Kwesi N. Tsiquaye

The complete nucleotide sequence of the genome of a hepatitis B virus isolated from a naturally infected chimpanzee

The complete nucleotide sequence of a strain of hepatitis B virus, originally isolated from a naturally infected chimpanzee, has been determined. Interesting features of the sequence include the presence of an in-phase stop codon in the pre-core region of the core antigen open reading frame. The sequence shows approximately 10% nucleotide divergence from all of the other hepatitis B virus sequences previously published and the possibility that this divergence is the result of passage through chimpanzees is discussed.

SPECIFICITY OF AN IMMUNOPRECIPITIN TEST FOR NON-A NON-B HEPATITIS

An immunodiffusion system detecting an antigen showing immunological identity with international laboratory reference sera was developed by use of acute-phase and recovery sera from patients with transmission-proven non-A, non-B acute hepatitis. In other liver diseases the antigen was also present in a high proportion of patients and there were similar findings in conditions with high levels of circulating immune complexes in the serum. Fractionation of antigen-containing sera by column chromatography, polyethylene glycol treatment, and reduction and alkylation also suggested that immune complexes may be responsible for antigenic activity. The precipitation lines did not develop in the presence of 10 mmol/l EDTA or at a pH less than 8.0 and the reactant in antibody containing sera was shown not to be an immunoglobulin. Although the transmission of non-A, non-B hepatitis by blood and blood products shows that viral antigens are likely to be present in the circulation, this study shows that immune reactions apparently closely associated with the infection may be detecting immune complexes rather than specific viral components and emphasises the need for careful evaluation of the specificity of other reported serological tests for non-A, non-B hepatitis.

Assay of HBV DNA in the plasma of HBV-carrier chimpanzees superinfected with non-A, non-B hepatitis

A dot hybridisation technique was used to monitor the levels of hepatitis B virus (HBV) DNA in the plasma of two HBV-carrier chimpanzees which had been inocula ed with documented infectious non-A, non-B hepatitis agents. A marked decrease in the quantity of HBV DNA in the plasma during the acute phase of the non-A, non-B hepatitis was observed in both carriers. The possible role of interferon or a similar antiviral agent in modulation of the HBV-carrier state is discussed. Hybridisation may become, in due course, the method of choice for examining blood samples for infectious hepatitis B virus.

Suramin inhibits duck hepatitis B virus DNA polymerase activity

Suramin, a polybasic anion, blocks the activity of the DNA polymerase encoded by the duck hepatitis B virus. The interaction with the virus was studied under conditions in which the property of the drug to bind with proteins was used with plasma obtained from infected ducks with viraemia. Inhibition of DNA polymerase activity associated with core particles from infected liver and circulating virions is irreversible, occurs in a dose-response fashion and suggests that inhibition results from suramin-virus interaction. The inhibition of the specific viral polymerase activity clearly indicates that this drug should be evaluated for the treatment of hepatitis B and infection caused by the related Hepadna viruses.

Experimental in ovo transmission of duck hepatitis B virus

Inoculation of fertile Pekin duck eggs with diluted serum containing DHBV into eggs incubated for 24 h and into the extra-embryonic cavities of 14-day-old embryos resulted in a high proportion of viraemic ducklings irrespective of the route of inoculation. Long-term observation of som of the ducks established that the viraemia induced experimentally is long-lasting and has persisted for periods up to 16 mth post-hatch. Separation of DHBV from the plasma of carrier ducks by rate zonal centrifugation was examined by DNA polymerase (DNAP) activity. Particles in the fraction with peak DNAP activity had a buoyant density of 1.16 g X cm-3 in sucrose and an estimated sedimentation coefficient, S20.w of 77. DHBV particles, the morphology of which could be resolved under the electron microscope, consisted of a coat (about 10 nm in thickness) surrounding a core with a diameter measuring 40 nm but not 27 nm as previously reported. Spike-like projections were found on the surface of the core as described previously by W.S. Mason, G. Seal and J. Summers, 1980, J. Virol. 36, 829-836.

A new method for detecting hepatitis B surface antigen in liver by silver staining

Staining of tubular and circular structures within the cisternae of the endoplasmic reticulum of the cytoplasm of liver cells infected with hepatitis B virus was enhanced by the use of 1% aqueous silver proteinate.