Journal of General Virology (1994), 75, 632639. Printed in Great Britain 637 Prediction of a putative fusion peptide in the S protein of hepatitis B virus

Sequence analysis of the S protein of hepatitis B virus (HBV) reveals a stretch of 23 hydrophobic amino acids in the amino-terminal region which shows a high degree of similarity with known fusogenic peptides from other viruses. Additionally, this sequence also appears to be highly conserved within the hepadnavirus family. Taken together, the different criteria used in this work suggest fusogenic activity in the amino-terminal region of the S protein of the envelope of HBV. None of the proteins of the envelope of hepatitis B virus (HBV), the prototype member of the hepadnavirus family, has yet been found to be involved in the fusion of the viral and cellular membranes which is necessary to allow the virus genome to enter the cytoplasm and carry out subsequent infective vents. In fact, the hepadnaviru