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The cultural and pathological examination of bulls serologically positive for brucellosis.

The genitalia from 34 bulls were examined for the presence of Brucella lesions using histological, bacteriological and serological methods. Tissue fluids extracted from the various genital organs and the serums were examined using the serum agglutination test (SAT), the Rose Bengal plate agglutination test (RBPT), the complement fixation test (CFT) and the indirect haemagglutination test (IHLT) for the presence of Brucella antibody. Titres to one or more of these tests were found in 17 bulls and B. abortus was cultured from 5 of these. The testing of tissue fluids from genital organs did not increase the number of serologically positive animals.

Agglutination Tests↗

Prevalence of camel brucellosis in Libya.

Sera of 967 camels of both sexes were tested for antibodies to Brucella using the Rose Bengal plate test, serum agglutination test and the complement fixation test. The prevalence of positive sera was 4.1 per cent. Samples collected for cultural examination revealed 9 isolates. Five isolates were from milk samples, 3 from aborted foetuses and one from a vaginal swab. All isolates were identified and biotyped as Brucella melitensis biovar 1.

Agglutination Tests↗

[Diagnosis of chlamydial infections in man and animals].

In this article the problems of immunodiagnostics of generalized and local chlamydial infections are discussed. Extensive material is used for the substantiation of the expediency of using serological methods for diagnosing zoonotic and anthroponotic chlamydial infections. A rational scheme of using the passive hemagglutination (PHA) test and the complement fixation test for the detection of generalized chlamydial infections, as well as the PHA test and the indirect immunofluorescence test for diagnosing urogenital chlamydial infections.

Animals↗

The serological responses of calves to live Salmonella dublin vaccine--a comparison of different serological tests.

The serological responses to live Salmonella dublin vaccine was assessed in three groups of calves; three-day-old colostrum-deprived (3DO C-), three-day-old colostrum-fed (3DO C+) and three-month-old (3MO), by the following tests; serum agglutination test (SAT), indirect haemagglutination test (IHA), complement-fixation test (CFT) and antiglobulin test (AGT). Serological activity was detected by all the tests in the 3MO calves. In the 3DO C+ calves no serological activity was detected by either the somatic SAT or IHA but low levels of CF and somatic AGT antibodies were produced. In 3DO C- calves serological activity, often at low levels, was detected by all the tests except the somatic SAT. High levels of flagellar agglutinins were detected in both groups of 3DO calves. It was concluded that with the exception of the flagellar SAT the tests were affected by the age of the calf and in 3DO calves also by the presence of colostral antibodies. However, the use of the SAT in 3MO calves would provide an indication as to the potency of salmonella vaccines.

Agglutination Tests↗

False positive Wassermann reaction associated with evidence of enterovirus infection.

A large proportion of high titre Coxsackie B5 complement-fixation tests was detected among sera giving false positive Wassermann reactions during 1969. Echo virus type 9 proved to be the prevailing enterovirus and is one of those which induces the formation of antibody to Coxsackie B5. One case of Echo virus type 9 meningitis is presented which produced a false positive Wassermann reaction and a high titre Coxsackie B5 complement-fixation test. The relationship between Echo virus type 9 infection, Coxsackie complement-fixation test results, and false positive Wassermann reactions is considered significant.

Adult↗

Prevalence of Brucella sp. antibodies in feral swine in Florida.

Serum samples collected from feral swine (Sus scrofa) throughout Florida (USA) from 1974 to 1989 were tested for antibodies to Brucella sp. by the card test, the standard tube test, the rivanol test or the complement fixation test. Seropositive swine were detected at six of 18 sites with a composite prevalence of 23.4% (238 of 1,015 samples; range = 5.5% to 33.3%) for sites with seropositive swine. At one site for which age and sex data were available there was no significant difference (P = 0.50) in seroprevalence between males and females. Antibody prevalence in adult (> or = 8 mo) and juvenile swine (< 8 mo), however, was significantly different (P < 0.05). Based on these data, Brucella sp. infections are limited only to certain populations of feral swine. To avoid the spread of Brucella sp. organisms, however, relocation of feral swine is not recommended.

Age Factors↗

Case report: field-acquired subclinical Babesia equi infection confirmed by in vitro culture.

A horse with no prior clinical history of equine piroplasmosis tested negative for Babesia caballi and Babesia equi in the complement fixation test before importation into the United States from France. After 5 years in residence in the United States, the animal tested serologically positive for B. equi by the complement fixation test, the immunofluorescent antibody test, and Western blot analysis. The carrier status of the horse was confirmed by culture of B. equi parasites. In vitro culture offers an efficient and comparatively inexpensive method to determine the carrier status of horses suspected of harboring B. equi.

Animals↗

Serum dilution neutralization test for California group virus identification and serology.

The serum dilution neutralization test was evaluated for serological diagnosis of California group arbovirus infections and identification of virus isolates. The technical advantages and the degree of subtype specificity of the serum dilution neutralization test over the hemagglutination inhibition test and the complement fixation test were demonstrated with paired specimens from human cases, single human survey sera, and sentinel rabbit sera. Twenty-one virus isolates from various geographical areas of the United States were also used to evaluate the efficacy of the serum dilution neutralization test for specific virus identification.

Adolescent↗

Detection of immunoglobulin G antibodies to cytomegalovirus antigens by antibody capture enzyme-linked immunosorbent assay.

An antibody capture enzyme-linked immunosorbent assay (ELISA) that uses horseradish-peroxidase-labeled antigen for the detection of immunoglobulin G (IgG) antibodies to cytomegalovirus (CMV) is described. A microtiter plate was coated with anti-human IgG and consecutively incubated with serum specimens, enzyme-labeled CMV antigen made from CMV-infected cell nuclei, and substrate. The CMV IgG antibody content was determined spectrophotometrically and expressed as absorbance. Furthermore, to reveal any nonspecific reactions, all sera were tested against an enzyme-labeled control antigen made from uninfected cell nuclei. The problem with nonspecific reactions was small and was circumvented by the addition of unlabeled control antigen to the conjugates. For epidemiological studies the test was not as sensitive as other serological tests. On the other hand, the IgG antibody capture ELISA was highly sensitive for detecting the serological antibody response in patients with primary and recurrent CMV infections. Thus, one positive serum remained positive at a serum dilution of 1:10(7). The specificity of the test was shown by a blocking experiment and by testing 126 complement fixation-positive sera, of which 97% were positive. There was a rather good correlation between the complement fixation test and the IgG antibody capture ELISA (rs = 0.79, P less than 0.001). The test is especially useful when tests for CMV antibodies of the IgM, IgA, and IgE classes are run by similar antibody capture ELISAs, since the same procedure and conjugate are used.

Antibodies, Viral↗

Enzyme immunoassays for serological diagnosis of bovine brucellosis: A trial in Latin America.

The results of a field trial conducted in Latin America with two indirect enzyme-linked immunosorbent assays (ELISAs) and two competitive ELISAs (CELISAs) for the detection of bovine antibody to Brucella abortus are reported. One of the CELISA formats performed most accurately. The percentage of positive reactions in the CELISA relative to the selected positive rose bengal agglutination test (RBT) and complement fixation test (CFT) results was 97.47%, the percentage of negatives relative to the selected negative RBT and CFT results for unexposed cattle was 98.32%, and the percentage of negatives in cattle vaccinated with B. abortus 19 was 96.51%. The same assay format under Canadian conditions had an actual sensitivity of 100%, a specificity of 99.90% in nonvaccinates, and a specificity of 97.7% in a strain 19-vaccinated population. Overall, the CELISA performed as expected and the results were not dissimilar from the results obtained in the Canadian study. This provided further evidence that this CELISA can in many instances differentiate infected cattle from those that are vaccinated or infected with a cross-reacting organism while still giving very few false-positive or false-negative results.

Agglutination Tests↗

Evidence of Brucella infection in marine mammals in the North Atlantic Ocean.

Between 1983 and 1996 a total of 1386 samples of serum were taken from four species of seal and three species of whale in the waters west of Iceland, the area of pack-ice north-west of Jan Mayen, the northern coast of Norway and the Kola Peninsula, the waters west of Svalbard, and the Barents Sea; they were tested for the presence of anti-Brucella antibodies with an indirect ELISA (protein G conjugate). The positive sera were re-tested with classical brucellosis serological tests, such as the serum agglutination test, the EDTA-modified serum agglutination test, the Rose Bengal test, and the complement fixation test, as well as an anti-complement ELISA. Anti-Brucella antibodies were detected in all the species investigated, except for the bearded seal (Erignathus barbatus), with the following prevalences: hooded seals (Cystophora cristata) 35 per cent; harp seals (Phoca groenlandica) 2 per cent; ringed seals (Phoca hispida) 10 per cent; minke whales (Balaenoptera acutorostrata) 8 per cent; fin whales (Balaenoptera physalus) 11 per cent; and sei whales (Balaenoptera borealis) 14 per cent. An isolate belonging to the genus Brucella was obtained from the liver and spleen of one of the seropositive minke whales. The findings suggest that antibodies against the surface lipopolysaccharide of Brucella species are widely distributed among marine mammals in the North Atlantic Ocean.

Agglutination Tests↗

The use of supplementary tests in the serological diagnosis of bovine brucellosis.

Comparative tests were carried out on serum samples using the Rose Bengal test (RBT), the complement fixation test (CFT), the antibovine globulin test (ABGT) by tube, plate and rapid variants, the mercaptoethanol test (MET) and the dithiothreitol test (DTT). Forty cows, from which Br. abortus had been recovered, gave strong reactions in all tests except for 2 cows in the SAT and 3 cows in the DTT Another group of 405 cows had not yielded Br. abortus on limited bacteriological examination. There was good correlation between the results of the CFT, RBT, tube ABGT, rapid ABGT and, to a lesser extent, the MET in cows with a CF titre greater than or equal to 16 or less than 4. In cows with CF titres of 8 the correlation was not as good while cows with a CF titre of 4 gave a wide range of reactions in these supplementary tests. A plate variant of the ABGT gave titres which were generally lower, by about 1 dilution, than those in the tube procedure. The results of the rapid ABGT correlated well with the results of the tube ABGT and the CFT in samples of high and low titre but not as well in samples of intermediate titre. The DTT gave titres which were usually lower than the corresponding MET titre. On the basis of the results obtained, tentative standards for the interpretation of the ABGT (tube) and MET were defined. It was concluded that these tests could be used to elucidate the status of a proportion of the cows which gave inconclusive results in the CFT.

Agglutination Tests↗

Serological and clinical diagnosis of hydatid disease in schistosomal patients.

Indirect haemagglutination test (I.H.A.T.), Latex test (L.A.), and Complement Fixation test (C.F.T.), were performed on 100 serum samples obtained from Egyptian patients suspected clinically to have Hydatid disease and 50 healthy controls. The results of clinical, laboratory and serologic investigations revealed Hydatid infection in six cases.

Adolescent↗

The Dutch Brucella abortus monitoring programme for cattle: the impact of false-positive serological reactions and comparison of serological tests.

The Dutch national Brucella abortus eradication programme for cattle started in 1959. Sporadic cases occurred yearly until 1995; the last infected herd was culled in 1996. In August 1999 the Netherlands was declared officially free of bovine brucellosis by the European Union. Before 1999, the programme to monitor the official Brucella-free status of bovine herds was primarily based on periodical testing of dairy herds with the milk ring test (MRT) and serological testing of all animals older than 1 year of age from non-dairy herds, using the micro-agglutination test (MAT) as screening test. In addition, serum samples of cattle that aborted were tested with the MAT. The high number of false positive reactions in both tests and the serum agglutination test (SAT) and complement fixation test (CFT) used for confirmation seemed to result in unnecessary blockade of herds, subsequent testing and slaughter of animals. For this reason, a validation study was performed in which three indirect enzyme-linked immunosorbent assays (ELISAs), the CFT and the SAT were compared using a panel of sera from brucellosis-free cattle, sera from experimentally infected cattle, and sera from cattle experimentally infected with bacteria which are known to induce cross-reactive antibodies (Pasteurella, Salmonella, Yersinia, and Escherichia). Moreover, four ELISAs and the MRT were compared using a panel of 1000 bulk milk samples from Brucella-free herds and 12 milk samples from Brucella abortus- infected cattle. It is concluded that the ELISA obtained from ID-Lelystad is the most suitable test to monitor the brucelosis free status of herds because it gives rise to fewer false-positive reactions than the SAT.

Agglutination Tests↗

Validation of an indirect enzyme-linked immunosorbent assay for the detection of antibody against Brucella abortus in cattle sera using an automated ELISA workstation.

An automated indirect enzyme-linked immunosorbent assay (I-ELISA) for the serological diagnosis of bovine brucellosis was developed and validated in-house. A total of 4,803 cattle sera from South Africa (n = 3,643), Canada (n = 652), Germany (n = 240), France (n = 73) and the USA (n = 195) was used. The South African panel of sera represented 834 sera known to be positive by the Rose Bengal test (RBT), serum agglutination test (SAT) and complement fixation test (CFT), 2709 sera that were negative by CFT, and 100 sera from animals vaccinated with a standard dose of Brucella abortus strain 19. Overseas sera were obtained from reference non-vaccinated brucella-free cattle (n = 834), naturally infected (n = 72), experimentally infected (n = 71), and vaccinated animals (n = 83). Also 100 sera collected from cattle in Canada and known to be positive by competitive ELISA (C-ELISA) were used. The intermediate ranges ("borderline" range for the interpretation of test results) were derived from two-graph receiver operating characteristics analysis. The lowest values of the misclassification cost-term analysis obtained from testing overseas panels, covered lower I-ELISA cut-off PP values (0.02-3.0) than those from local panels (1.5-5.0). The relatively low cut-off PP values selected for I-ELISA were due to the fact that the positive control used represents a very strong standard compared to other reference positive sera. The greater overlap found between negative and positive cattle sera from South Africa than that between reference overseas panels was probably due to the different criteria used in classifying these panels as negative (sera from true non-diseased/non-infected animals) or positive (sera from true diseased/infected animals). The diagnostic sensitivity of the I-ELISA (at the optimum cut-off value) was 100% and of the CFT 83.3%. The diagnostic specificity of I-ELISA was 99.8% and of the CFT 100%. Estimate of Youden's index was higher for the I-ELISA (0.998) than that for the CFT (0.833). Analysis of distribution of PP values in sera from vaccinated and naturally infected cattle shows that in vaccinated animals all readings were below 31 PP where in infected ones these values represented 43%. Therefore, it appears that I-ELISA could be of use in identifying some naturally infected animals (with values > 31 PP), but more sera from reference vaccinated and infected animals need to be tested to further substantiate this statistically. Of 834 sera positive by RBT, SAT and CFT, 825 (98.9%) were positive in the I-ELISA. Compared to C-ELISA the relative diagnostic sensitivity of the I-ELISA was 94% and of the CFT 88% when testing 100 Canadian cattle sera. Of 258 South African cattle sera, of which 183 (70.9 %) were positive by the I-ELISA and 148 (57.4 %) by the CFT, 197 (76.4%) were positive by C-ELISA when re-tested in Canada. One has to stress, however, that Canadian C-ELISA has not been optimised locally. Thus, the C-ELISA was probably not used at the best diagnostic threshold for testing South African cattle sera. This study shows that the I-ELISA performed on an automated ELISA workstation provides a rapid, simple, highly sensitive and specific diagnostic system for large-scale detection of antibodies against B. abortus. Based on the diagnostic accuracy of this assay reported here, the authors suggest that it could replace not only the currently used confirmatory CFT test, but also the two in-use screening tests, namely the RBT and SAT.

Agglutination Tests↗

[Indirect hemagglutination test for detection of toxoplasma antibodies (author's transl)].

A micromethod with stable reagents for the simple and rapid detection of toxoplasma antibodies with the indirect hemagglutination test (IHAT) is presented. The results obtained with this method are compared with the titers in the dye test and complement-fixation test and with two IHAT-kits recently offered by commercial firms. We propose to use the IHAT as a supplementary reaction to the methods commonly in use. The relationship between the Sabin-Feldman dye test and IHAT is dependent upon the stage of infection. A very good agreement is obtained with latent toxoplasma infections. On the contrary with some new infections (up to 6 months) the IHAT titer is clearly lower than the dye test titer. This discrepancy opens the possibility of determining the infection stage with a single serum-sample.

Antibodies↗