Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 4/11/2006
Publication Date: 7/9/2006
Citation: Williams, E.L., Stabel, J.R. 2006. Characterization of Cytokine gene expression in Periparturient dairy cows naturally infected with Mycobacterium avium subsp. paratuberculosis [abstract]. American Dairy Science Association Meeting. p. 110.
Technical Abstract: Johne’s disease (JD), caused by Mycobacterium avium subsp. paratuberculosis (MAP), is estimated to infect more than 22% of US dairy herds. Periods of immunosuppression, typically seen at parturition, may contribute to the transition from subclinical, or asymptomatic, to clinical stage of infection. Understanding the effects of stressors on disease may provide information that will help manage JD. The objective of this study was to characterize cytokine gene expression in periparturient dairy cows naturally infected with MAP. Twenty-two multiparous Holstein cows were placed into 3 groups consisting of 5 noninfected healthy cows, 12 subclinical cows, and 5 clinical cows. Blood was collected from the jugular vein 3 wks pre- and 4 wks post-calving. Peripheral blood mononuclear cells (PBMC) were isolated from the buffy coat fractions of blood and cultured for 24 h with and without concanavalin A. At 24 h, RNA was extracted from all cells and converted to first-strand cDNA. Real-time PCR was performed on each sample to evaluate the expression of the following genes: IFN-gamma, TNF-alpha, IL-12, IL-10, TGF-beta, IL-4 and beta-actin gene. All reactions were performed in triplicate and RT-PCR data was analyzed using delta-Ct values and Proc Mix procedure of SAS. Across the periparturient period, expression of IFN-gamma, TNF-alpha, and TGF-beta mRNA did not differ between nil- and stimulated PBMCs isolated from infected and control cows. ConA-stimulated PBMCs showed greater IL-12 mRNA expression for both subclinical (P <0.03) and clinical (P <0.04) cows compared to controls. Expression of IL-4 mRNA from nil- (P <0.03) and stimulated (P <0.01) PBMCs was greater in infected compared to healthy control cows. Expression of IL-10 mRNA from nil- (P <0.08) and stimulated (P <0.05) PBMCs was greater for infected cows compared to control cows. The data indicate an ability of parturition to regulate IL-12 and IL-4 gene expression, but not IFN-gamma, TNF-alpha, TGF-beta, or IL-10. Expression for the Th1 cytokine IL-12 and the Th2 cytokines IL-4 and IL-10 from infected cows were significantly elevated compared to healthy controls. Key Words: periparturient, cytokines, Mycobacterium avium subsp. paratuberculosis