Attenuation of FMDV Serotypes/Strains to Develop Stable and Effective Live, Attenuated, Vaccines

Foot-and-mouth disease virus (FMDV) is an animal pathogen which infects domesticated animals (cattle, pigs, sheep) but also many wild animals. In India, for example, FMDV in wild animals can continually re-infect domestic animals. FMDV is probably the most contagious mammalian virus known to man and disease can spread very rapidly. Infection does not kill animals, but when they recover, their agricultural productivity is much lower. The virus can also cause long-term ('persistent') infections that are inapparent: they are difficult to diagnose in the field, complicating disease control. FMDV causes disease around the globe and is a continual threat to UK agriculture by the import of contaminated animal products. Vaccines are available, but presently they are only used in emergency situations. The 2001 UK outbreak caused massive economic damage (billions of pounds), as the method of stopping disease spreading was mass animal slaughter: infected or not. Millions of healthy animals were destroyed.

The present vaccine is expesive to produce and since it only induces a protective immune response for relatively short periods, animals need to be vaccinated - and re-vaccinated - throughout their lives. Routine, repeated, vaccination is expensive. The primary method of FMDV control in Europe is mass-slaugter of both infected and surrounding sucesptible (healthy!) animals: this policy is socially and politically unacceptible in India.

The security of food supply in the future is a major issue. As the Indian economy develops, the demand for meat products will inexorably rise. Prices of animal products imported into the UK and animal feedstuffs will rise. To meet this increasing demand agricultural productivity must rise around the world, especially in countries with high population densities like the UK. Productivity can be increased by creating very large facilities, housing thousands of animals: a method shown to be effective in the US. The intensification of large-animal production creates opportunities of viruses such as FMDV to cause devastating economic damage. Increased international travel and trade means that this cannot be a problem the UK can solve in isolation: viruses move across national boundaries. With regards FMDV, the UK has adopted a 'vaccinate-to-live' policy. We argue this must be coupled with the development of new vaccines, or new methods of producing vaccines, to make this policy effective. This is the purpose of our research.

FMDV is the same type of virus as polio. There are two types of vaccine available for polio: live, 'attenuated', vaccines use virus strains that do cause an infection (and raise a life-long protective immune response), but do not cause paralytic poliomyelitis: the 'Sabin' vaccine. The second type is 'killed'. Here, poliovirus (which could cause poliomyelitis) is grown in cells in large quantities, then chemically inactivated so that it cannot grow at all - but the dead particles do raise a protective immune response: the 'Salk' vaccine. It is the latter type of 'killed' vaccine that is used to control FMDV. This means huge amounts of virus have to be grown (virus which can cause disease) in the production process. Inevitably, escapes of virus can occur from facilities and cause an outbreak in the surrounding completely sucestible animals - thought to have occurred in the UK 2007 FMDV outbreak.

The program of research we propose is to produce new live, attenuated,vaccines to bring about a transformation in FMDV disease control. Our strategy is to use modern molecular biology to change the virus, to make new strains that can protect animals without causing the debilitating disease - live, attenuated viruses, just like polio: much cheaper and safe to produce.

The aim of this project is to replace inactivated FMDV vaccines with live, attenuated, strains. The project will build upon - but greatly enhance - our present research into FMDV. We will use a combination of synthetic and molecular biological techniques to produce a large panel of attenuated viruses: candidate vaccine strains. The project brings together St Andrews (plus its SLoLa partners) with the Indian Veterinary Research Institute (IVRI), Bangalore.

1. The Asia 1 replicon, constructed at IVRI, will be supplied to, and modified by, St Andrews to incorporate the latest improvements to the system.

2. St Andrews will use two main strategies to modify the FMDV genome. Firstly, deletion forms of the genome that have already been shown to be attenuating will be constructed, along with new deletion/mutation forms. Secondly, synthetic biology will be used to codon-destabilise those regions of the genome encoding non-structural proteins, a strategy shown to be highly effective for other viruses.

3. St Andrews will generate a large panel of new Asia 1 replicons, each encoding a GFP 'reporter' protein rather than the capsid proteins. The fluorescence signal from GFP is used to measure the kinetics of RNA replication by medium-throughput microscopy. The viability or attenuation of RNA replication will be determined for each form.

4. Attenuated replicons will be transferred to IVRI where GFP will be replaced by capsid proteins to create a corresponding panel of infectious copies and virus rescued.

5. The attenuation of each virus type will be determined using tissue-culture cells

6. Those viruses showing adequate growth properties will go forward into animal studies

7. Serological, pathological and animal challenge studies will identify candidate vaccine strains

8. The genome stability of candidate vaccine strains will be determined

9. Replicons will be modified to increase/decrease the level of attenuation based upon the animal data

Key Areas of Impact: Our single aim is to produce new methods of controlling FMDV. Our strategy to achieve this is by producing live, attenuated, strains of FMDV. To replace the existing strategy of disease control by mass-slaughter and the very sub-optimal method of producing killed vaccines.

Public Engagement. We are committed to engage the public on the science it funds and promote debate. We will improve the impact of our public engagement activities - including internet profile through our project-specific web pages (www.fmdv.ac.uk) to make information widely available to academics and the public through peer review publications, scientific meetings, consultations, workshops, training courses and exhibitions. Many aspects of the science surrounding FMDV is of popular interest, in the case of the SLoLa already covered in the national/international press, radio and TV: we will continue to engage with the media.

Pathways to Products/Processes: Live, Attenuated Vaccines. We have the agreement of 3 international experts to participate in the management of our closely related SLoLa project. The FADH project will greatly benefit from the activites we are presently engaged in (and plan for the future). With regards the impact we wish to achieve in the area of vaccines, Tim Doel has worked for many years in the FMDV vaccine industry and his guidance on the SLola will be directly applicable and highly valuable to the FADH project. A consultant with much experience in the field of animal health has been employed by the University of St Andrews specifically to promote industrial involvment with reseach projects (e.g. Novartis, Merial, Meriden, MSD Animal Health - formerly Intervet/Schering-Plough Animal Health, Pfizer Animal Health and Sanofi UK). He has identified this application as of particular promise and is approaching potential industrial partners to become involved in the work at as early a stage as is possible. The applicants fully recognize this is an absolutely critical spect of this project achieving its potential impact on global agriculture.