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

Abstract

Bombyx mori densovirus (BmDNV-1), on the basis of the previously reported genome sequence, constitutes by itself a separate genus (Iteravirus) within the Densovirinae subfamily of parvoviruses. Inconsistencies in the genome organization, however, necessitated its reassessment. The genome sequence of new clones was determined and resulted in a completely different genome organization. The corrected sequence also contained conserved sequence motifs found in other parvoviruses. Some amino acids in the highly conserved domain in the unique region of VP1 were shared by critical amino acids in the catalytic site and Ca 2M -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 activity thus far unknown to occur in viruses. This viral phospholipase A 2 , which is required shortly after entry into the cell, showed a substrate preference for phosphatidylethanolamine and phosphatidylcholine over phosphatidylinositol.

A new virus infecting Myzus persicae has a genome organization similar to the species of the genus Densovirus FN1

“…The activity of PLA 2 is critical for the efficient transfer of the viral genome from late endosomes to the nucleus to initiate replication and thus for parvovirus infectivity (Zadori et al, 2001). This enzyme activity of the capsid was also demonstrated for BmDNV-1 (Li et al, 2001) and CeDNV (Fédière et al, 2002). Interestingly, this motif appears to be less conserved in the MpDNV structural proteins (30-36 % identity within a stretch of 39 aa with the other DNVs).…”

“…The function of the second region, the so-called PGY motif, highly conserved (70-98 % identity within a stretch of 39 aa in VP1) among vertebrate parvoviruses and DNVs (Dumas et al, 1992), was elucidated recently. Zadori et al (2001) showed that this region was part of the catalytic site of secretory phospholipase A 2 (PLA 2 ). The activity of PLA 2 is critical for the efficient transfer of the viral genome from late endosomes to the nucleus to initiate replication and thus for parvovirus infectivity (Zadori et al, 2001).…”

“…Zadori et al (2001) showed that this region was part of the catalytic site of secretory phospholipase A 2 (PLA 2 ). The activity of PLA 2 is critical for the efficient transfer of the viral genome from late endosomes to the nucleus to initiate replication and thus for parvovirus infectivity (Zadori et al, 2001). This enzyme activity of the capsid was also demonstrated for BmDNV-1 (Li et al, 2001) and CeDNV (Fédière et al, 2002).…”

Mutational Analysis of Narrow Pores at the Fivefold Symmetry Axes of Adeno-Associated Virus Type 2 Capsids Reveals a Dual Role in Genome Packaging and Activation of Phospholipase A2 Activity

“…PLA2 activity is thought to be required between the stage of perinuclear accumulation of virions and the stage of early gene expression (22,39,86). Injection of VP1-specific antibodies into the cytoplasm of cells prior to inoculation with CPV prevented infection, suggesting that this domain is accessible to antibody recognition within the cytoplasm (69).…”

Structure of Bombyx mori Densovirus 1, a Silkworm Pathogen

“…The parvovirus family has been divided into two subfamilies, the Parvovirinae, which infect vertebrates, and the Densovirinae, which infect invertebrates. Bombyx mori densovirus 1 (BmDNV-1) belongs to the Densovirinae subfamily (genus Iteravirus) (17) and causes potentially lethal flacherie disease in silkworms (28), thereby posing a major threat to silk production. So far, only CeDNV (from Casphalia extranea), DpDNV (from Dendrolimus punctatus), and BmDNV-1 belong to the genus Iteravirus, whereas BmDNV-2 and -3 have a bipartite genome with a total length of about 12.5 kb and have been excluded from the Parvoviridae and reassigned to a new family (Bidnaviridae) (31).…”