The sensitivity of an indirect enzyme-linked immunosorbent assay (ELISA) for bovine IgG serum antibody to Pasteurella haemolytica was compared with that of an indirect hemagglutination (IHA) test. Pasteurella haemolytica serotypes were grown in a chemically defined cell culture medium, and soluble antigens released into the growth medium were used in the ELISA and IHA test. An ELISA with serotype-1 antigen consistently detected antibody in sera that were positive by IHA test (correlation, 99%). Sera reacting with serotype-1 ELISA antigens also reacted with ELISA antigens prepared from other serotypes. Although ELISA titers determined by the 2 methods were approximately linear. Titer increases detected in paired serum samples by either test were similar. The ELISA was more sensitive than was the IHA in detecting colostral IgG antibody in serum of newborn calves. The ELISA uses a simple, stable antigen preparation and detects antibody to P haemolytica serotypes that commonly infect cattle.

An ELISA was used to detect IgG, IgM, and complement (C3) on the surface of canine erythrocytes. Erythrocytes were placed in wells of a microtitration plate and incubated with affinity purified, alkaline phosphatase-conjugated anti-canine IgG, IgM, or C3. Results of the ELISA were compared with the direct antiglobulin test (DAT) by preparing standard reference curves from canine blood type A erythrocytes that had been incubated with serial dilutions (1:2 to 1:8,192) of canine anti-A serum. The ELISA detected increased erythrocyte-bound immunoglobulin and complement at two- to fourfold dilutions greater than thoe required for positive results with the DAT. The ELISA required small sample and reagent volumes and detected lower concentrations of immune components than did the DAT.

The changes in serum total protein and immunoglobulin levels, and BVD, IBR and PI-3 viral neutralizing antibody titers in colostrum-conferred Korean native calves during the first 12 weeks postpartum were studied. The mean concentration of total protein, total immunoglobulin, IgG, IgM and IgA in sera of 9 calves at birth were 3.8 +- 0.5g/dl, 0.27 +- 0.15mg/ml, 0.06 +- 0.08mg/ml, 0.21 +- 0.11mg/ml, and extremely low concentration, respectively. Serum total protein level reached a maximum at 20 hours after birth, total immunoglobulin, IgG and IgM levels at 24 hours, and IgA level at 28 hours, respectively. Serum IgA level reached a minimum at 4 weeks old, IgM level at 5 weeks, total immunoglobulin level at 8 weeks, and IgG level at 10 weeks, respectively. After then those levels had begun to increase, but total protein level was still decreasing at 12 weeks old. The half-lives of IgG, IgM, and IgA were 21.1 days, 4.0 days, and 2.6 days respectively. In 10 Korean native cows immediately after parturition, serum neutralizing antibody titers specific to BVD, IBR and PI-3 virus were 8.7 +- 1.5 log2, 5.7 +-1.2 log2, and 6.8 +- 1.0 log2, respectively. And colostral neutralizing antibody titers against BVD, IBR, and PI-3 virus were 10.1 +- 1.4 log2, 6.8 +- 1.3 log2, and 7.8 +- 1.7 log2, respectively. Before suckling the colostrum, SN antibody titers against BVD, IBR, and PI-3 virus were undetectable from all of 9 Korean native calves. Nevertheless SN antibody titer against BVD virus reached a maximum level (9.2 +- 0.6 log2) at 24 hours after birth, that against IBR virus (6.1 +- 1.0 log2) at 20 hours after birth, and that against PI-3 virus (6.8 +- 0.9 log2) at 32 hours after birth, respectively. In 12 weeks old calves, the SN antibodies against BVD and IBR virus were still decreasing, but that against PI-3 virus reached a minimum at 10 weeks, and increased after 12 weeks of age. The half-lives of SN antibodies against BVD, PI-3 and IBR, virus were 16.0 days, 22.6 days, and 25.5 days, respectively.

Immunodeficiency in neonatal and young pigs was studied in terms of T-cell function. Generalized T-cell deficiency did not exist in young pigs on the basis of the in vitro response of blood mononuclear cells to a polyclonal T-cell mitogen, phytohemmagglutinin. However, immunodeficiency that extended from birth up to 4 weeks, was observed in serum antibody concentration and in vitro proliferative responses of blood mononuclear cells from young pigs exposed to a low antigen dose of a T-cell dependent antigen, egg white lysozyme. The low in vitro proliferative response to lysozyme was not attributable simply to a lack of interleukin-2 production, because supplementation with human interleukin-2 did not enhance the in vitro cellular response. Also, pokeweed mitogen-stimulated B cells from young pigs up to the age of 5 to 6 weeks produced immunoglobulin concentration, which also was not affected by the addition of human interleukin-2 to the in vitro cultures. The blood mononuclear cells obtained from pigs within the first 5 to 6 weeks after birth and incubated with monoclonal antibodies reactive to all T cells (MSA4), helper T cells (74-12-4) or suppressor/cytotoxic T cells (76-2-11) did not yield consistent excess of suppressor/cytotoxic T cells. This observed immunodeficiency cannot be attributed to a simple lack of functional T cells or to an excessive number of suppressor/cytotoxic T cells, but may be a property of the ability of specific T-cell clones to respond t o low concentration of T cell-dependent antigens or may be attributable to the induction of a suppressor T-cell population in response to in vitro stimulation with the polyclonal T-cell-dependent pokeweed mitogen system.

The uptake of colostral IgG and IgM, their serum half-lives, and the rates of endogenous synthesis of IgG and IgM were evaluated in 6 newborn foals fed bovine colostrum (principals) and 6 foals allowed to suckle their dams (controls). The principal foals were fed 400 ml of bovine colostrum (IgG, 10,000 mg/dl and IgM, 200 mg/dl) at 2-hour intervals, from 2 to 20 hours after foaling (total dose, 4 L). Serum IgG and IgM concentrations were determined by single radial immunodiffusion from birth to 98 days of age. At foaling, principal foals had no detectable serum equine IgG, but 1 control foal had serum equine IgG of 185 mg/dl. AFter ingestion of colostrum, there was no significant difference in the maximal serum bovine IgG concentration (range, 1,350 to 3,300 mg/dl) in the principal foals, and maximal serum equine IgG concentration (range, 500 to 6,000 mg/dl). The calculated biological bovine and equine IgG half-life in the principal and control groups was 9.4 and 26 days, respectively. Endogenous IgG synthesis was first detected in 1 principal foal at 3 days of age, but was detected first between 28 and 42 days in the other principal foals. Starting on day 56 there was no significant difference in serum equine IgG concentration between groups. At foaling, foals in both groups had low equine IgM concentrations. In the control foals, there was marked individual variation in the increases in equine IgM concentration (range, 5 to 73 mg/dl) after ingestion of colostrum. With the exception of day 49 after foaling, there was no statistical difference between groups for serum IgM concentration after day 3, and both groups had parallel rates of IgM synthesis. Bovine IgM was undetectable at foaling and maximal serum concentration ranged from 200 to 350 mg/dl following ingestion of colostrum. The calculated bovine and equine IgM half-lives were 8 and 5 days, respectively. The coefficients of absorption of bovine IgG and IgM were 30.9 and 84, respectively, in the principal foals. In the control foals, the coefficient of absorption of equine IgG and IgM was 35 and 30, respectively. One principal foal was excluded from the study because it died of aspiration pneumonia at 2 days of age.

Serum immunoglobulins of the IgG isotype recognizing common gram-negative cell core epitopes were serially measured by use of a direct ELISA on blood obtained from 10 neonatal swine. An R-mutant Escherichia coli (strain J5) was used as a plate antigen. Total serum IgG was measured by use of radial immunodiffusion. Half-lives of core antigen-specific IgG (6.81 days) and total serum IgG (14.85 days) were dramatically different (P less than 0.01).

Affinity-purified bovine immunoglobulin isotypes were bacteriolytic for Pasteurella haemolytica biotype A, serotype 1 (PHA-1). This bacteriolysis was specific and complement-dependent. The IgM and IgG1 were the most active isotypes in the classic complement cascade. These isotypes also induced bacteriolysis through the alternative complement cascade. The comparative bacteriolytic activities of IgG1 and IgM were equal within each cascade; however, the bacteriolytic activities of IgG1 and IgM were equal within each cascade; however, the bacteriolytic activities of IgG1 and IgM were lower in the alternative cascade than in the classical cascade. The IgG2 was more bacteriolytic than IgA in the classic and alternative complement pathways. Bovine immunoglobulins passively protected C57BL/6 mice from experimentally induced pasteurellosis. There were no major differences in the protection among hyperimmune sera, purified IgM, or purified IgG. Mice were protected from PHA-1 by approximately 1.9 microgram of IgG and 1.2 or 0.1 microgram of IgM. Elimination of murine complement with cobra venom factor 3 reduced PHA-1 clearance in passively immunized C57BL/6 mice. The protective effect of IgM mediated resistance was highly dependent on an intact complement system. The intact complement cascade was associated with enhanced clearance of PHA-1 from the liver. Although PHA-1 was susceptible to antibody complement-mediated bacteriolysis in vitro, the dependence on an intact complement cascade was not absolute in experimentally induced murine septicemic pasteurellosis.

Eight bovine hearts with lesions of eosinophilic myositis (EM) and 2 bovine hearts without EM lesions were collected at slaughter. Blood samples from these 10 hearts, and the heart of a newborn calf also were collected. Histologically, Sarcocystis cruzi was identified in the 8 hearts with EM lesions and the 2 hearts without EM lesions, but not in the heart of the newborn calf. Serum was harvested from the 10 blood samples and was used in homologous, modified, passive cutaneous anaphylaxis test. Antigen was prepared from S cruzi bradyzoites isolated from the 2 hearts without EM lesions. Serum samples from the 8 cattle with EM lesions reacted positively to S cruzi antigen. When heat-inactivated IgE in serum (56 C for 4 hours) was used, all passive cutaneous anaphylaxis responses were considered negative. Using ELISA, serum IgE concentrations from the 10 cattle with and without EM lesions were 2.2 to 9 U/ml. As determined by radial immunodiffusion, IgM concentrations were 80 to 215 mg/dl. Immunoglobulin G concentrations were 420 to 2,050 mg/dl, but most were less than or equal to 1,700 mg/dl. Immunoglobin A concentrations were 0 to 62 mg/dl; 1 steer with EM lesions had 0 mg/dl. Double-gel immunodiffusion confirmed the presence of Sarcocystis-specific precipitating antibodies. Sera from the 10 cattle with and without EM lesions formed at least 1 precipitin band.

Serum immunoglobulins of the IgG isotype recognizing common gram-negative cell core epitopes were serially measured, using a direct ELISA, on samples obtained from 20 neonatal Holstein calves. An R-mutant Escherichia coli (strain J5) was used as a plate antigen in this assay. Total serum IgG concentration was measured using radial immunodiffusion. Half-lives of core antigen-specific IgG (7.56 days) and total serum IgG (22.66 days) were dramatically different (P less than 0.0005). This may be an indication of cross-reactive consumption of core antigen-specific immunoglobulins.