Immune response of cattle to Brucella abortus outer membrane proteins measured by lymphocyte blastogenesis

Lymphocytes from cattle were tested in a blastogenesis test with outer membrane proteins isolated from smooth strain 2308 and rough strain 45/20 of Brucella abortus. The titration assay developed for measuring blastogenesis to microbial antigens (Baldwin, Antczak and Winter, this issue, pp. 319-333) was used to assess the response to both group 2 (porins) (Douglas et al., 1984) and group 3 proteins (Verstreate et al., 1982). Blastogenesis was evaluated for distinguishing cattle infected with virulent B. abortus strain 2308 from unimmunized cattle, cattle vaccinated with attenuated strain 19, or inoculated with Escherichia coli 0116:H31, known to cause serological cross-reactions with B. abortus (Nielsen et al., 1980). Strain 45/20 porin was the most effective for this purpose and data analyses utilizing the titration assay were better than those relying on a single point assay. When compared with BASA, an antigen preparation used in other studies (Kaneene et al., 1978a), responses to porin provided a more specific index of infection with B. abortus. Reactions to 45/20 porin occurred, however, in some heifers vaccinated as adults with strain 19 or inoculated with E. coli 0116:H31. Furthermore, nonpregnant heifers had negligible or only transient blastogenesis responses to the porin during the first 14 weeks after infection even though they developed strong 0 antibody responses. We do not recommend the blastogenesis test in its present form as a useful adjunct to serological tests, and could allow measurement of cell mediated immune responses relevant to protective immunity.

Comparison of enzyme-linked immunosorbent assay and complement fixation test for the detection of specific antibody in cattle vaccinated and challenged with Brucella abortus

An enzyme-linked immunosorbent assay (ELISA) and a complement fixation test (CFT) were applied to sera collected regularly from 60 cattle challenged with Brucella abortus strain 544. Of the 60 cattle, 48 were vaccinated with either B. abortus strain 19 or B. abortus strain 45/20 as calves or adults. The remaining 12 cattle were not vaccinated. Of the 27 sera from cattle found to be infected at slaughter, 9 showed aberrant reactions to the CFT in that a positive titer after challenge was delayed or transient. The performance of the ELISA in these nine cattle with aberrant reactions and the other cattle in the trial was as follows. After vaccination with strain 19 or strain 45/20, the number of weeks at which the ELISA was positive was significantly greater (P less than 0.001) than that for the CFT. The strain 19 vaccine also induced positive responses to the CFT and the ELISA for a significantly longer period (P less than 0.001) than did the strain 45/20 vaccine. For cattle with aberrant reactions, the number of weeks after challenge when the ELISA was positive was significantly greater (P less than 0.001) than that for the CFT. For noninfected cattle, the average number of weeks after challenge when the CFT was negative (35 of 40) was higher than that for the ELISA (18 of 40).

Differentiation of Brucella abortus and Yersinia enterocolitica serotype 09 infections: use of lymphocyte transformation test

Cell-mediated immune responses in cattle infected with Brucella abortus Strain 544, cattle infected with Yersinia enterocolitica serotype 09 and non exposed cattle were studied by an in vitro whole-blood lymphocyte stimulation procedure. A soluble Brucella polypeptide containing some lipopolysaccharide prepared from Brucella abortus strain 99 was used as antigen while Concanavalin A was used as mitogen. Results were assayed for (6-3H) thymidine incorporation into deoxyribonucleic acid. All the cattle from which Brucella abortus was recovered developed very high lymphocyte transformation responses while cattle infected with Yersinia enterocolitica 09 and non exposed cattle did not develop high lymphocyte stimulation reactions. The animals infected with Yersinia enterocolitica 09 were strongly positive to the Rose Bengal, serum agglutination, Complement fixation and Coombs' antibovine globulin tests. One lactating cow infected with Yersinia enterocolitica 09 was positive to the Brucella milk ring test. It was concluded that the lymphocyte stimulation assay could be used to differentiate bovine brucellosis from yersiniosis.

The instability of Brucella abortus strain 45/20 and a note on significance of using an unstable rough strain in the diagnosis of bovine brucellosis

The serum agglutinin titres of six heifers experimentally inoculated with live Br. abortus strain 45/20 were similar to those produced in six bullocks inoculated with virulent Br. abortus strain 544. However, the agglutinin response appeared slowly and disappeared earlier in the heifers than in the bullocks. It is concluded that Br. abortus strain 45/20 is an unstable strain, could revert to the smooth form and become highly agglutinogenic in non-pregnant heifers. The significance of using an unstable rough strain of Br. abortus vaccine in the diagnosis of bovine brucellosis is briefly discussed.

Serological investigation on cattle vaccinated with a killed Brucella abortus strain 45/20 adjuvant vaccine

Serum antibody reactions were monitored for a period of 18 months in 18 heifers which had been vaccinated with Brucella abortus Killed 45/20 adjuvant vaccine, using four standard serological procedures: the Rose Bengal, Serum agglutination, Complement fixation and Coombs antibovine globulin tests. The Rose Bengal and Serum agglutination tests were persistently negative during the experiment. Titres to the complement fixation test rose sharply for only four weeks after the second dose of the vaccine. Thereafter the titres fluctuated to positive levels at unpredictable intervals. One out of 14 heifers tested 12 months after vaccination was strongly positive to the complement fixation test but all the animals were absolutely negative at the end of the experiment. The Coombs test became strongly positive after the second dose of the vaccine for up to 34 weeks after primary vaccination. The animals were negative to the test at the end of the experimental period but some still retained suspicious titres. It was concluded that the Brucella abortus killed 45/20 adjuvant vaccine did not interfer stall with the Rose Bengal and Serum agglutination tests, that the fluctuations of the Complement fixation titres to positive levels at unpredictable intervals were undesirable and that the Coombs test showed little promise as an assay which would be used to differentiate antibody titres due to Brucella abortus Killed 45/20 adjuvant vaccine from those of natural infection. It would appear that the Complement fixation test and the Coombs antibovine globulin test could be safely used 12 and 18 months respectively, after immunization of cattle with the vaccine.

Evaluation of brucellin skin test for bovine brucellosis

The diagnostic efficiency of the Brucellin skin test for bovine brucellosis was evaluated using cattle of known history. The test was negative in six out of 14 heifers (42.9%) infected with virulent Brucella abortus (Br. abortus) strain 544. In four cattle vaccinated with a reduced dose of Br. abortus strain 19 vaccine (5 X 10(9) live organisms) the skin test became positive in all the animals but two weeks after immunization. However, all the vaccinates became negative 14 weeks after vaccination, whereas nine out of 14 heifers (64.3%) vaccinated with killed Br. abortus 45/20 adjuvant vaccine (Duphavac vaccine) were still positive 18 months post immunization. Four control cattle were persistently negative. It was considered that the procedure would be most useful for testing non-exposed cattle and should be used as a screen test. It is not useful as a diagnostic test for cattle immunized with Duphavac vaccine. A recommendation is made for interpreting the Brucellin skin test for the diagnosis of bovine brucellosis in non-exposed herds.

Use of an enzyme-linked immunosorbent assay in a bovine brucellosis eradication program

An enzyme-linked immunosorbent assay (ELISA) was developed and was compared with the complement fixation test (CFT) in a bovine brucellosis eradication program. The ELISA detected significantly more reactors than the CFT in both strain 19 vaccinated infected herds (1.79% versus 1.14%) and non-vaccinated infected herds (4.2% versus 3.59%) but not in either vaccinated or non-vaccinated brucella-free herds. The specificity for both tests in brucella-free herds was greater than 0.998. The specificity and sensitivity of the ELISA were compared with those of 3 other tests (the Rose Bengal test; the indirect haemolysis test [IHLT] and the CFT) on serum from 151 animals cultured at slaughter. The calculated specificity of the ELISA in this infected group was lower than for both the CFT and the IHLT (0.58 versus 0.67 versus 0.75). The sensitivity however was much greater (1.0 versus 0.73 versus 0.71). The value of the ELISA when used in an eradication program is discussed.

A comparative study of ELISA and other methods for the detection of Brucella antibodies in bovine sera

Enzyme-linked immunosorbent assay (ELISA), using beta-galactosidase and a fluorigenic substrate, was used for the detection of antibodies to Brucella abortus in bovine sera. Among 677 animals from 9 brucellosis-free herds, none reacted in the ELISA. Among 785 animals from 23 brucellosis-infected herds, 336 were positive in ELISA, 229 in the slow agglutination test (SAT), 185 in the complement fixation test (CFT), and 165 in the Rose-Bengal test (RBT). Experimental infections were conducted with two B. abortus strains. Al slaughter on day 101, after intraconjunctival infection of heifers with B. abortus strain 19 organisms, 3 animals were positive in the SAT, 3 in the CFT, 4 in the RBT and 11 in the ELISA, and Brucella organisms could be cultivated from 10 animals; among these, 2 scored positive in the SAT, 3 in the CFT, 3 in the RBT and 8 in the ELISA test. Seventeen heifers were infected with organisms of B. abortus strain 2308. On day 101, 11 heifers were found to be carriers, all of which yielded positive results in the CFT, RBT and ELISA tests, but not in the SAT.

Evaluation of the enzyme-linked immunosorbent assay in the detection of cattle infected with Brucella abortus

One group of 51 cattle was vaccinated with B. abortus S19 (S19) and a further 51 cattle were vaccinated with B. abortus S45/20 (S45/20). Forty-eight cattle (24 from each group) and a control group of 12 cattle were subsequently challenged with B. abortus S544. The enzyme-linked immunosorbent assay (ELISA) was used to detect specific IgG and IgM antibodies in these groups. All cattle vaccinated with S19 had high levels of IgG and IgM, but the S45/20 vaccine produced detectable antibody in only a few cattle. In those cattle where the challenge induced infection, the mean levels of IgG and IgM were much higher than those of the uninfected cattle in the same groups. When the isolation of B. abortus was compared at slaughter with the serological results, the ELISA, when used to detect specific IgG, was more sensitive but less specific than the serum agglutination test, complement fixation test and indirect haemolysis test, and more sensitive and more specific than the Rose Bengal test.

A brucellosis serological survey on beef cattle slaughtered at Cato Ridge Abattoir

A total of 5059 sera were collected from adult female beef cattle at Cato Ridge Abattoir and tested for Brucella abortus antibody levels over the period November, 1981 to August, 1982. The sera were screened using the Rose Bengal Plate Test, and the Complement Fixation Test was used as the definitive test. Seventy-seven sera (1,5%) had titres of 30 IU complement fixing B. abortus antibody per ml serum or greater.

Characterization of salt-extractable protein antigens from Brucella abortus by crossed immunoelectrophoresis and isoelectricfocusing

Salt-extractable protein antigens (CSP) from Brucella abortus strains 19 and 2308 (vaccine and virulent strains, respectively) were analysed by crossed immunoelectrophoresis (CIE) using rabbit antisera to protein antigens and by isoelectricfocusing (IEF) in polyacrylamide gels. The reference immunoelectrophoretic profiles developed for proteins from strain 19 and 2308 of B. abortus contained 20 and 25 immunoprecipitates, respectively. Serum from cows experimentally infected or hyperimmunized with live organisms produced up to 5 immunoprecipitates in CIE with the protein antigens. Absorption of rabbit sera with homologous B. abortus cells reduced, but did not eliminate all of the immunoprecipitates from rabbit sera, suggesting that the majority, but not all of the protein components, are exposed on the surface of the cell. In contrast, antibody to protein antigens in agglutinin-free absorbed serum from infected cattle could still be demonstrated by CIE, even though CIE with protein extracts from whole cells radioiodinated with the cell surface labeling reagent, diazoiodusulfanilic acid, indicated that these antigens may be at or near the surface of the cell. From CIE in heterologous systems we concluded that all proteins present in strain 19 preparations were partially or completely identical to those in strain 2308. The IEF studies paralleled the CIE studies and revealed that the protein profile from strain 2308 was more complex than the profile from strain 19. Major differences between the 2 strains were found in the pH region from 3.9 to 5.0, where strain 2308 exhibited 4 additional protein bands.

Immunoglobulin G1 Fc in colostral whey

Two IgG1 fragments were isolated from bovine colostral whey. Based on gel diffusion analysis, both fragments originated from the Fc portion of the molecule but were not identical to IgG1 Fc prepared by papain cleavage. The molecular weights were determined to be 66,000 and 14,000 daltons and it was hypothesized that the larger fragment could be a polymer of the smaller. No IgG1 Fab or IgG2 fragments could be demonstrated.

Epidemiology of bovine brucellosis in the Mexicali Valley, Mexico: literature review of disease-associated factors

The world literature was searched to document the variables known to affect the initiation, spread, maintenance, and/or control of bovine brucellosis. Each variable was classified into 1 of 3 categories, depending upon whether it was related to the animal population, to management, or to the biology of the disease. These variables were documented and categorized as the initial step for a quantitative path analysis on the epidemiology of bovine brucellosis in a defined geographic area in northern Mexico.

Analysis and in vivo assay of B. abortus agglutinating and non-agglutinating antibodies

Studies were made of physicochemical and immunochemical characteristics of Brucella abortus agglutinating and non-agglutinating antibodies in the sera of cattle repeatedly injected with living B. abortus (Strain 1119). Both agglutinating and non-agglutinating antibody were shown to be IgG1, and by immunodiffusion against rabbit anti-cattle gamma-globulin, agglutinating antibody gave a precipitation line of identity with that given by non-agglutinating antibody. Whilst agglutinating antibody increased clearance of antigen from the blood of passively protected mice, non-agglutinating antibody did not enhance clearance. Determination of the spleen infection index in mice pre-treated with agglutinating and non-agglutinating antibody showed that in animals passively immunized with non-agglutinating antibody the number of living (infecting) bacteria was approximately 4 times higher than in the case of agglutinating antibody. The possible potentiation of chronic B. abortus infection by non-agglutinating antibody is discussed.

Hemolysis in gel test for detection of bovine antibodies to Brucella abortus: comparison of antigens and test modifications

Killed Brucella abortus strain 1119-3 cells were treated with hot phenol/water or dimethyl sulfoxide to extract soluble crude lipopolysaccharide antigen. Antigen preparations were characterized with respect to protein and lipopolysaccharide content and were compared for efficacy in the hemolysis-in-gel test (HIGT) for detecting anti-Brucella antibodies. All antigens were equally effective in sensitizing bovine RBC in the HIGT and in detecting the presence of anti-Brucella antibodies. A slide modification of the HIGT was developed and compared with the plate HIGT. Seemingly, both tests were comparable.

Cellular and humoral responses of Brucella abortus-infected bovine fetuses

Fifty-nine bovine fetuses naturally and experimentally infected with Brucella abortus were studied. Lymphoid hyperplasia in multiple lymph nodes, lymphoid depletion in the thymic cortex, adrenal cortical hyperplasia, and disseminated inflammatory foci composed mainly of large mononuclear leukocytes were present in infected fetuses. Histopathologic changes in naturally infected fetuses were indistinguishable from those infected fetuses inoculated in utero. Fetuses inoculated with 1.0 X 10(3) to 1.0 X 10(5) colony-forming units of strain 2308 B abortus were aborted on postinoculation day (PID) 7 to 19. Fetuses obtained by PID 9 and 10 had increased immunoglobulin concentrations and antibody. Increased cortisol values were present in fetuses obtained as early as PID 6. The initial fetal inflammatory response was composed of large mononuclear leukocytes. In fetuses obtained by PID 9 to 10, moderate numbers of neutrophils mixed with mononuclear leukocytes were present in the inflammatory foci. This shift in the initial inflammatory reaction coincided with the appearance of agglutinating antibody.

Immune response to porin in cattle immunized with whole cell, outer membrane, and outer membrane protein antigens of Brucella abortus combined with trehalose dimycolate and muramyl dipeptide adjuvants

The immune response of cattle to nonliving vaccines derived from Brucella abortus rough strain 45/20 was studied. Vaccines contained trehalose dimycolate and a derivative of muramyl dipeptide. N-acetylmuramyl-L-alpha-aminobutyryl-D-isoglutamine. A factorial experiment was designed to test the effects of type of antigen, quantity of antigen, and quantity of mineral oil on the immune response to porin. Muramyl dipeptide was kept constant at 5 mg per dose, and 1 part of trehalose dimycolate was incorporated for two parts of dry matter. Over a 10-week period, blastogenesis responses to porin were largest in cattle immunized with outer membranes; the highest antibody titers to the porin-lipopolysaccharide complex were achieved by immunization with detergent-extracted outer membrane proteins. There was no advantage in the use of 25, rather than 5, mg of any of the antigens, but antibody responses were improved by increasing the quantity of oil from 0.6 to 1.8 ml per dose. In other animals, blastogenesis and antibody responses were sustained at high levels longer than 3 months after two vaccinations with outer membrane proteins. Intradermal injection of porin evoked inflammatory reactions histologically consistent with delayed-type hypersensitivity. Cross-reactions in cases of delayed-type hypersensitivity occurred with porin derived from a smooth strain of B. abortus but were less extensive than in the blastogenesis test. The magnitude of the delayed-type hypersensitivity and blastogenesis responses induced by vaccination exceeded those observed after natural or experimental infections. No ill effects were observed after vaccination. These findings provide a basis for the use of trehalose dimycolate and muramyl dipeptide adjuvants in evaluating nonviable vaccines for bovine brucellosis.

Failure of Brucella abortus lipopolysaccharide (LPS) to activate the alternative pathway of complement

Bovine erythrocytes (E) coated with either crude or purified preparations of Brucella abortus LPS were not lysed by human complement (C) in the presence of the chelating agent ethyleneglycol-bis-N, N'-tetraacetic acid (EGTA). On the other hand, bovine red cells coated with Salmonella typhimurium LPS were lysed by human C in EGTA. B. abortus LPS preparations did not cause fluid phase human C consumption in the presence of calcium and magnesium ions. However, as expected, S. typhimurium LPS consumed C from human serum in a dose-dependent fashion. The results of these experiments indicate that B. abortus LPS differs from the Enterobacterial LPSs in that it cannot activate the alternative pathway of C in human serum. Furthermore, the failure of B. abortus LPS to consume C in the fluid phase in the presence of calcium and magnesium ions suggests that the LPS cannot cause antibody-independent activation of the classical pathway.

The anamnestic response to Brucella abortus-infected and vaccinated cattle

Fifty-four cattle were sensitised to Brucella antigens either by vaccination with Brucella abortus strain 19 (S19) or B. abortus 45/20 (S45/20) and 24 of these were challenged 12 weeks after mating with virulent B. abortus strain 544 (S544). A further 12 cattle which were not vaccinated were exposed to S544. After 40 weeks, all these cattle (66), together with 5 cattle which were not sensitised by vaccination or challenge were subsequently inoculated with one dose of S45/20 and the anamnestic response was measured by the complement fixation test. Ten to 15 weeks later the cattle were slaughtered and tissues cultured. Of the 52 (2 died) vaccinated cattle, 35 gave a positive anamnestic response and 20 of these were not challenged. Of the 17 unvaccinated cattle, one gave a positive response and this animal had been exposed to S544 prior to the inoculation with S45/20. The results indicated that the method had a level of sensitivity of 75% and specificity of 100% in serologically negative cattle that had been exposed previously to Brucella antigens. An evaluation of the method for detecting serologically negative, but infected cattle was not possible as the number of cattle suitable for examination in this study was too low.

Derivation of monoclonal antibodies against Brucella abortus antigens

In vivo immunization, fusion, antibody detection, and cryopreservation procedures for monoclonal antibody production against antigens of Brucella abortus are described. Splenocytes from BALB/c mice immunized with irradiated B. abortus S2308 were fused with Sp2/O-Ag14 myeloma cells and 61 hybridomas secreting anti-Brucella antibodies were cloned. Hybridoma antibody synthesis was detected effectively and most efficiently by enzyme-linked immunosorbent assays. Antibodies from clones of hybridoma A23 reacted with S19 and S2308 whole bacterial cells, while hybridoma B49 reacted primarily with alkali--treated lipopolysaccharides of S19, S1119.3 and S2308. Cryopreservation of clones had no major effect on antibody synthesis. The application of monoclonal anti-Brucella antibodies in the differential diagnosis of bovine brucellosis is discussed.

Effect of oxytetracycline administration on antibody response to Brucella abortus vaccination in calves

In 5- to 7-month-old dairy calves, concurrent oxytetracycline administration and subcutaneous vaccination with 10(9) Brucella abortus strain 19 organisms reduced the percentage of animals with detectable humoral antibodies to Brucella abortus, when compared with untreated vaccinated calves of the same age range. The reduction of antibody reaction in the card test was less than that associated with the injection of 10(9) heat-killed Brucella abortus strain 19 organisms.