GB virus-C/hepatitis G virus infection in an area endemic for viral hepatitis, chronic liver disease, and liver cancer

BACKGROUND & AIMS

GB virus-C/hepatitis G virus (GBV-C/HGV) is a newly identified flavivirus, and little is known about its clinical significance. GBV-C/HGV was investigated in different populations, and its coinfection was investigated in patients with liver disease in Taiwan where hepatitis B and C are endemic.

METHODS

Viral RNA was studied in 70 high-risk individuals, 20 patients with chronic non-B, non-C hepatitis, 13 with non-A-E fulminant hepatitis, 100 with asymptomatic hepatitis B surface antigen carriage, 120 with hepatitis B surface antigen-positive chronic liver disease and hepatocellular carcinoma, 100 patients with chronic hepatitis C, and 100 healthy adults.

RESULTS

GBV-C/HGV infection was more frequent in high-risk groups (15%-30%) and hepatitis C virus carriers (10%) than in healthy adults (1%) and hepatitis B virus carriers (3.2%). Eighty-three percent of those infected had undergone blood transfusions previously. The prevalence in hepatitis B virus carriers increased with the severity of liver disease, being 1% in asymptomatic carriers and 10% in hepatocellular carcinoma. In chronic hepatitis C, clinical and virological data were comparable between those with and without coinfection.

CONCLUSIONS

In Taiwan, GBV-C/HGV infection is common in high-risk groups, and its coinfection seems to not aggravate the course of chronic hepatitis B or C.

Superinfection by homotypic virus in hepatitis C virus carriers: studies on patients with post-transfusion hepatitis

Although heterotypic superinfection and mixed infections of hepatitis C virus (HCV) may be possible for hepatitis flares in chronic hepatitis C, the possibility of homotypic HCV superinfection in HCV carriers with post-transfusion hepatitis has not been explored. Six HCV carriers with post-transfusion non-A, non-B hepatitis found in a prospective study of post-transfusion hepatitis were included. Serum samples before transfusion and during hepatitis were selected to determine genotypes of HCV and nucleotide sequences of the hypervariable region (HVR). The genotypes identified before and after transfusion were concordant in all. There were four with type 1b and one each with type 2a and type 2b. Amplified nucleotide sequences of the HVR before transfusion and during hepatitis were compared in four patients, and a > 95% homology was observed in three, suggesting persistence of original viruses. In contrast, only a 51% homogeneity was seen in a given patient, suggesting a homotypic HCV superinfection. Phylogenetic tree analysis validated further these findings. This study implies that HCV carriers can be reinfected by homotypic HCV, and this may contribute to hepatitis flares in chronic hepatitis C. These findings also confirm a weak or inadequate protective immunity in HCV infection and justify protection from reinfection of HCV of patients with chronic hepatitis C.

Serum hepatitis C virus titers in the progression of type C chronic liver disease. With special emphasis on patients with type 1b infection

The correlation of serum hepatitis C virus (HCV) titers to the progression of type C chronic liver disease remains controversial. We have investigated the relationship between serum HCV titers and different histological stages of chronic liver disease, including chronic persistent hepatitis (CPH), chronic active hepatitis and/or liver cirrhosis (CAH/LC), and hepatocellular carcinoma (HCC) in 94 well-characterized Taiwanese patients. The mean age of patients in the HCC group was significantly older than those in the CPH and CAH/LC groups, whereas those in the CAH/LC group had the highest mean serum alanine aminotransferase level among the three groups. The prevalence of HCV type 1b increased with the progression of histological severity, and the mean serum titer of the HCC group was significantly higher than that of CPH group. The difference of virus titers between the HCC group and those of the other two groups became more significant when only type 1b virus-infected patients were analyzed. In conclusion, elevated serum HCV titers are more frequently observed among Taiwanese patients with advanced type C chronic liver disease, an association not related to the high prevalence of HCV type 1b infection in such patients.

Long-term efficacy of ribavirin plus interferon alfa in the treatment of chronic hepatitis C

BACKGROUND & AIMS

Sustained response to interferon treatment for chronic hepatitis C is unsatisfactory. This study examined whether combining interferon alfa with ribavirin induces a better sustained efficacy than interferon alone in the treatment of chronic hepatitis C.

METHODS

Sixty noncirrhotic patients with chronic hepatitis C were randomly assigned to three groups. Group 1 received 1200 mg oral ribavirin daily plus 3 million units of recombinant interferon alfa 2a thrice weekly for 24 weeks, group 2 received the same dose of interferon alfa 2a alone for 24 weeks, and group 3 received no treatment. The patients were then followed up for an additional 96 weeks.

RESULTS

At the end of treatment, a complete response (normal serum alanine aminotransferase level and undetectable serum hepatitis C virus RNA) was achieved in 16 of the 21 patients in group 1 (76%), as compared with 6 of 19 in group 2 (32%) and none in group 3. At 96 weeks after the end of treatment, patients in group 1 sustained a higher complete response rate than patients in group 2 (43% vs. 6%).

CONCLUSIONS

Combined treatment with ribavirin and interferon alfa 2a for 24 weeks is more effective than interferon alfa 2a alone for the treatment of chronic hepatitis C. The biochemical and virological responses were sustained in about one half of the treated patients for at least 2 years after cessation of the therapy.

Characterization of human protein C gene promoter: insights from natural human mutants

Human protein C is a liver-produced plasma anticoagulant. Four heterozygous point mutations located in the promoter region have been identified in families with type I protein C deficiency and recurrent venous thrombosis. However, detailed analysis of regulatory elements and their interacting factors remains to be undertaken. This report presents results of biochemical and functional characterizations of several cis-elements located in the 5'-upstream regulatory region and the trans-acting factors that interact with them. A cloned DNA fragment from nucleotides (nt) -418 to +45 could confer tissue specificity, whereas nt -88 to +45 was sufficient for basal promoter activity of protein C gene. Five cis-elements corresponding to HNF-1, HNF-3, and NF-I/CTF binding sites have been identified. Four heterozygous mutations have been shown to disrupt HNF-3 [mutants of A(-32)G and T(-27)A] and HNF-1 [T(-14)C and C(-10)T] binding. Mutation in the NF-I-binding site also significantly impairs the promoter activity. Viewed as a whole, these results indicate that HNF-1, HNF-3, and NF-I/CTF play critical roles in transcriptional regulation of the protein C gene.

Transmission of hepatitis C virus between spouses: the important role of exposure duration

OBJECTIVES

Although interspousal transmission of hepatitis C virus (HCV) has been studied, the factors responsible for it remain unclear.

METHODS

To investigate the transmission of HCV between spouses and the related risk factors, 100 anti-HCV-positive index patients and their spouses were studied.

RESULTS

Overall, anti-HCV was detected in 17 (17%) spouses, 15 of whom were also positive for HCV RNA, and 11 couples were infected with the same genotype. The anti-HCV-positive rate was higher in spouses married longer than 20 yr compared with those married less than 20 yr (22 vs 6%, p < 0.05), and the infection was correlated with the duration of their actual exposure to the index patients but not with serum HCV titers. The infected couples had more frequent sexual contacts and more commonly shared tooth-brushes than those with uninfected spouses.

CONCLUSION

Spouses of patients with chronic hepatitis C have a higher risk of acquiring HCV that increases with longer marriage and duration of exposure, and they should be educated about how to avoid contracting HCV infection from their spouses.

A prospective study of transfusion-transmitted GB virus C infection: similar frequency but different clinical presentation compared with hepatitis C virus

To study the incidence and outcome of GB virus C (GBV-C) infection in blood recipients. Serum samples collected in a prospective study were examined for GBV-C RNA by a nested polymerase chain reaction assay. Among the 400 adults who underwent cardiac surgery, 40 were positive for GBV-C RNA, including six whose pretransfusion sera were already positive and seven coinfected with hepatitis C virus (HCV) during transfusion. The risk of transmission was estimated to be approximately 0.46% per donor. GBV-C viremia was detectable 1 week after transfusion and could persist for 8 years. However, no evident symptoms or signs were noted in the 25 patients infected by GBV-C alone, and the average peak serum alanine aminotransferase activity was 31 IU/L only (range, 12 to 123), with persistently normal levels in 20 patients. In the seven patients coinfected with HCV, the clinical courses of posttransfusion hepatitis were similar to those infected by HCV alone. In eight patients with posttransfusion non-A approximately E hepatitis, only one was positive for GBV-C RNA. Sixty samples were chosen to test hepatitis G virus (HGV) sequences, 26 of the 30 GBV-C positives were positive for HGV RNA in contrast to none of the 30 GBV-C negative samples. In conclusion, GBV-C can be transmitted by transfusion in approximately 9% of patients who underwent cardiac surgery. Nevertheless, this virus does not seem to cause classic hepatitis in most instances.

Subtyping of human T-lymphotropic virus type I by amplification of long terminal repeat sequences and restriction fragment length polymorphism analysis in carriers with multiple transfusions

Five major subtypes of human T-lymphotropic virus type I (HTLV-I) have been proposed: cosmopolitan, Japanese, West African, Central African, and Melanesian. Based on nucleotide variations specific to particular subtypes, it was possible to genotype HTLV-I rapidly by restriction fragment length polymorphism (RFLP) studies following polymerase chain reaction (PCR). In this study, the restriction patterns of two LTR fragments were analyzed using eight restriction endonucleases (AvaI, Eco57I, BsoFI, NdeI, SacI, DraI, MaeII, and MaeIII). Genotyping of HTLV-I was done in nine patients with adult T-cell leukemia or HTLV-I-associated myelopathy/tropical spastic paraparesis, in three prostitutes, and in 19 carriers with multiple transfusion in Taiwan. The subtyping results of RFLP studies using these eight restriction endonucleases were in accordance with those of phylogenetic analysis. A substitution of G by A at nucleotide position 503, which creates the DraI site but suppresses the SacI site, was found not only in the Japanese subtype but also in a minority of the cosmopolitan subtype. A mutation near the position of subtype-specific nucleotide variations might suppress the restriction site and lead to unexpected restriction patterns. Amplification of more than one proviral fragment and RFLP studies with a group of appropriate restriction endonucleases may provide rapid and accurate genotyping of HTLV-I. More carriers are required to evaluate the possibility of mixed infection with different HTLV-I subtypes.

Casein kinase II and protein kinase C modulate hepatitis delta virus RNA replication but not empty viral particle assembly

Hepatitis delta virus (HDV) contains two virus-specific delta antigens (HDAgs), large and small forms, which are identical in sequence except that the large one contains 19 extra amino acids at the C terminus. HDAgs are nuclear phosphoproteins with distinct biological functions; the small form activates HDV RNA replication, whereas the large form suppresses this process but is required for viral particle assembly. In this study, we have characterized the phosphorylative property of HDAg in a human hepatoma cell line (HuH-7) and examined the role of phosphorylation in HDAg function. As demonstrated by in vivo labeling and kinase inhibitor experiments, the phosphorylation levels of both HDAgs were diminished by the inhibitor of casein kinase II (CKII). Nevertheless, phosphorylation of only the small form could be markedly reduced by the protein kinase C (PKC) inhibitor, suggesting different phosphorylation properties between the two HDAgs. When these two kinase inhibitors were added separately to the transient-expression system, HDV RNA replication was profoundly suppressed. In contrast, the inhibitors did not affect the assembly of empty HDAg particle from HDAgs and hepatitis B virus surface antigen. To further examine the role of phosphorylation in HDAg function, two conservative CKII recognition sites at Ser-2 and Ser-123 of both HDAgs and one potential PKC recognition site at Ser-210 of the large HDAg were altered to alanine by site-directed mutagenesis. Transfection experiments indicated that mutation at Ser-2, but not Ser-123, significantly impaired the activity of the small HDAg in assisting HDV RNA replication. This property is in accordance with our observation that Ser-2, not Ser-123, was the predominant CKII phosphorylation site in the small HDAg. Our studies also excluded the possibility that the phosphorylation of Ser-2, Ser-123, or Ser-210, had roles in the trans-suppression activity of the large HDAg, in the assembly of empty virus-like HDAg particle, and in the nuclear transport of HDAgs. In conclusion, our results indicate that both CKII and PKC positively modulate HDV RNA replication but not the assembly of empty HDAg particle. The role of CKII in HDV replication may at least in part be accounted for by the phosphorylation of Ser-2 in the small HDAg. The effect of PKC on HDV RNA replication is, however, not to mediate the phosphorylation of the conservative Ser-210 in the large HDAg but rather to act on as-yet-unidentified Ser or Thr residues in the small HDAg or cellular factors. These findings provide the first insight into the roles of phosphorylation of the two HDAgs in the HDV replication cycle.

Rapid hepatic failure associated with a contracted liver mimicking cirrhosis in a case of nasopharyngeal carcinoma with liver metastasis

A 46-year-old women had an undifferentiated nonkeratinizing nasopharyngeal carcinoma, locally controlled by radiotherapy. Initially, she had normal liver function tests and normal hepatic ultrasonography. Seven months later, she experienced a rapidly progressive hepatic failure manifested by the development of ascites, elevation of serum bilirubin level, and prolongation of prothrombin time. Imaging studies showed a contracted liver and serum biochemical tests were compatible with chronic liver disease, except for an increase of alkaline phosphatase and gamma-glutamyl transpeptidase levels. An endoscopic retrograde cholangiogram ws compatible with changes of sclerosing cholangitis. The patient died of hepatic decompensation within two months. A liver necropsy disclosed diffuse infiltration of carcinoma cells into the hepatic sinusoids and obliterative angio-invasion of the tumor cells with massive fibrotic stroma replacing almost all hepatocytes. In situ hybridization demonstrated expression of Epstein-Barr virus transcripts EBER1 in the tumor cells and proved a metastatic nasopharyngeal carcinoma. The contracted liver is likely to be explained by the tumor-associated desmoplastic change and the obliterative angio-invasion of the tumor. It is important to be aware that, although rare, such an unusual pattern of liver metastasis may mimick cirrhosis clinically and cause rapid hepatic failure in patients with nasopharyngeal carcinoma.

Phylogenetic analysis of GB virus C: comparison of isolates from Africa, North America, and Taiwan

A group of flavi-like GB viruses (GBV-A, -B, and -C) has been discovered and partially characterized. Only GBV-C is found in humans. Nucleotide sequences of the putative helicase gene of the GBV-C genome were determined in 21 Taiwanese patients and compared with isolates from Africa and North America by phylogenetic analysis. The average similarities of Taiwanese isolates to those from West Africa, East Africa, Canada, and United States were 83%, 85%, 78%, and 82%, respectively. Phylogenetic analysis of the NS3 region showed that 81% of the Taiwanese isolates were more closely related to the East African isolate. GBV-C isolates from Taiwan could be classified into at least 3 groups. These data suggest that GBV-C isolates cloned from different geographic areas have genetic heterogeneity.

Identification of humoral antigenic determinants in the hepatitis C virus NS3 protein

Immunoblot analysis on serum samples from 90 patients with chronic hepatitis C virus infection revealed four putative immunogenic regions within the NS3 protein of the virus: E (around aa 1250/ 1251), A (within aa 1250-1334), A/B (around aa 1323 and 1334), and B/C (around aa 1407 and 1412). Among them, region E was most immunodominant, and region A was recognized much less frequently by patients with cirrhosis than by those with chronic hepatitis (10% vs. 46%, chi 2 = 12.05, P < .01). The results suggest that region A might be a potential prognostic marker to differentiate chronic hepatitis from cirrhosis.

Absence of extensive genetic heterogeneity of hepatitis C virus in antibody-negative chronic hepatitis C

Hepatitis C virus (HCV) carriers usually have antibodies to HCV; however, there are viremic individuals without these antibodies. To investigate whether variations of the viral genome are responsible for this discrepancy, the nucleotide and deduced amino acid sequences of HCV capsid and nonstructural regions obtained from 15 viremic patients were examined. These 15 patients were infected with type 1b HCV, and 10 did not have antibody to HCV assayed with second-generation tests. The nucleotide homology of the 5 seropositive and 10 seronegative patients with the HCV prototype sequence were 91.6% and 91.9%, respectively, in the capsid region. There was no apparent difference in the deduced amino acid sequences between the two groups of patients studied (94% vs. 95%). The nucleotide and amino acid sequences of a part of the nonstructural region 3 also showed similar results. These findings suggest that absence of antibodies against both capsid and nonstructural peptides in HCV carriers is not caused by genetic heterogeneity of the viral epitopes.

H-2Ld-alloreactive T cell hybridomas utilize diverse V alpha and V beta T cell receptor chains

We have sequenced the TCRs from Ld-specific alloreactive T cell hybridomas, whose reactivities we have found to be quite representative of those of a primary dm2 anti-BALB/cJ mixed lymphocyte reaction. We find V beta 6, V beta 7, V beta 8 and V beta 10 gene segments. V alpha usage is diverse, although closely related to that from peptide-specific Ld-restricted CTLs. V alpha-V beta selection provides evidence of preferential pairing. Amino acid frequency analysis shows that the alpha CDR2 region is rich in charged amino acids, in contrast to the beta CDR2 region. Our data suggests the beta chain may be more immunoglobulin-like than the alpha chain, and that charge complementarity may be important in TCR-MHC interactions. We do not consider our results to be contradictory to those previously reported but rather they may represent an early, more diverse response.

N-linked glycosylation of hepatitis B surface antigens is involved but not essential in the assembly of hepatitis delta virus

Hepatitis delta virus (HDV) is a defective virus requiring the hepatitis B virus (HBV) to provide hepatitis B surface antigens as the envelope protein. The hepatitis B surface antigens are posttranslationally modified by N-linked glycosylation, and its significance in HDV assembly was investigated with a cotransfection system using human hepatoma cell line Huh-7. After the N-linked glycosylation of HBsAg was blocked by tunicamycin treatment, the packaging of HDV in the culture system could be suppressed to a level as low as 5-10% of the untreated control. The extent of inhibition correlated with the increased concentrations of tunicamycin. In contrast, the loss of HBsAg glycosylation did not affect the efficiency of assembly of HBV particles. When the N-linked glycosylation site of small HBsAg at amino acid 146 was mutated from asparagine to glutamine, the mutant HBsAg packaged only a modest amount of HDV particles. The quantity and kinetics of formation of HDV particles in culture system were reduced by the depletion of HBsAg glycosylation. Therefore HDV, similar to influenza and vesicular stomatitis viruses, depends on glycosylation of the envelope proteins as a signal for envelope protein maturation and for virion formation.

Serotypes, genotypes and levels of hepatitis C viremia in pregnant women in Taiwan

The correlation between a new serotyping method for grouping different genotypes of hepatitis C virus (HCV) and those identified by a polymerase chain reaction (PCR) assay with type-specific primers was investigated in 3,400 pregnant women. The correlation between HCV genotypes and serum HCV levels in HCV-positive pregnant women was studied as well. The new serologic assay used an enzyme-linked immunosorbent assay (ELISA) based on highly group-specific recombinant peptides (C14-1 and C14-2) within the NS4 region and detected group-specific antibodies against different HCV genotypes. Serum HCV levels were assayed by a competitive PCR method. In all, 43 pregnant women were found to be positive for HCV antibodies by the second-generation ELISA method and were positive for HCV-RNA by PCR with primers from the 5' untranslated region. All 43 had defined genotypes: 28 (65%) with HCV 1b, 11 (26%) HCV 2a, 3 (7%) HCV 2b and 1 (2%) HCV 1b + 2a. In 40 (93%) of the 43 viremic pregnant women, the results of serotyping by ELISA showed complete agreement with those determined by PCR genotyping, and none of the women showed a group different from that of the HCV genotype. In addition, serum levels of HCV 1b were significantly higher than those of HCV 2a. The results show that this new serotyping assay is highly sensitive and specific for the determination of HCV genotypes and that serum HCV levels in pregnant women with genotype 1b are higher than those with genotype 2a.

Serotyping of hepatitis C virus in chronic type C hepatitis in Taiwan: correlation with genotypes

To evaluate the usefulness of a new serologic assay to group hepatitis C virus (HCV), genotypes identified by this serotyping method were compared to those identified by a polymerase chain reaction (PCR) assay with type-specific primers in 71 Taiwanese patients with chronic type C hepatitis. The group-specific antibodies against different HCV genotypes were detected by using an enzyme-linked immunosorbent assay (ELISA) based on group-specific recombinant peptides (C14-1 and C14-2) within the NS4 region. Among 71 patients positive for current second-generation HCV antibodies, HCV RNA was detected in 55 patients by PCR with primers from the 5' untranslating region, and in 52 by genotype-specific PCR. In 49 (89%) of 55 viremic patients, the results of serotyping by ELISA showed complete agreement with those determined by PCR genotyping, and none of the patients showed a group opposite to that of HCV genotype. The positive rate of group-specific antibodies (69/71;97%) was even better than that of the PCR (55/71;78%). We conclude that this new serotyping assay is highly sensitive and specific for the determination of HCV genotypes, and will be useful in future epidemiologic studies, as well for clinical application.

Clinical significance of serum hepatitis C virus titers in patients with chronic type C hepatitis

OBJECTIVES

To investigate the relationship between serum hepatitis C virus (HCV) titers and clinicopathological characteristics of chronic type C hepatitis.

METHODS

Serum HCV cDNA concentrations were determined by a competitive polymerase chain reaction assay in 60 Taiwanese patients with chronic type C hepatitis.

RESULTS

The concentration of serum HCV cDNA ranged between 10(2) and 10(8) copies/mL. The titers of serum HCV (logarithmic transformed copies of HCV cDNA/mL serum) were not significantly correlated with clinicopathological characteristics with respect to either sex of the patients, source of infection, higher serum ALT level (>150 IU/L) or histological severity. In contrast, serum HCV titers were significantly higher in patients with age above 50 yr and with type 1b HCV infection. Moreover, the influence of advancing age on serum HCV titer was genotype-independent by multivariate analysis.

CONCLUSIONS

These results suggest that advancing age and genotype are both important determinants of HCV viremia and that the pathogenesis of HCV infection might not be caused by direct cytotoxicity of the virus.

Hepatitis C viral infection in thalassemic children: clinical and molecular studies

To determine and correlate the liver function profile, hepatitis C virus (HCV) genome, anti-HCV, genotypes, quantitation, and nucleotide sequence variability in polytransfused thalassemic children, 61 such children were studied prospectively for 4 y. Twenty-six had HCV infection. The average age, number of transfusions, and alanine aminotransferase (ALT) levels of the HCV-infected group were higher than those of the 35 children without HCV infection. None was infected after the initiation of anti-HCV screening in donor blood. Liver biopsies were performed in six HCV-infected and eight HCV-noninfected thalassemic children, and portal fibrosis was found more frequently in the HCV-infected group. Quantitation of HCV RNA was done by the competitive polymerase chain reaction method, and the titer was about 1 x 10(6) to 5 x 10(8) copies/mL. The titer did not change significantly over the 4-y follow-up period and did not correlate with ALT levels. Nineteen HCV-infected patients were genotyped; 15 were Okamoto/Simmonds type II/1b, two were type III/2a, and two were type IV/2b. The hypervariable region of the HCV genome (E2/NS1) was cloned and sequenced in two serum samples from one patient collected at a 2-y interval, as the ALT levels decreased. The variation rate was estimated to be 1.2-1.7 x 10(-2)/nucleotide/y. The results showed that, in polytransfused thalassemic children, 43% (26/61) contracted HCV. We conclude that HCV infection may cause elevated ALT levels and portal fibrosis of the liver, whereas the viral titer and genotypes do not parallel ALT levels.

Envelope gene sequences of human T-lymphotropic virus type 1 in Taiwan

Three major types of HTLV-1 had been proposed, the Melanesian type, the Zairian type, and the cosmopolitan type, which was further divided into subtypes A, B and C, according to the phylogenetic tree constructed from LTR sequences of current HTLV-isolates. In this study, the envelope gene sequences of HTLV-1 from 9 Taiwanese were analyzed. Based on the phylogenetic tree constructed by unweighted pair group method and the sequence homology analysis by GCG computer programs, the envelope gene sequences of HTLV-1 proviruses from these 9 Taiwanese belonged to subtype A or subtype B of the cosmopolitan type and were closely related to HTLV-1 from Japan. Twelve subtype-specific nucleotide variations were deduced from the comparison of complete or partial envelope gene sequences of 16 HTLV-1 isolates of known subtypes as well as those of 9 Taiwanese. These data provided the basis for subtyping the cosmopolitan type of HTLV-1 by amplification of envelope gene sequences and restriction fragment length polymorphism studies. A more extensive survey based upon this proposal was warranted.