Macrobrachium rosenbergii nodavirus (MrNV) is a pathogen of freshwater prawns that poses a threat to food security and causes significant economic losses in the aquaculture industries of many developing nations. A detailed understanding of the MrNV virion structure will inform the development of strategies to control outbreaks. The MrNV capsid has also been engineered to display heterologous antigens, and thus knowledge of its atomic resolution structure will benefit efforts to develop tools based on this platform. Here, we present an atomic-resolution model of the MrNV capsid protein (CP), calculated by cryogenic electron microscopy (cryoEM) of MrNV virus-like particles (VLPs) produced in insect cells, and three-dimensional (3D) image reconstruction at 3.3 Å resolution. CryoEM of MrNV virions purified from infected freshwater prawn post-larvae yielded a 6.6 Å resolution structure, confirming the biological relevance of the VLP structure. Our data revealed that unlike other known nodavirus structures, which have been shown to assemble capsids having trimeric spikes, MrNV assembles a T = 3 capsid with dimeric spikes. We also found a number of surprising similarities between the MrNV capsid structure and that of the Tombusviridae: 1) an extensive network of N-terminal arms (NTAs) lines the capsid interior, forming long-range interactions to lace together asymmetric units; 2) the capsid shell is stabilised by 3 pairs of Ca2+ ions in each asymmetric unit; 3) the protruding spike domain exhibits a very similar fold to that seen in the spikes of the tombusviruses. These structural similarities raise questions concerning the taxonomic classification of MrNV.
White tail disease in the giant freshwater prawn Macrobrachium rosenbergii causes significant economic losses in shrimp farms and hatcheries and poses a threat to food-security in many developing countries. Outbreaks of Macrobrachium rosenbergii nodavirus (MrNV), the causative agent of white tail disease (WTD) are associated with up to 100% mortality rates. There are no interventions available to treat or prevent MrNV disease however. Here we show the structure of MrNV virus-like particles (VLPs) produced by recombinant expression of the capsid protein, using cryogenic electron microscopy. Our data show that MrNV VLPs package nucleic acids in a manner reminiscent of other known nodavirus structures. The structure of the capsid however shows striking differences from insect and fish infecting nodaviruses, which have been shown to assemble trimer-clustered T = 3 icosahedral virus particles. MrNV particles have pronounced dimeric blade-shaped spikes extending up to 6 nm from the outer surface of the capsid shell. Our structural analysis supports the assertion that MrNV may belong to a new genus of the Nodaviridae. Moreover, our study provides the first structural view of an important pathogen affecting aquaculture industries across the world.
24Macrobrachium rosenbergii nodavirus (MrNV) is a pathogen of freshwater prawns that poses 25 a threat to food-security and causes significant economic losses in the aquaculture industries 26 of many developing nations. A detailed understanding of the MrNV virion structure will 27 inform the development of strategies to control outbreaks. The MrNV capsid has also been 28 engineered to display heterologous antigens, thus knowledge of its atomic resolution 29 structure will benefit efforts to develop tools based on this platform. Here we present an 30 atomic-resolution model of the MrNV capsid protein, calculated by cryogenic electron 31 microscopy (cryoEM) of MrNV virus-like particles (VLPs) produced in insect cells, and three-32 dimensional image reconstruction at 3.3 Å resolution. CryoEM of MrNV virions purified from 33infected freshwater prawn post-larvae yielded a 6.6 Å resolution structure confirming the 34 biological relevance of the VLP structure. 35Our data revealed that unlike other known nodaviruses structures, which have been shown 36 to assemble capsids having trimeric spikes, MrNV assembles a T=3 capsid with dimeric spikes. 37We also found a number of surprising similarities between the MrNV capsid structure and 38 that of the Tombusviridae. 1. An extensive network of N-terminal arms lines the capsid 39 interior forming long-range interactions to lace together asymmetric units. 2. The capsid shell 40 is stabilised by three pairs of Ca 2+ ions in each asymmetric unit. 3. The protruding spike 41 domain exhibits a very similar fold to that seen in the spikes of the tombusviruses. These 42 structural similarities raise questions concerning the correct taxonomic classification of MrNV. 43 44 45
White tail disease in the giant freshwater prawn Macrobrachium rosenbergii causes significant economic losses in shrimp farms and hatcheries and poses a threat to food-security in many developing countries. Outbreaks of Macrobrachium rosenbergii nodavirus (MrNV), the causative agent of white tail disease (WTD) are associated with up to 100% mortality rates. Recombinant expression of the capsid protein of MrNV in insect cells leads to the production of VLPs closely resembling the native virus. We have investigated the structure of MrNV VLPs by cryogenic electron microscopy, determining a structure of the viral capsid at 7 angstroms resolution. Our data show that MrNV VLPs package nucleic acids in a manner reminiscent of other known nodavirus structures. The structure of the capsid however shows striking differences from insect and fish infecting nodaviruses, which have been shown to assemble trimer-clustered T=3 icosahedral virus particles. MrNV particles have pronounced dimeric blade-shaped spikes extending up to 6 nm from the outer surface of the capsid shell.Our structural analysis supports the assertion that MrNV along with the related virus of marine shrimp Penaeus vannamei nodavirus (PvNV) may represent a new genus of the Nodaviridae.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.