Livestock Vaccines: Safeguarding Health and Sustainability

Published on 21 April 2009 in Sustainability and Communities , Food, health and wellbeing

Introduction

Vaccine technology developed by research scientists at the Moredun Research Institute in Edinburgh is helping Scottish producers maximise the productivity and profitability of their farmed livestock, whilst at the same time farm sustainably and without degrading natural resources. Scottish beef and sheep meat production is valued in excess of Â£500million each year and endemic infectious diseases are a major constraint on livestock productivity. Any reduction in the impact of these diseases that can be made in a sustainable manner will make a significant contribution to the continued profitability of the livestock sector. The old adage that "prevention is better than cure" is particularly relevant when discussing sustainable livestock farming and therefore the development and application of effective vaccines are highly desirable outputs for research activity.

Key Points

Vaccines offer green solutions for diseases as they are sustainable, reducing reliance on pharmacological drugs and pesticides.

The use of vaccines has multiple benefits such as improving animal health and welfare by controlling animal infections and infestations; improving public health by controlling zoonoses and food borne pathogens in animals; solving problems associated with resistance to antibiotics and anthelmintics; keeping animals and the environment free of chemical residues; maintaining biodiversity. All of these attributes should lead to animal farming sustainability and economic benefit.

Moredun Research Institute scientists have developed new functional genomic technologies at such as full genome sequencing and proteomics which have speeded up the identification and characterisation of potential vaccine candidates.

Prototype vaccines for several endemic diseases of livestock, including caseous lymphadenitis (CLA), Haemonchus contortus and sheep scab have now been developed and tested by Moredun.

In April 2009 Moredun launched a new company (Innocul8) to support a variety of commercialisation strategies to aid the development of vaccines for a range of economically important diseases.

Research Undertaken

Moredun has a very strong tradition of applied research and in translating its research into practical outputs such as vaccines for pasteurellosis and clostridial diseases. The discovery of Iron Regulated Proteins (IRPs) in Mannheimia haemolytica led directly to the development of novel and effective vaccines for the prevention of pneumonia in sheep and cattle. The Heptavac P family and Bovipast are vaccine market leaders in the industry and generates over £16 million in sales annually.

At its most basic a vaccine mimics a natural infection by stimulating a protective immune response in the host animal. However a vaccine should not be harmful. It can be a weakened version of the original pathogen (attenuated vaccines); it can be a killed version of the original pathogen (the most common bacterial and viral vaccines); it can be a part of the pathogen (sub units such as toxins or surface components) or more recently it can be a nucleic acid vaccine where the nucleic acid coding for the pathogen’s gene is directly transcribed and translated by the host animal.

Vaccines are a major objective for all the projects in the Scottish Government funded Programme 2 “Control of Endemic Disease” Work Packages being conducted at Moredun. The research that leads to developing an effective vaccine takes several distinct stages that can takes several decades to complete:

The impact of a particular disease is recognised through surveillance and epidemiological studies
The causal agent of a disease is determined through diagnosis and experimental infections
The pathogen is analysed molecularly and the most important components to be included in a vaccine are identified and characterised
The immunological responses of the host to the vaccine components are investigated
The efficacy of the prototype vaccine is tested and measured in a experimental system in the natural host.

An example of this process can be shown with Caseous Lymphadenitis (CLA); a chronic bacterial disease of sheep and goats. CLA was first recognised as a problem in the early 1990s when UK sheep were initially infected from imported goats. In the following years the disease spread quickly establishing itself in pedigree sheep flocks before moving into the main commercial sheep flocks.

Researchers at Moredun and SAC developed the necessary tools for vaccine development such as an experimental model of infection in sheep and expertise in the molecular dissection of the bacteria that causes the disease (Corynebacterium pseudotuberculosis). A diagnostic blood test to monitor the immune status of animals for developed and launched in 2005. A potential vaccine candidate was then identified in a specific toxin from the bacterium and the gene isolated. Purified toxin material was produced by recombinant DNA methodology and has now been used to successfully immunise and protect sheep against an experimental CLA infection and it is hoped that, with the assistance of Innocul8, this prototype vaccine can be developed further in the future.

Policy Implications

The World Health Organisation and the Food and Agricultural Organisation estimate that a 50% increase in food supply will be needed to feed a world population of 9 billion people by 2050, in addition to >30% more water, >40% more energy. These are significant challenges.

The Scottish Government funded Programme 2’s researchers play a major role in the Scottish science agenda with a specific focus on the endemic diseases caused by parasites, viruses and bacteria. These diseases reduce livestock productivity, adversely affect welfare, cause mortality and morbidity and result in wasted greenhouse gas emissions if an animal dies before scheduled slaughter.

The programme’s scientific outputs – disease control programmes, diagnostics and vaccines all help to reduce or prevent disease and all contribute to mitigation against climate change. We can really take action by improving animal health and welfare. IPCC targets a 20% reduction in CO₂ through improved animal feeding, reproduction and health and we can do this while also improving the economics of livestock farming.

This research brings benefits to Scotland, the UK, the EU and worldwide – and in difficult times we can export our technological solutions to allow others in developed and developing countries to help themselves

Author

Professor Willie Donachie willie.donachie@moredun.ac.uk

Topics

Sustainability and Communities , Food, health and wellbeing