Heterologous replacement of the supposed host determining region of avihepadnaviruses: high in vivo infectivity despite low infectivity for hepatocytes.

Hepadnaviruses, including hepatitis B virus (HBV), a highly relevant human pathogen, are small enveloped DNA viruses that replicate via reverse transcription. All hepadnaviruses display a narrow tissue and host tropism. For HBV, this restricts efficient experimental in vivo infection to chimpanzees.

Transgenic mice replicating hepatitis B virus but lacking expression of the major HBsAg.

Hepatitis B Virus (HBV) transgenic mice replicating the viral genome at high level but lacking expression of the small envelope protein (HBsAg) have been produced using a terminally redundant viral DNA construct (HBV 1.4). The generation of viable infectious progeny was dependent on sex and age of mice.

Rise in gamma interferon expression during resolution of duck hepatitis B virus infection.

Gamma interferon (IFN-gamma) expression plays a crucial role in the control of mammalian hepatitis B virus (HBV) infection. However, the role of duck INF-gamma (DuIFN-gamma) in the outcome of duck HBV (DHBV) infection, a reference model for hepadnavirus replication studies, has not yet been investigated. This work explored the dynamics of DuIFN-gamma expression in liver and peripheral blood mononuclear cells (PBMCs) during resolution of DHBV infection in adolescent ducks in relation to serum and liver markers of virus replication, histological changes and humoral response induction.

Phenotyping hepatitis B virus variants: from transfection towards a small animal in vivo infection model.

The existence of vaccine escape and drug resistant hepatitis B virus (HBV) variants is now well established, and various of the underlying prototypic mutations have been defined. Genotypic detection of such variants allows to predict their clinical phenotype. However, the relevance of non-predefined mutations occurring during therapy can be assessed only by phenotypic assays.

Characterization of duck leucocytes by monoclonal antibodies.

cDNAs encoding CD3epsilon, CD4 and the alpha-chain of CD8 of ducks were cloned. Monoclonal antibodies against Pekin duck CD4 and CD8alpha revealed that the antigens were expressed by the majority of thymocytes and by subpopulations of CD3+ cells in peripheral tissues. CD8alpha cell surface expression was also found on 90% of bursal cells.

The interferon system of non-mammalian vertebrates.

Genetic analysis in mice and other mammals showed that the interferon (IFN) system is important for resistance to viral and bacterial infections. IFN is thought to play a similar role in non-mammalian species, although knowledge is lagging behind. Molecular cloning revealed low but significant conservation of IFN genes in birds and fish.