In ruminants, pregnancy results in up-regulation of a large number of IFN-stimulated genes (ISG) in the uterus. Recently, one of these genes was also shown to increase in peripheral blood leukocytes (PBL) during early pregnancy in sheep. Our working hypothesis is that conceptus signaling activates maternal gene expression in PBL in dairy cattle. The objectives of this study were to characterize ISG expression in PBL from pregnant (n = 20) and bred, nonpregnant (n = 30) dairy cows. Steady-state levels of mRNA for Mx1, Mx2, beta2-microglobulin, ISG-15, IFN regulatory factor-1, and IFN regulatory factor-2 were quantified. Holstein cows were synchronized to estrus and artificially inseminated (d 0). Blood samples were collected (coccygeal venipuncture) on d 0 and 16, 18, and 20 d after insemination for progesterone analysis and PBL isolation. Pregnancy was confirmed by transrectal ultrasonography at approximately 40 d after breeding. A status x day interaction was detected for Mx1, Mx2, and ISG-15 gene expression. When analyzed within day, levels of mRNA for ISG-15 and Mx1 were greater in pregnant compared with bred, nonpregnant cows on d 18 and 20, respectively. Expression of the Mx2 gene increased in the pregnant group compared with bred, nonpregnant cows on d 16, 18, and 20 after insemination. beta2-Microglobulin, IFN regulatory factor-1, and IFN regulatory factor-2 were not different between groups. The results clearly indicated that components of the innate immune response are activated in PBL during the period of pregnancy recognition and early embryo signaling. The physiological implications of these changes on maternal immune function are as yet unknown; however, they do provide a unique opportunity to identify bred, nonpregnant, cows 18 d after insemination in dairy cattle.

Early embryonic losses are much higher in nuclear transfer (cloned) pregnancies, and this is a major impediment to improving the efficiency of cloned

Johne's disease of cattle is widespread and causes significant economic loss to producers. Control has been hindered by limited understanding of the immune response to the causative agent,Mycobacterium aviumsubsp.paratuberculosis, and lack of an effective vaccine and sensitive specific diagnostic assays. The present study was conducted to gain insight into factors affecting the immune response toM. aviumsubsp.paratuberculosis. A persistent proliferative response toM. aviumsubsp.paratuberculosispurified protein derivative and solubleM. aviumsubsp.paratuberculosisantigens was detected in orally infected neonatal calves 6 months postinfection (p.i.) by flow cytometry (FC). CD4⁺T cells with a memory phenotype (CD45R0⁺) expressing CD25 and CD26 were the predominant cell type responding to antigens. Few CD8⁺T cells proliferated in response to antigens until 18 months p.i. γδ T cells did not appear to respond to antigen until 18 months p.i. The majority of WC1⁺CD2⁻and a few WC1⁻CD2⁺γδ T cells expressed CD25 at time zero. By 18 months, however, subsets of γδ T cells from both control and infected animals showed an increase in expression of CD25, ACT2, and CD26 in the presence of the antigens. Two populations of CD3⁻non-T non-B null cells, CD2⁺and CD2⁻, proliferated in cell cultures from some control and infected animals during the study, with and without antigen. The studies clearly show multicolor FC offers a consistent reliable way to monitor the evolution and changes in the immune response toM. aviumsubsp.paratuberculosisthat occur during disease progression.