Laboratoire Matière et Systèmes Complexes

Leptophages : How to find a haystack around a needle

Olivier Schiettekatte, PhD in microbiology (Institut Pasteur).

Leptospires are spiral-shaped environmental bacteria. They are responsible for a neglected disease which can lead to a threatening pulmonary hemorrhage syndrome : leptospirosis. The common animal reservoirs of the pathogenic bacteria are the rodents, and the disease is transmitted from soiled environmental waters through wounds. Leptospirosis causes one million severe cases each year worldwide, mainly in tropical developing areas ; moreover, carriage in cattle is responsible for significant economical loses.

In order to understand the life cycle of Leptospira spp., we focused on their viruses, named leptophages. Three leptophages infecting Leptospira biflexa were identified by the Biology of Spirochetes Unit (Pasteur Institute) [1]. To complete phage characterization, the three bacteriophages were morphologically described, structurally resolved, and sequenced [2]. Since bacteriophages are able to be maintained as prophages in the genomes of their hosts, a screening of genetic homologies between these leptophages and a pool of environmental Leptospira genomes were done. Surprisingly, sequence homologies were found in numerous genomes, including genomes from pathogenic species, suggesting a wide distribution of Leptospira prophages [2]. This was unattended as none pathogenic-infecting leptophage is known. In order to classify these Leptospira genomes and understand this phenomenon, an international collaboration led to the analysis of 500 genomes. Thanks to this zoom out, 30 new species were identified and subsequently characterized, including a whole new lineage [3].

LE4 phages on Leptospira biflexa (Schiettekatte et al. 2018)

This presentation includes results from :

[1]. Saint Girons I, Margarita D, Amouriaux P, Baranton G. First isolation of bacteriophages for a spirochaete : Potential genetic tools for Leptospira. Res Microbiol. 1990 ;141(9):1131-1138. doi:10.1016/0923-2508(90)90086-6

[2]. Schiettekatte O, Vincent AT, Malosse C, et al. Characterization of LE3 and LE4, the only lytic phages known to infect the spirochete Leptospira. Sci Rep. 2018 ;8(1):11781. doi:10.1038/s41598-018-29983-6

[3]. Vincent AT, Schiettekatte O, Goarant C, et al. Revisiting the taxonomy and evolution of pathogenicity of the genus Leptospira through the prism of genomics. Martins EAL, ed. PLoS Negl Trop Dis. 2019 ;13(5):e0007270. doi:10.1371/journal.pntd.0007270

Lundi 17 juin à 12h45 en salle 454A.