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Erysipelas, caused by infection withErysipelothrix rhusiopathiae(ER) is an important emerging disease in laying hens. We have earlier observed prominent mannose-binding lectin (MBL) acute phase responses in experimentally ER infected chickens. The present study aimed to further examine immune responses to ER by using chickens selectively bred for high (L10H) and low (L10L) serum MBL levels. Chickens were infected with ER at 3 weeks of age and immune parameters and bacterial load were monitored in blood until day 18 after infection. Blood and spleen leukocytes collected on day 18 were stimulated in vitro with ER antigens and blast transformation of different T-cell populations was assessed. The ER infection gave a very varied outcome and no clear differences were observed between L10H and L10L chickens with respect to leukocyte counts, bacterial load or clinical outcome. Nonetheless, rapid innate responses, e.g., heterophilia and increased serum MBL levels were noted in bacteraemic chickens. All ER infected chickens also showed transient increased expression of mannose receptor MRC1L-B and decreased expression of major histocompatibility complex II on monocytes day 1 after infection indicating monocyte activation or relocation. In vitro ER stimulation showed antigen specific blast transformation of CD4+, TCRγ/δ−CD8αβ+ and TCRγ/δ+CD8αβ+ spleen cells from all infected chickens. For CD4+ and TCRγ/δ−CD8αβ+ cells the proportions of blast transformed cells were significantly higher for samples from L10L chickens than those for samples from L10H chickens. This is the first observation of ER-specific T-cells in chickens and interestingly a Th1-type response comprising cytotoxic T-cells was indicated.

To investigate whether the procedure used to snare and restrain pigs during collection of blood samples would alter in vitro functional capacity of leukocytes in the samples.8 gilts.Catheters were surgically inserted into the jugular vein of gilts to enable blood sample collection without restraint. After collection of a control sample, gilts were restrained by use of a snare and samples were collected at 0.5, 3.5, and 6.5 minutes after start of restraint (0 minutes). At each time point, plasma beta-endorphin and cortisol concentrations as well as WBC counts were recorded, and functional capacity of leukocytes in cultures of whole blood was assessed by means of mitogen-induced proliferation and interleukin-2 activity, virus-induced interferon-alpha concentration, and phagocytosis of zymosan particles.Concentrations of plasma beta-endorphin and cortisol were increased at 3.5 and 6.5 minutes after start of restraint. At these times, virus-induced interferon-alpha concentration was decreased, whereas proliferative response to Concanavalin A and phytohemagglutinin increased in samples collected at 6.5 minutes.It was possible to snare pigs for the purpose of collecting blood samples and restrain them without causing excessive stress that would affect immunologic variables, provided that the collection procedure was completed within a few minutes.

Immune capacity traits show considerable genetic variation in outbred populations. To identify quantitative trait loci (QTLs) for immune capacity in the pig, various measures of immune function (total and differential leukocyte counts, neutrophil phagocytosis, mitogen-induced proliferation, IL-2 production, and virus induced IFN-α production in whole blood cultures, and Ab responses to two Escherichia coli antigens) were determined in 200 F2 animals from a wild pig–Swedish Yorkshire intercross. The pedigree has been typed for 236 genetic markers covering all autosomes, the X chromosome and the X/Y pseudoautosomal region. Through interval mapping using a least-squares method, four QTLs with significant effects were identified; one for total leukocyte counts, one for mitogen-induced proliferation, one for prevaccination levels of Abs to E. coli Ag K88, and one for Ab response to the O149 Ag. In addition, several putative QTLs were indicated. The results from the present study conclusively show that it is possible to identify QTLs for immune capacity traits in outbred pig populations by genome analysis.

The ability to produce interferon-alpha (IFN-alpha) in vitro was measured in blood from 200 F2-crosses between European wild boar and Swedish Yorkshire pigs, originating from a reference pedigree for gene mapping. A total of 200 pigs of 44 litters, descendent from 4 boars and 22 sows, were stressed by transportation together with non-littermates for 5 h. Blood samples were collected from each individual twice, i.e. immediately before transportation and the day after transportation. IFN-alpha production was induced in whole blood cultures by a monolayer of fixed, Aujeszky's disease virus infected, porcine kidney cells. In general, the amount of IFN-alpha produced was significantly lower (p = 0.02) the day after transportation, although the ability to produce IFN-alpha showed a large individual variation (p0.001). However, both the levels of IFN-alpha produced and the decrease after transportation varied between the four parental offspring groups. Also, indications of single genes with significant effects on the ability to produce IFN-alpha were found. These results confirm a genetic influence on the ability to produce IFN-alpha. In addition, stress, such as transportation and mixing, may decrease the level of IFN-alpha produced.