John W Coatney ¹ Adam C Krull ¹ Patrick John Gorden ¹ Jan Shearer ¹ Samuel Humphrey ^2,3 Steven Olsen ^2,3 Paul J Plummer ^1,4 Jennifer H Wilson-Welder ^2,3*

• ¹ College of Veterinary Medicine, Iowa State University, Ames, Iowa, United States
• ² National Animal Disease Center, Agricultural Research Service (USDA), Ames, Iowa, United States
• ³ United States Department of Agriculture (USDA), Washington, United States
• ⁴ College of Veterinary Medicine, University of Tennessee, Knoxville, Knoxville, Tennessee, United States

We wish to submit the enclosed manuscript to Frontiers in Veterinary Microbiology, and for inclusion in special issue 'Exploring Infectious Agents in Ruminant Foot Disease'. Digital dermatitis is a bacterial infection affecting the skin just above the hoof, causing lameness in production cattle and other ruminants globally. While many factors contribute to disease development, the main pathogens are spirochetes in the genus Treponema. Little work has been done characterizing cellular or memory responses to bacteria in acute digital dermatitis. The use of an inducible model allows for the study of animals with known infection history. The manuscript describes the evaluation of immune responses following experimental induction of digital dermatitis in two groups of cattle, one group developing digital dermatitis lesions, healing the lesions and then re-inducing lesions a second time. The second group of cattle were only experimentally induced a single time. Antibody and cellular responses were measured at the conclusion of the infection period. While protection was observed in some cattle that had been previously infected, no major differences were observed in immune responses between groups. This study indicates that repeated exposure may lead to some protection, but further study is needed to determine the mechanism of that protection.