The aim of the study was to evaluate quick and easy semiquantitative tests for the detection of serum immunoglobulins that are commonly used for to trace the foals with the failure of passive immunity transfer. We compared the four most employed methods -zinc sulphate turbidity tests using photometric or visual reading, glutaraldehyde test and refractometric determination of total protein concentration in serum. Radial immunodiffusion test was used as a reference method. Thirty-eight blood serum samples from foals were used for quantitative estimation of immunoglobulins. The tested methods were correlated with reference method and their availability for tracing of cases of unsuccessful passive transfer immunogobulins was evaluated.The results obtained so far have not allowed us to recommend without reservation any of the compared methods as a reliable test for the determination of blood serum Ig concentrations in newborn foals. On the other hand, the practical usefulness of two of the tested methods (visual reading of turbidity, refractometry) for rapid field identification of hypogammaglobulinaemic foals was confirmed. Of the two, we prefer the refractometric method (sensitivity: 94.11; specificity: 83.30 and predictive value: 88) for common use because it is quicker and easier than other methods. This study pointed out the critical points of the mentioned problem, which have to be studied further.

The objectives of the present study was to describe different dynamics of humoral immune responses to experimental infection in piglets of different stages of infection and immunity. Two groups of piglets originating from non-immune (group 1) and immune (group 2) sows at the age of 3 weeks were subdivided as follows: a half of each group of piglets was exposed to a low-dose infection with Actinobacillus pleuropneumoniae (APP) strain 9. At the age of 8 weeks, all four groups of piglets were challenged with a high infection dose of APP of the same strain. Isotype characterization of the specific antibodies in sera and in bronchoalveolar lavage fluids (BALF) to a lipopolysaccharide was carried out, besides monitoring clinical signs and post-mortem examinations. A typical primary immune response was observed in specific antibody-free piglets infected with a challenge infection. Colostrum-derived immunoglobulin-G (IgG) antibodies persisted in sera and BALF of piglets up to the age of 8 weeks. However, they did not prevent induction of specific-primary antibody response, either in 8 or 4 weeks of age, when levels of specific colostrum-derived antibodies were still high. It was demonstrated by the increase of specific IgM antibodies in sera. The infection induced an increase in the levels of IgA antibodies in BALF regardless the severity of infection and presence of specific colostrum-derived antibodies. The specific antibodies of IgG isotype increased only in BALF from piglets without colostrum-derived antibodies.

Genetic determination of tuberculin hypersensitivity 545 I wish to acknowledge the excellent technical assistance from Ms.E. Johnston and expert secretarial assistance from Ms. D. Sutherland.A dominant inheritance of the ability of CB line chickens t o react t o tuberculin over the inability of the WB line t o develop this type of immune reaction was observed. The tuberculin reactivity in this line seems to be determined by one locus and is associated with the B locus.The involvement of the B locus in the regulation of tuberculin reactivity in other inbred lines of chickens is supported by the reactivity of the CA.IB (N6F2) birds in which the B allele of the IB line was introduced into the CA genotype. The CA.IB (N6F2) chickens manifest strong tuberculin sensitivity, corresponding t o the type of reaction of the IB line, not t o the weaker type of response of the CA line. The intensity of the tuberculin reaction of the CA and CC lines resembles that of the CB line, but the proportion of nonreactive birds is higher in these t w o lines than in CB chickens.

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