Complete nucleotide sequence of the cloned infectious genome of Junonia coenia densovirus reveals an organization unique among parvoviruses.

We previously constructed a recombinant plasmid, pBRJ, encompassing an infectious Junonia coenia densovirus (JcDNV) genome (M. Jourdan et al. (1990). Virology 179, 403-409). We report here the complete viral sequence of pBRJ. The genome, 5908 nucleotides (nt) long, consists of an internal unique sequence flanked by long (517 nt) inverted terminal repeats. The first 96 bases of one extremity can fold into a typical Y-shaped hairpin structure. The opposite extremity is incomplete, lacking 88 nt. These terminal structures, similar to those of dependoviruses, human parvovirus B19 and Bombyx mori densovirus (BmDNV), strongly suggest a common mechanism of DNA replication for these parvoviruses. JcDNV genomic organization is unique among parvoviruses in that coding sequences are evenly distributed in the 5' half of both strands. On one strand, the major open reading frame (ORF1) encodes the four structural proteins. On the complementary strand, ORF2, ORF3 (included in ORF2), and ORF4 probably encode nonstructural proteins. JcDNV genome has little DNA homology with vertebrate parvoviruses and surprisingly even less with the two densoviruses presently sequenced. ORF1 contains the highly conserved PGY and G-rich regions and ORF2 the NTP-binding domain common to most structural and to all nonstructural vertebrate parvoviral ORFs, respectively. The single homology between JcDNV and BmDNV is unexpectedly located in JcDNV NTP-binding domain and BmDNV ORF2 assumed to encode structural polypeptides. Only a weak homology exists between JcDNV and Aedes DNV in their NTP-binding domain.