[Distribution of immunoglobulin isotypes and Salmonella antibodies in blood serum and meat juice of pigs]. / Die Verteilung von Immunglobulinisotypen und von Salmonellaantikörpern in Blutserum und Fleischsaft von Schweinen.

Using the close linear regression between the logarithm of the dilution degree of a sample and the logarithm of the extinction measured in an ELISA both the relative concentrations of immunoglobulines of the isotypes IgG, IgM and IgA and of the LPS antibodies against S. Typhimurium of the different isotypes in blood sera and meat juice of 15 slaughtered pigs were detected and compared. Furthermore the total concentration of antibodies against LPS of S. Typhimurium according to the "meat juice ELISA" were compared. Distribution of immunoglobulines between serum and meat juice revealed individual differences between the animals as well as between the different immunoglobulin-isotypes. Within the same isotype the ratio of the concentrations of anti-LPS Salmonella Typhimurium antibodies between serum and meat juice was significantly closer than relating the whole of immunoglobulines of the referred isotype. In order to detect pig herds with a high level of Salmonella exposure a comparison of the 1:30 diluted meat juice samples with the 1:400 diluted blood sera is justified, however, for detailed epidemiological or scientific studies there is a need to consider the existing differences between the immunoglobuline-isotypes as well as between the specificity of antibodies and of total immunoglobulines. While the concentration of Salmonella antibodies of the isotypes IgG1, IgG2 and IgA showed a clear and statistically significant correlation between both one below the other and with the total amount of Salmonella antibodies, this connection could not be established for the total amount of immunoglobulines of different isotypes and the IgM-antibodies.

[Intracellular survival of Salmonella strains in Caco-2 cells]. / Intrazelluläres Uberleben von Salmonellen in Caco-2-Zellen.

In the in vitro model using Caco-2 cells at different stages of differentiation the invasion and intracellular survival of virulent (predominant infection strains) and less virulent (predominant attenuated mutant strains) Salmonella strains were studied. The statistical evaluation of experimental data has shown that the logarithmized colony forming unit after 18 hours of incubation in differentiated cells (14 days old) is a suitable parameter for the determination of intracellular survival. Using this parameter a relationship between intracellular survival and Salmonella virulence (LD50 mouse) was demonstrated and quantified. The model presented could be suitable for the replacement of animal experiments after further investigations.

[Usefulness of serological examinations in the analysis of Salmonella infections in pig herds]. / Die Brauchbarkeit serologischer Untersuchungen bei der Analyse des Salmonellengeschehens in Schweinebeständen.

The development of the antibody concentration against lipopolysaccharide (LPS) of S. Typhimurium und S. Choleraesuis in rearing pigs during the fattening period and in breeding sows of the corresponding age was recorded. The studies revealed the following results. Antibodies of isotypes IgG1 and IgG2 revealed a more pronounced specificity against the according Salmonella serovar than IgM antibodies. The calculated "antibody percent value" based on the total amount of Salmonella antibodies is mainly determined by the IgM antibodies in sera and meat juice, respectively. In fattening pigs a significant increase of antibodies against IgM and total Ig was observed between week 3 and 10 after beginning of the rearing period. In breeding pigs this increase was detectable already earlier. In only 3 out of 10 groups an increase of IgG1 and IgG2 was also seen. The detected significant increase of total Ig and IgM in the other groups might be the result of a less intensive exposure to salmonellas or it might be due to an increase of unspecific antibodies induced by other antigens. Serological investigations represent a valuable tool to record the intensity and development in time of the Salmonella exposure in pigs farms. Examination of total Ig is an appropriate method to detect pig herds with a high level of Salmonella exposure, for detailed epidemiological studies in pig farms the examination of antibody isotypes will give more comprehensive information.

[The humeral immune response of swine after experimental infection with Salmonella typhimurium]. / Untersuchungen zur humoralen Immunantwort des Schweines nach experimenteller Infektion mit Salmonella Typhimurium.

LPS antibody reaction of S. Typhimurium was detected in a total of 111 two- to ten-week-old pigs, which had been exposed to experimental oral infection with this serovar in 16 separate experiments. The total antibody level was determined according to the meat juice ELISA provided for the Salmonella control programme and the antibody concentrations of the isotopes IgG1, IgG2, IgA and IgM. Although there were significant differences between the individual experiments with respect to the reaction intensity and proportion of the individual immune globulin isotypes, the following general statements on the dynamics of the antibody reaction can be made: Clearly elevated antibody levels could be observed one week after the onset of infection. After one and two weeks, respectively, 22.5 and 52.9% of the infected animals showed antibody levels which were to be evaluated as positive in the sense of the Salmonella control programme (> or = 40%). While the concentration of the IgM-related antibodies decreased again during the second week already, the antibody concentration of IgG1 and IgG2 continued to increase until the end of the experiment after 3 weeks. The clear differences in the reactions between the experiments cannot be explained solely by defined conditions of infection such as strain of infection, infective dose or age of the pigs. Obviously, other non-defined or non-recognized factors may have a decisive influence on the dynamics of the antibody reaction in the animal groups.