Rizzetto M

Immunofluorescence detection of new antigen-antibody system (delta/anti-delta) associated to hepatitis B virus in liver and in serum of HBsAg carriers.

A new antigen-antibody system associated with the hepatitis B virus and immunologically distinct from the HB surface, core, and e systems is reported. The new antigen, termed delta, was detected by direct immunofluorescence only in the liver cell nuclei of patients with HBsAg positive chronic liver disease. At present, the intrahepatic expression of HBcAg and delta antigen appears to be mutually exclusive. No ultrastructural aspect corresponding to the delta antigen could be identified under the electron microscope. delta antibody was found in the serum of chronic HBsAg carriers, with a higher prevalence in patients with liver damage. The nuclear fluorescence patterns of HBcAg and delta antigen were similar; it is only possible to discriminate between the two antigens by using the respective specific antisera.

A new hepatitis B virus strain in patients with severe anti-HBe positive chronic hepatitis B

In hepatitis B virus carriers who are anti-HBe positive despite ongoing viral replication (HBcAg in liver and HBV-DNA in serum) the natural course of hepatitis is severe and the response to interferon is low. We investigated whether a new hepatitis B virus (HBV) strain could be involved. A translational termination codon at the carboxyterminal end of the pre-C region responsible for the lack of HBeAg secretion was found in 18 of 19 HBV clones isolated from seven pedigreed patients with this clinical syndrome. The same findings were confirmed by direct sequencing. One of these patients underwent a liver transplant and HBV infection of the new liver resulted in high titered viremia and intrahepatic expression of HBcAg, without detectable HBeAg in serum. Another patient was superinfected by hepatitis delta virus (HDV) and developed high titres of total and IgM anti-HD. In spite of this, chronic hepatitis remained unchanged during 7 years of follow-up. These data strongly suggest that a viable precore minus mutant of hepatitis B virus is responsible for the lack of HBeAg in the serum of these patients. The HBV variant may explain the peculiar geographic distribution of anti-HBe positive hepatitis. The variations in the virus genome sequence may cause the more severe form of liver disease and modify the pathogenicity in the case of HDV superinfection.

EPIDEMIOLOGY OF HBV-ASSOCIATED DELTA AGENT: GEOGRAPHICAL DISTRIBUTION OF ANTI-DELTA AND PREVALENCE IN POLYTRANSFUSED HBsAg CARRIERS

The epidemiology of infection with the hepatis-B-virus (HBV)-associated delta agent was assessed from the prevalence of antibody to delta in 1206 HBsAg-seropositive subjects from various parts of the world. Anti-delta was prevalent in unselected HBsAg-positive Italians, whether residents in Italy or elsewhere, and in drug addicts and polytransfused HBsag carriers throughout the world, suggesting that delta-associated infection is spread through contact in Italy and parenterally in other countries. Parenteral transmission of the delta agent was confirmed by a separate survey of the prevalence of anti-delta in 648 polytransfused patients with chronic blood disorders, which showed a higher prevalence of anti-delta in HBsAg-positive haemophiliacs than in the general HBsAg-positive population of Italy, Germany, and the U.S.A. In view of the failure to detect delta in the absence of markers of HBV, the prevalence of anti-delta among polytransfused HBsAg carriers suggests that the delta-associated agent is transmitted by superinfection or coinfection of HBsAg carriers, the HBsAg carrier state possibly providing a rescue function to the superinfecting agent.

Serological response to the hepatitis delta virus in hepatitis D.

Sera from 74 hepatitis B surface antigen-positive individuals, who presented with acute hepatitis delta virus (HDV) infection which ran a self-limited course in 58 and progressed to chronicity in 16, were tested over time for HDV markers. In self-limited disease the serum pattern varied from early HD-antigenaemia followed by IgM and IgG anti-HD seroconversion, to the appearance of IgM and IgG anti-HD without antigenaemia, or the isolated expression of either the IgM or the IgG antibody. The typical case of IgM anti-HD was transient and appeared with a mean delay of 10-15 days from admission in the different serological subgroups. The IgG antibody usually developed several weeks later during convalescence. In contrast, patients with disease destined to become chronic had a brisk IgM antibody response and IgG anti-HD was detectable with a mean delay of 15 days; generally, the IgM and the IgG antibody persisted over the follow-up time. IgM antibody to HDV is often the only serological test positive in the clinical stage of hepatitis D and repeated testing for this marker is necessary to diagnose acute HDV co-infection. The serological follow-up provides important prognostic information: waning of IgM confirms resolution of HDV infection, persistence predicts chronicity.

Serologic markers with fulminant hepatitis in persons positive for hepatitis B surface antigen. A worldwide epidemiologic and clinical survey.

Of 377 cases of fulminant hepatitis in persons positive for hepatitis B surface antigen (HBsAg) in Greece, Italy, the United States, the United Kingdom, the Central African Republic, Taiwan, Egypt, and India, only 52% could be attributed to infection with hepatitis B virus, which was defined as the presence of the IgM antibody to the hepatitis B core antigen (IgM anti-HBc) and the absence of serum markers of infection by extraneous viruses. Thirty percent of cases were caused by coinfection with hepatitis B virus and hepatitis delta virus or by infection with hepatitis delta virus superimposed on carriers of chronic HBsAg. In 18.5% of the patients, the absence of IgM anti-HBc indicated that they were not known to carry HBsAg, but no obvious superimposed factor of hepatitis could be identified. The cause of fulminant hepatitis is complex, and major risk factors are a pre-existing HBsAg state and hepatitis delta virus infection. Superinfection of HBsAg carriers by non-A, non-B viruses seems to be the cause in a consistent proportion of cases.

Rapidly progressive HBsAg-positive hepatitis in Italy The role of hepatitis delta virus infection

Serum or liver markers of hepatitis delta virus (HDV) infection were found in 20 of 22 (90%) Italian patients presenting with an ostensible type B hepatitis that ran an accelerated course to cirrhosis. The features of the illness conformed to a syndrome of HDV infection in young males carrying the hepatitis B surface antigen (HBsAg); a latent HBsAg state was documented in many patients by a history of prior exposure to the hepatitis B virus (HBV) or by the absence of IgM antibodies to the HB core antigen. Characteristic of the disease were the clinical overture as a severe hepatitis, the lobular involvement by an extensive necroinflammatory reaction, the exuberant expression of intrahepatic hepatitis delta antigen and an atypical HBV profile of inactive infection or accelerated seroconversion from HBeAg to anti-HBe. Superimposed upon HBV infection, HDV may create a rapidly progressive course which resembles very aggressive hepatitis B but is infrequently observed in hepatitis B alone.

Treatment of chronic delta hepatitis with α-2 recombinant interferon

The Hepatitis Delta Virus (HDV), a defective ribonucleic acid virus dependent on the Hepatitis B Virus (HBV) is a cause of severe liver disease that often leads to cirrhosis and death. Since the HDV finds in the HBV infection a biological niche in which to thrive indefinitely, the major victims of its infection are the carriers of HBsAg. Spontaneous resolution of chronic HDV hepatitis has been observed rarely and therapeutic attempts with steroids or azathioprine and levamisole have been discouraging. With the advent of recombinant DNA technologies several human alpha-interferons (IFNs) have been synthesized by genetic engineering and the availability of large amounts of the drug has dramatically altered the therapeutic prospects of viral hepatitis. In view of the wide range of biological activities of IFN, including inhibition of viral nucleic acid replication, we have tested the tolerance and the efficacy of this drug in chronic HDV hepatitis. The preliminary results of this study are reported.

Prognostic significance of in-vitro complement fixation in liver biopsy specimens from patients with acute viral hepatitis type B.

The prognostic significance of in-vitro complement fixation (V.C.F.) by hepatitis-B core antigen/antibody immunocomplexes in hepatitis-B surface antigen (HBsAg) positive liver biopsy specimens was prospectively evaluated in 47 patients presenting with acute viral hepatitis type B. 34 of 37 V.C.F.-negative patients made an uneventful recovery and became HBsAg negative; in all patients with a V.C.F.-positive test chronic hepatitis and persistent antigenaemia developed. The V.C.F. test is a simple and reliable prognostic indicator of persistent infection and of progression of apparently acute hepatitis to a chronic liver disorder.

Hepatitis Delta Virus in Acute and Chronic Liver Disease

Hepatitis delta virus (HDV) is a defective hepatotropic RNA agent that replicates only in hosts who are simultaneously infected with hepatitis B virus (HBV).1,2 The virion is a spherical 36-nm particle, composed of a lipoprotein envelope. The surface antigen of HBV (HBsAg) contains delta antigen (HDAg) and an RNA molecule of 1.7 kilobases (kb) (HDV-RNA).1,2 The detection of HDAg requires treatment with detergents, but nucleocapsidic structures are not seen electron microscopically within the HBsAg envelope of the particle.3 HDAg is composed of two major proteins, 24,000–27,000 M r and 27,000–29,000 M r molecular weight.3,4 HDV-RNA is considered the genome of the defective agent. It was reverse transcribed to make complementary DNA (cDNA) that was cloned using appropriate vectors.5–11 DNA clone fragments of different length, spanning the entire HDV genome, were obtained and sequenced.5–11 No significant homology was observed between HDV-RNA and HBV-DNA or between HDV-RNA and host DNA. HDV-RNA contains 1679–1683 nucleotides and five open reading frames (ORF) of more than 100 amino acids in both genomic and antigenomic strands.2’5–11 The largest ORF, present on the antigenomic strand (+) and coding for 214 amino acids, was expressed in bacteria; the resultant fusion protein reacted with human antibodies to HDAg (anti-HD) by Western blot analysis.5

118 KEY ROLE OF CHYMASE IN THE HEPATIC PRODUCTION OF ANGIOTENSIN II AND IN THE DEVELOPMENT OF EXPERIMENTAL LIVER CIRRHOSIS AND ITS COMPLICATIONS

117 GENE DELIVERY OF DIMETHYLARGININE DIMETHYLAMINOHYDROLASE-1 REDUCES PORTAL PRESSURE IN BILE DUCT-LIGATED RATS G. Mehta, V. Sharma, A. Habtesion, V. Balasubramaniyan, N.A. Davies, R. Jalan, V.S. Budhram-Mahadeo, R.P. Mookerjee. UCL Institute of Hepatology, Royal Free Hospital, Royal Free Hampstead NHS Trust and UCL, Medical Molecular Biology Unit, Rayne Institute, UCL, London, UK E-mail: gautam.mehta@ucl.ac.uk