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Open Access Research article

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

Yi-Ting Yang12, Der-Yen Lee3, Yongjie Wang45, Jer-Ming Hu6, Wen-Hsiung Li78, Jiann-Horng Leu109, Geen-Dong Chang11, Huei-Mien Ke127, Shin-Ting Kang12, Shih-Shun Lin13, Guang-Hsiung Kou2* and Chu-Fang Lo1142*

Author Affiliations

1 Institute of Bioinformatics and Biosignal Transduction, College of Bioscience and Biotechnology, National Cheng Kung University, Tainan, Taiwan

2 Department of Life Science, National Taiwan University, Taipei, Taiwan

3 Technology Commons, College of Life Science, National Taiwan University, Taipei, Taiwan

4 Laboratory of Quality and Safety Risk Assessment for Aquatic Products on Storage & Preservation (Shanghai), Ministry of Agriculture, Shanghai, China

5 College of Food Science and Technology, Shanghai Ocean University, Shanghai, China

6 National Taiwan University, Institute of Ecology and Evolutionary Biology, Taipei, Taiwan

7 Biodiversity Research Center, Academia Sinica, Taipei, Taiwan

8 Department of Ecology and Evolution, University of Chicago, Chicago, USA

9 Institute of Marine Biology, College of Life Sciences, National Taiwan Ocean University, Taipei, Taiwan

10 Center of Excellence for the Oceans, National Taiwan Ocean University, Keelung City, Taiwan

11 Institute of Biochemical Sciences, College of Life Science, National Taiwan University, Taipei, Taiwan

12 Ph.D. Program in Microbial Genomics, National Chung Hsing University and Academia Sinica, Taipei, Taiwan

13 Institute of Biotechnology, National Taiwan University, Taipei, Taiwan

14 Center of Bioscience and Biotechnology, National Cheng Kung University, Tainan, Taiwan

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BMC Genomics 2014, 15:628  doi:10.1186/1471-2164-15-628

Published: 25 July 2014

Abstract

Background

Penaeus 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).

Results

We 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.

Conclusions

From 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).

Keywords:
PmNV; Genome; Baculovirus; Nudivirus; OBs; Polyhedrin