NUCLEOTIDE-SEQUENCE OF AN INFECTIOUS MOLECULARLY CLONED GENOME OF GROUND-SQUIRREL HEPATITIS-VIRUS

The complete nucleotide sequence of an infectious cloned genome of ground squirrel hepatitis virus (GSHV), a nonpathogenic member of the hepadnavirus group, was determined. The genome is 3311 base pairs long and contains the major open reading frames described for the related human and woodchuck hepatitis B viruses (HBV and WHV, respectively). These reading frames include genes for the major structural proteins (the surface and core antigens); unassigned open reading frames (A and B), the longer of which is presumed to encode the viral DNA polymerase; and an open reading frame preceding and continuous with the surface antigen gene. The arrangement of these open reading frames is similar to that encountered in the genomes of HBV and WHV: all of the reading frames are encoded on the same strand, they are positioned in the same fashion with respect to each other and a large portion (at least 51%) of the genome can be translated in 2 reading frames. Comparisons of the predicted translational products of the 3 mammalian hepadnaviruses reveal 78% amino acid homology between the proteins of GSHV and WHVand 43% homology between those of GSHV and HBV. A perfect direct repeat of 10-11 base pairs, separated by .apprx. 46 to 223 base pairs, present in the 3 mammalian viruses and in duck hepatitis B virus; the position of the repeats near the 5'' termini of the 2 strands of virion DNA suggests a role in viral replication.