Antibody response to diphtheria toxoid in rainbow trout (202 fish belonging to 28 full-sib pairs within 14 half-sib groups) and Atlantic salmon (791 fish belonging to 34 full-sib pairs within 12 half-sib groups) was determined by analyzing blood samples taken on three different occasions. The fish were immunized twice with the antigen during the experiment. Antibody levels were measured by an enzyme-linked immunoadsorbent assay (ELISA). A method of estimating titers from three serum dilutions was worked out to avoid end-point titration of the large number of samples. The rainbow trout responded well to immunization, and genetic variation in antibody titers was observed both before and after the first immunization (h2 = 0.2). The Atlantic salmon had high initial titers to diphtheria toxoid and the response to immunization was weak. This suggests an impact of natural or cross-reacting antibodies. The heritabilities for antibody levels were lower in this species (0.12 and less). There were high genetic and phenotypic correlations between the antibody measurements at the three samplings. Antibody response to diphtheria toxoid correlated negatively with survival after challenge with V. anguillarum. No correlation was observed between antibody level and production traits (mean slaughter weight and survival rate) for full-sib groups reared at different sea locations.

Antibody responses to Aeromonas salmonicida A-layer were analysed in family material of Atlantic salmon (Salmo salar), consisting of 791 fish belonging to 34 full-sib groups within 12 paternal half-sib groups. The fish were immunized twice and blood samples were collected three times. Significant increase in antibody titre from first to second, and from second to third sampling, was observed. Genetic variation in antibody titres was observed at the three samplings with estimated heritabilities ranging from 0.16 to 0.20, and a significant heritability estimate was recorded in the antibody response after the second immunization (h(2) = 0.16). Moderate to high genetic (r = 0.5-0.72) and phenotypic (r = 0.29-0.57) correlations were found between the titre values at different samplings, and between selected titres and titre increases. Production parameters, such as mean slaughter weight and mean survival rate were obtained for fish which were reared commercially in the sea, and which belonged to the same full-sib groups as those analysed for A. salmonicida A-layer antibodies. No significant correlation between the mean antibody titre to A. salmonicida A-layer in this study and mean slaughter weight and survival rate in full-sib family material in the sea was observed.

SUMMARY:Norwegian dairy goats were tested for possible associations between the goat lymphocyte antigen system (GLA) and antibody response to the antigens diphtheria toxoid, human-serum albumin and tetanus toxoid. The serum titres to these antigens following immunization, and their GLA-specificities, were determined in 96 twin pairs. The antibody response and GLA specificity were compared between twins: twins sharing one or more GLA specificities showed a more similar primary-antibody response to diphtheria toxoid than twins with no common specificity. The main point in comparing twins is that the MHC specificity then serves as a marker for the complete haplotype, including MHC class-II genes. However, a gene substitution model that only tests the effect of the observed class-I alleles revealed that animals with GLA specificity Eu2 had a significantly higher anti-diphtheria response than Eu2-negative animals. ZUSAMMENFASSUNG: Untersuchungen über Beziehungen zwischen Ziegen MHC (GLA) und Antikörperreaktion auf Diptherietoxin, humanes Serum Albumin und Tetanustoxin mit Zwillingsmodell Norwegische Milchziegen wurden in Hinblick auf mögliche Assoziationen zwischen Ziegen Lymphozytenantigensystem (GLA) und Antikörperreaktion auf Antigene Diptherie Toxin, humanes Serum Albumin una Tetanustoxin untersucht. Die Serumtiter nach Immunisation und die GLA-Spezifität wurden an 96 Zwillingspaaren erhoben und zwischen Zwillingen verglichen; Zwillinge mit ein oder mehr GLA Spezifitäten zeigten ähnlichere Primärantikörperreaktion auf Diptherie Toxin als solche ohne gemeinsame Spezifität. Der wesentliche Vorteil der Zwillinge ist, daß MHC-Spezifität als Marker für den gesamten Haplotyp dienen kann, einschließlich MHC Klasse-II gene. Allerdings, ein Gen-Substitutionsmodell, das nur die Wirkungen der beobachteten Klasse-I Allele prüft, zeigte, daß Tiere mit GLA-Spezifität EU2 signifikant höhere Antidiptheriespiegel als EU2 negative Tiere hatten.

Total IgM level and antibody titre to Vibrio anguillarum O-antigen after bath-vaccination, and specific antibody response to V. salmonicida O-antigen at three different samplings were analysed in family material of Atlantic salmon (Salmo salar), consisting of 791 fish belonging to 34 maternal full-sib groups within 12 paternal half-sib groups. The fish were immunized twice, and blood samples collected three times. After the third blood sampling, the fish were challenged with V. anguillarum. Medium to low genetic variation was recorded in total IgM and in the antibody titres against V. anguillarum O-antigen and V. salmonicida O-antigen, with heritability estimates of 0.12, 0.18 and from 0.03 to 0.12, respectively. Moderate to high genetic and phenotypic correlations were found between the V. salmonicida O-antigen titres at different samplings. Genetic and phenotypic correlations between the initial titres were moderate to low. The effect of different immune traits, including Aeromonas salmonicida A-layer titres (previously described), on the ability to survive the challenge was examined. The likelihood of surviving the challenge was affected positively by the A. salmonicida A-layer titre at the second sampling, and almost significantly affected by the initial V. anguillarum O-antigen titre. Production traits, such as mean slaughter weight and mean proportion of survivors in a corresponding full-sib material, were obtained in the sea-rearing period. No significant full-sib correlation between immune parameters and production traits was detected.

The serum antibody titers to diphtheria toxoid and human serum albumin were determined in 103 goat kids from lines selected for 12 yr for high or low antibody response to diphtheria toxoid. In the 12th yr, six groups of kids were immunized with different preparations of the antigens. In all groups but one, the antigens were emulsified in Freund's incomplete adjuvant with added sonicated Mycobacterium paratuberculosis. The groups received the following treatments: Group 1 was immunized with both antigens mixed in the same syringe, Group 2 got both antigens injected separately, Group 3 got both antigens injected separately, but with a lower concentration of M. paratuberculosis, Group 4 was immunized with diphtheria toxoid only, Group 5 was immunized with human serum albumin only, and Group 6 was immunized with both antigens mixed, but without any M. paratuberculosis. The animals were immunized at 4 wk of age, and the antibody titers were determined 3 wk later by ELISA and passive hemagglutination. The mean antibody titers to both antigens were different between the selected lines (P < .03). There was no effect of separate vs combined injections of antigens. However, there were indications of antigen suppression or competition between the antigens. Animals receiving only one antigen seemed to mount a higher antibody response to that antigen than did animals immunized with two antigens.

A herd of Norwegian dairy goats was subject to selection for high and low antibody response to diphtheria toxoid for 12 yr, or approximately 5.5 generations because sires were used for one mating season, whereas dams were used several years. The herd comprised approximately 100 milking goats. Only sires were tested and selected, five to seven sires were used in each line each year, and the percentage of male kids used for breeding varied between 15 and 50%. The mean phenotypic values of the lines diverged until the 4th yr, but the lines did not diverge any further. The means of both lines decreased during the experimental period. The restricted maximum likelihood (REML) estimate of the heritability of the trait in the base population was .19, whereas the realized heritability approached zero in the last six cycles of selection. Using the REML-estimate of heritability in an individual animal model, the mean breeding values (BLUP) of the lines were significantly different. The difference in mean BLUP values between the lines increased throughout the study. Yet, this increase was only 40% from the 2nd to the 12th yr. No effect of a major gene was observed in a test based on individual BLUP.

Linkage studies on seven erythrocyte antigen loci, the major histocompatibility complex (MHC) and the haemoglobin beta gene cluster (HBB) were performed in 48 Norwegian goat families. Close linkage was excluded between the erythrocyte antigen B-system and the MHC, between the erythrocyte antigen N7 locus and HBB, and between the MHC and the HBB.