Characterization of a new densovirus infecting the German cockroach, Blattella germanica

Abstract

A new DNA virus (Parvoviridae: Densovirinae, Densovirus) was isolated and purified from descendants of field-collected German cockroaches, Blattella germanica. Viral DNA and cockroach tissues infected with B. germanica densovirus (BgDNV) were examined by electron microscopy. Virus particles, about 20 nm in diameter, were observed both in the nucleus and in the cytoplasm of infected cells. Virus DNA proved to be a linear molecule of about 1?2 mm in length. BgDNV isolated from infected cockroaches infected successfully and could be maintained in BGE-2, a B. germanica cell line. The complete BgDNV genome was sequenced and analysed. Five open reading frames (ORFs) were detected in the 5335 nt sequence: two ORFS that were on one DNA strand encoded structural capsid proteins (69?7 and 24?8 kDa) and three ORFs that were on the other strand encoded non-structural proteins (60?2, 30?3 and 25?9 kDa). Three putative promoters and polyadenylation signals were identified. Structural analysis of the inverted terminal repeats revealed the presence of extended palindromes. The genome structure of BgDNV was compared with that of other members of the family Parvoviridae; the predicted amino acid sequences were aligned and subjected to phylogenetic analyses.

Expression Strategy of Densonucleosis Virus from the German Cockroach, Blattella germanica

“…2H), in accordance with the bioinformatically predicted start point, provided that transcription is driven by the P1 promoter (37). Therefore, in contrast to NS transcripts, the 5Ј untranslated region for VP mRNAs is very short and comprises only 3 nt, exactly the same as for CpDNV (7).…”

“…3D, panel 2, lane 2. We cloned and sequenced all of the bands; subsequent analysis revealed that the largest two (approximately 2.2 and 2.4 kb, indicated by an arrow with a vertical line and a simple arrow, respectively) indeed corresponded to the full spliced and unspliced transcripts, respectively, with a transcription stop point at nt 2494, 19 nt downstream from the predicted polyadenylation signal (AAUAAA, nt 2513 to 2518) (37) (Fig. 2F).…”

“…As this principle could not be strictly applied to DNVs possessing ambisense genomes, it was decided to define the genome strand encoding NS proteins as plus strand and depict genomes so that NS ORFs are located on the left while VP ORFs are located on the right (52). In our previous work (37), where the complete sequence of the BgDNV genome was presented, we put it in the opposite orientation, so that VP ORFs were on the left. In the present work, the BgDNV genome is given in the conventional orientation.…”

“…The DNV of the German cockroach, Blattella germanica (BgDNV), was discovered in a cockroach colony that originated from a natural population in a pig farm in North Carolina and maintained in the laboratory for 5 years. The structural organization of this virus was described in our previous work (37).…”

Structure and Expression Strategy of the Genome of Culex pipiens Densovirus, a Mosquito Densovirus with an Ambisense Organization

“…The genus Pefudensovirus is represented by the DNV isolated from the cockroach Periplaneta fuliginosa. DNVs isolated from the cockroach Blatella germanica and the cricket Acheta domestica (3,13,23) have similar physicochemical properties since their genomes are also only 5.4 kb long, the sequences encoding their structural proteins are split in two ORFs in different frames, and their short (200 to 220 nt) telomeres fold into simple fold-back hairpins. However, their sequences are quite dissimilar.…”