The team are the first to observe at a single-molecule level how the genetic material (genome) that forms the core of a single-strand RNA virus particle packs itself into its outer shell of proteins. Lead researcher Professor Peter Stockley said their results overturn accepted thinking about the process and could open a chink in the armour of a wide range of viruses.
"If we can target this process, it could lead to a completely new class of anti-virals that would be less likely to create resistant viruses than existing drugs, which tend to target individual proteins," Professor Stockley said.
A number of important viruses like the common cold and polio have RNA (ribonucleic acid) instead of DNA as their genetic material. The observations reveal that the viruses' RNA initially has a much greater volume than the virus particles created after they are packed inside their protein shell.
"We realised that the RNA genome must have to be intricately folded to fit into the final container, just like when you pack to go on holiday and need to fold your clothes to fit into the space in your suitcase," said co-author Dr Roman Tuma from the University of Leeds' Faculty of Biological Sciences.
When the team added proteins to the viral RNA they saw an immediate collapse in its volume.
"It seems that viral RNAs have evolved a self-folding mechanism that makes closing the 'viral suitcase' very efficient. It's as though 'the suitcase and the clothes' work together to close the lid and protect the content," Dr Tuma said.
"The viral RNAs, and only the viral RNAs, can do this trick of folding up to fit as soon as they see the 'suitcase' coming. That's the important thing. If we can interfere in that process we've got a completely novel drug target in the lifecycle of viruses," Professor Stockley said.
"At the moment there are relatively few antiviral drugs and they tend to target enzymes that the virus encodes in its genome. The problem is that the drugs target one enzyme initially and, within the year, scientists are identifying strains that have become resistant. Individual proteins are extremely susceptible to this mutation. A fundamental process like the one we're looking at opens the possibility of targeting the collective behaviour of essential molecules, which could be much less susceptible to developing resistance," explained Professor Stockley.
The same phenomenon is seen in both bacterial and plant viruses. "While we have not proved it yet, I would put money on animal viruses showing the same mechanism too," Professor Stockley added.
The team used sophisticated instrumentation custom built at the University that allowed them to make the first ever single-molecule measurements of viral assembly. This allowed researchers to observe individual viral particles one at a time. "The specific collapse, which can only be seen in such assays, was totally unexpected and overturns the current thinking about assembly," Professor Stockley said.
The team also includes PhD student Alexander Borodavka, whose Wellcome Trust studentship funded the new research. They have recently secured a grant from the Biotechnology and Biological Sciences Research Council (BBSRC) to extend their research.
"We're now perfectly positioned to pursue questions about how this mechanism works in other viruses and we're already thinking about ways to start designing new antiviral drugs that would target this newly recognised feature of viral lifecycles," Professor Stockley said.
The research is published in the Proceedings of the National Academy of Sciences (PNAS).
Ralf Richter, David Brockwell, Eric Hewitt, Jessica Kwok, Emanuele Paci and MAPS/FMH, BBSRC (Jun 2017), £600,000
Eric Blair, Adrian Whitehouse, Nicola Stonehouse, Alison Baker, Richard Bayliss, Joan Boyes, Ryan Seipke, Sally Boxall and MAPS/FMH, BBSRC (Jun 2017), £376,000
Stefan Kepinski, Yoselin Benitez-Alfonso, Tom Bennett, Michelle Peckham, BBSRC (Jun 2017), £331,000
Roman Tuma, Lars Jeuken, Paul Millner, Sheena Radford, Peter Stockley and MAPS/FMH, BBSRC (Jun 2017), £222,000
Vas Ponnambalam, Darren Tomlinson, Stephen Wheatcroft, BHF (May 2017), £107,878
Graham Askew in collaboration with Bangor University, BBSRC (Mar 2017), £477,383
Stephen Muench, BBSRC (Mar 2017), £132,945
Nic Stonehouse, MRC (Mar 2017), £906,341
Bill Kunin, Steve Sait, BBSRC (Mar 2017), £602,831
Adrian Goldman, EU (Mar 2017), £546,576
Sheena Radford, Wellcome Trust (Mar 2017), £1,836,482
Tom Bennett, Royal Society (Mar 2017), £15,000
Jamie Johnston, Royal Society (Mar 2017), £15,000
Beatrice Filippi, Royal Society (Mar 2017), £15,000
Ryan Seipke, BBSRC (Feb 2017), £52,116
Mary O'Connell, BBSRC (Feb 2017), £46,986
Hannah Dugdale, NERC (Feb 2017), £504,138
Anastasia Zhuravleva, EPSRC (Jan 2017), £100,792
Richard Bayliss, Cancer Research UK (Jan 2017), £1,600,000
John Barr, EU (Jan 2017), £339,000
Mark Harris, Royal Society (Jan 2017), £250,000
Alison Dunn, NERC (Jan 2017), £105,000
Alex Breeze, Pancreatic Cancer Research Fund (Jan 2017), £180,000
Alison Dunn, NERC (Dec 2016), £18,000
Lisa Collins, BBSRC (Dec 2016), £1,681,835
Brendan Davies, Leverhulme Trust (Dec 2016), £247,555
Alan Benson, Mark Drinkhill, Ed White, British Heart Foundaion (Dec 2016), £217,223
Adrian Goldman, Royal Society (Dec 2016), £82,999
Lisa Roberts, Alex Breeze, Brendan Davies, Timothy Devinney, Oliver Harlen, Joseph Holden, Anthea Hucklesby, Pamela Jones, Philip Mellor, RCUK (Nov 2016), £484,172
Lisa Roberts, Alex Breeze, Brendan Davies, Timothy Devinney, Oliver Harlen, Joseph Holden, Anthea Hucklesby, Pamela Jones, Philip Mellor, Wellcome Trust (Nov 2016), £119,343
Katie Field, Rank Prize Funds (Nov 2016), £20,000
Jessica Kwok, Royal Society (Nov 2016), £14,948
John Ladbury, Cancer Research UK (Oct 2016), £4,250
Miriam Wittmann, Martin Stacey, Edward Vital, Lupus UK
(Oct 2016), £34,010
Valerie Speirs, NC3Rs
(Oct 2016), £90,000
Nicola Stonehouse, Morgan Herod, David Rowlands, BBSRC
(Sep 2016), £436,424
Joseph Cockburn, Wellcome Trust
(Sep 2016), £100,000
John Barr, Public Health England
(Sep 2016), £94,471
Helen Miller, DSM Nutritional Products A/S
(Sep 2016), £54,680
Steven Clapcote, Vitaflo International Ltd
(Sep 2016), £39,285
Juan Fontana Jordan De Urries
, Royal Society
(Sep 2016), £21,793
Jing Li, Sarah Calaghan, Mark Drinkhill, British Heart Foundation
(Sep 2016), £117,585
Sheena Radford, Alison Ashcroft, BBSRC (Sep 2016), £457,216
Patricija Van Oosten-Hawle, An-Jung Chen, David Westhead, NC3Rs
(Sep 2016), £354,456
Glyn Hemsworth, BBSRC (Sep 2016), £1,024,034
David Jayne, Paul Millner, MRC (Aug 2016), £207,860
Sheena Radford, Alison Ashcroft, BBSRC (Aug 2016), £457,215
Patricija Van Oosten-Hawle, Dave Westhead, An-Jung Chen, NC3Rs (Aug 2016), £354,456
Peter Henderson, EU - European Union
EU - European Union
(Jul 2016), £123,897
Adrian Goldman, EU - European Union
(Jul 2016), £116,290
Urwin, Howard Atkinson, NERC
(Jul 2016), £105,053
Eileen Ingham and colleagues in Engineering and M&H, EPSRC (Jul 2016), £3,867,449
Michael Colman, MRC (Jul 2016), £200,956
Tim Benton, Fresca Group Ltd
(Jul 2016), £52,082