RCUK-CONICYT Mucosal health and microbiota during sea lice parasitism: effect of oral delivery of immunomodulants

Lead Research Organisation: University of Plymouth
Department Name: Sch of Biological and Marine Sciences

Abstract

The mucosal surfaces (skin, intestine and gills) of fish are constantly interacting with a wide range of pathogens and, in
concert with the resident mucosal microbiota, are the first line of host defence. Several immune factors have been
described in fish mucus and their presence and abundance can be affected by pathogen infection. As a consequence, the
mucosa-associated microbiota can be affected and this may lead to dysbiosis, a microbial imbalance on or inside the body,
which reduces the beneficial role of microbiota on the innate immune system and may lead to secondary infections by
opportunistic microbes. Sea lice (Lepeophtheirus salmonis and Caligus spp.) infections are the most economically
important causative agents of disease in marine-farmed salmonids worldwide. Caligus rogercresseyi is the main
ectoparasite affecting the Chilean salmon industry with estimated costs of up to $120 million annually. This parasite
damages external surfaces of the integument providing portal of entry for secondary infectious pathogens, and infected fish
also become stressed which leads to immunosuppression with consequent increased susceptibility to the secondary
infections. Other Caligid parasites (Caligus rogercresseyi and other Caligus spp.) have detrimental impacts on mariculture
operations in both developing and developed parts of the world which causes economic losses of US$ 100's millions
annually. The development of novel methods to prevent or reduce sea lice infection is therefore a high priority for the
industry. An essential prerequisite for improved treatments strategies is a better understanding of relationship between
host-microbiome-parasite at the epidermal interface. Therefore, the aim of this research programme is to evaluate the
influence of sea lice parasitism on mucosal health, including aspects of the immune response and host microbiota. We will
evaluate the effect of immunomodulants on susceptibility to sea lice infection, and on gut and mucus quality by determining
epidermal mucus proteomic responses, microbiota changes and mucosal transcriptomic changes. We will correlate the
responses of the host and the sea lice during the early stages of parasitism in order to develop new strategies (i.e. identify
antigens for vaccines, targets for RNAi, probiotics, prebiotics, immunomodulants) for sea ice control.

Planned Impact

Copepod parasites (sea lice) are a major factor limiting growth in the global salmonid aquaculture sector. Economic losses associated with Caligid infections cost the Chilean aquaculture industry in excess of US$100 million per year. This has detrimental socioeconomic impacts and reduces food security. Caligid sea lice infection is also an emergent threat to nonsalmonid
finfish mariculture in the developing blue economies of North Africa and the Middle East. New therapies and approaches to louse control are urgently required and such strategies can be developed by providing a better understanding of the host-immune-microbiome-parasite interactions. Our main goal is to elucidate the relationship between mucosal health, diet and microbiota in salmon, with knowledge then being transferred to other aquaculture species in the North African/Middle Eastern aquaculture sectors - including Egypt, Turkey, Morocco, Tunisia and Greece where sustainable non-salmonid mariculture is increasingly impacted by Caligid sea lice.

The primary beneficiary of the research is the Chilean aquaculture industry where there is an urgent requirement to develop new approaches to control Caligus, however to develop such therapies basic biology of the interaction between the mucosal immune system and the host mucosal microbiota and the interaction with parasite is urgently required. The findings will have direct impact on the research against the salmon louse Lepeophtheirus salmonis that is a major pest in Northern European salmon aquaculture in UK.

Benefits to the aquaculture sectors of beneficiary regions will come in the form of new potential therapeutics and/or new targets for therapeutics to alleviate the burden of louse infection on fish. Provision of new therapeutics will improve economic growth and sustainability (via improved survival and feed conversion efficiency) in the sector, as well as improve the welfare of the animals themselves.

Consumers will benefit from this research via improvements to fish welfare and associated improvements to food quality. The Atlantic salmon, and other marine finfish, are excellent sources of protein and Omege-3 oils. Improved volumes of these high quality food products on the market will benefit consumers, particularly those of developing countries where the consumption of seafood is below internationally recommended levels. One primary aim is to explore the impact of dietary immunomodulants on louse pathobiology, especially in reducing susceptibility to secondary bacterial infections. Our fundamental research on host-microbe-parasite interactions will generated data which will reveal targets for future treatment strategies. By limiting secondary infections in farmed salmonids we hope to reduce the reliance of Chilean producers on antimicrobials, driving down the prevalence of such drugs and antimicrobial resistant bacteria (and antibiotic residues) in the food chain.

Finally, by identifying tools to reduce the prevalence and abundance of C. rogercresseyi on farmed fish, we hope to reduce the transmission of these organisms to wild fish, and so fishing industries and downstream seafood processing industries (for both farmed and wild fish products) are also potential beneficiaries of this research.

The results from the project will be disseminated via the Marine Alliance for Science and Technology for Scotland (MASTS) aquaculture forum and the Scottish Aquaculture Innovation Centre (SAIC). These are both avenues through which the impact of our project targets key governmental, industrial and strategic plans for aquaculture research. Through our industrial partners (BioMar), who are a sponsor of several major international meetings organised by the World and European Aquaculture Societies, we will reach additional audiences.Through these mechanisms, and as described comprehensively in our "Pathways to Impact Plan", these impacts will be ensured.

Publications

10 25 50
 
Description Our overarching aims and objectives of this project were to evaluate the influence of sea lice parasitism on Atlantic salmon mucosal health, including aspects of immune responses, mucus barrier and microbiota. These objectives were met.
Our results showed histological alterations in skin mucosa after sea lice challenge. Infested fish showed significant differences in their skin structure, with increased numbers of mucus cells per mm of epidermis. RNAseq analysis of epidermal samples evidenced consistent increases in gene expression in lice infested fish compared to control fish. Overall, approx. 900 genes were up regulated and 800 down regulated in comparison to uninfected control fish. Differentially regulated genes include a large number of mucin genes, lectins and several members of interleukin family increased in expression following lice infection. Microbiomic and proteomic data have also revealed differences correlated with lice infestation. Collectively, the data generated is useful for further understanding of mucosal immune function, as well as lice infestation dynamics.
Exploitation Route The data have been used in a number of outputs including conference presentations and workshops. Manuscripts are currently being written for submission to peer reviewed journals. A number of other outputs were positively impacted by knowledge and experience gained from the current project. These include multiple publications and two journal special issues on the topics of fish microbiomes and feed additives. The researchers involved in this grant (JR, Chile; DLM and ML, UK) have edited a Special Issue (Research Topic) in the scientific journal Frontiers in Microbiology, called Aquaculture Microbiology: The Role and Importance of Microbial Communities in Diversified and Sustainable Aquaculture. This Research Topic covers a broad range of questions about the main challenges in aquaculture and how they are being addressed, using many different experimental approaches based in omics technologies. Currently this topic includes 29 papers involving 184 authors in the field and more than 79,000 views, showing great impact worldwide. In addition, DLM also coedited a Functional Aquafeeds Special Issue for the Journal of the World Aquaculture Society.
This project has helped to facilitate knowledge transfer and enhanced collaboration between the project partners, with subsequent collaborative grant proposals currently under review and in preparation. Further, student exchange opportunities were facilitated by this project; an MSc student from the University of Plymouth worked at the Universidad de Chile for several weeks, performing research activities and sampling in the field.
This grant has provided opportunities to enhance our engagement with industry and incorporate the new techniques and methodologies in sea lice in vivo challenges, as well as sharing knowledge, ideas and data generated within the project. The project has generated a significant volume of data, which is continuously being mined. Therefore, further outputs including publications and industry engagement are anticipated.
Sectors Agriculture, Food and Drink,Environment,Pharmaceuticals and Medical Biotechnology

 
Description Conference oral presentation 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Industry/Business
Results and Impact Zindrili R et al., 2019

IMPACT OF SEA LICE (Caligus rogercresseyi) INFECTION LEVEL ON THE SKIN TRANSCRIPTOME OF ATLANTIC SALMON (Salmo salar). Oral presentation International Society for Fish and Shell fish Immunology, Las palmas, Spain, June 2019.

Over one hundred delegates from international backgrounds present at the event. Attendees to the talk asked questions and engagement with interested parties took place throughout the event.
Year(s) Of Engagement Activity 2019
URL http://isfsim.org/
 
Description News article for BBC 
Form Of Engagement Activity A press release, press conference or response to a media enquiry/interview
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Public/other audiences
Results and Impact News report published in which project data was not included, but the project data helped to define the narrative and context of the news piece and the contribution to it from D Merrifield. A written interview was provided to the journalist and information and quotes from the interview were used in the news piece "El piojo que está provocando un aumento sin precedentes en el precio del salmón" (The louse that is causing an unprecedented increase in the price of salmon) in respect to Chilean salmon farming. the news report was written by Laura Plitt for BBC Mundo Ciencia and was published on Feb 7th 2017. available at: http://www.bbc.com/mundo/noticias-38881804
Year(s) Of Engagement Activity 2017
URL http://www.bbc.com/mundo/noticias-38881804
 
Description Presentation and participation at a workshop 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact 35 postdoctoral and Academic scientists from the UK, Mexico, Spain and elsewhere participated at a workshop in which the results from the present project were disseminated. This generated great interest from the audience with requests for further information and enquiries about opportunities for collaboration. The event details are as follows: Presenter Ana Rodiles (Plymouth University). Co-authors: Natalia Catalan, Ela Krol, Alessandro Busseti, Ted Henry, Martin Llewellyn, Samuel Martin, Jaime Romero, Daniel L. Merrifield. Talk title: The impact of sea lice (Caligus rogercresseyi) parasitism on the mucosal microbiota of Atlantic salmon (Salmo salar) in Chile. Workshop details: Supported by the British Council and CONACYT Researcher Links scheme. Felipe Carrillo Puerto, Quintana Roo, Mexico. 12-14 September 2017.
Year(s) Of Engagement Activity 2017
URL https://sustainableaquaticresourcesmexico.weebly.com/
 
Description Presentation and participation at a workshop 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Around 25 postdoctoral and academic scientists from Europe participated at a workshop in which the results from the present project were disseminated. . This generated great interest from the audience with requests for further information and enquiries about opportunities for collaboration. The event details are as follows: Presenter: Ana Rodiles (Plymouth University). Co-authors Natalia Catalan, Ela Krol, Alessandro Busseti, Ted Henry, Martin Llewellyn, Samuel Martin, Jaime Romero, Daniel L. Merrifield. Talk title: The impact of sea lice (Caligus rogercresseyi) parasitism on the mucosal microbiota of Atlantic salmon (Salmo salar) in Chile. Workshop details: Understanding the Beneficial Role of the Microbiota in Animals and Plants. Baeza, Spain. 9-12 October.
Year(s) Of Engagement Activity 2017
URL https://www.unia.es/oferta-academica/congresos-jornadas-encuentros-y-otras-actividades-formativas/of...
 
Description Presentation at the Mucosal Health in Aquaculture conference, Olso, Norway 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Industry/Business
Results and Impact Zindrili, R. et al., 2019

TRANSCRIPTOME RESPONSES IN SKIN OF ATLANTIC SALMON FOLLOWING TWO DIFFERENT LEVELS OF INFECTION OF SEA LICE (Caligus rogercresseyi). Oral presentation: International conference Mucosal Health in aquaculture, Olso, Norway September 2019.

Attendees of the presentation asked questions after the talk. Engagement with interested parties took place throughout the conference.
Year(s) Of Engagement Activity 2019
URL https://mucohealthaqua.com/
 
Description Project press releases 
Form Of Engagement Activity A press release, press conference or response to a media enquiry/interview
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Industry/Business
Results and Impact Plymouth University initial PR https://www.plymouth.ac.uk/news/research-launched-into-impact-of-sea-lice-upon-salmon-fisheries

International Aquafeed - the aquaculturalist blog initial PR http://theaquaculturists.blogspot.co.uk/2016/04/21042016-funding-awarded-for-research.html

The Fish Site initial PR http://www.thefishsite.com/fishnews/27516/new-project-looks-at-sea-lice-impact-on-salmon-fisheries/

Fish Farming Expert http://www.fishfarmingexpert.com/news/anglo-chilean-lice-research-launched/

BBC Mundo http://www.bbc.com/mundo/noticias-38881804
Year(s) Of Engagement Activity 2016,2017
 
Description Project website 
Form Of Engagement Activity Engagement focused website, blog or social media channel
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Public/other audiences
Results and Impact The project website is periodically updated with key project information. It contains the contact details of all participants and acknowledges the funding bodies
Year(s) Of Engagement Activity 2016,2017
URL https://salmonlousemicrobiome.org/
 
Description Scientific workshop 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact 30 postdoctoral and Academic scientists from the UK, Mexico, Spain and elsewhere participated at a workshop in which the results from the present project were disseminated. This generated great interest from the audience with requests for further information and enquiries about opportunities for collaboration. The event details are as follows: Presenter Ana Rodiles (Plymouth University). Talk title: The influence of the diet on the gut microbial composition of Atlantic salmon (Salmo salar). Workshop details: Genomics in Aquaculture Mex-UK: a new set of tools to increase sustainable production of seafood. Supported by the British Council-Researcher Links and CONACyT. Merida, Mexico. 17-21 January 2017.
Year(s) Of Engagement Activity 2017
URL https://sites.google.com/site/genomicsinaquaculturemxuk/home
 
Description The influence of the diet on the gut microbial composition of Atlantic salmon (Salmo salar)". In the Workshop "Genomics in Aquaculture: a new set of tools to increase sustainable production of seafood." Merida, Mexico. 17-21 January 2017. 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Postgraduate students
Results and Impact ca. 40 scientists attended this workshop where Dr Ana Rodiles presented work on salmon microbiomics including outlining details and preliminary results of current project. This sparked questions and discussion afterwards.
Year(s) Of Engagement Activity 2017
 
Description Workshop attendance and contribution from project partners to discussion sessions 
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 project and generated data were discussed by project partners as participants at the 1st International Fish - Microbiota Workshop. Trondheim, Norway, June 19th to 21st.
Year(s) Of Engagement Activity 2017
URL https://www.ntnu.edu/1ifmw