Genome organization of the densovirus from Bombyx mori (BmDNV-1) and enzyme activity of its capsid

Bombyx mori densovirus (BmDNV-1), on the basis of the previously reported g enome sequence, constitutes by itself a separate genus (Iteravirus) within the Densovirinae subfamily of parvoviruses. Inconsistencies in the genome o rganization, however, necessitated its reassessment. The genome sequence of new clones was determined and resulted in a completely different genome or ganization. The corrected sequence also contained conserved sequence motifs found in other parvoviruses. Some amino acids in the highly conserved doma in in the unique region of VP1 were shared by critical amino acids in the c atalytic site and Ca2+-binding loop of secreted phospholipase A(2), such as from snake and bee venoms. Expression of this domain and determination of enzyme activity demonstrated that capsids have a phospholipase A(2) activit y thus far unknown to occur in viruses. This viral phospholipase A(2), whic h is required shortly after entry into the cell, showed a substrate prefere nce for phosphatidylethanolamine and phosphatidylcholine over phosphatidyli nositol.