The role of the Marek's disease virus (MDV) Meq oncoprotein in the pathogenesis of Marek's disease and the development of MDV vaccine strains

Lead Research Organisation: The Pirbright Institute
Department Name: Avian Infectious Diseases

Abstract

Marek's disease (MD) is a common disease of chickens involving paralysis and commonly death from the growth of highly malignant T lymphomas (cancers of white blood cells). Unusual for a cancer, MD is caused by a transmissible agent, Marek's disease virus (MDV). MDV is very contagious and is a major threat to the poultry industry worldwide, but it can be controlled by vaccination. More than 5 billion vaccine doses a year are used in an attempt to control the disease. However, there is a continuous evolution of the virus towards greater virulence and consequently new vaccines are required. The mechanisms by which the virus gains virulence and produces tumours remain very poorly understood. Similarly, the factors that determine an effective vaccine strain remain unclear. With financial support from the BBSRC, we have been studying a protein called Meq that is made by MDV in the cancer cells. Our recent results have demonstrated unequivocally that this protein is absolutely essential for the induction of tumours by MDV (it is therefore known as an oncoprotein). Moreover it has been possible to identify specific protein:protein interactions involving Meq that are necessary for its function as an oncoprotein. We have made various defined mutations in the Meq-encoding gene that produce attenuated (non-pathogenic) MDV that we showed can be used as vaccines. This is a proposal to build on this work in order to determine the precise contribution that Meq makes to the development of Marek's disease in its various pathological manifestations / including malignant and paralytic forms / and to try and understand better what constitutes an effective vaccine strain of MDV.

Technical Summary

Recently, we identified a binding motif (20PLDLS24) for the cell co-repressor CtBP in the Meq nuclear oncoprotein encoded by MDV. This is similar to binding sites in oncoproteins EBNA3A and EBNA3C of Epstein-Barr virus (EBV). MDV is a lymphotropic alphaherpesvirus of chickens that / like EBV / can induce malignant disease. The T cell hyperplasia it produces is responsible for many of the symptoms of the fatal disease of chickens known as Marek's disease (MD). By constructing mutants of Meq in a bacterial artificial chromosome (BAC) clone of MDV, we showed that this interaction between Meq and CtBP is essential for oncogenicity in chickens. This genetically engineered, attenuated strain of MDV very effectively protects chicks from further challenge with very virulent strains of MDV and has potential as a vaccine. In order to determine the role of the leucine zipper in Meq and of Meq dimerisation in lymphomagenesis, specific point mutations were engineered into the highly oncogenic RB-1B-BAC to produce virus completely lacking a functional Meq leucine zipper and virus encoding Meq that cannot homodimerize, but can still bind to c-Jun. Both of these mutant viruses are non-oncogenic. We conclude that the leucine zipper is necessary for the oncogenic activity of Meq and/or the establishment of long-term MDV latency in T cells. Moreover, it appears that the ability to form repressive homodimeric Meq complexes is an absolute requirement for the cancer associated with virulent MDV. We will determine the roles of Meq in non-malignant, but rapidly fatal CNS-associated MD. We will identify specific target chicken genes that are regulated by Meq and establish the roles of interacting protein partners of Meq. It should also be possible to establish what role Meq plays in viral latency and replication in vivo and explore the molecular characteristics of MDV that constitute an effective vaccine for the prevention of MD.
 
Description We showed that transformed lymphoblastoid cell lines induce de novo tumours and vaccination with CVI988 can prevent tumours.
We also showed that MD tumour cell lines are composed of monoclonal T cell populations and large tumour clones can be identified in blood of MDV infected birds even before the tumours can be visualised.
Our studies on epigenetic analysis have identified differential patterns in global methylation profiles in the genome of Marek's disease virus-transformed cells. Similarly, Chromatin immunoprecipitation (ChIP) analysis with MDV oncoprotein Meq (meq-ChIP) on MDV tumour cell DNA has identified global binding profiles of Meq.
Exploitation Route The findings from the project can be examined with application in other virus-induced neoplastic diseases
Sectors Agriculture

Food and Drink

Healthcare

 
Description Dissecting the molecular pathways of MDV oncoprotein Meq for understanding pathogenesis and aid vaccine development
Amount £440,000 (GBP)
Funding ID BB/R007896/1 
Organisation Biotechnology and Biological Sciences Research Council (BBSRC) 
Sector Public
Country United Kingdom
Start 03/2018 
End 03/2021
 
Description Role of PML bodies in avian herpesvirus infections: Generating a tool box of reagents to understand innate restriction of virus infection in chicken
Amount £7,000 (GBP)
Organisation The Houghton Trust 
Sector Charity/Non Profit
Country United Kingdom
Start 09/2016 
End 09/2017
 
Description OIE Reference Laboratory 
Organisation World Organisation for Animal Health, France
Country France 
Sector Public 
PI Contribution As the Reference Lab, we have contributed to the diagnostic procedures and preparation of manual
Collaborator Contribution Collaborators has published our activities and prepared the book
Impact Publication of the Manual on diagnostic tests
 
Description AN INTERVIEW WITH PROFESSOR VENUGOPAL NAIR 
Form Of Engagement Activity Engagement focused website, blog or social media channel
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Postgraduate students
Results and Impact Professor Venugopal Nair is a Research Group Leader at The Pirbright Institute, a visiting Professor of Avian Virology at the Department of Zoology, and a Jenner Investigator at the Jenner Institute, University of Oxford. He is also a member of the Microbiology Society, and in this interview, he tells us more about his research into viral diseases of livestock.
Year(s) Of Engagement Activity 2020
URL https://microbiologysociety.org/membership/meet-our-members/focus-area-viruses/an-interview-with-pro...
 
Description Chaired the Poultry Disease group meeting 
Form Of Engagement Activity A formal working group, expert panel or dialogue
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Professional Practitioners
Results and Impact Poultry Disease group is a forum of veterinary practitioners to discuss the advances in poultry diseases that could be translated from research labs to the farms
Year(s) Of Engagement Activity 2017
 
Description Inauguration of the UK-China Centre of Excellence for Research on Avian Diseases (CERAD) and Symposium on Recent Advances in Avian Disease Research 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Inauguration of the UK-China Centre of Excellence for Research on Avian Diseases (CERAD) and Symposium on Recent Advances in Avian Disease Research. This was held in Binzhou, Shandong province in China in 2015
Year(s) Of Engagement Activity 2015
 
Description Invitation to give keynote talk on 'Control of avian diseases: Challenges and opportunities' 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Gave the Keynote talk on 'Control of avian diseases: Challenges and opportunities' at this International Symposium organized with an aim to gather international virology experts from both human and veterinary fields to share research experience, update findings and contribute their expertise through presentation and interactive discussion. The topics will cover a wide range of virology research common in both human and animal aspects. In addition, technological platforms such as vaccine development, and novel assays will be emphasized and addressed.
Year(s) Of Engagement Activity 2018
URL http://www.biotec.or.th/virus-symposium2018/index.php
 
Description Invitation to talk at the Vaccine Symposium "Vaccines at different levels of complexity from subunit to whole cell formulations" jointly organised by the Centre of Genomic Regulation (CRG), Radboud UMC and MSD Animal Health, with the support from the MycoSynVac project 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Gave a talk and participated in the discussion on the challenges and research opportunities for innovation in poultry disease control
Year(s) Of Engagement Activity 2017
URL http://www.crg.eu/
 
Description Invited to talk at the International Conference on Building Human and Animal Health Capacities organised by the Jordan University of Science and Technology 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Participated in the discussion and talked on 'The recent advances in vaccination-based control of poultry diseases'. The need for increased awareness of the pathogen diversity in the design of vaccines and the opportunities from advances in vaccine technologies were discussed
Year(s) Of Engagement Activity 2017
URL http://www.just.edu.jo/conferences/bhahc/Pages/default.aspx
 
Description Keynote talk at the World Veterinary Poultry Association meeting 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Invited to give the keynote talk on 'Avian tumour viruses: their contribution to our understanding of cancer' at the World Veterinary Poultry Association XXth Congress in Edinburgh
Year(s) Of Engagement Activity 2017
URL http://www.wvpac2017.com/
 
Description Organised the 3rd UK-China CERAD meeting in Guildford, UK in July 2017 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact The 3rd UK-China CERAD meeting helped to bring together professional from both countries to identify challenges and exploit the opportunities for improved control of poultry diseases and increasing food security.
Year(s) Of Engagement Activity 2017
URL http://www.uk-china-cerad.org/
 
Description Poultry Health course 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Poultry Health Course is run as a residential and online course to transfer recent advances in avian disease research from the laboratory to the field.
Year(s) Of Engagement Activity Pre-2006
URL http://www.poultryhealthcourse.com/
 
Description Second Symposium of the UK-China Centre of Excellence for Research on Avian Diseases held in March 2016 in Binzhou, Shandong Province, China 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact The second international meeting of the UK-China CERAD was attended by a number of delegates from both UK and China and reviewed the progress. Plans were drawn of further activities and plans for securing additional grants.
Year(s) Of Engagement Activity 2016