Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: March 8, 2010
Publication Date: July 11, 2010
Citation: Stabel, J.R., Bannantine, J.P., Eda, S., Robbe-Austerman, S. 2010. Induction of B Cell Responses upon Experimental Infection of Neonatal Calves with Mycobacterium avium subsp. paratuberculosis [abstract]. American Dairy Science Association. Journal of Dairy Science. 93(E-Supplement 1):33. Technical Abstract: Animal models are useful for studying host responses to infection and aid in the development of diagnostic tools and vaccines. The current study was designed to compare the effects of different methods of experimental infection: Oral (Mycobacterium avium subsp. parauberculosis (MAP) strain K-10; Oral/DXM (pretreatment with dexamethasone before oral inoculation with strain K-10); IP (intraperitoneal inoculation with strain K-10); and Oral/M (oral inoculation with mucosal scrapings from a clinical cow) in neonatal calves. The objective of this study was to determine if infection with MAP over 12-month period would invoke changes in the percentages of total B cells in the peripheral blood mononuclear cell population and in subpopulations of B cells as determined by CD5, CD25, and CD45RO markers. Over the course of the study, the percentage of total B cells in nonstimulated and antigen-stimulated cell cultures increased (P < 0.01) for orally and intraperitoneally infected calves, with the highest percentages noted at 3 and 6 months post-infection. Oral infection of calves with a clinical strain of MAP (Oral/M) resulted in increased percentages of CD5dim and CD5bright B cells, regardless of in vitro stimulation, by 9 and 12 months post-infection. Experimental infection by all methods resulted in increased expression of CD25+B cells and CD45RO+ B cells early in the study but the most significant results were observed at 12 months for calves pre-treated with dexamethasone before oral inoculation with strain K-10 (Oral/DXM) and Oral/M calves. Immunoblot analyses demonstrated the greatest reactivity to a whole-cell sonicate of MAP in sera from IP calves and the lowest was observed in calves orally inoculated with strain K-10. Further evidence of strong MAP-specific antibody responses in the IP calves was demonstrated using the EvELISA method. In summary, the method of experimental inoculation with MAP did affect the induction of B cell subpopulations and the appearance of MAP-specific antibody during the 12-month study period.