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Comparison of the enzyme-linked immunosorbent assay and the indirect hemagglutination and complement fixation tests for detecting antibodies to Mycoplasma hyopneumoniae.

Caesarean-derived, colostrum-deprived swine were exposed to a broth culture of a low passage field isolate of Mycoplasma hyopneumoniae by intranasal inoculation. The intranasal-inoculated swine subsequently were commingled with their litter-mates to effect transmission via contact-exposure. Sera were collected from the swine at two to four week intervals for approximately one year postexposure and evaluated by the enzyme-linked immunosorbent assay (ELISA), indirect hemagglutination and complement fixation tests. The intranasal-exposed swine seroconverted earlier, developed higher titers and remained indirect hemagglutination and complement fixation positive longer than the contact-exposed swine. It was concluded that the antibody response of intranasal-exposed swine was artificially high and that sera from such swine were not suitable for evaluating the sensitivity of mycoplasmal pneumonia of swine serodiagnostic tests. The indirect hemagglutination test was relatively insensitive and technically cumbersome and the least promising as a practical field test. The complement fixation test appeared to be slightly more sensitive in detecting early antibody production (especially in contact-exposed swine) but it was the least sensitive in detecting late antibodies. The ELISA was generally the most sensitive procedure. Individual high ELISA titers were from ten to 32 times greater than maximum complement fixation and indirect hemagglutination titers. The most striking difference among the three tests was the persistence of high ELISA titers late in the study. All swine were ELISA positive at necropsy approximately one year postexposure despite the fact that lungs were devoid of lesions and culturally and immunofluorescent negative for M. hyopneumoniae.

Animals↗

A reappraisal of the complement fixation test using soluble Mycobacterium avium antigen for the detection of M. paratuberculosis infection in cattle.

Serums from 263 cattle suspected of having paratuberculosis on the basis of clinical signs, were tested for antibodies to Mycobacterium paratuberculosis with a complement fixation test (CFT) employing a heat extracted, soluble M. avium antigen. Microscopic examination confirmed that 172 (65.4%) clinically affected animals had paratuberculosis, the remainder being disease-free. The specificity and sensitivity of the CFT was 92.3% and 74.4% respectively. Phenol treatment of serums before testing was compared with no treatment and was found to have no significant effect on the CFT titres. Results obtained are discussed in relation to the cause of false negative and false positive reactions.

Animals↗

An improved quantitative micro-complement fixation test.

The technical procedures for a simple quantitative micro-complement (C) fixation test are described. Major advantages of the present technique compared with the previously described method are: a) a simple measurement of the residual hemolytic activity of C by counting the radioactivity released from 51Cr-labeled sensitized sheep erythrocytes (51Cr-EA); b) an increased sensitivity of the test, brought about by the use of a relatively small number of 51CR-EA per reaction volume; and c) an increased specificity of the test, achieved by maintaining a constant amount of C available for the specific antigen--antibody reaction.

Adenoviridae↗

The complement fixation test and African trypanosomiasis: I. Experimental infection and re-infection in cattle before and after treatment.

The complement fixation test was applied to assess antibody responses in cattle infected with T. brucei, T. congolense, and T. vivax which had been treated and re-infected. After the first infection, the specificity of the results was low in T. congolense, fair in T. brucei, and high in T. vivax infected animals. After re-infection with the same trypanosoma species as used for previous infections, the specificity of CF results was high in all cases. After a foregoing T. vivax infection, specific titres of T. congolense and to a lesser degree of T. brucei infections were frequently masked by residual T. vivax titres. After treatment of trypanosoma-infected cattle the fasted drop of CF antibody titres occurred in T. congolense cases, followed by T. brucei infections. T. vivax titres persisted over prolonged periods.

Animals↗

Comparison of radioimmunoassay with the complement fixation test and the indirect haemolysis test in the field diagnosis of bovine brucellosis.

Sera were collected from female cattle in 118 commercial herds being subjected to a programme to eradicate brucellosis by test and slaughter, in an area in which vaccination of heifer calves with Brucella abortus strain 19 was compulsory. Of 4583 sera positive by the Rose Bengal plate test, the brucellosis radioimmunoassay was positive for 1524, the complement fixation test for 1363 and the indirect haemolysis test for 1141. These figures, and supporting evidence from the eradication programme, suggest that the radioimmunoassay may be a useful supplementary test in problem herds.

Animals↗