Identification and analysis of a new hepadnavirus in white storks

We identified, cloned, and functionally characterized a new avian hepadnavi nus infecting storks (STHBV). STHBV has the largest DNA genome of all avian hepadnaviruses and, based on sequence and phylogenetic analysis, is most c losely related to, but distinct from, heron hepatitis B virus (HHBV). Uniqu e for STHBV among the other avian hepadnaviruses is a potential HNF1 bindin g site in the pries promoter. In common only with HHBV, STHBV has a myristy lation signal on the S and not the preS protein, two C terminally located g lycosylation sites on the precore/core proteins and lacks the phosphorylati on site essential for the transcriptional transactivation activity of duck- HBV preS protein. The cloned STHBV genomes were competent in gene expressio n, replication, and viral particle secretion. STHBV infected primary duck h epatocytes very inefficiently suggesting a restricted host range, similar t o other hepadnaviruses. This discovery of stork infections unravels novel e volutionary aspects of hepadnaviruses and provides new opportunities for he padnavirus research. (C) 2001 Academic Press.