structural:scholar_edition, linguistic:voice_change, linguistic:paraphrasing, quality:corruption
Life cycle

Parvoviruses replicate their genome via rolling hairpin replication, a unidirectional, strand displacement form of DNA replication that is initiated by NS1. Replication begins once NS1 binds to and makes a nick in a replication origin site in the duplex DNA molecule at the end of one hairpin. Nicking releases the 3′-end of the nicked strand as a free hydroxyl (-OH) to prime DNA synthesis with NS1 remaining attached to the 5′-end. The nick causes the adjacent hairpin to unfold into a linear, extended form. At the 3′-OH, a replication fork is established using NS1's helicase activity, and the extended telomere is replicated by the DNA polymerase. The two telomere strands then refold back in on themselves to their original configurations, which repositions the replication fork to switch templates to the other strand and move in the opposite direction toward the other end of the genome.