Sponge-based environmental DNA detection as a useful tool in monitoring Mycobacterium tuberculosis complex markers in European bison (Bison bonasus)

The European bison (Bison bonasus), also called wisent, is the largest terrestrial mammal in Europe, classified by the International Union for Conservation of Nature (IUCN) as a "Near Threatened" species. Tuberculosis (TB) represents a well-known threat to wisent, especially nowadays when infectious diseases are emerging to this species, due to locally high population density and frequent translocation (and consequently increased exposure to infectious diseases). There is an urgent need to control the TB-epidemiological situation in the European bison environment. This study aimed to assess the usefulness of the sponge-based environmental-DNA (eDNA) for monitoring TB in free-ranging and captive European bison herds based on the knowledge of the TB-epidemiological situation in the past. Between 2022 and 2024, eDNA samples (n = 84) were collected from European bison or their environment in eight herds from different regions of Poland. The real-time PCR techniques with IS6110, IS1081, and MPB70 as targets were used to detect MTC DNA markers in the samples. The MTC DNA IS6110 and IS1081 were simultaneously detected in 17/84 (20.2%) samples. No sample was positive for MPB70. The highest number of positive results for both markers (IS6110 and IS10081 targets) was in the captive herd in Bieszczady-Muczne, followed by the free-ranging herd in the nearby Bieszczady Mountains. Even though detecting nucleic acid, especially at low eDNA signal, does not necessarily indicate viable pathogens, our results suggest this new approach could represent a suitable complementary tool for TBC surveillance in wildlife-livestock interface of particular interest in endangered species.