Genetic diversity of Treponema paraluisleporidarum isolates in European
lagomorphs
Abstract
The bacterium Treponema paraluisleporidarum causes syphilis in
Lagomorphs. In a set of 1,095 samples from four species – European
brown hare (Lepus europaeus), mountain hare (Lepus timidus), Corsican
hare (Lepus corsicanus) and European rabbit (Oryctolagus cuniculus) –
we genotyped the strains that infect wild lagomorphs. Samples originate
from Sweden, the Netherlands, the United Kingdom, Germany, the Czech
Republic and Italy. The phylogenetic analyses of two informative gene
targets (tp0488 and tp0548) showed high genetic diversity among the
lagomorph-infecting treponemes. More specifically, we found a high
number of nucleotide variants and various short repeat units in the
tp0548 locus which have not been described for human syphilis and
primate yaws causing Treponema pallidum. While the functional aspect of
these short repeat units remains subject to ongoing investigations, it
likely enables the pathogen to better survive in its lagomorph host. Our
data did not support any geographic clustering which is equally
reflected in the host population genetics as shown by mitochondrial
genome data corresponding to the sampled lagomorph populations. This is
unexpected and in contrast with what has been shown for nonhuman primate
infection with T. pallidum. In the future, the combination of
multi-locus sequence typing and WGS from modern and ancient samples from
a wide geographic range and multiple lagomorph species will contribute
to a better understanding of the epidemiology and evolutionary path of
lagomorph-infecting treponemes. In conclusion, our current study
demonstrates a high genetic variation of the syphilis-causing pathogen
in a higher number of positively PCR-tested European lagomorphs
(n=496/1095).