Susceptibility of broiler chickens to Campylobacter: impacts of the gut environment and immune status on colonisation

Lead Research Organisation: University of Liverpool
Department Name: Institute of Infection and Global Health

Abstract

Campylobacter spp. are very important food borne bacteria and the most common cause of bacterial diarrhoea in the EU. Campylobacter caused an estimated 700,000 cases of infection in the UK in 2010. Each year there are around 100 deaths as a result of this infection. It is estimated that Campylobacter infections cost the UK economy over £1 billion per year. Infection is characterised by acute and sometimes bloody diarrhoea, particularly in children. The last few years have seen a marked rise in cases in elderly populations and in such people, particularly those with bowel cancer, infection can be fatal. Chicken meat is the most important source and vehicle for human Campylobacter infections and around 80% of chickens on sale in the UK are Campylobacter-positive. Campylobacter are commonly found in the intestinal tract of chickens and other food animals. Contamination of chicken meat takes two forms. Carcass surfaces can carry high levels of Campylobacter and this leads to cross-contamination in both domestic and commercial catering. This is an important risk factor for infection. However, and perhaps more importantly, Campylobacter have been recovered from deep leg and breast muscle tissues of up to 27% of chickens tested. Furthermore, liver tissues are also commonly contaminated. In these tissues the bacteria will be better protected from the effects of cooking. Undercooked chicken meat and chicken liver are internationally important vehicles of Campylobacter infection.

To improve public health in the UK it is essential that the number of contaminated chickens on sale is reduced. The ultimate aim of the proposed research in working with the UK chicken industry is to identify cost-effective control measures, which can be implemented across the poultry industry. One common feature of Campylobacter in chicken production is that there is a delay before flocks become colonised by the bacteria. The length of the delay varies between flocks and has not been accurately chracterised. The reasons for the delay have not been clearly identified and the proposed project seeks to address this important data gap and thereby identify mitigation strategies to prevent colonisation. If the mechanisms that appear to give young chickens enhanced resistance to Campylobacter can be identified it may be possible to extend the Campylobacter-free phase until the animals are sent for slaughter. Past research suggests that one mechanism is the transfer of anti-Campylobacter antibodies to the yolk of eggs laid by infected hens. If this is so, it will have implications for vaccination for Campylobacter in both broiler birds and breeders. However, past work has only examined this in isolation and our work has shown that young chickens can have a population of gut bacteria that inhibit Campylobacter. It may be that both play a part in this process. Again, this may highlight new novel ways in which to prevent Campylobacter colonisation of chickens, either directly or through dietary manipulation.

Our work will focus on chickens reared intensively in housed systems as these comprise ~90% of the UK market. The work will be in direct collaboration with one of the three biggest poultry producers in the UK, with other producers and all the major UK food retailers supporting the work. We will conduct studies on housed flocks to determine when birds first become Campylobacter-infected and relate this to changes in the bird gut, where Campylobacter colonises, and changes in levels of maternal antibodies. We will use modelling to investigate direct and indirect drivers of colonisation and to identify possible targets for mitigation against colonisation.

Our aim is to provide the UK poultry industry with science-based and cost-effective control options, which will help it meet customer demands and comply with forthcoming EU legislation aimed at reducing the number of chickens that are Campylobacter-positive

Technical Summary

Chicken is the main source of human Campylobacter and this threat must be reduced. The proposed work will determine mechanisms behind the delay before broiler chickens become Campylobacter-positive in housed flocks. The project is in partnership with poultry producers to identify cost-effective control measures to protect chickens against Campylobacter.

Past work suggested that maternal antibodies provide chicks with some protection against Campylobacter in early life. However, this was done in isolation and other protective factors were not studied. Campylobacter-negative chicks can have gut bacteria that inhibit C. jejuni. In most flocks, the 'protective bacteria' were not present when birds reached 3-4 weeks of age and flocks rapidly became Campylobacter-positive.

We will determine whether maternally-derived antibodies and/or gut microbiota and/or gut architecture is the most important in determining broiler susceptibility to Campylobacter. We will study Ross 308 birds, the most common type in the UK. The field studies will relate changes in naturally acquired maternal anti-Campylobacter antibodies and gut microbiota with events in flock management, like diet change and with the presence of Campylobacter. State of the art techniques will be used to determine microbiota.

Laboratory experiments will test field-generated hypotheses in a controlled manner. B-cell deficient breeders will be produced by surgical bursectomy. This creates B-cell- and thus antibody-deficient hens. These will be used to form breeding flocks producing progeny deficient in maternal antibodies. We can then determine definitively the role of maternal antibodies in the resistance of chicks to Campylobacter. We will use modelling to investigate dynamics of chicken gut microbiota and its impact and maternal antibodies as direct and proximal drivers of colonisation in commercial chicken production. These models will be used to identify targets for mitigating Campylobacter colonisation.

Planned Impact

Campylobacter is the most important food borne zoonosis in the UK and the wider EU. In the UK it is estimated that there are 700000 cases of infection each year and that chicken-associated Campylobacter infection costs the UK economy ~£1 billion per year. Chicken is overwhelmingly the most important vehicle for human infection and is believed to be responsible for up to 80% of infections. ~80% of chickens on sale in the UK are Campylobacter-positive. Contaminated chicken presents two health threats. Surface contamination levels can be very high and contamination of deep muscle and liver tissues has been reported in up to 27 and 60% of samples tested respectively. The project seeks to better understand the processes that occur during the early development of chickens that leads them to become colonised by Campylobacter.
We seek to accurately determine when broiler flocks first become Campylobacter-positive, as there is a delay before this happens, and will be investigating the roles in this process of maternally acquired anti-Campylobacter antibodies and changes in gut microbiota and gut architecture for the first time all together. Such processes that are driven by bird age and/or diet and this project proposes to study these by laboratory studies, but also importantly in the field on commercial farms. By determining the reasons for changes to susceptibility to this major zoonotic pathogen, we will be able to identify farm-based control measures that will reduce levels of Campylobacter in UK poultry and not rely on biosecurity alone. In particular, our work will importantly inform studies on the use of vaccines and the use of pre- and/or probiotics. The project is in partnership with the UK poultry industry and all major UK retailers. Thus the beneficial impacts of our work can quickly be transferred to stakeholders.
 
Description Campylobacter is the leading cause of foodborne bacterial gastro-enteritis. Over 70% of UK retail poultry is contaminated by Campylobacter. As such understanding its biology is essential in developing effective controls to reduce these levels.

In this project (with collaboration with Leicester and Newcastle) we have investigated how antibody, transferred via the egg or newly synthesised in the chick and the micro biome (the population of microbes in the chicken gut) influence gut health and Campylobacter infection. In this we have developed and applied techniques that allow us not only to measure antibody but for the first time assess its function in Campylobacter infection. The work has shown four significant findings:

1. That antibody responses make little difference to the numbers of Campylobacter bacteria in the main site of colonisation (the caeca) in the production lifetime of chickens.
2. Antibody reduces Campylobacter levels in the upper intestinal tract and this may explain why it is less frequently found here
3. In time antibody responses do play a role in clearance, but this is very slow at 10-12 weeks old when most animals are slaughtered at around 6 weeks.
4. Antibody from the mother hen (maternally-derived antibody) levels drop more quickly in modern production environments and may afford less protection than previously thought.

The findings are significant as they suggest that maternal antibody is less important in preventing infection and its earlier depletion may explain why the 'lag phase' when birds are not infected may be shorter than previously thought. More importantly the findings here show antibody is very poor at clearing Campylobacter and that vaccines that designed to produce and antibody response may not be very effective.
Exploitation Route This is a collaborative project so material taken from fieldwork and experimental infections has been given to Prof Julian Ketley at University of Leicester for micro biome analysis. This, along with our immunology and bacteriology data feeds to Prof Steve Rushton at University of Newcastle to develop mathematical models of the microbiota-immune-infection interactions in the developing chicken gut.

Our immunological data is of huge significance in understanding immunity to Campylobacter in the chicken and in particular in vaccine development. The lack of clearance by antibody responses shows that vaccine approaches that are designed to elicit humoral immunity are unlikely to be effective within the production age of birds. Unlike Salmonella where vertical transmission is important, it also is unlikely that breeder vaccination will have much impact both in terms of transmission and given that maternal antibody levels decline sharply in terms of protection through enhanced maternal immunity.
Sectors Agriculture, Food and Drink

 
Description Data presented at conferences in 2015 has been identified as important in vaccine development. This has led to a relationship with Ceva Animal Health in both collaboration and consultancy in vaccine development and to conducting a Campylobacter vaccine trial with Pacific Genetech a Sino-american company in 2017.
First Year Of Impact 2016
Sector Agriculture, Food and Drink,Pharmaceuticals and Medical Biotechnology
Impact Types Economic

 
Description Caecal Microbiome Transplant:a novel approach to Campylobacter control and improving broiler chicken gut heath
Amount £268,745 (GBP)
Funding ID BB/R008914/1 
Organisation Biotechnology and Biological Sciences Research Council (BBSRC) 
Sector Public
Country United Kingdom
Start 04/2018 
End 03/2020
 
Description Rapid diagnostics and control strategies for enteric bacterial pathogens in backyard and commercial poultry production in Thailand and the Philippines
Amount £916,765 (GBP)
Funding ID BB/R013136/1 
Organisation Biotechnology and Biological Sciences Research Council (BBSRC) 
Sector Public
Country United Kingdom
Start 04/2018 
End 03/2021
 
Title Avian Infection Models 
Description Development and refinement of novel infection models to study infection, co-infection and transmission by food borne bacterial pathogens 
Type Of Material Model of mechanisms or symptoms - non-mammalian in vivo 
Year Produced 2013 
Provided To Others? Yes  
Impact Publications and directly funded industrial research 
 
Description A twisted bugs life 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? Yes
Geographic Reach National
Primary Audience Public/other audiences
Results and Impact Hands on presentation/exhibit at Liverpool's World Museum then at the national festival in London. Giant walk through gut to understand how Campylobacter make people ill and various activities to show how one can reduce their risk of infection.

Much interest in how chicken can be source of infection and what can be done to reduce risks for adults and children
Year(s) Of Engagement Activity 2014
URL http://www.bbsrc.ac.uk/society/exhibitions/gb-bioscience-festival/twisted-bugs-life.aspx
 
Description Brazil Poultry Industry meeting 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Lively discussion

None as yet
Year(s) Of Engagement Activity 2014
 
Description Christmas Lecture 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Public/other audiences
Results and Impact Lot's of interest and questions about infectious disease and vaccination

Interest in the lab's work.
Amusement of colleagues to being dressed as Father Christmas and Rudolph
Year(s) Of Engagement Activity 2013
 
Description Exchange visit Poultry Research an Diagnostic Dept, University of Georgia, Athens 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Professional Practitioners
Results and Impact Exchange visit to the University of Georgia to meet with researchers and vets working on foodborne pathogens and poultry research, to discuss work from this and other projects and to discuss future collaborations around Campylobacter in poultry in the UK and the USA to compare the different production systems and the epidemiology and infection biology of campylobacter in such systems. Professor Paul Wigley (PI) presented a overview of current work at Liverpool also covering this project
Year(s) Of Engagement Activity 2016
 
Description Healthy tums, happy bums 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Public/other audiences
Results and Impact Lot's of interest in food safety and what can be done to safer handle and prepare food

General public interest
Year(s) Of Engagement Activity 2013
URL http://news.liv.ac.uk/2013/06/14/food-safety-on-the-menu-at-liverpools-world-museum/
 
Description Poultry Disease Group 
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 Contribution to Poultry Disease Group Forum through presentations and discussion. Excellent forum to link academia, industry and policymakers

Frequent requests for information, links to industry
Year(s) Of Engagement Activity 2010,2011,2012,2013
 
Description Presentation to CEVA Animal health 
Form Of Engagement Activity A formal working group, expert panel or dialogue
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Industry/Business
Results and Impact Meeting/visit to CEVA in Bordeaux to discuss development of poultry vaccines with their international poultry committee. This has become recurring activity with presentations made twice in 2016 and further made for July 2017
Year(s) Of Engagement Activity 2015,2016
 
Description Presentations to representatives from poultry breeders, producers and retailers 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Public/other audiences
Results and Impact The talks stimulated much discussion towards methods of reduction of Campylobacter and improvements that could be made to health and welfare

Retailers and producers highly interested in research presented and how it may be applied. Improved understanding of impact of infection on animal welfare
Year(s) Of Engagement Activity 2010,2011,2012,2013,2014
 
Description School Visit-Neston 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Schools
Results and Impact Primary school visit explaining about animals using bones in a demonstration. Was enjoyed by children who understood more about the biology of current and extinct animal species

None yet
Year(s) Of Engagement Activity 2014,2015,2016
 
Description Talks on infectious disease to 6th form and parents & talk to 5th and 6th form on use of animals in science 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Schools
Results and Impact General discussion afterwards. Specific interest from some individuals

Students undertaking work experience in lab.
Applications to our degree programmes
Year(s) Of Engagement Activity 2007,2009,2010
 
Description Thai Poultry Industry Meeting 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Many questions but limited time

Questions on what future contra strategies may be
Year(s) Of Engagement Activity 2013
 
Description Workshop and visits to Corpoica, Pollo Fiesta, Colombian NIH and Biotech Institutes in Bogota, Colombia on foodborne pathogens and food safety 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Professional Practitioners
Results and Impact The key objective of our visit was to understand the structure and challenges faced by the Colombian poultry industry in controlling the foodborne pathogens, Campylobacter and Salmonella, and to disseminate our findings and the approaches that we have taken within the UK and ultimately to explore translation of work to improving food safety in Colombia. This was facilitated through meetings with academics and the poultry industry, as well as visiting poultry farms and slaughterhouses, which provoked discussion around biosecurity on the farms and how this could be improved as well as interventions within the slaughterhouse. These included the production company Pollo Fiesta, researchers from Corpoica, Universities and the National Institute for Health. Alex Royden a BBSRC DTP PhD student also spent time at Corpoica and helped train staff in some of our isolation procedures developed here which helped overcome some of the issues they had with contamination when trying to isolate Campylobacter.
Year(s) Of Engagement Activity 2017
 
Description Workshops on Campylobacter and Salmonella Bangkok and Pattaya, Thailand 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Other academic audiences (collaborators, peers etc.)
Results and Impact Workshops promoted discussion and development of Thai research programme

Visiting Thai students
Year(s) Of Engagement Activity 2012,2013