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A study of cattle infected with Brucella abortus and which showed aberrant serological reactions.

Sixty cows, 48 of which had been vaccinated with live Brucella abortus strain 19 (S19) or with killed B. abortus strain 45/20 (S45/20) and 12 of which were unvaccinated animals, were challenged with B. abortus strain 544. Ten of the 27 cattle found to be infected after challenge showed aberrant serological reactions to the Rose Bengal Plate test, serum agglutination test and/or complement fixation test. These 10 cattle were all previously vaccinated with S19 or S45/20. It was concluded that infection in cattle vaccinated with S19 or S45/20 may be more difficult to detect than infection in animals that have no history of vaccination.

Animals↗

Development and evaluation of an extra chromosomal DNA-based PCR test for diagnosing bovine babesiosis.

Subclinical infections of bovine babesiosis, caused primarily by Babesia bigemina or Babesia bovis are a challenge to current diagnostic methods. In this study, the development and evaluation of a PCR test for sensitive and specific detection of B. bigemina or B. bovis is described. The target selected for amplification is part of the apocytochrome b gene, conserved in both Babesia spp. and located on the linear approximately 6.0 kb extra chromosomal DNA. The test was evaluated to detect the parasites over a period of 5 (B. bigemina) and 10 months (B. bovis) post infection in experimentally infected cattle. Analysis of DNA extracted from blood samples drawn from the experimental cattle in a blind study revealed an overall sensitivity of 85 and 64% for B. bovis and B. bigemina respectively, while the specificity was 97% for B. bovis and 91% for B. bigemina. The test results were compared with the recently developed ribosomal DNA-based polymerase chain reaction (PCR) test and to the complement fixation test for both Babesia spp. The extra chromosomal DNA-based test was 20% more sensitive than that of ribosomal DNA-based tests. This test may be a more desirable alternative to the currently used, complement fixation test.

Animals↗

Diagnostic sensitivity and specificity of an enzyme-linked immunosorbent assay for the diagnosis of Brucella ovis infection in rams.

An enzyme-linked immunosorbent assay (ELISA) for antibody to Brucella ovis was compared with a standard complement fixation test. Sera of 176 rams from uninfected flocks gave 175 negative and one suspect ELISA reaction (diagnostic specificity 99.4%) whereas the complement fixation test yielded 167 negative, seven suspect and two anticomplementary reactions (diagnostic specificity of 96.0%). Diagnostic sensitivity was evaluated on sera of 79 rams from which B. ovis had been isolated. The ELISA showed 75 positive and four suspect reactions, while complement fixation test revealed 64 positive, 13 suspect and two negative results. Considering both positive and suspect reactions, the diagnostic sensitivity was 100% for ELISA and 97.5% for complement fixation test. The ELISA method was considered more specific, more sensitive and technically more advantageous than complement fixation test as a serodiagnostic test for B. ovis infection in rams.

Animals↗

Experimental studies on Brucella abortus in moose (Alces alces).

Four moose (Alces alces) were inoculated conjunctivally with B. abortus biovar 1 to determine their susceptibility to brucellosis, and to describe the serology, bacteriology, hematology, clinical chemistry, and pathology associated with infection. All moose became infected. Two moose were killed at day 70 post-exposure, one (83F) died acutely at day 85, and one was killed at day 166. None of the moose had clinical signs, except for 83F immediately before death. Infected moose were readily detected serologically by the buffered antigen plate test, Brewer card test, standard tube agglutination test, and complement fixation test as used for brucellosis in cattle. With the exception of samples from 83F taken 24 hours before death, clinical chemistry, and hematology results were stable for all moose, and similar to normal values seen in cattle. Lesions seen in all moose were indicative of endotoxemia, and moose 83F died of acute endotoxic shock. Brucella abortus biovar 1 was isolated from several tissues in all moose, most notably from lymph nodes where counts often exceeded 4 x 10(4) colony forming units per g of tissue. Thus infection with B. abortus will kill moose, and progression of the disease is likely rapid under field conditions. Moose appear to be a dead-end host for brucellosis.

Agglutination Tests↗

Antibodies to Crimean-Congo haemorrhagic fever virus in domestic animals in Iraq: a seroepidemiological survey.

A seroepidemiological survey to determine the prevalence of Crimean-Congo haemorrhagic fever (CCHF) virus and its circulation among animals in Iraq was carried out in 1980. Sera were collected from 2205 animals of different species in three different faunal areas of the country. Sera were tested by complement fixation test for quantitative determination of antibodies to CCHF virus. Among 769 sheep tested 443 (57.6%) were positive; 279 of 562 (49.64%) goat sera; 122 of 411 (29.28%) cattle sera; 148 of 252 (58.73%) horse sera; 23 of 99 (23.23%) camel sera and 5 of 35 (14.28%) sera collected from unclassified small mammals in Iraq have had antibodies to CCHF virus.

Animals↗

Immunity to human cytomegalovirus measured and compared by complement fixation, indirect fluorescent-antibody, indirect hemagglutination, and enzyme-linked immunosorbent assays.

The complement fixation test is currently the test employed most frequently to determine the presence of antibody to human cytomegalovirus. Several other techniques have been adapted for this purpose. A comparison of cytomegalovirus antibody titers was made between the complement fixation test, a commercially available enzyme-linked immunosorbent assay, an indirect immunofluorescent technique, and a modified indirect hemagglutination test. Forty-three serum samples were tested for antibodies by each of the above procedures. The enzyme-linked immunosorbent, immunofluorescent, and indirect hemagglutination assays were in close agreement on all samples tested; the titers obtained with these methods were all equal to or greater than the complement fixation titer for 38 of the 41 samples (92.6%). Two samples were anticomplementary in the complement fixation test but gave readable results in the other tests. The complement fixation test was the least sensitive of the procedures examined. The commercial enzyme-linked immunosorbent assay system was the most practical method and offered the highest degree of sensitivity in detecting antibodies to cytomegalovirus.

Antibodies, Viral↗

A molecular defect in thrombasthenic platelets.

An IgG antibody found in the serum of a thrombasthenic patient reacted in complement fixation with platelets from 350 normal individuals but was nonreactive with platelets from eight other thrombasthenic patients. ADP-induced aggregation of normal platelets was inhibited by the patient's antibody. Family studies using the quantitative complement fixation test showed that healthy heterozygotes were easily distinguishable from normal or thrombasthenic individuals since their platelets had an intermediate amount of the reactive antigen. Indirect immunoprecipitation tests using this serum and soluble membrane antigens labeled with iodine-125 that had been extracted from normal platelets by the detergent Nonidet P-40 gave a single radioactive peak at 120,000 mol wt in sodium dodecyl sulfate polyacrylamide gel electrophoresis. A similar estimate of the molecular weight was obtained from Sephadex G-200 filtration of the soluble antigens extracted from normal platelets by spontaneous release or chaotropic agents and tested in complement fixation with the patient's serum. These findings strongly suggest that the molecule recognized by this antibody is absent or structurally modified in thrombasthenia cases and that it may be involved in platelet aggregation.

Adenosine Diphosphate↗

Immunodiffusion test antigen from bluetongue virus-infected newborn mouse brains.

Three methods of extracting bluetongue virus (BTV)-infected newborn mouse brains to prepare immunodiffusion (ID) test antigen were used. The most readily readable and reproducible results were obtained with fluorocarbon-extracted brains homogenized in 8.5% sucrose. Mouse brain- and reference cell culture-derived antigens gave a line of identity with anti-BTV serum. Extracts of noninfected brains were nonreactive. ID tests on field-collected bovine sera, comparing the two types of antigen, resulted in only 73% agreement due to a greater sensitivity of cell culture-derived antigen. A 70.5% agreement resulted when comparing mouse brain-derived antigen in ID tests with complement fixation tests, the latter being least sensitive. ID test results with sera from experimental sheep gave 95.9% agreement between cell culture- and mouse brain-derived antigens. Between ID, which detects antibody to the BTV common or group antigen, and virus neutralization, which detects type-specific antibody, the agreement was 71.4% with postchallenge sera. Data from pre- and postinjection sera, however, indicate the possible activity in Texas of viruses other than International BTV Types 10, 11, 13, and 17.

Animals↗

Rapid detection of IgM and IgG antibodies to herpesviridae virus.

In this study, the immunoconcepts EA indirect enzyme antibody technique (colorzyme) was used not only for detection of IgG antibodies but also for quantitative detection of IgM antibodies to Herpes Simplex virus (HSV), Cytomegalovirus (CMV) and Epstein Barr Virus (EBV) to diagnose recent iactivei infection. Reference reactive and negative antisera and randomly collected human sera were tested by complement fixation test (CFT) against HSV antigens and tested also by immunofluorescent (IF) and colorzyme Immunoconcepts EA tests. All sera that were negative to HSV, CMV and EBV antibodies by CFT were negative by IF and colorzyme EA tests. All antibody positive sera and reference positive antisera were also positive by IF and colorzyme EA tests with slight variation in antibody titres between CFT and colorzyme test results. Human sera which were negative or IgM positive to HSV, CMV and EBV by ELISA as well as negative and positive reference sera from different diagnostic kits were retested by IF and colorzyme EA for IgM antiviral reactivity results were concordance by the three rests. All incubations in colorzyme test were at room temperature and only an ordinary microscope used in IF test or plate washers and readers needed for ELISA test. The colorzyme immunoconcepts is a simple, rapid and sensitive for viral diagnosis and can be used in any private laboratory.

Antibodies, Viral↗

Antigen-induced production of interferon-gamma in samples of peripheral lymph nodes from sheep experimentally inoculated with Mycobacterium avium subsp. paratuberculosis.

The production of interferon-gamma (IFN-gamma) in response to Johnin purified protein derivate was measured in samples of the prescapular lymph node (PLN) from 10 sheep, aged 2 years, and nine sheep, aged 1 year that had been inoculated orally with Mycobacterium avium subsp. paratuberculosis within their first month of life. Ten non-inoculated sheep, aged 1 year, constituted the negative control group. The results obtained in the PLN IFN-gamma assay were compared with those derived from serological tests: a complement fixation test (CFT), agar gel diffusion test (AGID) and enzyme-linked immunosorbent assay (ELISA), as well as an IFN-gamma test on samples of blood. Among the 19 inoculated sheep, 16 gave positive reactions in the PLN IFN-gamma assay on samples incubated overnight, and 18 tested positive when the assay was applied to PLN samples incubated for 48h. In comparison, three, four and seven inoculated sheep gave positive reactions in the ELISA, CFT and in the blood IFN-gamma assay on samples incubated overnight, respectively. The AGID and IFN-gamma assay on blood samples incubated for 48h detected eight inoculated animals. Twelve inoculated sheep, that tested positive in the PLN IFN-gamma assay were clinically normal, gave negative results in an IS900-based polymerase chain reaction (PCR) assay on samples of ileum and ileocaecal lymph node and had no histological evidence of paratuberculosis, but tested positive on more than two occasions in sequential serological testing before necropsy. None of the 10 non-inoculated sheep tested positive in the AGID, CFT, ELISA, blood IFN-gamma assay on samples incubated overnight and for 48h or the PLN IFN-gamma assay on samples incubated overnight, but one gave a positive result in the PLN IFN-gamma assay on samples stimulated for 48h. It is likely that the positive reactions obtained by the PLN IFN-gamma assay in the 12 inoculated sheep that tested negative in the PCR assay and histopathological examination represents immunological evidence of latent infection or previous exposure to M. paratuberculosis rather than active infection.

Animals↗

Circulating immune complexes in schistosomiasis.

Circulating immune complexes (CIC) were investigated by the [125I]Clq binding test, the complement fixation test (CFT) and optical density measurement after redissolving 3% polyethylene glycol precipitates of serum from patients infected by Schistosoma mansoni. A highly significant correlation was obtained among these three techniques. More than 60% of the patients demonstrated significantly higher values than control individuals. The level of CIC was found to be higher in the mild than in the hepatosplenic form of the disease. Parasite antigen, IgG, IgM and IgE were characterized in these CIC. In experimental schistosomiasis in mice, maximum levels of CIC, evaluated by the CFT, were observed between the 40th and the 70th day of infection.

Animals↗

An epidemic of respiratory syncytial virus in elderly people: clinical and serological findings.

In 1984-1985, an outbreak of respiratory syncytial virus (RSV) infection occurred in two geriatric wards. Among 68 patients (mean age +/- SD = 82.5 +/- 12.5 with respiratory signs, 52 had signs caused by RSV infection. Among all patients, the clinical and serological attack rates were 61.2% and 75.0%, respectively. The most frequent clinical presentation was intensive coughing (96.1%) and fever (96.1%) associated with expectorate (63.5%). The duration of the respiratory symptoms was 5 to 7 days. The disease gradually resolved, although in eight (15.4%) patients complications occurred. For periods of up to 1 year after infection, 172 sera were obtained and tested by complement fixation test (CFT), fluorescent assays for titrating specific IgG, IgA, and IgM, and Western blotting. Specific IgM appeared in six (11.5%) of the infected patients and peaked 2 to 6 months after infection, and there was no significant correlation with severity of clinical symptoms. However, higher peak G and A antibody responses were observed in persons with rales (CFT: P = 0.008; IgG: P = 0.042; IgA: P = 0.020), cough (IgG: P = 0.034), sputum (IgG: P = 0.030), dyspnea (CFT: P = 0.024), conjunctivitis (CFT: P = 0.025), and bronchitis (CFT: P = 0.018). The temporal patterns of IgA and CFT results were found to be similar, whereas IgG peaked later, i.e., between 2 and 6 months. The patients with the most severe symptoms had the highest antibody titers obtained by conventional tests and by Western blots. Thus, RSV can be an epidemic pathogen among elderly persons, although this illness is usually mild.

Aged↗

Evaluation of serological tests for diagnosis of Brucella melitensis infection of goats.

Five serological assays were evaluated for the diagnosis of brucellosis in goats: the rose bengal test (RBT), complement fixation test (CFT), radial immunodiffusion (RID) with Brucella and Yersinia enterocolitica O:9 polysaccharides, counterimmunoelectrophoresis (CIEP) with cytosol, and enzyme-linked immunosorbent assay (ELISA) with polyclonal and protein G conjugates and smooth lipopolysaccharide (S-LPS), native hapten polysaccharide (NH), or cytosol antigens. For optimal sensitivity, RBT had to be used with sera-antigen at a 3:1 dilution. In the RID test, Brucella melitensis biotype 1 NH could not be replaced by Brucella abortus biotype 1 or Y. enterocolitica 0:9 polysaccharides. In the ELISA, S-LPS and NH gave similar results and the protein G conjugate increased the specificity. With the sera from 55 B. melitensis culture-positive goats, the sensitivity was 100% for RBT, CFT (titer > or = 4), and ELISA with S-LPS or NH; 94% for RID; and 93% for CIEP. All tests were negative (100% specific) when testing the sera from 127 brucella-free goats. Larger discrepancies among the results of the serological tests were obtained with sera from goats of areas where brucellosis is endemic. When the sera of 20 young goats vaccinated subcutaneously (10(9) CFU of B. melitensis Rev 1) and bled 6 months later were examined, the specificities were as follows: NH ELISA, 60%; CFT and S-LPS ELISA, 75%; RBT, 80%; CIEP, 90%; and RID, 94%. With the sera from 10 young goats vaccinated conjunctivally (10(9) CFU of B. melitensis Rev 1) all tests were 100% specific 4 months after vaccination. The proportion of goats giving a positive reaction after vaccination decreased faster in RID than in other tests.

Animals↗

Evaluation of allergic and serological tests for diagnosing Brucella melitensis infection in sheep.

A total of 291 unvaccinated sheep from Brucella melitenesis-infected flocks were examined for delayed-type hypersensitivity (DTH) responses with Brucellergene commercial allergen and with cold saline extract and cytosol from rough B. melitensis 115, and their sera were tested in the rose bengal test (RBT), complement fixation test (CFT), and enzyme-linked immunosorbent assay (ELISA) with lipopolysaccharide. DTH reactions were maximal after 72 h, with no intensity differences among allergens, inoculation sites (eyelid and tail), and doses tested. There were no differences in the results recorded by visual inspection and palpation of inoculation sites, by measuring skin thickness with a caliper, or by microscopic examination of samples taken at necropsy. Six days after DTH testing, energy was observed in 100% of the animals, and 100% reactivity was recovered only after 24 days. All animals were necropsied, and thorough bacteriological searches were performed. The sensitivities found with the 140 animals from which B. melitensis was isolated were ELISA, 100%; DTH, 97.1%; RBT, 92.1%; and CFT, 88.6%. Those results put into question the value of RBT and CFT as screening and confirmatory tests for sheep brucellosis and at least indicate that their standardization should be modified. For 151 tested sheep from which B. melitensis was not isolated, the percentages of positive animals were ELISA, 100%; DTH, 94.0%; RBT, 57.6%; and CFT, 53.6%. All tests were negative for 100 tested sheep from Brucella-free flocks. The different results of bacteriological and immunological tests suggest the usefulness of developing indirect tests able to distinguish truly infected animals from those that have developed an immunological response.

Allergens↗

Q fever seroprevalence and associated risk factors among students from the Veterinary School of Zaragoza, Spain.

Q fever is a zoonosis related to the existence of Coxiella burnetii infected animals. The authors studied the seroprevalence and risk factors associated to C. burnetii infection in veterinary students in Zaragoza (Spain). Sera were collected at the beginning and the end of the academic year (1994-1995) and were tested by Complement fixation test to detect antibodies against C. burnetii. 10.02 and 11.02% seroprevalences were observed at the beginning and the end of the study respectively. The cumulative incidence through the period of study was 0.0157. Risk factors associated to C. burnetii were multiple: students coursing the speciality in Food Inspection and Technology or the speciality of Animal Production; to practise with living animals in general and particularly with ruminants and to contact frequently with persons who worked with animals, particularly with veterinarians, farmers and animal traders. In parallel, the students coursing the first course showed a significant lower seroprevalence. Male students from the fifth course were significantly more seroprevalent than females, where sex was a protection factor. Concerning the clinical signs asked in the questionnaire, cardiovascular disturbances, flu and/or pneumonia, sweating, transient hyperthermia or spondylitis were associated factors. Conversely, a good response after treatment of symptoms was a protection factor. The only risk factor associated with incidence along the year of study was practising in farms. The authors recommend a revision of hygiene measures to control risk factors and the diagnostic of C. burnetii infection when populations at risk show the associated symptoms.

Adult↗

[The duration of Cytomegalovirus complement fixation antibodies in patients with CMV hepatitis].

38 sera from 5 patient with cytomegalovirus infection were examined in different times for cytomegalovirus antibodies by complement fixation test. High titres of complement fixation antibodies for cytomegalovirus antibodies were found starting on the 4 th weeks of the disease. These high titres were irregular. Cytomegalovirus antibodies were still present in all sera until the 178 th week, but in some sera until the 204 th week of the disease.

Antibodies, Viral↗