PhD on equines’ parsitic fly olfaction

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INRAE presentation

The French National Research Institute for Agriculture, Food, and Environment (INRAE) is a major player in research and innovation. It is a community of 12,000 people with 272 research, experimental research, and support units located in 18 regional centres throughout France. Internationally, INRAE is among the top research organisations in the agricultural and food sciences, plant and animal sciences, as well as in ecology and environmental science. It is the world’s leading research organisation specialising in agriculture, food and the environment. INRAE’s goal is to be a key player in the transitions necessary to address major global challenges. Faced with a growing world population, climate change, resource scarcity, and declining biodiversity, the Institute has a major role to play in building solutions and supporting the necessary acceleration of agricultural, food and environmental transitions.

Work environment, missions and activities

You will be welcomed in the Joint Research Unit Infectiology and Public Health (UMR ISP) which aims to combat infectious diseases in livestock and humans. Under the "One Health" concept, it brings together teams specialized in infectious pathologies involving viruses, bacteria, parasites at the interface between humans, animals and the environment. Among the pathogens studied within ISP, arthropods are of major and growing interest. These pests for humans, animals and crops, are characterized by exceptional prolificacy and dispersal capacity and prove extremely difficult to combat. In addition, the development of resistance requires the implementation of new control strategies. Within the Macro-parasite Control and Resistance (CRéM) team co-led by Foteini Koutroumpa (CR, team leader and co-supervisor 1 of the thesis) and Cédric Neveu (DR, thesis director 1) you will study the Chemical Ecology of the horse endoparasitic fly Gasterophilus intestinalis in collaboration with the Insect Biology Research Institute (IRBI-UMR CNRS 7261) directed by David Giron (DR, thesis director 2) and under the supervision of Elfie Perdereau (IR, head of the Chemical Ecology platform and co-supervisor 2 of the thesis). Chemical Ecology is the study of the attractive or repulsive properties of molecules emitted and/or used by organisms to exchange information with their congeners and with their environment. Indeed, these molecules can be used to keep a parasite away from its host. A second application of the Chemical Ecology is in the diagnosis of diseases. It has been shown that people with cancer, for example, could be screened thanks to the changes observed in their volatilome (set of volatile molecules emitted = odors) compared to a healthy individual [3-4].

Currently, the biological cycle and damage caused by Gasterophilus bot flies are known [5-12], but in terms of diagnosis invasive approaches such as gastroscopies or post-mortem examination is most often necessary to demonstrate the link between the presence of these parasites and the host's health. Most often, these parasites go undetected because they are eliminated during treatment with macrocyclic lactones (MLs), which target gastrointestinal nematodes. However, these nematodes have developed resistance to MLs [13, 14], which will no longer be sufficient for their control if new policies are not adopted in the future. Furthermore, MLs are the only molecules efficient against bot flies. Without treatment, the number and frequency of infestations will increase.

This project has two main objectives: i) one diagnostic (type and severity of infection) which aims to associate the physiological and parasitic status of equines with their odor signature and ii) to find natural molecules from the Chemical Ecology of the parasite or the host which could be used as active ingredients in alternative or rational control strategies.

The first objective of the project, which focuses on the diagnosis of infestation by bot flies and nematodes, will be addressed through a protocol based on monitoring by gastroscopies and coproscopies. At the same time, monitoring of volatile emissions throughout the year will be carried out and associated with the level of parasitism. The second objective is divided into two complementary approaches: First, we will conduct a chemical analysis for the identification of molecules from the volatilomes of adult bot flies and their host, equines. And in a second approach, we will focus on the olfactory receptors of this insect. Using molecular approaches, we will identify these ion channel receptors, and then characterize their expression in the different developmental instars. Finally, we will decipher their function in order to use them as targets against these parasites. This project offers a multidisciplinary approach ranging from epidemiology and classical chemical ecology to molecular biology and the characterization of pharmacological targets. It therefore involves field monitoring, analytical chemistry, olfactory behavior, transcriptomics, heterologous expression and electrophysiology.

The ambition of our project is to establish a diagnostic test using molecules emitted by infested equines. Monitoring the change in emissions according to the parasite load will help define new thresholds of parasitism in line with the animal welfare concern. This new approach of parasitism management, adapted to the physiological state of the animal and according to the needs, is an opportunity to avoid the acceleration of the resistance observed to MLs in nematodes and to perpetuate their rational use over time. We will also establish a list of molecules that are potentially attractive or repellent for G. intestinalis. Finally, at the molecular level, we will for the first time identify the chemosensory receptors of G. intestinalis and choose two of them in order to functionally characterize them by associating them to their natural ligands and their antagonists.

1. Hashim, O. et al 2022. Mol. Pharmacol. DOI: 10.1124/molpharm.122.000499
2. Miclon, M. et al 2023. Pathogens. DOI: 10.3390/pathogens12040540
3. Fu, W., et al 2022. ACS Omega. DOI: 10.1021/acsomega.1c05060
4. Guest, C., 2021. PLoS One DOI: 10.1371/journal.pone.0245530
5. Jendrny, P., 2021. BMC Infectious Diseases DOI: 10.1186/s12879-021-06523-8
6. Cogley, T.P., Cogley, M.C., 1999. Vet. Parasitol. DOI: 10.1016/s0304-4017(99)00119-3
7. Cogley, T.P., Cogley, M.C., 2000. Vet. Parasitol. DOI: 10.1016/s0304-4017(99)00191-0
8. Dart, A.J. et al 1987. Aust. Vet. J. DOI: 10.1111/j.1751-0813.1987.tb09669.x
9. Escartin-PeÑA, M., Bautista-Garfias, C.R. 1993. Med. Vet. Entomol. DOI: 10.1111/j.1365-2915.1993.tb00682.x
10. Mashayekhi, M., Ashtari, B., 2013. Medicine URL:http://www.bepls.com
11. Sequeira, J.L., et al 2001. Vet. Parasitol. https://doi.org/10.1016/s0304-4017(01)00536-2.
12. Waddell, A.H. 1972. Aust. Vet. J. DOI: 10.1111/j.1751-0813.1972.tb02261.x
13. Lyons, E.T. et al 1994. Vet. Parasitol. DOI: 10.1016/0304-4017(94)90117-1
14. Sallé, G., et al 2020. Int. J. Parasitol. 50, 125-132. DOI: 10.1016/j.ijpara.2019.11.004

Vous serez plus particulièrement en charge :

• Chemical analyses of horse samples to identify diagnostic markers of infestation (a part already in good progress by the host team).
• Sampling of larvae in the field during the summer.
• Behavioral tests in the laboratory and in the field, as well as electrophysiology tests on adult flies (summer activities).
• Obtaining and analyzing transcriptomic data.
• Functional tests in Xenopus oocytes.

Special conditions of activity :

• Fieldwork
• Work at two sites, the INRAE at Nouzilly and the University of Tours site at the IRBI
• Travel to Hungary for electrophysiological tests on flies

Training and skills

• Recommended education : Master's degree/Engineering (Bac+5)
• Desired experience : Previous experience in entomology, particularly insect chemosensory behavior, relevant statistical analyses, and good English communication skills (minimum B1)
• Appreciated experience : Field sampling, molecular biology, TEVC in Xenopus oocytes
• Required skills : Excellent oral and written communication skills, committed, rigorous, interpersonal skills, and good team integration abilities

INRAE's life quality

By joining our teams, you benefit from (depending on the type of contract and its duration):

- up to 30 days of annual leave + 15 days "Reduction of Working Time" (for a full time);
- parenting support: CESU childcare, leisure services;
- skills development systems: training, career advise;
- social support: advice and listening, social assistance and loans;
- holiday and leisure services: holiday vouchers, accommodation at preferential rates;
- sports and cultural activities;
- collective catering.

How to apply

I send my CV and my motivation letter