Award details

Host-pathogen interactions important in the movement of Campylobacter jejuni from the broiler chicken gut to edible tissues (CampAttack)

Reference	BB/R019363/1
Principal Investigator / Supervisor	Professor Steven Rushton
Co-Investigators / Co-Supervisors	Professor Aileen Mill
Institution	Newcastle University
Department	Sch of Natural & Environmental Sciences
Funding type	Research
Value (£)	132,593
Status	Completed
Type	Research Grant
Start date	01/08/2018
End date	31/01/2022
Duration	42 months

Abstract

Campattack technical summary Key tenets of sustainable chicken production are that the animals' health and welfare should be protected and that the end products should not endanger public health. Worldwide most (>75%) chickens are Campylobacter-positive at point of sale, mainly with C. jejuni, and it is estimated that 80% of human cases (~500000) in the UK are chicken-associated. Most UK chickens are grown using intensive systems (broiler production), which can compromise bird welfare and raise the Campylobacter public health threat. There is increasing evidence that edible tissues of chicken, particularly liver, are C. jejuni-positive. Our preliminary data show that infection of liver tissues is a consequence of colonisation of the upper gut with strains of C. jejuni that are inherently better able to leave this organ. Host inflammatory responses, the levels of which are C. jejuni strain-dependent, also play an important role. Building on a strong novel dataset, which has identified a suite of C. jejuni genes and host innate immune responses involved in extra-intestinal spread, our proposed studies will determine the major processes underlying this important bird and public health scenario. We and our industrial partner Merck Animal Health will conduct in vitro experiments, using novel chicken epithelial cell lines, and infect commercial chickens (Ross 308) in in vivo experiments with wild type C. jejuni and strains with mutations in some of the genes that we have identified as being of high importance. We will also use birds inherently deficient in key immune processes. A range of host immune responses will be measured in all experiments. The identification of the most important pathogen mechanisms and host immune responses involved in the extra-intestinal spread of C. jejuni will inform breeding programmes and immunity-based controls. We will use modelling to investigate the relative importance of the underlying biological mechanisms.

Summary

Sustainable production of safe chicken is an international priority and it is estimated that in the next 20 years chicken production will have to quadruple to satisfy growing global demand. The key question is whether this can be done in a way that does not increase the public health threat of contaminated chicken meat and preserves chicken health and welfare. Most chicken meat consumed internationally is produced in large-scale intensive (broiler) systems and most birds in the UK (>75%) are Campylobacter-positive at retail, mainly with C. jejuni, posing a huge public health threat. Campylobacter is the most common cause of bacterial diarrhoea in the UK and despite millions of pounds of research funding it is estimated that contaminated chicken caused >500000 human campylobacteriosis cases in the UK in 2016 with around 100 deaths, mainly in elderly people. Infection is characterised by severe abdominal pain and acute (sometimes bloody) diarrhoea and costs the UK economy over £1 billion per year. In addition, Campylobacter are not only major chicken-associated human pathogens, they also compromise the health, welfare and performance of broilers. Campylobacter contamination of chicken takes two forms. First, surface contamination of carcasses, as a result of spillage of gut contents during slaughter, can lead to cross-contamination in the kitchen. Second, and perhaps of greater importance than currently thought, is contamination within muscle and liver tissues, which increases the health risk by facilitating bacterial survival during cooking. Until recently it was believed that Campylobacter only colonised the lower gut of the chicken (the caecum). However, spread from the gut to edible tissues is associated with the ability of certain Campylobacter strains to colonise the upper intestine of the chicken, where the gut lining (mucosa) is more easily damaged. As Campylobacter comprise a diverse population in broilers, with different strains varying in their effects ongut integrity and their ability to spread to edible tissues like liver and muscle, it is important to better understand the host-pathogen interactions of different types if the bacteria are to be controlled in chickens and the public health threat reduced. In particular, it is essential to identify the key host immune responses and the bacterial genes most important in these interactions - and in colonisation of the whole gut and extra-intestinal spread. This information, which is currently not available, is essential for the development of immunity-based and other control measures. This multidisciplinary research programme will enhance understanding of the influence of Campylobacter strain on bird gut health, host innate immune responses and spread to edible tissues and thus the public health threat. The quantitative information and modelling will be used to give direct advice to industry about Campylobacter infection biology in broiler chickens, providing an unprecedented basis for interventions to mitigate the on-going challenge of Campylobacter contamination in chicken meat. These interventions potentially include new vaccines and/or genetically more resistant chickens.

Impact Summary

Please see lead documents

Committee	Research Committee A (Animal disease, health and welfare)
Research Topics	Animal Health, Microbial Food Safety, Microbiology
Research Priority	X – Research Priority information not available
Research Initiative	X - not in an Initiative
Funding Scheme	X – not Funded via a specific Funding Scheme

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BB/S003428/1 Group selection as a novel tool to screen and improve biological pesticides

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