Hepatitis delta virus (HDV) genotype 11 is the predominant genotype in Taiwan and is associated with less progressive disease than genotype I. Although the Taiwan-3 (T3) clone was the first genotype 11 HDV isolated in Taiwan, its replication in cultured cells has not previously been established. Here, we demonstrate that cloned T3 HDV is capable of replicating in cultured cells. Furthermore, we show that: (1) the replication level of T3 clones is 100-fold lower than that of a genotype I HDV prototype of Italian origin;, (2) both forms of the genotype 11 T3 delta antigen are expressed; and (3) T3 HDV undergoes RNA editing during replication, with 4.8%, of the T3 genomes showing evidence of editing. The low level of RNA replication may be related to the milder clinical outcomes of genotype 11 HDV infections. (C) 2003 Elsevier Science (USA). All rights reserved.