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Published on: April 19, 2016
Detection of a fourth orbivirus non-structural protein
Mourad Belhouchet1, Fauziah Mohd Jaafar, Andrew E Firth
1Vector-Borne Viral Diseases Programme, Institute for Animal Health, Pirbright, United Kingdom.
Plos One
|October 25, 2011
Summary
A new viral protein, non-structural protein 4 (NS4), has been identified in Orbivirus. This protein, encoded by an overlapping open reading frame in segment 9, is found in both insect-borne and tick-borne viruses and associates with cellular structures.
Area of Science:
- Virology
- Molecular Biology
- Protein Biochemistry
Background:
- The Orbivirus genus comprises diverse viruses transmitted by insects and ticks.
- Orbivirus genomes consist of 10 dsRNA segments encoding structural and non-structural proteins.
- Previously identified non-structural proteins include NS1-NS3, with VP6 (helicase) encoded by segment 9.
Purpose of the Study:
- To identify and characterize a novel protein encoded by an overlapping open reading frame (ORFX) in Orbivirus segment 9.
- To determine the cellular localization and potential functions of this newly identified non-structural protein, designated NS4.
Main Methods:
- Bioinformatic analysis to identify the overlapping ORF (ORFX) in segment 9.
- Western blotting and confocal fluorescence microscopy using antibodies against recombinant NS4.
- Expression analysis in mammalian and insect cells infected with Bluetongue virus (BTV) or Great Island virus (GIV).
- Assessment of NS4's interaction with nucleic acids (dsRNA and DNA) and its association with lipid droplets.
Main Results:
- An overlapping ORF (ORFX) in segment 9 encodes a new non-structural protein, NS4.
- NS4 is synthesized in mammalian cells infected with BTV or GIV, and in insect cells infected with BTV.
- NS4 localizes to cytoplasmic and nuclear aggregates and associates with lipid droplets.
- GIV NS4 protects dsRNA from RNAse III cleavage, while both GIV and BTV NS4 protect DNA from DNAse.
- Bioinformatic analysis suggests NS4 contains coiled-coils, binds nucleic acids, associates with membranes, and resembles nucleolar protein UTP20.
Conclusions:
- NS4 represents a newly discovered non-structural protein in Orbivirus, with implications for viral replication and host-pathogen interactions.
- NS4's ability to bind nucleic acids and associate with cellular components like lipid droplets suggests diverse functional roles.
- Further research into NS4's specific functions, particularly its differential interaction with dsRNA based on viral origin, is warranted.
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