Peter Karayiannis

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.

MUTATION PREVENTING FORMATION OF HEPATITIS B e ANTIGEN IN PATIENTS WITH CHRONIC HEPATITIS B INFECTION

Some patients with chronic hepatitis B virus (HBV) infection are HB e antigen (HBeAg) negative, have circulating HBV particles, and often have especially severe chronic hepatitis. To test the hypothesis that the absence of HBeAg production may be due to a change in the nucleotide sequence of the pre-core region of the genome, 18 Greek and 3 non-Greek patients positive for HB surface antigen underwent direct sequencing of HBV-DNA amplified from sera. In 7 out of 8 HBeAg negative patients, two mutations (guanosine to adenosine) were found in the terminal two codons of the pre-core region, giving the sequence TAGGACATG. The remaining patient had the first mutation only. The sequence TGGGGCATG was found in 4 of 5 of the HBeAg positive patients. The first mutation results in a translational stop codon that is predicted to result in failure to produce HBeAg. The rest of the pre-core region in the HBeAg negative patients was otherwise homologous to that of the HBeAg positive patients and to known sequences.

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.

Identification of Unique Hepatitis C Virus Quasispecies in the Central Nervous System and Comparative Analysis of Internal Translational Efficiency of Brain, Liver, and Serum Variants

ABSTRACT Reports of cerebral dysfunction in chronic hepatitis C virus (HCV) infection have led to the suggestion that HCV may infect the central nervous system (CNS). We used reverse transcription-PCR, cloning, and sequencing to define quasispecies for the HCV internal ribosomal entry site (IRES) and hypervariable region 1 (HVR1) in autopsy-derived brain, liver, lymph node, and serum samples. There was evidence of tissue compartmentalization of sequences in the brain in two patients, with between 24 and 55% of brain-derived IRES sequences absent from the serum, and significant phylogenetic and phenetic clustering of the brain and lymph node HVR1 sequences. The IRES initiates cap-independent translation of the viral polyprotein. Two unique brain-derived IRES mutations (C204→A and G243→A), which have previously been associated with lymphoid replication and altered translational efficiency in cell culture, were found in one patient. We used a dicistronic reporter vector to test whether brain-derived variants showed altered IRES-mediated translational efficiency, which might favor CNS infection. The translational efficiencies of the brain-derived IRES sequences were generally reduced compared to those of the master serum and liver sequences in rabbit reticulocyte cell lysates and two human cell lines, HuH7 (liver) and CHME3 (microglial). The C204→A and G243→A mutations showed preserved translational efficiency in HuH7 cells but reduced efficiency in CHME3 cells. Our data provide evidence that the CNS is a site of HCV replication, consistent with the recent demonstration of negative-strand HCV RNA in brain, and suggest that IRES polymorphisms may be important as a viral strategy of reduced translation to favor latency in the CNS.

A double blind, placebo‐controlled study to assess the effect of famciclovir on virus replication in patients with chronic hepatitis B virus infection

SUMMARY. This is the first double‐blind controlled study of famciclovir, an oral antiviral agent, as potential therapy for chronic hepatitis B virus (HBV) carriers. A fall of more than 90% in HBV DNA levels was noted in six of 11 evaluable patients treated with a 10 day course of oral famciclovir. Further studies with more prolonged therapy are ongoing.

High risk of non-A non-B hepatitis after a first exposure to volunteer or commercial clotting factor concentrates: effects of prophylactic immune serum globulin

After a first exposure to factor VIII concentrates, 9/9 British patients treated with U.S.A.‐derived commercial products, and 10/12 treated with British volunteer (NHS) products, developed acute non‐A, non‐B (NANB) hepatitis. Hepatitis following commercial products was more severe, and of shorter incubation. High previous exposure to NHS blood products seemed to prevent NHS but not commercial factor VIII‐induced hepatitis; the latter was also not attenuated by administration of U.S.A.‐derived commercial immune serum globulin (ISG). After a first exposure to NHS factor IX concentrates without ISG, 4/4 patients developed short incubation NANB hepatitis; one also contracted prolonged incubation hepatitis B. One patient treated with ISG and factor IX of proven infectivity did not develop hepatitis, suggesting protection by ISG. Observed differences between concentrates might be attributable to their content of different NANB agents, but dose‐related effects could provide alternative explanations. This data provides a basis for comparative assessment of new products of possible reduced infectivity in only small numbers of patients.

Delayed anti-HCV antibody response in HIV-positive men acutely infected with HCV.

Objective:An epidemic of acute hepatitis C virus (HCV) infection among HIV-positive men who have sex with men is occurring in urban centers in Western Europe and the United States. Early diagnosis and treatment of HCV results in improved sustained virological response rates. This study compared the sensitivity of reverse transcriptase PCR (RT–PCR) versus antibody screening for the diagnosis of early HCV infection in HIV-positive patients and estimated the length of time from HCV infection to the development of anti-HCV antibodies. Design:Patients from the St Marys Acute Hepatitis C Cohort (SMACC) were recruited retrospectively and prospectively between 2004 and 2008. Methods:Archived plasma samples, obtained at 1–3 monthly intervals for routine monitoring of HIV viral load were assayed retrospectively for HCV in order to assess the sensitivity of RT–PCR and enzyme-linked immunosorbent assay (ELISA). Results:Forty-three HIV-positive patients with early HCV infection were identified. The median CD4 cell count was 570 cells/μl. The median alanine transaminase at the time of the first positive HCV PCR was 65 IU/ml. At this time, 75% of patients had a negative HCV antibody test. Three months later, 37% of patients still had a negative result. After 9 months, 10% of patients had a negative test and 5% remained negative after 1 year. Conclusion/discussion:Delayed seroconversion in HIV-positive individuals with acute HCV may result in delayed diagnosis and treatment. Where there is a clinical suspicion of recent HCV infection, for example, elevated alanine transaminase levels, HIV-infected patients should be screened for HCV RNA by RT–PCR.

TRANSFER OF A FUNCTIONING HUMORAL IMMUNE SYSTEM IN TRANSPLANTATION OF T-LYMPHOCYTE-DEPLETED BONE MARROW

To test the effect of transplantation of T-cell-depleted bone marrow on recipient immune function the results of pre-transplantation immunisation with tetanus toxoid and hepatitis-B vaccine were studied in 38 donor-recipient pairs. Immunisation of the donor alone resulted in transfer of an antibody response to the recipient; immunisation of both donor and recipient resulted in potentiation of the antibody response in both magnitude and duration. These findings indicate that donor T-cell-depleted marrow can transfer humoral immunity to the recipient and that appropriate pre-transplant immunisation schedules may be of benefit to the recipient.

Predicting spontaneous clearance of acute hepatitis C virus in a large cohort of HIV-1-infected men

Objective An epidemic of acute hepatitis C virus (HCV) infection in HIV-positive men-who-have-sex-with-men (MSM) is emerging in Europe, Australia and the USA. The aim of this study was to characterise the natural history of primary HCV in this setting and to assess host and viral factors which predict spontaneous clearance. Methods This prospective longitudinal cohort study was carried out in 112 HIV-positive patients who were followed in a single centre (the St Marys Acute HCV Cohort). Plasma and peripheral blood mononuclear cells (PBMCs) were obtained at monthly intervals for 3 months and at 3-monthly intervals thereafter for a median of 45 months (IQR=29–69 months). The primary end point was spontaneous clearance of HCV. Cox regression was used to assess the impact of clinical and virological variables on outcome, including liver function, CD4 count, rate of HCV RNA decline, T cell response and clonal sequence evolution within the HCV E2 envelope gene. Results 15% of patients cleared HCV spontaneously, while 85% progressed towards chronicity. The latter group included a significant proportion of ‘fluctuating’ progressors (37.5%), in whom a fall followed by a rise (>1 log10) in viraemia was observed. This was associated with superinfection with new HCV strains and partially effective T cell responses. Spontaneous clearance was strongly associated with a 2.2 log10 viral load drop within 100 days of infection (HR=1.78; p<0.0001), elevated bilirubin (≥40 μmol/l; HR=5.04; p=0.006), elevated alanine aminotransferase (ALT; ≥1000 IU/ml; HR=2.62; p=0.048) and baseline CD4 count ≥650×106/l (HR=2.66; p=0.045), and only occurred in patients with genotype 1 infection. Evolution to spontaneous clearance occurred in patients with low viral diversity in the presence of an early multispecific T cell response. Conclusions Spontaneous clearance of acute HCV in HIV-positive men can be predicted by a rapid decline in viral load, high CD4 count, elevated bilirubin and ALT, and is associated with low viral diversity and strong T cell responses.

Contribution of low level HBV replication to continuing inflammatory activity in patients with anti-HBe positive chronic hepatitis B virus infection.

The relationship between the histological diagnosis and serological and tissue markers of HBV replication in 41 Greek and 29 British patients with chronic HBV infection were studied. All the nine Greek and 13 British patients who were HBeAg positive had HBV-DNA in serum and HBcAg expression in the hepatocytes. The majority (73%) of these patients had active liver disease. Forty seven per cent of the Greek and 19% of the British patients who were anti-HBe positive continued to display HBcAg in the liver with or without HBV-DNA detected in serum. All but three of these patients had persistently active liver disease. Continuing inflammatory activity in the liver, however, was also found in 31% of anti-HBe positive patients who had no evidence of HBV replication. In these patients, other factors such as delta agent, NANB viruses, alcohol abuse or an autoimmune reaction initiated by HBV may be contributory.