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Q fever is a cosmopolitan disease affecting both humans and many animal species. Although sheep are often implicated in human Q fever outbreaks, the disease remains largely underestimated in meat sheep flocks. In order to fulfil this gap, a preliminary study was performed aiming to investigate the serological and molecular aspects of infection with Coxiella burnetii among meat sheep flocks in Belgium. Five Belgian sheep flocks were recruited for this work. Indirect ELISA was used, and in addition, real-time PCR was performed on samples of milk, rectal and vaginal swabs, to understand the dynamics of bacterial shedding. Despite the low overall apparent seroprevalence of 1.39% (95% CI: 0.04–7.5), a high rate of bacterial shedding was found, with 27.7% of tested sheep (N = 72) with a positive result to PCR, especially through the rectal and vaginal routes and in seronegative animals. Furthermore, Coxiella burnetii DNA was detected in 26.76% of seronegative animals. It can be concluded that an overall good clinical condition of the sheep cannot be used to exclude the presence of C. burnetii in a flock. Furthermore in the diagnosis of Q fever in sheep, serology alone was not a sensitive diagnostic tool. On the contrary, molecular biology allowed to detect bacterial shedding, which is an essential element in order to assess the risk due to the contact with shedding animals. At the light of these results, the role of meat sheep flocks in the epidemiology of Q fever in Belgium needs to be better understood.

Summary Groups of yearling sheep were trickle infected with Teladorsagia circumcincta for 8 weeks, then the infection cleared with anthelmintic and both these animals and a group of parasite naive sheep were challenged with 50 000 infective T. circumcincta larvae. The previously infected sheep demonstrated acquired immunity to the parasite, manifested by reduced worm burdens which were evident as early as 2 days after challenge. Cannulation of the common efferent gastric lymph duct allowed the kinetics of their local cell traffic to be monitored, and the phenotype of these lymphocytes was analysed. A blast cell response, consisting of both T and B lymphocytes, was observed in both groups of sheep, however this occurred more rapidly in the previously infected, immune animals. CD4+, CD8+ and CD25+ blast cell output peaked at day 3 in the previously infected animals, whereas CD21+ blast cell output peaked slightly later at day 5. In the control group the peak output of all phenotypes of blast cells occurred more slowly, peaking 10 days after infection.

Interferon-gamma (IFN-gamma) and interleukin (IL)-10 are cross-regulatory cytokines capable of driving and controlling the adaptive host immune response. The inter-relationship between IFN-gamma and IL-10 expression has not been defined in sheep despite biological evidence suggesting that they perform similar functions to their orthologues described in other species. To address this, we have developed a quantitative (q)PCR method to assess relative levels of IFN-gamma and IL-10 mRNA expression in activated ovine peripheral blood mononuclear cells (PBMC) and compared the kinetics of mRNA expression with amounts of cytokine secreted by the cells over a 96h period. PBMC were collected from sheep immunised with the nominal antigen ovalbumin (Ova) and re-stimulated in vitro with antigen and the T cell mitogen concanavalin A (ConA). The recall response to antigen was characterised by a single peak in IFN-gamma mRNA expression at 48h of culture (13-fold increase over unstimulated cells) and relatively lower expression of IL-10 mRNA (average 2-3-fold increase over the 96h culture period). Antigen-driven IFN-gamma protein concentration was greatest at the end of the culture period (96h) whereas IL-10 protein level was not elevated above that observed in unstimulated cells. The typical response to ConA was greater for both cytokines, with IFN-gamma mRNA expression peaking at 6h of culture (133-fold increase) then declining rapidly whereas IL-10 mRNA expression peaked at 24h (16-fold increase) and declined more gradually. Despite these differences in the relative kinetics of mRNA expression in mitogen-activated PBMC, the typical pattern of protein expression of the two cytokines was similar. Both showed a gradual rise in protein concentration starting from 12h of culture which was still rising at the end of the culture period (96h). These data demonstrate that the kinetics of mRNA expression for IFN-gamma and IL-10 in activated ovine PBMC do not necessarily correlate with detectable protein in culture.

Individual differences in the exploratory response to novelty were found to be related with the vulnerability to develop stress-induced immunological alterations. We studied the effect of exposure to inescapable shock on antibody formation against sheep red blood cells (SRBC) in rats selected according to their locomotor activity in a novel situation. Interestingly, antibody titers were only enhanced in shocked animals with the highest locomotor activity. These results emphasize the importance of taking into account individual differences for the study of the mechanisms involved in stress-induced immunomodulation, suggesting a behavioral procedure (novelty reactions) to deal with individual variability in the effects of stress on the immune system. © 1992 Elsevier Science Publishers B.V. All rights reserved.

Differential expression of ovine CD1 was examined using a combination of reverse transcription-polymerase chain reaction (RT-PCR) with sequence-specific primers and Northern and in situ hybridization techniques. The aim of the study was to establish the patterns of CD1 expression at the molecular level and address questions posed by previous studies in other species regarding expression patterns of CD1. A 'pan-CD1' probe based on the exon 4 (alpha 3) region was used in addition to isotype-specific probes for SCD1B (the exon 3 region of clone SCD1B42) and SCD1D (the exon 3 region of clone SCD1D). Widespread expression of CD1 (including thymus, peripheral blood lymphocytes, lung and intestine) was identified using both the exon 4 and SCD1D probe. SCD1B expression was more restricted, being identified in equivalent levels only in the thymus and in scattered populations of dendritic cells. These results highlight the difference in expression patterns between group 1 and group 2 CD1 family members and establish SCD1D as the CD1 family member with the widest pattern of expression, consistent with a differential role for the different CD1 family members.