The bacterial expression vectors carrying the replication-associated (Rep) and capsid-associated (Cap) genes of beak and feather disease virus were constructed and expressed.

The ATPase and GTPase activities of the recombinant Rep protein were measured.

The substrate and ion preference, the optimal condition, the effects of inhibitors, and the presence of Cap protein on the ATPase and GTPase activities of the Rep proteins were examined.

The effects of the Walker A motif, the Walker B motif, and a novel GYDG motif of the Rep protein on the ATPase and GTPase activities were tested using the deletion mutants of the Rep protein.