The genome and occlusion bodies of marine Penaeus monodon nudivirus (PmNV, also known as MBV and PemoNPV) suggest that it should be assigned to a new nudivirus genus that is distinct from the terrestrial nudiviruses

Abstract

BackgroundPenaeus monodon nudivirus (PmNV) is the causative agent of spherical baculovirosis in shrimp (Penaeus monodon). This disease causes significant mortalities at the larval stage and early postlarval (PL) stage and may suppress growth and reduce survival and production in aquaculture. The nomenclature and classification status of PmNV has been changed several times due to morphological observation and phylogenetic analysis of its partial genome sequence. In this study, we therefore completed the genome sequence and constructed phylogenetic trees to clarify PmNV’s taxonomic position. To better understand the characteristics of the occlusion bodies formed by this marine occluded virus, we also compared the chemical properties of the polyhedrin produced by PmNV and the baculovirus AcMNPV (Autographa californica nucleopolyhedrovirus).ResultsWe used next generation sequencing and traditional PCR methods to obtain the complete PmNV genome sequence of 119,638 bp encoding 115 putative ORFs. Phylogenetic tree analysis showed that several PmNV genes and sequences clustered with the non-occluded nudiviruses and not with the baculoviruses. We also investigated the characteristics of PmNV polyhedrin, which is a functionally important protein and the major component of the viral OBs (occlusion bodies). We found that both recombinant PmNV polyhedrin and wild-type PmNV OBs were sensitive to acid conditions, but unlike the baculoviral OBs, they were not susceptible to alkali treatment.ConclusionsFrom the viral genome features and phylogenetic analysis we conclude that PmNV is not a baculovirus, and that it should be assigned to the proposed Nudiviridae family with the other nudiviruses, but into a distinct new genus (Gammanudivirus).Electronic supplementary materialThe online version of this article (doi:10.1186/1471-2164-15-628) contains supplementary material, which is available to authorized users.

The Genome of the Nucleopolyhedrosis-Causing Virus from Tipula oleracea Sheds New Light on the Nudiviridae Family

“…Based on the concatenated alignment of 37 nudivirus-related genes from 18 dsDNA viruses, including four endogenous nudiviruses (three bracoviruses and the endogenous nudivirus of N. lugens [NlENV]) (Table 5), a highly supported phylogenetic tree was obtained by maximum likelihood analyses. The interrelationships between baculovirus, nudivirus, bracovirus, and hytrosavirus families were in accordance with previous results (30,39,64). ToNV clearly belonged to the Nudiviridae clade and not to the Baculoviridae (Fig.…”

“…To date, few Nudiviridae have been genetically characterized (27,58,59,(62)(63)(64). This study presents the first fully sequenced occluded nudivirus from a Diptera, the crane fly T. oleracea.…”

“…A common genome feature of the Baculoviridae is the presence of clusters of repeated imperfect palindromic AT-rich sequences called homologous repeat (hr) regions that serve as origins of viral DNA replication (60) and as transcriptional enhancers (61). Direct repeats (dr) are also common genome features in Nudiviridae (58,59,(62)(63)(64) and Hytrosaviridae (32,33). In the genome of ToNV, five different dr regions were detected, mainly outside coding regions, except for dr4, which was found within orf084 ( Fig.…”

“…7A). The ToNV ORF059 sequence also displayed 58 conserved sites with two major occlusion body proteins (MOBPs) characterized from shrimp nudiviruses infecting P. monodon (64,68) and P. vannamei (69) (Fig. 7B).…”

“…Twenty genes previously identified (28), including those coding for the DNA polymerase (DNApol) and the helicase, the four RNA polymerase subunits (P47, LEF-4, LEF-8, and LEF-9), and the late expression factor 5 (LEF-5), all the per os infectivity factors (P74, PIF-1, PIF-2, PIF-3, PIF-4 [19 kDa], PIF-5 [ODV-E56], PIF-6 [Ac68], and PIF-7 [VP91/95]), Ac81, the very late factor 1 (VLF-1), the sulfhydryl oxidase (P33), the viral phosphatase (38K), and the major capsid protein (VP39), were found in the ToNV genome. The later gene had been misidentified in PmNV and annotated as the 31K structural protein (64).…”