Molecular cloning and disease association of hepatitis G virus: a transfusion-transmissible agent

An RNA virus, designated hepatitis G virus (HGV), was identified from the plasma of a patient with chronic hepatitis. Extension from an immunoreactive complementary DNA clone yielded the entire genome (9392 nucleotides) encoding a polyprotein of 2873 amino acids. The virus is closely related to GB virus C (GBV-C) and distantly related to hepatitis C virus, GBV-A, and GBV-B. HGV was associated with acute and chronic hepatitis. Persistent viremia was detected for up to 9 years in patients with hepatitis. The virus is transfusion-transmissible. It has a global distribution and is present within the volunteer blood donor population in the United States.

Editing efficiency of hepatitis delta virus RNA is related to the course of infection in woodchucks

Based on evidence in vitro which shows that the small form of hepatitis delta virus (HDV) antigen (S-HDAg) initiates virus replication, whereas the long form (L-HDAg) encoded by the edited L-genome inhibits replication, we first put forward the hypothesis that HDV RNA editing efficiency, i.e. the intracellular L/S-genome ratio, could be a determining factor on the course of the infection. In order to analyse the precise sequence of events after infection, woodchuck carriers of woodchuck hepatitis virus (WHV) were superinfected with HDV and sequential changes in HDV RNA editing efficiency were analysed in relation to the duration of viraemia. Our findings show that: (1) in both transiently and persistently viraemic woodchucks, the percentage of L-genome is higher at the early stage of onset of the disease than at the late stage; (2) at the early stage of onset the percentage of L-genome is higher in cases with transient viraemia than in those with persistent viraemia; (3) a relatively greater decrease in L-genome is seen later in transiently viraemic animals than in those that remain persistently viraemic. In view of the above findings in vivo and other supporting evidence in vitro, we propose a hypothesis for the pathogenesis of HDV. This hypothesis predicts the outcome of acute infection and we suggest a gene therapeutic approach for this disease based on the intracellular accumulation (or increase) of the L-genome.

Fulminant hepatitis associated with hepatitis B virus e antigen-negative infection: importance of host factors

The precore stop-codon variant of hepatitis B virus (HBV) has been implicated in fulminant hepatitis. The precore/core regions of such variants from two sets of patients with interpartner transmission resulting in fulminant hepatitis in the contact, were sequenced to establish whether further sequence variations in the core region are specifically associated with the fulminant disease. In both sets of patients, there was sequence diversity of the precore/core region from the wild type, leading to numerous amino acid substitutions in the core region. Between the infecting source and the contact, there was only one amino acid change in one set of patients and none in the other. In addition, in the second set of patients, serum samples from four different time points were investigated. Sequence data showed no variation in each patient at the nucleotide level in the core region, even in the case of the source, who was followed for 3 years. In this same pair of subjects, the remainder of the genome was sequenced and was identical at the nucleotide level. Therefore, it appears that, at least in some cases of fulminant hepatitis caused by infection with the precore variant, the nucleotide sequence of the patient with fulminant hepatitis is identical to that observed in the asymptomatic source of infection. These data indicate that the severity and outcome of infection in such cases are unrelated to any additional variation in the entire HBV genome, and that the changed clinical picture is dependent on host factors, possibly the HLA environment.(ABSTRACT TRUNCATED AT 250 WORDS)

Recombinant vaccinia viruses expressing hepatitis A virus structural polypeptides: detection of an anti-VP0 response in convalescent-phase sera

We have generated a number of recombinant vaccinia viruses which expressed the hepatitis A virus (HAV) structural polypeptides VP1, VP2, VP3, and VP4, either alone or in combination. The relevant sequences encoding these polypeptides were amplified from cloned cDNA by PCR and then cloned into the insertion vector pGS62. The presence of the HAV structural polypeptide-encoding sequences in the recombinant viruses was confirmed by Southern blot analysis, whilst their transcription and translation were demonstrated by Northern (RNA) blot analysis and immunodetection, respectively. Immunoprecipitation studies using these constructs have detected the presence of an anti-VP0 response in human convalescent sera following HAV infection. The significance of this finding and the usefulness of these constructs in studying cell-mediated immunity during recovery from HAV infection are discussed.

The GB hepatitis viruses

The genomes of three new flavi-like viruses, GBV-A, GBV-B and GBV-C have been identified. Nucleic acid molecules corresponding to the genomes of GBV-A and GBV-B were isolated from tamarins with hepatitis which had been infected with the GB agent. RNA sequences corresponding to GBV-C have been shown to be present in sera from humans with non-A-E hepatitis. Sequence comparisons show that these three viruses are more closely related to each other and to hepatitis C virus (HCV) than to any other known viruses. Together with HCV they appear to form a discrete cluster of related viruses within the larger genus of flaviviridae. The pathological significance of these viruses and their association with hepatitis is currently emerging.

Fibrosing cholestatic hepatitis in a renal transplant recipient associated with the hepatitis B virus precore mutant

A patient with evidence of chronic infection with hepatitis B virus (seropositive for hepatitis B surface antigen, and with antibody to hepatitis B e antigen) underwent renal transplantation, which subsequently failed. The patient developed abnormal liver function tests and 8 months after the removal of the transplanted kidney, hepatitis B virus DNA was detected in the serum in the absence of hepatitis B e antigen. Liver biopsy revealed the presence of fibrosing cholestatic hepatitis. Sequence analysis of the serum hepatitis B virus DNA showed the presence of the pre-core mutant. This case shows that fibrosing cholestatic hepatitis can occur outside the setting of liver transplantation, and coincided with the development of the pre-core mutant of hepatitis B virus.

A unique insertion in the S gene of surface antigen--negative hepatitis B virus Chinese carriers

The presence of unique hepatitis B virus (HBV) variants has been investigated in two Chinese patients with chronic liver disease, whose sera were positive for HBV-DNA by dot blot hybridization or polymerase chain reaction (PCR) but hepatitis B surface antigen (HBsAg)-negative by conventional polyclonal antibody based immunoassays. PCR amplification of HBV-DNA followed by direct sequencing showed an insertion of six nucleotides, which introduced two additional amino acids between codons 122 and 123 in one patient (Isolate 1), whereas a nine nucleotide insertion in the other patient (Isolate 2) gave rise to three amino-acids between codons 123 and 124 immediately upstream from the 'a' determinant in the S gene. These insertions have not been described previously in any published sequences of the known subtypes and were absent from sequences of 30 HBsAg-positive Chinese patients from the same region. In the cases under study, the insertion is associated with four consecutive adenine molecules from nucleotides 516 to 519. It seems likely that this area is a hot spot for insertions in HBV. We found none of the previously described amino-acid deletions or substitutions in the pre-S1, pre-S2 and S genes, which are involved in unusual antigenic profiles. This finding suggests that genetic mutations in the S gene outside the 'a' determinant may be responsible for failure to detect HBsAg in some Chinese patients with chronic hepatitis caused by HBV infection.

Partial control of hepatitis delta virus superinfection by immunisation of woodchucks (Marmota monax) with hepatitis delta antigen expressed by a recombinant vaccinia or baculovirus

We have successfully limited the level of hepatitis delta viraemia occurring after superinfection of hepadna-virus infected woodchucks by prior immunisation with the short form of the hepatitis delta virus antigen expressed by a recombinant baculovirus or vaccinia virus. This phenomenon occurred in the absence of detectable circulating antibody to hepatitis delta virus antigen and in the absence of evidence of priming of the humoral immune response and may reflect the induction of a cytotoxic T-cell response. The latter would control viraemia by rapid lysis of delta antigen expressing hepatocytes. It is suggested that the T-cell epitopes involved may be located on the carboxyl end of the delta protein (amino acids 77-195).

Short report: prednisolone withdrawal followed by lymphoblastoid interferon in the therapy of adult patients with presumed childhood-acquired chronic hepatitis B virus infection

Eighteen patients with presumed childhood acquisition of chronic hepatitis B virus infection were initially entered into this randomized controlled trial. Twelve were treated with prednisolone for 4 weeks followed, after a 2-week gap, by thrice weekly lymphoblastoid alpha-interferon for 12 weeks. Two of these had previously acted as untreated controls. Three of the 12 patients (25%) [who were initially hepatitis B virus (HBV) surface antigen (HBsAg), 'e' antigen (HBeAg) and HBV-DNA positive] became HBeAg and HBV-DNA negative during therapy and remained so after 12 months post-therapy follow-up. One of these also lost HBsAg. A further two patients lost HBeAg and HBV-DNA during therapy but relapsed 6 and 9 months later. Two additional patients were HBV-DNA negative but HBeAg positive at the end of follow-up. None of the eight untreated control patients seroconverted during an identical follow-up period. Two further patients were HBsAg and HBeAg positive but HBV-DNA negative at the start of therapy. These were omitted from the final analysis: both subsequently lost HBeAg. The treatment response was associated with a rise in aspartate aminotransferase, peaking 2-6 weeks after prednisolone withdrawal, loss of HBV-DNA 0-8 weeks later and subsequent normalization of liver function tests. Treatment was well tolerated.

Interferon therapy is effective in treatment of hepatitis B-induced polyarthritis

A patient with acute hepatitis B developed significant polyarthritis. After 10 months of observation he had not cleared the virus and continued to have symptomatic joint problems, with migratory polyarthralgia, tenosynovitis of the left wrist, and a large knee effusion. Hepatitis B surface antigen (HBsAg) and hepatitis B virus (HBV) DNA levels were measured in the synovial fluid and were found to be virtually identical to serum levels, indicating the potential infectivity of this fluid. The patient was treated with 14 weeks of thrice-weekly lymphoblastoid interferon and cleared all markers of viral replication. The arthritis resolved with the disappearance of measurable HBsAg. Interferon may be effective therapy for this disorder.

In situ hybridization studies in hepatitis A infection

An in situ hybridization method using radiolabeled oligonucleotide probes was developed to study primary sites of hepatitis A virus replication in an experimental animal model of infection. Hepatitis A genomic sequences were demonstrated in hepatocytes of four marmosets with acute hepatitis A by use of antisense probes. In two of these animals, staining was also found when a sense probe was used, which is consistent with active replication in the hepatocytes. The specificity of the hybridization signal was confirmed by neutralization with "cold" (i.e., unlabeled) probes and by absence of hybridization with non-A hepatitis and reverse antisense probes. The hepatocyte appeared to be the only cell type showing staining. No hybridization was found in other organs, including the intestine (n = 4) and, in one animal, the kidney and spleen.

Improved serologic detection of hepatitis C virus with a paramagnetic microparticle assay using multiple antigenic sequences

A paramagnetic microparticle (MP) assay for antibody to hepatitis C virus (anti-HCV) was developed, in which the probe for antibody consisted of synthetic peptides corresponding to HCV capsid and nonstructural c-100 regions, as well as a recombinant protein corresponding to the nonstructural c33c region. Assay performance was evaluated by testing serum from 108 geographically diverse patients with non-A, non-B hepatitis (NANBH). The frequency of anti-HCV reactivity detected with the MP assay and with an enzyme-linked immunosorbent assay (ELISA) for c-100 was 91 and 70 percent, respectively. All c-100 HCV ELISA-reactive specimens also reacted on the MP assay. In addition, anti-HCV seroconversion in three plasma donors was detected one to two blood collection dates earlier by the MP assay than by the c-100 HCV ELISA and at similar blood collection dates by the MP assay and a second-generation anti-HCV ELISA. Serologic responses to the three distinct antigenic regions of HCV in NANBH patients varied: reactivity to all three antigens was most common (49%), reactivity to both capsid and c33c (40%) was next most common, and single-antigen reactivity was rare (4%). MP assay reactivity of 825 volunteer donors was 0.1 percent. These results demonstrate both the utility of additional HCV antigens for an effective anti-HCV screening assay and the application of paramagnetic MP technology to serologic testing for HCV infection.

Effect of cyclosporin-A in woodchucks with chronic hepatitis delta virus infection

Four woodchucks chronically infected with hepatitis delta virus (HDV) were treated with cyclosporin-A (CyA) for 11 weeks. All animals had detectable HDAg in the liver and two of them were also positive for HDAg and HDV-RNA in serum. Reappearance of HDV in serum was noted in one of the two non-viraemic animals and increased viraemia in the two viraemic. HDV-RNA levels became elevated within a week of starting treatment and an inverse relationship between HDV-RNA and WHV-DNA became apparent during the treatment period. With discontinuation of treatment, HDV-RNA levels either returned to pretreatment levels or became negative. The remaining animal showed no return of viraemia during CyA treatment; HDV-RNA remained negative and WHV-DNA levels did not change. Liver biopsies revealed a slight increase in lobular activity during CyA treatment in the animals showing increased viraemia. These data are consistent with the hypothesis that the host immune response exerts a negative control on the level of HDV viraemia and that HDV influences HBV replication independently of the host immune response. In an animal that may have been clearing HDV, immunosuppression did not result in recurrence of viraemia.

Serological response and detection of viraemia in acute hepatitis C virus infection

The serological response during acute hepatitis C virus (HCV) infection was examined by enzyme-linked immunosorbent assay (ELISA) in sequential serum samples from 13 haemophiliacs following their first exposure to factor VIII concentrates contaminated with HCV. The commercially available C100-3 peptide and a new 22 kDa recombinant protein (p22) encoded by the nucleocapsid region of the viral genome were used for antibody detection, whilst a nested polymerase chain reaction (PCR) method was used for the detection of viraemia. In addition, eight sporadic cases of acute HCV infection were studied. The results in haemophiliacs demonstrated that seroconversion to the C100-3 antigen occurred in only one-third of the patients within 12 weeks of disease onset, but all of the patients had a diagnostic serological response to p22 during this phase of the disease. The new test was positive in all the sporadic cases at a time when the commercially available test was negative. Although PCR offers a sensitive method for the detection of recent HCV infection, the complex methodology makes it unsuitable for diagnostic laboratories. The new ELISA test with p22 may therefore have a useful diagnostic role in acute disease.

Seroprevalence of hepatitis C virus nucleocapsid antibodies in patients with cryptogenic chronic liver disease

The serological responses to two different hepatitis C virus antigens were studied by enzyme-linked immunosorbent assay in a variety of chronic liver diseases and in healthy blood donors. The study population comprised 97 cases of cryptogenic chronic liver disease (40% with a history suggestive of parenterally transmitted non-A, non-B hepatitis and 60% without such a history), 87 cases of other well-characterized chronic liver diseases and 96 voluntary blood donors. The commercially available C100-3 assay and a new assay utilizing a 22 kD recombinant protein (c22) from the nucleocapsid region of the virus were used for antibody detection. Overall in the non-A, non-B hepatitis group, 77% were positive for anti-c22, 55% were positive for anti-C100-3 and 24% were negative by both tests. In the parenterally transmitted chronic liver disease group, 82% were positive for anti-C100-3 and 90% were positive for anti-c22 (not significant). In the cryptogenic chronic liver disease cases 36% were positive for anti-C100-3 and 67% were positive for anti-c22 (p less than 0.001). Only in one case (a patient with hepatitis B virus infection) was anti-C100-3 detected without concomitant anti-c22. None of the voluntary blood donors had detectable hepatitis C virus antibodies. The new enzyme-linked immunosorbent assay test for anti-c22 would appear to be a more sensitive indicator of chronic hepatitis C virus infection than the existing commercial test, suggesting a useful diagnostic role in both cases of cryptogenic chronic non-A, non-B hepatitis liver disease and for the screening of blood products for prevention of hepatitis after transfusion.

An in situ hybridization, molecular biological and immunohistochemical study of hepatitis delta virus in woodchucks

The presence of hepatitis delta virus genomic RNA and hepatitis delta antigen was investigated in woodchuck liver and extrahepatic tissues by in situ hybridization using synthetic radiolabeled probes, Northern-blot analysis and immunohistochemical staining for hepatitis delta antigen. Hepatitis D virus RNA and hepatitis delta antigen were detected in the nuclei of infected hepatocytes but in none of the other tissues examined. Northern-blot analysis of total cell RNA confirmed these findings and revealed a series of hepatitis D virus transcripts, including full-length genomic RNA and dimers and trimers of hepatitis D virus RNA that may represent replicative intermediates. Use of single-stranded probes showed genome-size monomers and dimers to be both of genomic and antigenomic polarity, although dimers were found to be predominantly antigenomic. These findings document the strict hepatotropism of hepatitis D virus and support the rolling-circle model of genome replication for this unique, defective RNA virus.

A recombinant vaccinia virus expressing hepatitis A virus structural polypeptides: characterization and demonstration of protective immunogenicity

A recombinant vaccinia virus containing most of the P1 region of hepatitis A virus (HAV) was constructed. Cell lysates of cultures infected with the virus contained HAV proteins detectable by radioimmunoassay. Western blot analysis revealed the presence of a single protein of Mr 60K to 62K, bearing epitopes from structural polypeptides VP4, -3 and -2, and the N terminus of VP1. The size of the protein suggests that at least some of the vaccinia virus thymidine kinase is also expressed. Inoculation of tamarin monkeys with the recombinant virus resulted in the development of a specific anti-HAV immune response which was protective against challenge with a virulent strain of HAV. Recombinant viruses expressing the above region of HAV or the proteins expressed by such viruses may be useful in the development of a vaccine suitable for use in man.

Association of a precore genomic variant of hepatitis B virus with fulminant hepatitis

A variant of hepatitis B virus has been described recently in HBsAg+ Mediterranean patients who lack HBeAg and who have an unusual and severe form of chronic hepatitis. This variant is unable to produce HBeAg because of the presence of a novel translational stop codon at the end of the precore region of the genome. By direct sequencing of DNA, generated by the polymerase chain reaction, we have evaluated the association between infection with this variant and the fulminant course of hepatitis B. Eighteen patients with fulminant hepatitis B were studied. Of the 15 cases from whose serum viral DNA could be sequenced, the variant was found in the admission sera of 8 of 9 HBeAg- patients but in none of 6 HBeAg+ patients who had fulminant hepatitis B. Patients harboring the variant progressed more rapidly into hepatic encephalopathy, but those infected with the variant strain alone had a greater likelihood of survival than those infected with the normal strain or a mixture. The mutant strain may emerge spontaneously during fulminant hepatitis as occurs in chronic hepatitis B infection during seroconversion from HBeAg to antibody. Alternately, and perhaps less commonly, patients may be infected with the variant ab initio.

Incidence of hepatitis B viraemia, detected using the polymerase chain reaction, after successful therapy of hepatitis B virus carriers with interferon-alpha

Thirty-nine patients (62 sera) who, after interferon-alpha therapy for chronic hepatitis B virus (HBV) infection, were seronegative for HBeAg and HBV-DNA by dot blot hybridisation, were tested using the polymerase chain reaction (PCR) for residual viraemia. Overall, 59% of the HBsAg-positive sera and 43% of the HBsAg-negative sera were positive by PCR. All except one of the HBsAg-negative patients had seroconverted to anti-HBs. Between 13 and 18 months after therapy, 33% of the HBsAg-positive and 20% of the HBsAg-negative patients remained viraemic. Eighteen months after the end of treatment, no patient tested was positive. Twenty-three patients were tested sequentially over periods from 1 to 43 months: Thirteen lost HBV-DNA by PCR, three remained positive, five remained negative, and two patients relapsed. The merits and disadvantages of PCR for assessing interferon treatment of HBV carriers are discussed.

Treatment of hepatitis B virus infection with interferon. Factors predicting response to interferon

Several randomised controlled trials have been undertaken to evaluate the efficacy of alpha-interferon in the therapy of chronic hepatitis B. In patients with HBe antigen-positive disease acquired in adult life the response rates vary from 25-50%. In those infected at birth, response rates are lower. Twenty-one pretreatment variables were assessed for their significance in response prediction using data from 114 patients given alpha-interferon for chronic hepatitis B virus infection. In those patients who had received a minimum of 90 million units per m2 total dose over 12 weeks, a negative anti-human immunodeficiency virus antibody status (p less than 0.001), chronic active hepatitis on liver biopsy (p less than 0.005), high AST level (p less than 0.001), low hepatitis B virus DNA level (p less than 0.001) and a history of acute hepatitis (p less than 0.005) were all associated with an increased likelihood of response on univariate analysis. On stepwise logistic regression analysis, hepatitis B virus DNA, AST and a history of acute hepatitis predicted response independently (p less than 0.05). The most reliable combination of predictive factors was a negative anti-human immunodeficiency virus antibody status, with either a positive history of acute icteric hepatitis and AST greater than 45 IU per liter or no history of acute icteric hepatitis and AST greater than 85 IU per liter, which predicted response in 77% with a specificity of 79% (p less than 0.001). The loss of HBsAg in addition to HBeAg and hepatitis B virus DNA was more likely to occur in patients with chronic infection of less than 2 years duration (p less than 0.001).

Immunization of woodchucks with recombinant hepatitis delta antigen does not protect against hepatitis delta virus infection

To assess the role of immunization against hepatitis delta antigen in the prevention of hepatitis delta virus infection, woodchuck carriers of woodchuck hepatitis virus were immunized with a 64 amino acid portion of hepatitis delta antigen from its N-terminal region. The protein was expressed in Escherichia coli and contained a major immunogenic epitope. A significant anti-hepatitis delta response was observed that did not, however, protect the animals from hepatitis delta virus superinfection. Unexpectedly, the period of detectable viremia was longer in the immunized than in the control animals. We conclude that immunization with this recombinant hepatitis delta antigen does not afford protection against subsequent hepatitis delta virus exposure.

Hepatitis C virus antibodies in subjects with and without liver disease in the United Kingdom

The prevalence of antibody to hepatitis C virus, evidence of previous or current infection with this agent of parenterally transmitted non-A, non-B hepatitis, was determined in 340 subjects residing in the United Kingdom. The antibody was detected in 3 per cent of unselected blood donors and in 60 per cent of patients with chronic post-transfusion non-A, non-B hepatitis. Evidence for infection was also found in 30 per cent of intravenous drug abusers, and in 75 per cent of haemophiliacs receiving commercial factor VIII concentrate. The infection is uncommon in renal units and amongst sexually promiscuous groups attending sexually-transmitted disease clinics. Although the seropositivity rate in primary biliary cirrhosis and chronic B and delta hepatitis was very low (0-2 per cent), in patients with autoimmune and alcoholic liver disease it was 14-16 per cent which, although lower than that quoted in studies from Spain and Italy, is considerably higher than would be expected by chance. The reason for the high incidence of non-A, non-B hepatitis in this latter group of patients is unclear.

Vaccine-induced escape mutant of hepatitis B virus

In southern Italy, 44 contacts of hepatitis B virus carriers, including infants of carrier mothers, became HBsAg positive despite passive and active immunisation according to standard protocols. In 32 of these vaccinees infection was confirmed by the presence of additional markers of viral replication. In 1 infant, serious disease occurred. The virus from this patient is an escape mutant with a different sequence from that of the isolate from the mother. A point mutation from guanosine to adenosine at nucleotide position 587 resulted in an aminoacid substitution from glycine to arginine in the highly antigenic a determinant of HBsAg. This mutation is stable: it is present in an isolate from the child 5 years later. In some of these patients, including this child, the a determinant, to which a large part of the vaccine-induced immunity is directed, has been partly lost. Binding to HBsAg of a monoclonal antibody, previously mapped to the region of the mutation, was reduced in the child relative to that of the mother.

Anti-HBs response in seroconverting chronic HBV carriers following alpha-interferon treatment

The antibody response to hepatitis B surface antigen (anti-HBs) was studied in 15 chronic hepatitis B virus (HBV)-infected patients who seroconverted following treatment with alpha interferon. The levels of anti-HBs (IU/l) attained were significantly lower than those recorded in patients with convalescent symptomatic or asymptomatic acute infection and in hospital personnel who received a plasma derived HBV vaccine.