Treponemes in wild lagomorphs: Genetic diversity and relatedness to human pathogenic T. pallidum
Veterinary Medical Science
Final Report Abstract
The genus Treponema contains several spiral-shaped bacteria some of which are relevant to human and animal health. While human syphilis caused by Treponema pallidum is a wellstudies disease, there is limited information on syphilis caused by Treponema paraluisleporidarum ecovar Lepus (TPeL) infecting hares and ecovar Cuniculus (TPeC) infecting rabbits. Although rabbit syphilis was first reported in 1920, there is, until today, only a single laboratory-maintained rabbit infecting strain whose genome was completely sequenced in 2011. The first documented case of syphilis in a hare (Lepus spec.) was published in 1957. To gain a better insight into the biology, epidemiology, and genetics of European lagomorph infecting TPeC/L, we analysed a total of 5,017 hare and 184 rabbit samples from nine European countries – CZ, ES, FI, GB, DE, HU, IT, NL and SE – for the presence of TPeC/L infection. We coupled antibody detection with qPCR analysis in all cases where we had a swab or tissue sample from the genital of the leporid. Using a nucleic-acid amplification test allowed us to screen for the direct presence of the pathogen. As a result, we demonstrate that infection is geographically widespread in Europe, with infections in European brown hares, Mountain hares, and wild and domestic rabbits. At least in European brown hares, the infection was positively correlated with age which argues for a sexual transmission route. In a subset of 531 positive tested and clinically inspected hares, we found only few animals with skin crusts and ulcerations in the face or genital region, which is suggestive of a high level of pathogen-host adaptation. The Multi-Locus Sequence Typing (MLST) system was originally designed to distinguish strains of the yaws bacterium Treponema pallidum subsp. pertenue. Yet, the close genetic relatedness of the lagomorph syphilis-causing bacterium and T. pallidum allowed us to discriminate different TPeC/L strains equally. The phylogenetic analyses of the two MLST gene targets (tp0488 and tp0548) in 194 samples revealed a high genetic diversity among the leporid-infecting treponemes. In addition, we found several nucleotide variants and short repeat units in the tp0548 locus, which are unknown for human syphilis and yaws. Compared to what we have experienced in nonhuman primate yaws, lagomorph infecting strains show no geographic clustering, which is also reflected in the host population genetics. Like T. pallidum, TPeC/L is a highly conserved bacterium. Therefore, genomes must be compared in full length to identify differences between rabbit and hare-infecting strains and leporid and primate-infecting treponemes. We, therefore, selected MLST-based genetically distinct TPeC/L strains from different lagomorph species to target-enrich the Treponema DNA using Pooled Sequence Genome Sequencing (PSGS) and targeted DNA capture followed by high-throughput sequencing. This generated nine draft genomes of rabbit and hare-infecting strains and one complete genome of a mountain hare-infecting strain. Based on the first complete genome sequence of a hare infecting strain, our analyses indicate a high similarity of the TPeL and TPeC genome (strain Cuniculi A). Furthermore, our first phylogenetic analyses reveal that the TPeC Cuniculi A genome appears to be evolutionary modern compared to the hare infecting TPeL. However, more analyses need to be done before a final statement can be made and more samples from naturally infected hares and rabbits from a wider geographic area need to be analysed to get a deeper insight into the genetic diversity of lagomorph syphilis.
Publications
-
(2019): A metataxonomic tool to investigate the diversity of Treponema. Front Microbiol 10, 2094
Hallmaier-Wacker, L.K.; Lüert, S.; Gronow, S; C. Spröer, Overmann, J.; Buller, N.; Vaughan-Higgins, R.J. and Knauf, S.
-
(2019): First report of hare treponematosis seroprevalence of European brown hares (Lepus europaeus) in the Czech Republic: seroprevalence negatively correlates with altitude of sampling areas. Bmc Vet Res 15, 350
Nováková, M.; Najt, D.; Mikalová, L.; Kostková, M.; Vrbová, E.; Strouhal, M.; Posautz, A., Knauf, S and Šmajs, D.
-
(2020): High syphilis seropositivity in European brown hares (Lepus europaeus), Lower Saxony, Germany. Transbound Emerg Dis 67, 2240–2244
Hisgen, L., Abel, L.; Hallmaier-Wacker, L.K.; Lueert, S.; Siebert, U.; Faehndrich, M.; Strauss, E.; Voigt, U.; Nováková, M.; Šmajs, D. and Knauf, S.
-
(2020): High syphilis seropositivity in European brown hares, Lower Saxony, Germany
Hisgen, L.; Abel, L.; Hallmaier-Wacker, L.K.; Lüert, S.; Siebert, U.; Faehndrich, M.; Strauss, E.; Voigt, U.; Nováková, M.; Šmajs, D. and Knauf, S.
-
(2021): The distribution of lagomorph syphilis caused by Treponema paraluisleporidarum in Europe. Eur J Wildlife Res 67, 92
Hisgen, L.; Abel, L.; Hallmaier-Wacker, L.K.; Lüert, S.; Lavazza, A.; Trogu, T.; Velarde, R.; Nováková, M.; Gyuranecz, M.; Ågren, E.; Barlow, A.; Šmajs, D.; and Knauf S.
-
(2022): Syphilis seropositivity and Treponema paraluisleporidarum strain diversity in European brown hares. 6th World Lagomorph Conference, Montpellier, France
Hisgen, L.; Gyuranecz, M.; Hallmaier-Wacker, L.K.; Lavazza, A.; Lüert, S.; Nováková, M.; Siebert, U.; Strauss, E.; Trogu, T.; Velarde, R.; Voigt, U.; Šmajs, D.; Knauf, S.
