DNA-REPLICATION IN THE AUTONOMOUS PARVOVIRUSES

Both ends of the linear single-stranded parvoviral DNA genome contain short palindromic sequences which form duplex hairpins containing cis-acting information required for replication and encapsidation. DNA synthesis is primed directly by the 3' end, and genomes are replicated through multimeric duplex intermediates by unidirectional, leading-strand synthesis. Unit-length genomes are excised from these concatemers, and their telomeres replicated, by the viral NS1 protein, which introduces a single-strand nick into specific origin sequences, becoming covalently attached to the 5' end at the nick and providing a 3' hydroxyl which primes synthesis of a new copy of the telomere. Progeny DNA synthesis requires ongoing replication and is dependent upon packaging.