Disease Progression and Serological Assay Performance in Heritage Breed Pigs following Brucella suis Experimental Challenge as a Model for Naturally Infected Feral Swine

Authors

Vienna R. Brown, USDA APHIS Wildlife ServicesFollow
Ryan S. Miller, USDA APHIS Veterinary Services, Fort Collins,
Courtney F. Bowden, USDA APHIS Wildlife Services
Timothy J. Smyser, USDA APHIS/Wildlife Services/NWRCFollow
Nicholas A. Ledesma, USDA APHIS Veterinary Services, Ames, IA
Aim E. Hartwig, Colorado State University, Fort Collins
Paul Gordy, Colorado State University, Fort Collins
Aaron M. Anderson, USDA APHIS Wildlife Services, Fort Collins
Stephanie M. Porter, Colorado State University, Fort Collins
Kate Alexander, Colorado State University, Fort Collins
Zane Gouker, Colorado State University, Fort Collins
Tom Gidlewski, National Wildlife Disease ProgramFollow
Richard A. Bowen, USDA APHIS Wildlife Services, Fort Collins,
Angela M. Bosco-Lauth, Division of Vector-Borne Diseases, Arboviral Disease Branch, Centers for Disease Control and Prevention, Fort Collins, COFollow

ORCID IDs

Stephanie M. Porter https://orcid.org/0000-0001-6664-6451

Date of this Version

2023

Citation

Brown, V.R.; Miller, R.S.; Bowden, C.F.; Smyser, T.J.; Ledesma, N.A.; Hartwig, A.; Gordy, P.; Anderson, A.M.; Porter, S.M.; Alexander, K.; et al. Disease Progression and Serological Assay Performance in Heritage Breed Pigs following Brucella suis Experimental Challenge as a Model for Naturally Infected Feral Swine. Pathogens 2023, 12, 638. https:// doi.org/10.3390/pathogens12050638

Comments

CC BY

Abstract

Invasive feral swine (Sus scrofa) are one of the most important wildlife species for disease surveillance in the United States, serving as a reservoir for various diseases of concern for the health of humans and domestic animals. Brucella suis, the causative agent of swine brucellosis, is one such pathogen carried and transmitted by feral swine. Serology assays are the preferred field diagnostic for B. suis infection, as whole blood can be readily collected and antibodies are highly stable. However, serological assays frequently have lower sensitivity and specificity, and few studies have validated serological assays for B. suis in feral swine. We conducted an experimental infection of Ossabaw Island Hogs (a breed re-domesticated from feral animals) as a disease-free proxy for feral swine to (1) improve understanding of bacterial dissemination and antibody response following B. suis infection and (2) evaluate potential changes in the performance of serological diagnostic assays over the course of infection. Animals were inoculated with B. suis and serially euthanized across a 16-week period, with samples collected at the time of euthanasia. The 8% card agglutination test performed best, whereas the fluorescence polarization assay demonstrated no capacity to differentiate true positive from true negative animals. Froma disease surveillance perspective, using the 8%card agglutination test in parallel with either the buffered acidified plate antigen test or the Brucella abortus/suis complement fixation test provided the best performance with the highest probability of a positive assay result. Application of these combinations of diagnostic assays for B. suis surveillance among feral swine would improve understanding of spillover risks at the national level.