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Duck hepatitis is a convenient model of hepatitis B virus (HBV) infection, but the lack of immunological reagents hampers investigation of pathogenesis and vaccine development. The aim of this study was to define T-cell epitopes in the surface peptide recognized by vaccinated immune birds. Blastogenesis assays were used to test the proliferative response of spleen mononuclear cells to synthetic peptides spanning the pre-S/S region in 22 naïve and 13 immunized and challenged immune ducks. Roughly ≥50% of the immune ducks responded to five immunodominant peptides eliciting a statistically greater proliferative response than in naïve birds. Fewer ducks responded to an additional six peptides. No statistically significant difference could be shown for the response to 11 peptides between the immune ducks and the naïve ducks. There was no clustering of the immunodominant peptides which were located throughout the surface antigen at sites of major swings in hydrophobicity. A number of peptides which induce lymphoblastogenesis in vaccinated immune ducks have been identified. Their role in spontaneous recovery from duck hepatitis B infection merits investigation. [ABSTRACT FROM AUTHOR]

Commentary. Discusses a paper by Peter Simmonds, et al, which was published in the July 18, 1998 issue of `The Lancet.' Aspects of the transfusion-transmittable virus known as TTV; The pathogenic role of TTV; Suggestion that TTV may be a parvovirus; The strong circumstantial evidence of transmission of TTV by transfusion; Effects of the discovery of TTV.

Aim: Steam autoclaving is the gold standard for decontaminating dental instruments, but worldwide disinfection is still widely employed. We have evaluated a range of procedures for their ability to inactivate duck hepatitis B virus contaminating dental syringes.Methods: Residual infectivity of virus suspensions following 2% glutaraldehyde treatment, ultrasonication or steam sterilisation at 121 degrees or 134 degrees was assayed by injecting day-old ducklings and examining their livers for viral DNA 2.5 weeks later. Dental syringes were contaminated with DHBV positive blood, then treated by the same methods. An anaesthetic cartridge containing water was loaded into the syringe and 400microl aliquots used to inject day-old ducklings. Used dental syringes were examined by Scanning Electron Microscopy.Results: Suspension test:- ultrasonic treatment failed to inactivate DHBV in suspension, but complete inactivation was achieved by 2% glutaraldehyde and autoclaving. Syringe test:- neither ultrasonic treatment nor glutaraldehyde inactivated DHBV. Autoclaving at 134 degrees (3 minutes) permitted transmission to 1/16 ducklings but steam sterilisation at 121 degrees (15 minutes) was effective. Electronmicroscopy demonstrated organic debris (biofilm) in the lumen of used syringes.Conclusion: Short autoclaving cycles, albeit at raised temperatures, may fail to inactivate the virus because of poor steam penetration, inadequate heat transfer and the accumulation of protective biofilm. [ABSTRACT FROM AUTHOR]

Abstract: Many viruses including HIV, hepatitis C and hepatitis B, have an outer lipid envelope which maintains inserted viral peptides in the “correct” functional conformation and orientation. Disruption of the lipid envelope by most solvents destroys infectivity and often results in a loss of antigenicity. This communication outlines a novel approach to viral inactivation by specific solvent delipidation which modifies the whole virion rendering it non-infective, but antigenic. Duck hepatitis B virus (DHBV) was delipidated using a diisopropylether (DIPE) and butanol mixture and residual infectivity tested by inoculation into day-old ducks. Delipidation completely inactivated the DHBV (p <0.001). Delipidated DHBV was then used to vaccinate ducks. Three doses of delipidated DHBV induced anti-DHBs antibody production and prevented high dose challenge infection in five out of six ducks. In comparison, five of six ducks vaccinated with undelipidated DHBV and four of four ducks vaccinated with glutaraldehyde inactivated DHBV were unprotected (p <0.05). Although this solvent system completely inactivated DHBV, viral antigens were retained in an appropriate form to induce immunity. Delipidation of enveloped viruses with specific organic solvents has potential as the basis for development of vaccines. [Copyright &y& Elsevier]

There is little recent data of the seroprevalence of hepatitis B in Australia. We have surveyed a large cohort of endoscopy patients attending a teaching hospital in central Sydney, and related the presence of hepatitis B virus (HBV) markers with putative risk factors for exposure using the SAS statistical package. Of the 2115 patients tested: 2.1% (45/2115) were HBV surface antigen positive, 0.75% (14/2115) viraemic, 9.5% (200/2115) anti-HBs and anti-HBc positive, 20.1% (430/2115) vaccinated (anti-HBs only) and the remaining 70% were susceptible. The adjusted OR of HBV infection was significantly increased in patients who had been diagnosed with human immunodeficiency virus (36.3-fold), born in Asia or Pacific islands (12.4-fold), born in North Africa, Middle East & Mediterranean countries (6-fold) or born abroad elsewhere in the world (2.7-fold), had household contact with someone diagnosed with hepatitis between 1980 and 1990 (3.9-fold), injected drugs between 1980 and 1990 (4.4-fold), resided in a military establishment for 3 months (2.3-fold) or in a hospital for 3 months (2.2-fold), never been vaccinated for hepatitis B (2.8-fold), received blood transfusion due to an accident and/or a haemorrhage (1.92-fold) and finally been a male gender (1.59-fold). The prevalence of HBV in this hospital population was higher than predicted on the basis of notifications to the passive surveillance scheme. Most HBV patients had multiple risk factors for infection, but the hierarchy of odds ratios provides a rational basis for targeted programmes to identify asymptomatic HBV carriers who might benefit from treatment. [ABSTRACT FROM AUTHOR]

Background: Reports from around the world indicate that multiply transfused patients are at increased risk of hepatitis C virus (HCV) infection, with reported rates of between 4% and 44%. Such reports are mostly of haematological and renal patients. As recipients of blood products in the newborn period, premature infants share this risk, but there is little information regarding their risk. Aim: To assess the risk of HCV infection in children who, as premature neonates, received multiple blood products prior to the introduction of screening of donated blood for HCV. Methods: Premature infants born between January 1985 and January 1990 who had attended our high-risk follow-up clinic were selected on the basis of the number of transfusions of blood, platelets or fresh frozen plasma they received in the newborn period. Ethical approval to offer HCV testing to parents was obtained from the Central Sydney Area Health Service Ethics Review Committee. Parents of infants who received three or more transfusions were then contacted by mail with the approved letter explaining the study, and offered HCV testing. Detection of anti-HCV antibodies was undertaken using second, and later third generation enzyme immunoassay kits. Samples which were found to be ‘indeterminate’ were tested using a Wellcozyme HCV western blot assay (Murex Diagnostics Ltd, Datford, UK). Hepatitis C virus–ribonucleic acid (RNA) was detected using an ‘in-house’ polymerase chain reaction (PCR) assay. Alanine transaminase (ALT) was also measured, with values above 55 U/L considered abnormal. Results: Consent was obtained for 45 children (25 males, 20 females). The mean (± SEM) gestational age and weight of the children at birth was 26.7 ± 0.2 weeks and 938 ± 27 g, respectively. The children received 198 transfusions of blood products, an average of 4.4 U per child. All of the infants except for one were negative for anti-HCV antibodies. One infant was ‘indeterminate’ (low positive on third generation test but negative on second generation test), but proved negative subsequently on both western blot and PCR testing. HCV–RNA was not detected in any of the infants on PCR testing. All of the samples had normal ALT values, the mean being 16 U/L (range 8–52). Conclusion: None of the children consenting to this study had evidence of current HCV infection. Because of the sample size, we were not able to estimate the true risk of infection from this study, except that the upper limit for the risk is about 1/200 per transfused blood sample. [ABSTRACT FROM AUTHOR]