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PubMed1974

Evaluation of micro complement fixation tests for antibodies against group A streptococcal M and M-associated antigens in rabbit and human sera.

Variables involved in micro complement fixation (CF) tests for type-specific (TSM) and non-type-specific (NTSM) antibodies against preparations of streptococcal M protein were studied. Sera of rabbits immunized with purified M protein which contained high titers of anti-TSM and low titers of anti-NTSM antibodies reacted type specifically in the CF tests when relatively low concentrations of M protein were employed. In contrast to these artificially induced TSM antibody responses, the sera of rheumatic fever patients demonstrated elevated CF antibody titers (1:80 to 1:320) in the presence of both high and low concentrations of M antigen. The CF test cannot distinguish TSM and NTSM antibodies when the latter predominate. The CF test can be employed with confidence for the detection of NTSM antibodies, provided that the test sera are known to lack type-specific antibodies against the M protein used in the test.

Animals↗
PubMed1975

New complement-fixation test for the human reovirus-like agent of infantile gastroenteritis. Nebraska calf diarrhea virus used as antigen.

A complement-fixation (C.F.) test for the human reovirus-like agent of infantile gastroenteritis has been developed using the serologically related Nebraska calf diarrhoea virus (N.C.D.V.) as antigen. Most infants and children who shed the agent in stools and/or who demonstrated serological (C.F.) evidence of infection with a reovirus-like-particle-positive human stool-filtrate C.F. antigen also demonstrated serological evidence of infection when a concentrated N.C.D.V. preparation was employed AS C.F. antigen. The N.C.D.V., which was previously shown to be related to the human reovirus-like agent, was found to be related antigenically to the epizootic diarrhoea of infant mice (E.D.I.M.) virus also. Studies on the prevalence of C.F. antibody in sera from infants and young children revealed a pattern of rapid acquisition of antibody to both the human reovirus-like agent and the N.C.D.V. as over 80 percent of these individuals possessed antibody to each agent by 36 months of age. A strong positive association was found in the results obtained with the two antigens. The ready availability of cell-culture grown N.C.D.V., and its ability to serve as a "substitute" C.F. antigen for the human reovirus-like agent, should enable the serodiagnosis of many cases of disease due to the human agent and facilitate seroepidemiological studies of such infections. In addition, the observation that a large proportion of individuals infected with the human reovirus-like agent develop serological evidence of infection not only to the human agent but to the calf agent as well may have important implications in the immunoprophylaxis of disease caused by the human reovirus-like agent.

Animals↗
PubMedDate not supplied

[Determination of antibody kinetics in Mediterranean spotted fever using the Weil-Felix agglutination test, complement fixation and indirect immunofluorescence].

The kinetics of antibodies in human cases of Mediterranean spotted fever was studied by applying Weil-Felix (WF) agglutination with Proteus OX antigens, complement fixation (CF) and indirect immunofluorescence (IF) tests with Rickettsia conorri antigen to 46 sera from 21 patients. The kinetics of specific (CF and IF) and nonspecific (WF) antibodies was similar. The percentage of the positive sera and geometric mean titers of antibodies reached the maximum after 14 days from the onset of illness.

Agglutination Tests↗
PubMed2002

Combined S99/RB51 antigen for complement fixation test for serological diagnosis of brucellosis in cattle and sheep.

AIMS: To assess the efficiency of a single antigen for the complement fixation (CF) test, prepared by combining Brucella abortus smooth strain 99 (S99) with Brucella abortus rough strain RB51(RB51), in detecting cattle and sheep infected or vaccinated with Brucella spp. METHODS AND RESULTS: Serum samples from B. abortus-infected and RB51-vaccinated cattle were tested by the CF test using S99, RB51 and the combined S99/RB51 as antigens. Likewise, serum samples from Brucella melitensis-infected, RB51-vaccinated and Brucella ovis-infected sheep were tested by the CF test using S99, RB51, hot saline (HS) and combined S99/RB51 as antigens. Comparative analysis of the CF results showed that no reduction of sensitivity or specificity occurs when S99/RB51 antigen is used instead of specific antigens used separately. CONCLUSIONS: The results of this study indicated that combined S99/RB51 antigen used in the CF test, because of its specificity and sensitivity, could be used in animal brucellosis surveillance systems to improve the efficiency of the preliminary screening of herds. SIGNIFICANCE AND IMPACT OF THE STUDY: This study proposes an improved antigen for the CF test for the epidemiological survey of animal brucellosis. It could represent advantages over standard protocols because of its ability to detect antibody responses following infection or vaccination withBrucella strains of rough and smooth phenotype.

Animals↗
PubMed2001

Field validation of the use of RB51 as antigen in a complement fixation test to identify calves vaccinated with Brucella abortus RB51.

In order to confirm the efficiency of an experimental RB51-based complement fixation (CF) test in identifying cattle vaccinated with Brucella abortus strain RB51, 831 sera from 110 vaccinated and 48 unvaccinated Hereford heifers of Iowa, collected for studies conducted in different years, were sent to Italy without coding to be tested in a CF test using RB51 as antigen. Most of the calves, aged from 3 to 10 months, were vaccinated subcutaneously with the recommended dosage of 10(10) CFU of RB51 commercial vaccine, while only six calves received 10(9) CFU of the same vaccine. Serum samples for serologic testing, collected until 16 postinoculation weeks (PIW), were also tested by routine surveillance tests for brucellosis such as rose bengal plate and CF tests performed with B. abortus smooth strain 99 as control antigen. RB51 CF test results obtained by testing sera from cattle vaccinated in 1999 indicate that the sensitivity of the reaction is 97% at 2 to 3 PIW and 90% until 8 PIW and decreases to 65% at 12 PIW, the specificity remaining at 100%. Collectively, the results of this study confirm that serologic standard tests fail to detect antibodies to RB51 while the RB51-based CF test is able to monitor antibody responses to RB51 until 15 to 16 PIW with a specificity of 100%. In addition, unlike the RB51-based dot blot assay, which is the only test currently used to monitor antibody responses to RB51, the CF test also detected specific responses following vaccination with 10(9) CFU of RB51, although seroconversion was only 50% at 8 PIW. In conclusion, because of high specificity and sensitivity, the CF test described here can be used to efficaciously monitor serologic responses following RB51 vaccination in cattle and could also be employed to detect RB51 infection in humans exposed to this strain.

Animals↗
PubMed1991

Comparison of seroreactivity of rams with brucellosis in a complement fixation test, whole cell ELISA and by immunoblotting.

In rams with ovine brucellosis, a high degree of serological correlation exists between the complement fixation (CF) test which utilises antigen extracted from bacteria with hot saline, and the ELISA reactivity using methanol-fixed Brucella ovis as the assay reagent. Since the whole cell ELISA (CELISA) detects mainly antibodies against surface antigens of B. ovis, it was concluded that the similar findings of the two serological tests is due in part to the presence of membrane antigens in the CF test antigen following hot saline extraction of intact bacteria. Immunoblots with pooled sera representing different CF titres confirmed that the major immunoreactive antigens of B. ovis were located in four zones: alpha, beta, gamma 1 and 2 with corresponding apparent molecular masses of 55 and 60 kDa; 27 and 29 kDa; 18.5-20 kDa and 17-18 kDa, respectively. These zones of reactivity were consistently present in immunoblots when assayed against different B. ovis isolates even though Coomassie brilliant blue staining of SDS-PAGE gels revealed some differences in polypeptide banding patterns. However, these intensely-stained CBB bands located at 38 and 40 kDa which distinguished three of the seven B. ovis isolates were considerably less reactive in immunoblots compared to polypeptides that were located at positions equivalent to alpha, beta or gamma reactivities. Intensity of immunoblot reactivity against polypeptides located in the alpha, beta and gamma zones intensified with increasing CF titre. Sera with CF titres greater than 32 also tended to react against bands of higher apparent molecular masses located at 65, 70, 73, 78, 80 and 86 kDa.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗