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Comparison of different serotests for specific Toxoplasma IgM-antibodies (ISAGA, SPIHA, IFAT) and detection of circulating antigen in two cases of laboratory acquired Toxoplasma infection.

Two symptomatic Toxoplasma infections of laboratory personnel have been serologically followed up for 5.5 and 10 months, respectively. Results obtained by commonly used test systems (indirect fluorescent antibody tests for IgG and IgM antibodies, complement fixation test) were compared with those of two recently developed and improved tests for IgM detection (immunosorbent agglutination assay [ISAGA] and solid-phase indirect haemadsorption assay [SPIHA] as well as with those of a test designed for the detection of circulating antigen (cag-ELISA).

Adult↗

Responses of pony mares to the agent of contagious equine metritis 1977.

Reproduction of contagious equine metritis 1977 in Pony mares was achieved with cultures of an unclassified Gram-negative coccobacillus. Infected mares developed a vaginal discharge and associated inflammatory changes of the cervix and vagina. There was evidence of variation in pathogenicity between different strains of the organism. Although all infected mares made spontaneous clinical recoveries, the Gram-negative coccobacillus persisted in the genital tracts of a considerable proportion for a variable period after challenge. Recovery of the organism was not associated solely with the occurrence of oestrus. None of the mares has carried over infection into the following breeding season. There was no evidence of localization of the organism in the urinary tract. Cytological examination of smears of cervical and urethral swabs was of diagnostic value only during the clinical phase of the infection. A serological response was demonstrable in all mares that became infected after exposure to the Gram-negative coccobacillus. The complement-fixation test gave more specific and clear-cut results than either the agglutination or the antiglobulin test, with which there was a problem with non-specific reactions. The experimental findings indicate the value of the complement-fixation test for confirming recent cases of contagious equine metritis in the mare.

Animals↗

Characterization and evaluation of a soluble antigen complex prepared from the yeast phase of Histoplasma capsulatum.

Soluble yeast-phase (YPS) antigen preparations (Reeves et al., 1972) were obtained from three strains of Histoplasma capsulatum. These were analyzed by agar-gel diffusion and complement fixation tests with human sera from known cases of histoplasmosis. Two of the preparations contained the H and M antigens normally found in histoplasmin, whereas the third preparation contained the H but not the M antigen. In addition, a group of unknown antigens, designated as the Y (yeast) antigens, were demonstrated in all three YPS preparations. On the basis of Sephadex gel filtration data, the molecular weight of the YPS M antigen was estimated to range from 117,000 to greater than 200,000; that of the YPS H antigen was estimated to range from about 60,000 to greater than 200,000; and that of the Y antigens was estimated to range from less than 10,000 to 100,000. Complement fixation tests with human homologous and heterologous sera showed that the Y antigens were specific for H. capsulatum; Y antigens were not detected in the single lot of histoplasmin used in this study. When 60 human histoplasmosis sera and serum samples from nine animals experimentally infected with H. capsulatum were analyzed, it was found that antibodies to the Y antigens occurred with about the same frequency as antibodies to the H antigen but with less frequency than that of antibodies to the M antigen. When used in rabbits as immunogens for the preparation of specific antisera to H. capsulatum, the components of the YPS preparations caused the formation of numerous cross-reacting antibodies. The data from this study show that the value of the YPS preparations for the serological diagnosis of histoplasmosis rests on the specificity of the H, M, and Y antigens and on the fact that the primary production of antibodies is restricted to these antigens in the course of natural infections. The YPS preparations were found to be stable for a period of at least 11 months under a variety of storage conditions and temperatures. Data obtained with various killing agents and metabolic inhibitors suggest an improved method for preparing the YPS antigens by using a suitable strain and killing the cells with iodoacetate.

Animals↗

Indirect hemagglutination test for chlamydial antibodies.

An indirect hemagglutination (IHA) test is described for chlamydial antibodies in psittacosis diagnostic sera; for this test tanned sheep erythrocytes sensitized with a deoxycholate extract of Chlamydia psittaci grown in Vero cell monolayers were used. Adaptation of the IHA test to the Microtiter system decreased sensitivity; nevertheless, the Microtiter-IHA test was more sensitive than the complement fixation test. Lymphogranuloma venereum antibodies also were detected by using antigen extracted from C. psittaci.

Animals↗

Contagious bovine pleuropneumonia in northern Tanzania, culture confirmation and serological studies.

After an absence of about 25 years contagious bovine pleuropneumonia (CBPP) appeared again in 1990 in Tanzania. It was preceded by a spread in Kenya to an area bordering Tanzania. Due to the frequent cattle movements across the border it was soon introduced into Loliondo in northern Tanzania. One month after the first cases, CBPP was suspected in a total of 9 herds comprising 1,500 cattle. However, few animals showed clear clinical signs and frequent antibiotic treatment at an early stage further obscured the clinical picture. In one herd with acute cases, the diagnosis was confirmed by autopsy and Mycoplasma mycoides subsp. mycoides, SC type, was isolated. From this herd several serum samples were positive in the complement fixation test and gave high absorbance values in an ELISA with M. mycoides subsp. mycoides antigen. From 5 other herds with suspected cases blood samples were negative by the complement fixation test but in the enzyme-linked immunosorbent assay at least one in each herd was positive.

Animals↗

A comparison of selected immunological techniques used to detect anti-leishmanial antibodies in the sera of two reptile species.

European green lizards (Lacerta viridis) and spiny-tailed agamids (Agama caudospinosum) were obtained from areas endemic for human leishmaniasis. Serum antibody titres against Leishmania agamae, a reptilian leishmanial species, in normal lizards and lizards injected with Leishmania agamae promastigotes were measured by 5 immunological methods commonly used in the serodiagnosis of the human and mammalian leishmaniasis viz. immobilisation test (IMM), direct agglutination (DA), complement-fixation test (CFT), indirect haemagglutination (IHA) and enzyme-linked immunosorbent assay (ELISA). Correlation coefficients (r) were determined for comparisons between each method and linear regression equations calculated to convert antibody titres by one method to those by another. In each lizard species, the IMM test gave the lowest values while the highest were obtained with ELISA. The highest mean titre obtained by ELISA was between 2 and 10 times that obtained by the other methods for both control and immune sera. The methods of preparing the leishmanial antigen extracts affected the IHA and ELISA titres, while the source of complement was critical in obtaining good CFT values. Correlations ranging from 3% to 77% were found for the control animals but higher values ranging from 65% to 96% were obtained with the immunised lizards. Overall, the best correlation was with IHA and ELISA (r greater than 0.82) and with ELISA values for different antigen preparations compared with each other for both control (r greater than 0.67) and immune (r greater than 0.90) sera. ELISA thus appears the most sensitive method for detection and quantitation of anti-flagellate antibodies in normal lizard serum and for the determination of titres in immune serum. ELISA is the most applicable technique for screening reptiles and other lower vertebrates for anti-parasite immunoglobulins, and for screening potential carriers or reservoirs of infective flagellates in epidemiological studies aimed at disease control, especially in areas where human infections are prevalent.

Agglutination Tests↗

Asian influenza in 1963 in two general practices in Cambridge, England.

A clinical, epidemiological and virological investigation was conducted on patients in two general practices in Cambridge, England, during an influenza epidemic between February and April 1963. The epidemiological pattern differed from that of the 1957-58 Asian influenza epidemic in that the overall incidence was considerably lower (3.2%) and that the highest attack rates were not in school children but in pre-school children (71.5 per 1000 persons).Virological investigation confirmed the diagnosis of Influenza A2 infection in 56 of 63 patients (89%). Isolations were made in 29 of 51 specimens tested. Serological studies revealed that the complement fixation test was more reliable than hemagglutination - inhibition or neutralization tests. Clinical features resembled those reported in previous epidemics, cough, headache and limb pains being prominent features.

Adolescent↗

Counterimmunoelectrophoresis compared with complement fixation and passive haemagglutination tests in the evaluation of the immune response in Campylobacter infections.

The immune response was studied in 238 human patients with Campylobacter jejuni/coli (CJC)-infections in Rotterdam by the counterimmunoelectrophoresis (CIE) test, a commercial complement fixation test (CFT) and the passive haemagglutination test (HA). Antibodies became detectable in the three tests around 4 days after the onset of complaints. Between the 7th and the 20th days after onset of illness 79%, 80% and 53% of the patients demonstrated antibodies by the CIE, the CFT and the HA, respectively. The HA took 30 days to reach 60% positive serum samples and this percentage declined to 35 by the 50th day. Antibody titres demonstrated in the CIE and the CFT declined more slowly. CIE and CFT performed with antigens from a limited number of heat-stable serotypes can be used in the evaluation of the humoral immune response in CJC-infections.

Antibodies, Bacterial↗

African swine fever. I. Antiserum production.

These studies report on the production of African swine fever antiserum for use in serological tests. The first attempt to obtain antiserum was made by inoculating ASF virus - infected pig blood into the lactiferous sinus of lactating bovines. This failed to result in the development of detectable antibody, but resulted in propagation of the virus over a 14 to 21 day period. In the second attempt use was made of a tissue culture - attenuated virus to produce resistance in normal pigs. Clinical response to inoculation with the attenuated virus was limited to a one day increase of temperature. These pigs were subsequently orally exposed to virulent ASF virus and later challenged by intramuscular injection. The sera were subjected to testing by the modified direct complement-fixation test and the agar gel double-diffusion technique in order to follow the development of antibodies. Some sera were also conjugated with fluorescein isothiocyanate and used for the detection of viral antigen by the fluorescent antibody technique. It was found that inoculation with the attenuated virus brought about the development of low antibody levels in the pigs. This antibody level did not increase following oral exposure. One pig following intramuscular challenge underwent a series of ascending temperature peaks, coinciding with increased complement-fixing titres.

Animals↗

Latent carriers of brucellosis.

Of 272 heifers subjected to a brucellosis anamnestic test following one injection of K45/20A vaccine, 53 (19%) gave a positive result to the anti-bovine globulin test and 21 (8%) gave a complement fixation test titre at 1/16 or more. Three heifers (1%) gave a positive serum agglutination test (SAT) titre (60 iu or more) 12 weeks after the second injection of K45/20A vaccine. One of the three aborted at seven months' gestation (Brucella abortus culture positive), another had an SAT level of 100 iu 10 days after calving while the SAT titre of the third heifer continued to fall and remain negative after a normal calving. All the remaining heifers continued to give negative SAT. Recommendations are made for interpreting the anamnestic test for the diagnosis of the latent carrier state.

Agglutination Tests↗

Detection of complement fixation by enzyme linked immunosorbant assay (COMPELISA).

A method is described by which complement fixation is detected with an enzyme linked immunosorbant assay (ELISA) technique. The method obviates the need for sensitised sheep red blood cells as an indicator of complement fixation and the titration of complement is not critical. The dose response curve has the advantage of being steep and the test result is read photometrically. As test serum and complement do not react together serum anticomplementary effects are eliminated. The ELISA complement fixation test (COMPELISA) was more sensitive than the conventional CFT for detecting brucella antibodies.

Antibodies, Bacterial↗

FRACTIONATION ON CROSS-LINKED DEXTRAN, SEPHADEX G-25, OF SERA FROM SHEEP INFECTED WITH JOHNE'S BACILLI. PRELIMINARY REPORT.

Ten sera collected during the winter months from six sheep infected with Johne's bacilli were fractionated on Sephadex G-25 columns, and all fractions tested for complement-fixing antibody, anticomplementary properties and for supplementing and inhibitory activities when added to complement-fixation tests of a heterologous antigen-antibody system: bovine or ovine antiserum with Brucella abortus antigen. Serum from a normal sheep was similarly fractionated and examined. The complement-fixing activity with a carbohydrate fraction of Johne's bacilli was confined principally to supernatant fractions of the earlier eluates containing the greater part of the serum proteins. Some of the unheated earlier and later fractions displayed a limited degree of supplementing effect. Inhibitory activity was demonstrated by certain of the earlier and later eluates after they had been heated, particularly those of antisera with initially low complement-fixing antibody titer.

Animals↗

Studies on acute disseminated encephalomyelitis produced experimentally in Rhesus monkeys; complement-fixing antibodies.

1. Animals injected with emulsions of monkey brain with adjuvants show a complex pattern of antibody response as determined by complement fixation tests. 2. Organ-specific complement-fixing antibodies to constituents of brain tissue may be formed which fix complement with brain tissues of various animal species but fail to react with other organs or with rabbit placenta. 3. Antibodies may be formed to some constituent of brain other than nervous tissue. It would seem that these can be detected by the strong complement fixation given with rabbit placenta. 4. Sera from individual animals may contain antibodies to the brain or placenta constituents, to both, or to neither. Occasional individual sera show unique patterns of antibody response as determined with various additional antigens such as fetal brain, posterior pituitary, or peripheral nerves. 5. No evidence of any etiological relationship between the development of encephalomyelitis and the complement-fixing antibodies to brain demonstrable in the sera could be found. The complement-fixing antibody to the placental constituent was unrelated to the encephalomyelitis.

Animals↗