Structure and replication of the genome of the hepatitis δ virus

The hepatitis δ virus can be found in the serum and liver of some hepatitis B virus patients. We now report that the RNA genome of serum-derived δ virus is single-stranded and circular. Livers of infected chimpanzees or woodchucks contained as many as 300,000 copies of genomic strand RNA per average cell, and at least some of this RNA had a circular conformation. Also present in the liver were RNA species complementary to the virion RNA. The genomic RNA was 5-22 times more abundant than this antigenomic strand. Some of the antigenomic RNA was complexed with genomic RNA, as evidenced by the fact that at least 34% of the antigenomic RNA was resistant to digestion with either RNase A in 0.3 M NaCl or S1 nuclease. Some of the antigenomic RNA was in a circular conformation. These and other findings showed that the structure and replication of hepatitis δ virus are in many ways similar to those of the previously described plant viroids, virusoids, and satellite RNAs.