Behavioural and immunological control methods for Culicoides biting midges in the UK

Lead Research Organisation: University of Surrey
Department Name: Veterinary Medicine & Science

Abstract

Culicoides biting midges are the most important biological vectors of arboviruses of ruminants in Europe, where they act as vectors of bluetongue and Schmallenberg viruses and potentially other emerging threats. This studentship tests the following hypotheses which are relevant to reducing the impact of Culicoides-borne arboviruses. 1. The presence of adult Culicoides in animal housing has a major role in overwintering and spread of arboviruses, but can be addressed in part through vector-proof accommodation. 2. Immunological responses to over-exposure of vector salivary proteins can be harnessed to reduce the survival of bloodfeeding Culicoides with future potential for vaccine design. The student will examine Culicoides populations at cattle holdings in the UK already established by The Pirbright Institute (TPI: Academic lead) and APS Biocontrol (Industrial Partner). Winter survival of adult Culicoides within animal housing will be investigated using standardised suction trap and vacuum surveys. Results from this direct sampling will be compared with models of seasonal abundance based on outside light-suction trap sampling already conducted by TPI. To improve our understanding of biosecurity in animal housing, the efficacy of ultraviolet-based traps and air curtains will then be examined using behavioural assays in the laboratory to complement testing of insecticide impregnated screens already completed at TPI. In the subsequent two field seasons, at time of peak transmission of Culicoides-borne arboviruses,
efforts will be made across selected sites to exclude Culicoides from housing through implementation of optimized procedures and the degree of bio-containment assessed by the abundance of Culicoides versus outside collections.

The studentship will also examine development of vaccines based on responses of hosts to unnaturally high doses of arthropod saliva. Preliminary data in collaboration with Dr Alasdair Nisbet of the Moredun Institute demonstrated that inoculated of sheep with a Culicoides extract produce elevated levels of serum antibodies. Feeding on the blood of postvaccination sheep reduces survival in Culicoides when compared to unvaccinated controls. Serum from naturally exposed cattle and sheep will initially be screened for anti-Culicoides antibody levels, assessing the seasonality of exposure and the likely degree of saliva protein cross-recognition between Culicoides species. Sampling will compare hosts in areas known to be dominated by specific Culicoides fauna and saliva proteins purified from colony-reared lines with homologous field-collected species extractions. Conserved immunogenic Culicoides saliva proteins across samples will be identified by western blot assays and proteomics. A vaccination trial of sheep with purified Culicoides saliva proteins will then analyse immunological responses (e.g. titre and isotype(s) of serum antibodies and the potential presence of cytokines). Cell mediated immune responses will be examined using proliferation assays and cytokine production of in vitro exposed peripheral blood cells from vaccinated sheep to saliva proteins (combined and fractionated). Laboratory survival and fecundity rates of Culicoides blood-fed on vaccinated and control sheep will then be statistically assessed. The student placement will last three months and will aim to devise techniques for the collection of saliva from C.impunctatus, utilizing the expertise of Dr Alison Blackwell (APS Biocontrol) with this species. This will provide a significant resource for all collaborating partners in the project and is enabled by geographic distance between the partners with APS being based in Scotland. In addition, the student will also work with the APS team to estimate commercial potential for containment facilities in the UK which was a major area of discussion during the 2007 incursion of bluetongue virus when movement restrictions were implemented.

Publications

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Studentship Projects

Project Reference Relationship Related To Start End Student Name
BB/M016196/1 05/10/2015 04/10/2019
1646419 Studentship BB/M016196/1 05/10/2015 04/10/2019 Laura Tugwell
 
Description I have developed several immunoassays to detect the presence of antibodies in ruminant and equine serum against Culicoides biting midge salivary proteins. An ELISA has been developed and optimized to confidently determine titre (amount of) antibodies found in a serum sample against the Culicoides salivary proteins. This has been used to assess how levels of antibodies in the host changes throughout different times of the year. Also a Western Blot assay has been developed and optimized to detect which specific Culicoides salivary proteins are immunogenic. Thus far, there appears to be no differences in antibody titres in cattle and horses during different times, and seasons, of the year.

Furthermore this grant has allowed for an in-depth study of the role of animal housing in the survival of adult Culicoides at farms during the winter. There are no other studies published which measure Culicoides abundance at such regular time intervals (daily) and for such a long period of time (currently 17 months). This has allowed for detailed analysis in the daily conditions required for survival in the environment. In addition a laboratory study has been conducted as part of the research funded on this grant investigating the effect of cold temperatures on the flight activity of Culicoides biting midges. Studies suggest that Culicoides midges in SE England cannot sustain flight below 6 degrees Celsius. This compliments findings in the in-depth farm study whereby Culicoides midges were not present on days when temperatures were below around 6 degrees Celsius.
This work has been followed up by a field study placement in Kielder Forest, NE England, which outlined differences in behavior and cold temperature tolerance between the Culicoides species in SE England and those in NE England. For the first time, results from these studies indicate that C. scoticus are more active than C. obsoletus. Together, the results have a significant impact on disease outbreak surveillance and future policy decisions.
Exploitation Route Identifying the specific Culicoides salivary proteins which evoke an immune response could be key in future applications such as vector vaccine design to aid with the prevention of arbovirus incursions. This information will also perhaps be used in future immunotherapy techniques for the treatment of sweet-itch in horses. The investigations into the effects of animal housing for overwintering of Culicoides and subsequent arboviruses could be replicated by other teams in other locations around the UK (and in Europe). This could determine species differences and therefore influence epidemiology and disease outbreak decisions. Additionally the cold temperature tolerance of Culicoides midges would highly benefit any others involved in the surveillance of Culicoides. The data can be used to predict abundances based on the temperatures and also influence when teams are carrying out surveillance.
Sectors Agriculture, Food and Drink,Other

 
Description Avacta Animal Health - Culcoides saliva 
Organisation Avacta Life Sciences
Country United Kingdom 
Sector Private 
PI Contribution Supply of Culicoides salivary proteins to Avacta Animal Health.
Collaborator Contribution Technical advice and financial contribution.
Impact None
Start Year 2017
 
Description Invited presentation at the Friedrich Loeffler Institute (January; Riems) 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Formal presentation on biting midges and bluetongue to professional audience with question session and collaborative meetings
Year(s) Of Engagement Activity 2019
 
Description Open Day at Univeristy 
Form Of Engagement Activity Participation in an open day or visit at my research institution
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Public/other audiences
Results and Impact The Pirbright Institute had a stand at University of Surrey's open Day to demonstrate the work carried out at the Institute, one of the University's partners. Aim was to show prospective students the possibilities of study and careers at the Institute.
Year(s) Of Engagement Activity 2017
 
Description Poster Presentation at International Conference 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Other audiences
Results and Impact Poster presentation of research funded by this grant at an International Conference, "International Congress of Entomology (ICE)" in Florida October 2016. This led to several discussions about the work as well as a good networking event.
Year(s) Of Engagement Activity 2016
URL https://esa.confex.com/esa/ice2016/meetingapp.cgi/Paper/112607
 
Description STEM day workshop at local school 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Schools
Results and Impact I led a 'disease and germs' themed workshop for primary school children aged 4-7 which also involved discussing animal health.
Year(s) Of Engagement Activity 2019
 
Description School Careers Event 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Schools
Results and Impact Careers Event for Secondary school children (aged approx 13-14 years old) - event called TeenTech involving secondary schools from around the region. Over 300 children attended with their teachers but only small groups would come up to the Institute's stand at a time.
Year(s) Of Engagement Activity 2018
 
Description School Visit - STEM activity 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Schools
Results and Impact As part of Science Day at Tillingbourne school, a team of us set up stations with different scientific themes and the students went round to each station in turn.
Year(s) Of Engagement Activity 2018
 
Description Talk presented at UK VBD conference 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Professional Practitioners
Results and Impact Formal presentation of some of my research findings regarding culicoides overwintering followed by a question session. Held at the UK Vector-borne disease (VBD) Conference in Norwich.
Year(s) Of Engagement Activity 2018
URL http://www.hpruezi.nihr.ac.uk/about-us/news-and-events/vbd-uk-2018/