Immunological response of live-captured wild elk (cervus canadensis) to treponema-associated hoof disease antigens

Authors: Wilson-Welder, Jennifer; MANSFIELD, KRISTIN - Washington Department Of Fish & Wildlife; HAN, SUSHAN - Colorado State University; HOENES, BROCK - Washington Department Of Fish & Wildlife; ALT, DAVID - Retired ARS Employee; Humphrey, Samuel; Olsen, Steven

Submitted to: Frontiers in Veterinary Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/26/2025
Publication Date: 2/5/2026
Citation: Wilson-Welder, J.H., Mansfield, K., Han, S., Hoenes, B., Alt, D., Humphrey, S.B., Olsen, S.C. 2026. Immunological response of live-captured wild elk (cervus canadensis) to treponema-associated hoof disease antigens. Frontiers in Veterinary Science. https://doi.org/10.3389/fvets.2025.1652577.
DOI: https://doi.org/10.3389/fvets.2025.1652577

Interpretive Summary: There was public concern that a severe hoof disease affecting wild elk in the pacific northwest was causing a decline in the population. The hoof disease caused debilitating lameness, hoof overgrowth, and sometimes loss of the hoof itself. Caused by several bacteria like human periodontal disease, spiral shaped bacteria from the genus Treponema are found at the leading edge of the hoof lesions. The Washington Department of Fish and Wildlife conducted a study to evaluate the survival and productivity of elk in the affected area with and without the hoof disease. As part of that study, some elk were evaluated for adaptive or memory immune responses to bacteria found in the hoof lesions. In general, immune responses correlated with severity of disease, with higher responses seen in animals with late-stage disease. No animals were observed with high levels of bacteria responsive immunity in the healthy state, as would be observed if a vaccine or existing immunity was present. Thus, naturally occurring immunity to this disease may be rare. More study is needed to determine the role of immunologically based protection for this and other treponeme driven hoof diseases.

Technical Abstract: A severe hoof disease is affecting wild elk (Cervus canadensis) in the pacific northwest. Causing severe lameness, tissue ulceration and necrosis, hoof overgrowth and often loss of the hoof itself, bacteria from the genus Treponema are found at the forefront of the lesions. As part of a larger study evaluating survival and ability of effected elk to raise young, lymphocytic responses to Treponemal antigens were evaluated in live-captured female elk from the endemic area. Effected animals exhibited serum antibody titers that correlated with disease severity and had increased antigen reactive B cells in peripheral blood when compared to healthy or naïve elk. However, we found no evidence that a high antibody titer led to decreased disease. T lymphocytic response, CD4+ and CD8+ was mildly proliferative to Treponemal antigen, correlating with advanced stages of lesion development. Interestingly, elk with early-stage lesions also had treponeme specific gamma-delta T cell proliferation. While these cells are known in other ruminants (cattle and sheep) to home to skin and have high affinity for bacterial and spirochetal antigens, their exact role in this and other treponeme driven hoof diseases is not fully understood. In general, all of the initially healthy animals had low lymphocytic responses indicating naturally acquired immunity in natural infection is probably rare. More study is needed to determine the roles of lymphocytes in protection or perpetuation of this bacterial driven hoof disease.