PCR amplicon. All methods appear to be specific, but methods based on the 5'UTR appear to be more sensitive.

Hepatitis-associated aplastic anemia

BACKGROUND

Hepatitis-associated aplastic anemia is a variant of aplastic anemia in which aplastic anemia follows an acute attack of hepatitis. The aplastic anemia, however, is often fatal if untreated. To characterize the illness, investigate the role of hepatitis viruses, and assess the response to immunosuppressive treatment, we studied patients with the syndrome who were referred to the National Institutes of Health (NIH).

METHODS

Standard hematologic and biochemical tests and measurements of bone marrow cellularity were used to monitor the patients' response to treatment. Serum was assayed for antibodies and antigens related to hepatitis A, B, and C viruses and for the RNA of hepatitis C and GB virus C by the polymerase chain reaction. All patients were treated with antithymocyte globulin and cyclosporine.

RESULTS

Ten patients with hepatitis-associated aplastic anemia were referred to the NIH between 1990 and 1996; all had the typical features of this syndrome. There was evidence of activated CD8 T lymphocytes in the blood. Serologic tests for hepatitis A, B, and C viruses were negative; RNA of hepatitis C virus was undetectable in all patients, but RNA of GB virus C was detected in three patients. Seven of the patients responded to intensive immunosuppressive treatment; the three who did not respond all died within one year of treatment, two from complications of stem-cell or marrow transplantation.

CONCLUSIONS

The hepatitis of the hepatitis-associated aplastic anemia does not appear to be caused by any of the known hepatitis viruses. We recommend immunosuppressive treatment for patients who do not have an HLA-matched related donor available for bone marrow transplantation. Several features of the syndrome suggest that it is mediated by immunopathologic mechanism.

GB hepatitis agent in cadaver organ donors and their recipients

BACKGROUND

The cloning of yet another hepatitis virus, GB virus-C (GBV-C), has provided the opportunity to study the prevalence, and clinical and laboratory characteristics, associated with GBV-C infection among cadaver organ donors and recipients of organs from infected donors.

METHODS

Stored sera from a cohort of cadaver organ donors from eight organ procurement organizations, representing different geographic regions of the United States previously screened for hepatitis C virus (HCV) infection, were tested for GBV-C RNA by polymerase chain reaction using degenerate primers derived from the NS3 helicase and 5'-untranslated regions of the GBV-C genome. Pre- and posttransplantation clinical data, and prevalence of GBV-C RNA among recipients of organs from GBV-C RNA-positive and -negative donors, were studied at one of the organ procurement organizations.

RESULTS

Twenty-one of 76 (27.6%) anti-HCV ELISA1-positive donors tested positive for GBV-C RNA compared with 6 of 82 (7.3%) ELISA1-negative donors (P=0.001). The prevalence of GBV-C RNA, extrapolated to all cadaver organ donors, was 8.3% (95% confidence interval [CI]: 5.6-11.1%) and was higher than the prevalence of HCV RNA (2.4%). Among ELISA1-positive donors, GBV-C RNA was present in 13 of 35 (37%) donors with HCV RNA, compared with 8 of 41 (20%) donors without HCV RNA (odds ratio [OR]=2.44, P=0.09). Blood alcohol level of more than 100 mg/dl (OR=9.43, P=0.05) and a positive anti-HCV ELISA2 (OR=4.58, P=0.001) were significantly associated with GBV-C infection. In addition, there was a trend toward an association between history of drug abuse (OR=5.23, P=0.06) and younger age (OR=0.97/year, P=0.06) with GBV-C infection. Organs from four GBVC-positive donors and 47 GBV-C-negative donors procured by the New England Organ Bank (Newton, MA) were transplanted into 6 and 79 recipients, respectively. Among recipients of organs from GBV-C RNA. positive donors, the posttransplantation prevalence of GBV-C RNA (25%) was not significantly higher than among recipients of organs from GBV-C RNA-negative donors (23%). Among recipients in whom both pre- and posttransplantation sera were available, one of three (33%) recipients of kidneys from GBV-C RNA-positive donors acquired GBV-C RNA after transplantation, compared with 4 of 40 (10%) recipients of kidneys from GBV-C RNA-negative donors. After a median follow up of 6 years, the posttransplantation prevalence of liver disease, and graft and patient survival, were not significantly different between recipients of organs from GBV-C RNA-positive and -negative donors.

CONCLUSIONS

Although GBV-C could be transmitted by organ transplantation, the results of this study preclude definitive conclusions. Further studies are required to determine the risk of transmission of GBV-C by organ transplantation and its role in posttransplantation liver disease.

GB virus C/hepatitis G virus and other putative hepatitis non A-E viruses

The identification of the major agents causing human hepatitis (Hepatitis A, B, C, D and E Viruses) was achieved during the last 30 years. These viruses are responsible for the vast majority of human viral hepatitis cases, but there are still some cases epidemiologically related to infectious agents without any evidence of infection with known virus, designated as hepatitis non A-E. Those cases are considered to be associated with at least three different viruses: 1--Hepatitis B Virus mutants expressing its surface antigen (HBsAg) with altered epitopes or in low quantities; 2--Another virus probably associated with enteral transmitted non A-E hepatitis, called Hepatitis F Virus. Still more studies are necessary to better characterize this agent; 3--Hepatitis G Virus or GB virus C, recently identified throughout the world (including Brazil) as a Flavivirus responsible for about 10% of parenteral transmitted hepatitis non A-E. Probably still other unknown viruses are responsible for human hepatitis cases without evidence of infection by any of these viruses, that could be called as non A-G hepatitis.

Identification of conserved nucleotide sequences within the GB virus C 5'-untranslated region: design of PCR primers for detection of viral RNA

Recently, the discovery of a new human RNA virus, GB virus C (GBV-C), was reported. GBV-C was isolated from the serum of a West African individual using degenerate oligonucleotide PCR primers designed from a consensus sequence of the NS3 helicase genes of hepatitis C virus (HCV), GBV-A, and GBV-B. Seven other individuals were shown to be infected with GBV-C via RT-PCR using these primers. Subsequently, degenerate PCR primers based upon a consensus sequence of the eight original isolates were designed. These primers were shown to be superior to the original set. However, since they were derived from a region of the viral genome exhibiting up to 17% nucleotide sequence divergence, mismatch between the primers and template may result in an underestimation of the true GBV-C prevalence. To overcome this potential problem, we obtained the sequences at the 5'-untranslated region (UTR) of the GBV-C genome from 35 infected individuals and identified regions of high sequence conservation among the isolates. We describe the design and testing of PCR primers derived from conserved sequences within the 5'-UTR of the GBV-C genome. These primers were shown to be as effective as the helicase-derived primers in detecting GBV-C RNA in human sera.

Prevalence studies of GB virus-C infection using reverse transcriptase-polymerase chain reaction

Among the three recently described GB viruses (GBV-A, GBV-B, and GBV-C), only GBV-C has been linked to cryptogenic hepatitis in man. Because of the limited utility of currently available research tests to determine antibody response to GBV-C proteins, the prevalence of GBV-C RNA in human sera was studied using reverse transcription-polymerase chain reaction (RT-PCR). The prevalence of GBV-C is higher among volunteer blood donors with elevated serum alanine aminotransferase (ALT) levels (3.9%) than among volunteer blood donors with normal ALT levels (0.8%). Higher rates were also noted among commercial blood donors (12.9%) and intravenous drug users (16.0%). GBV-C was frequently detected in residents of West Africa, where the prevalence was > 10% in most age groups. Approximately 20% of patients diagnosed with either acute or chronic hepatitis C virus (HCV) were found to be positive for GBV-C RNA. In addition, GBV-C RNA sequences were detected in individuals diagnosed with non-A-E hepatitis, with clinical courses ranging from mild disease to fulminant hepatitis. Fourteen of sixteen subjects with or without clinically apparent hepatitis were positive for GBV-C RNA more than 1 year after the initial positive result.