The complete nucleotide sequence of a new insect picorna-like virus, Ectropis obliqua picorna-like virus (EoPV), which causes a fatal infection of Ectropis obliqua larvae, has been determined. The genomic RNA of EoPV is 9394 nt in length and contains a single, large open reading frame (nt 391-9351) encoding a polyprotein of 2987 aa. Sequence comparisons with other viral polyproteins revealed that the consensus sequences for picornavirus RNA helicase, protease and RNA-dependent RNA polymerase proteins are found on the genome in order in the 59R39 direction. All structural genes were located at the 59 terminus. In terms of sequence similarity, identity and genome organization, EoPV resembles mammalian picornaviruses and three other insect picorna-like viruses: Infectious flacherie virus of silkworm, Sacbrood virus of honeybee and Perina nuda picorna-like virus (PnPV). Phylogenetic analysis showed that EoPV is most closely related to PnPV and suggests that these four insect picorna-like viruses might constitute a new group of insect-infectious RNA viruses.

We examined the intracellular localization of NS5 protein of Dendrolimus punctatus cytoplasmic polyhedrosis virus (DpCPV) by expressing NS5-GFP fusion protein and proteins from deletion mutants of NS5 in baculovirus recombinant infected insect Spodoptera frugiperda (Sf-9) cells. It was found that the NS5 protein was present at the plasma membrane of the cells, and that the N-terminal portion of the protein played a key role in the localization. A transmembrane region was identified to be present in the N-terminal portion of the protein, and the detailed transmembrane domain (SQIHMVWVKSGLVFF, 57-71aa) of N-terminal portion of NS5 was further determined, which was accorded with the predicted results, these findings suggested that NS5 might have an important function in viral life cycle.

The nucleotide sequence of a novel icosahedral DNA virus infecting Dendrolimus punctatus has been determined. The genome is 5039 nt long and includes inverted terminal repeats of 200 nt containing 131 nt long J-shaped terminal hairpins. The 'plus' strand of the genome contains three large open reading frames (ORFs), the left and the mid-ORFs (within the left ORF) in the left-half encoding the non-structural proteins and the right ORF in the right-half encoding viral capsid proteins. NS1 protein contains conserved replication initiation and DNA-dependent ATPase/helicase domains. VP1 protein contains a conserved PGY and phospholipase A2 motifs and shows high identities with VPs of Casphalia extranea densovirus and Bombyx mori densovirus-1 belonging to the genus Iteravirus. Phylogenetic analysis also revealed that this virus is most closely related to Casphalia extranea densovirus and Bombyx mori densovirus-1. Consequently, this virus was considered as a new third member of the genus Iteravirus of the subfamily Densovirinae, and designated Dendrolimus punctatus densovirus.

In this study, Dendrolimus punctatus tetravirus (DpTV) has been identified as a new member of the genus Omegatetravirus of the family Tetraviridae that may be related serologically to Nudaurelia capensis v virus (NvV). DpTV particles are isometric, with a diameter of about 40nm and a buoyant density of 1?281 g cm3 in CsCl. The virus has two capsid proteins (of 62 500 and 6800 Da) and two single-stranded RNA molecules (RNA1 and RNA2), which are 5492 and 2490 nt long, respectively. RNA1 has a large open reading frame (ORF) encoding a polypeptide of 180 kDa; RNA2 contains two partially overlapping ORFs encoding polypeptides of 17 and 70 kDa. The 180 kDa protein, which contains consensus motifs of a putative methyltransferase, helicase and RNA-dependent RNA polymerase, shows significant similarity to those of other tetraviruses. The 17 kDa protein is a PEST (Pro/Glu/Ser/Thr) protein of unknown function. The 70 kDa protein is the coat protein precursor and is predicted to be cleaved at an Asn-Phe site located after residue 570. The 70 kDa protein shows 86 and 66% identity to its homologues in NvV and Helicoverpa armigera stunt virus, respectively. Secondary-structure analysis revealed that the RNAs of DpTV have tRNA-like structures at their 39 termini.