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Sheep tick (Ixodes ricinus). © INRA, CHAUBET Bernard

Tick-fighting tactics

A new look at the pathogens transmitted by ticks and their screening

Using high-throughput sequencing (NGS), INRA scientists have been working on better identifying the pathogens - both old and new - carried by ticks.  Thus the risks attached to the diseases transmitted by ticks will be better evaluated …. so that both humans and animals can be better protected!

Updated on 10/14/2016
Published on 09/08/2015

For many years now, physicians and veterinarians have regularly observed the appearance of diseases linked to tick bites, but whose aetiological diagnosis - or in other words, identification of the causal pathogen - is  impossible to establish.  Ticks are known to be vectors (or carriers) of both human and animal diseases (the second most important vector in the world after mosquitoes and the leading vector in Europe). These so-called vector-borne diseases can also be emerging diseases; i.e. new in our regions.  In France, the cost of diseases spread by ticks in livestock units is estimated at €35 million a year.  Although a certain number of pathogens (bacteria, protozoa and viruses) are already known to be transmitted via this arthropod, new agents are constantly being described (the most recent being Bourbon virus, a fatal virus identified in 2015 in the USA).  In this context that impacts both animal and human health, it is urgent to apply a One Health approach in order to inventory all the micro-organisms harboured by ticks, including those which are responsible for diseases in humans and/or animals.

Exploring the tick microbiota using high-throughput sequencing

Scientists from INRA, ANSES, the National Veterinary School in Alfort, the company Pathoquest and Institut Pasteur, working together in the Joint Research Unit for Parasite and Fungus Immunology and Molecular Biology (UMR BIPAR), have explored all the micro-organisms present in ticks (i.e. the microbiota) using high-throughput Next Generation Sequencing (NGS). This technology, combined with bioinformatics and the use of sequencing databases (big data), is able to identify the sequences of bacteria, viruses and parasites and assign them to known or as yet unknown species.  NGS can circumvent the problems attached to cultivating unknown organisms (composition of culture medium, oxygen requirements, etc.) or the impossibility of evidencing unknown bacteria using specific PCR.  Rapid and reliable, this technology is gradually revolutionising the field of diagnostics. 

New micro-organisms identified

The scientists extracted all the RNA (ribonucleic acids) - indicative of the presence of viable micro-organisms - from ticks (Ixodes ricinus) collected in Alsace and the French Ardennes. The RNA thus sequenced (using Illumina HiSeq2000) enabled the compilation of a table of all the micro-organisms - bacteria, viruses and protozoa - present in the ticks.  The team was thus able to demonstrate the unexpected presence of Borrelia miyamotoi  and Neoehrlichia mikurensis bacteria, both of which can cause serious fevers, and new species of the Babesia and Theileria parasite species that may be associated with disease.  Many of the new viruses identified in these ticks are currently being characterised.

This work has therefore been able to compile an accurate portrait of the micro-organisms associated with ticks.  This knowledge is particularly important because we know today that in most cases, a single tick can harbour several pathogens, all potentially transmissible.  The team is now working on identifying the level of pathogenicity of each of the bacterial, viral or parasitic species they have identified.  These micro-organisms will be sequenced in full.  From this research, it is hoped that it will be possible to develop preventive, screening and diagnostic tools for the future.  To exploit these findings, some partnerships with industrial actors are already planned, and the scientists wish to develop relationships with companies working in the human and/or animal health sectors.

Contact(s)
Scientific contact(s):

  • Muriel VAYSSIER-TAUSSAT (33 (0)1 4977 4655) INRA-ANSES-ENVA Joint Research Unit for Parasite and Fungus Immunology and Molecular Biology (UMR BIPAR) Laboratoire de Santé Animale-14 Rue Pierre et Marie Curie-94706 Maisons-Alfort
Associated Division(s):
Animal Health
Associated Centre(s):
Jouy-en-Josas

Find out more

  • Vayssier-Taussat M, Moutailler S, Michelet L, Devillers E, Bonnet S, Cheval J, et al. (2013) Next Generation Sequencing Uncovers Unexpected Bacterial Pathogens in Ticks in Western Europe. PLoS ONE 8(11): e81439. DOI: 10.1371/journal.pone.0081439
  • Bonnet, S., Michelet, L., Moutailler, S., Cheval, J., Hébert, C., Vayssier-Taussat, M., & Eloit, M. (2014). Identification of parasitic communities within European ticks using next-generation sequencing. PLoS Negl Trop Dis, 8(3), e2753.
  • Vayssier-Taussat, M., Cosson, J. F., Degeilh, B., Eloit, M., Fontanet, A., Moutailler, S., ... & Zylbermann, P. (2015). How a multidisciplinary ‘One Health’ approach can combat the tick-borne pathogen threat in Europe. Future Microbiology, 10(5), 809-818.