Interferon-gamma producing CD4+ T cells quantified by flow cytometry as early markers for Mycobacterium avium ssp. paratuberculosis infection in cattle.

Current diagnostic methods for Johne's disease in cattle allow reliable detection of infections with Mycobacterium avium ssp. paratuberculosis (MAP) not before animals are 2 years of age. Applying a flow cytometry-based approach (FCA) to quantify a MAP-specific interferon-gamma (IFN-γ) response in T cell subsets, the present study sought to monitor the kinetics of the cell-mediated immune response in experimentally infected calves. Six MAP-negative calves and six calves, orally inoculated with MAP at 10 days of age, were sampled every 4 weeks for 52 weeks post-inoculation (wpi). Peripheral blood mononuclear cells (PBMC) were stimulated with either purified protein derivatives (PPD) or whole cell sonicates derived from MAP (WCSj), M. avium ssp. avium or M. phlei for 6 days followed by labeling of intracellular IFN-γ in CD4+ and CD8+ T cells. No antigen-specific IFN-γ production was detectable in CD8+ cells throughout and the responses of CD4+ cells of MAP-infected and control calves were similar up to 12 wpi. However, the mean fluorescence intensity (MFI) for the detection of IFN-γ in CD4+ cells after WCSj antigen stimulation allowed for a differentiation of animal groups from 16 wpi onwards. This approach had a superior sensitivity (87.8%) and specificity (86.8%) to detect infected animals from 16 wpi onwards, i.e., in an early infection stage, as compared to the IFN-γ release assay (IGRA). Quantification of specific IFN-γ production at the level of individual CD4+ cells may serve, therefore, as a valuable tool to identify MAP-infected juvenile cattle.

T cell reactions of Eimeria bovis primary and challenge-infected calves.

Eimeria bovis infections commonly have clinical impact only on young animals, as homologous reinfections generally are under immunological control. So far, the nature of the immune responses delivering protection to calves has not been investigated. In this study we therefore analysed local and peripheral proliferative T cell activities of primary and challenge-infected calves and investigated the occurrence of T cell phenotypes in the peripheral blood and in mucosal gut segments isolated either by bioptic means or by necropsies.We show that lymphocytes of E. bovis-infected calves exhibit effective, transient antigen-specific proliferative responses in the course of prepatency of primary infection but fail to react after homologous reinfection suggesting early abrogation of parasite development. Whilst in primary infection an expansion of peripheral CD4+ T cells was observed, reinfection had no effect on the proportions of CD4+, CD8+ subsets or gammadeltaTCR+ T cells. In contrast, both E. bovis primary and challenge infections had an impact on local tissue T cell distribution. Primary infection was characterised by a CD4+ T cell infiltration early in prepatency in ileum and later in colon mucosa, whereas CD8+ T cells were only found accumulating in the latter gut segment. Challenge infection led to infiltration of both CD4+ and CD8+ T cells in small intestine and large intestine segments indicating protective functions of both cell types. In contrast, infiltration of ileum and colon mucosa with gammadeltaTCR+ T cells was restricted to primary infection.

New aspects in the pathogenesis of abomasal displacement.

Impaired abomasal motility and an increased accumulation of gas are prerequisites for displacement of the abomasum in the cow. Predisposing factors are the breed (e.g. Holstein-Friesian, Simmental-Red-Holstein cross breeds and Guernsey), genetic background, twin pregnancy, first weeks of lactation, metabolic disorders (ketosis, increased lipomobilisation, insulin resistance), high-concentrate and low-fibre diets, as well as other concomitant diseases, such as endometritis, mastitis and claw disorders. There does not appear to be a strong correlation between increased milk yield or endotoxaemia and abomasal displacement. Recent studies have focused on possible functional disorders of the enteric nervous system within the abomasal wall, since cattle with abomasal displacement have an increased activity of neuronal nitric oxide synthase, as well as decreased acetylcholine sensitivity. In addition, there appear to be significant differences between breeds in the levels of the neurotransmitters substance P (SP) and vasoactive intestinal peptide (VIP) in the abomasal wall. For example, SP (stimulatory) was significantly less in German Holsteins in comparison to the German Fleckvieh, whereas VIP (inhibitory) was markedly increased. These risk factors may explain why Holstein cows are more susceptible to abomasal displacement than other breeds.

Comparison of laparoscopic-guided abomasopexy versus omentopexy via right flank laparotomy for the treatment of left abomasal displacement in dairy cows.

OBJECTIVE: To compare results obtained by use of laparoscopyassisted abomasopexy versus omentopexy via right flank laparotomy for the treatment of dairy cows with left displaced abomasum (LDA). ANIMALS: 120 dairy cows with an LDA. PROCEDURE: In a prospective clinical trial, cows were randomly allocated to the abomasopexy group (laparoscopy-assisted abomasopexy) or to the control group (omentopexy via right flank). Data were obtained during the first 5 days after surgery and 6 weeks and 6 months after surgery. RESULTS: 59 of 60 cows in the abomasopexy group and all 60 cows in the control group were treated successfully. Median duration was shorter for the laparoscopic procedure (27.5 minutes), compared with that for the control group (38 minutes). Five cows in the abomasopexy group had wound complications and 2 had LDA relapses, compared with 2 wound complications and no relapses in the control group. During the 5 days after surgery, the abomasopexy group had a significantly higher increase in rate of energy intake and milk yield and a more rapid return to reference range for serum glutamic dehydrogenase activity and total bilirubin concentration, compared with results for the control group. CONCLUSIONS AND CLINICAL RELEVANCE: Success rates were almost equal for both methods. Advantages of the laparoscopic abomasopexy procedure include practicality, low risk of complications, and rapid postoperative recovery. Contraindications are cardiopulmonary diseases. Other disadvantages include the cost of the instruments and inability to perform the procedure in cows with abomasal adhesions.