牛布鲁菌病补体结合试验测量不确定度评估

本试验应用补体结合试验方法对牛布鲁菌病进行检测,分别从溶血素效价测定、补体效价测定、抗原效价测定及血清效价测定4个方面分析了补体结合试验测量不确定度来源,并计算了合成不确定度、扩展不确定度,最终样品测量结果报告值为:X=(1.06±0.043) mg/mL(95％置信区间),即本试验中判定的可以抑制50％溶血的血清最高效价所对应的溶血素浓度为1.06mg/mL,不确定度U为0.043.     

Diagnosis of bovine brucellosis by enzyme immunoassay of milk

Enzyme-immunoassays using lipopolysaccharide as antigen were developed for the detection of bovine IgG1, IgG2 or IgA Brucella antibodies (Ab) in milk. The results of these tests were compared with those of the milk ring test (MRT) by analyzing 3212 bulk milk samples from farms located in regions where brucellosis is prevalent. Among the 105 herds detected by ELISA and/or MRT, 29 infected herds were detected by ELISA only. The 40 MRT-positive herds were also ELISA positive. Five herds became infected during the study and were detected by ELISA 15 days to 6 months prior to detection by MRT. The ELISA IgG1 titration (IgG1 ELISA) detected 92.8% of the herds found positive in the three ELISA assays. The concomitant use of IgA ELISA raised the sensitivity to 100% but slightly decreased the specificity. The IgG2 ELISA did not improve the diagnosis. The sensitivity of MRT and IgG1 ELISA was compared by testing successive dilutions in negative milk of 110 individual MRT positive milks samples. On average, IgG1 ELISA was 22 times more sensitive than MRT.     

Assessment of an intradermal test for the detection of bovine brucellosis

Forty-eight cattle were sensitised toBrucella antigens either by vaccination withBrucella abortus strain 19 (S19) orB. abortus 45/20 (S45/20) and 24 of these and 12 unvaccinated cattle were subsequently challenged with virulentB. abortus strain 544 (S544). All these cattle (n=60), together with 12 control cattle which were neither vaccinated nor challenged, were subsequently subjected to an intradermal test using a S45/20 protein antigen. Reactions were interpreted subjectively by observation and palpation and were measured to the nearest mm with calipers at 48 and 72 hours after injection of protein antigen. Ten weeks later the cattle were slaughtered and tissues cultured for the presence ofB. abortus. Two of the 48 vaccinated cattle died, 40 of the remaining 46 gave a positive response to the intradermal test at 48 hours and 36 were positive at 72 hours. In the controls any increase in the skin thickness had disappeared by 72 hours. An increase in skin thickness was still present at 72 hours in all other cattle except those vaccinated with S19 only. The intradermal test was found to be sensitive but not specific in detecting infected cattle and both sensitive and highly specific if used (with the exception of S19) to detect exposure toBrucella antigen.     

The vaginal mucus agglutination test in the diagnosis of bovine brucellosis

Of 1140 vaginal mucus agglutination tests (VMAT) on specimens obtained in 1971-72 from 663 dairy cows in seven herds infected with brucellosis, 97 were positive. When the VMAT was positive one or more serological tests were also positive. Of the 97 corresponding serum agglutination tests 80 sera had titres of more than 533 international units. Only 69.8 per cent of VMAT from serologically positive cows were positive. No evidence was found of non-specific agglutinins in vaginal mucus and positive VMAT reactions appeared to be specific for field infection. Three cows showed evidence of local agglutinins in the vagina. Hence herd testing by VMAT has no advantage over tests of blood serum but the test could be an aid in establishing whether individual cattle are infected.     

Diagnosis of brucellosis by serology

Serological diagnosis of brucellosis began more than 100 years ago with a simple agglutination test. It was realized that this type of test was susceptible to false positive reactions resulting from, for instance, exposure to cross reacting microorganisms. It was also realized that this test format was inexpensive, simple and could be rapid, although results were subjectively scored. Therefore, a number of modifications were developed along with other types of tests. This served two purposes: one was to establish a rapid screening test with high sensitivity and perhaps less specificity and a confirmatory test, usually more complicated but also more specific, to be used on sera that reacted positively in screening tests. This led to another problem: if a panel of tests were performed and they did not all agree, which interpretation was correct? This problem was further compounded by the extensive use of a vaccine which gave rise to an antibody response similar to that resulting from field infection. This led to the development of an assay that could distinguish vaccinal antibody, starting with precipitin tests. These tests did not perform well, giving rise to the development of primary binding assays. These assays, including the competitive enzyme immunoassay and the fluorescence polarization assay are at the apex of current development, providing high sensitivity and specificity as well as speed and mobility in the case of the fluorescence polarization assay.     

Value of the antiglobulin test and indirect immunofluorescence test in the serological diagnosis of bovine brucellosis]

In investigations of 5881 sera from brucella infected herds and 8635 sera from negative herds the antiglobulin test (AgT) because of its high susceptibility was shown to be a valuable method in early diagnosis of brucellosis and clearing of non-specific LA-reactions. However, all infected animals are not detected with the AgT. Therefore it is not adaptable to use in selection controlling, also in combination with other methods. In the final steps of the eradication measures against bovine brucellosis the AgT offers a very valuable serological complementary method. The indirect fluorescence test has no diagnostical advantages in comparison with the AgT and is not recommended for practical brucellosis serology.     

The effects of IgG2 and of antigen concentration on prozoning in the complement fixation test for bovine brucellosis.

Addition of Brucella-specific IgG2 to solutions of Brucella-specific IgG1 initially induced prozoning and at higher concentrations prevented all reaction in the complement fixation test (CFT) for bovine brucellosis. Some infected cattle may be diagnosed as brucellosis-free due to a high ratio of specific IgG2 to IgG1. Increasing the concentration of antigen in the CFT reduced the tendency to prozone.     

A comparison of five serological tests for bovine brucellosis.

Five serological assays: the buffered plate antigen test, the standard tube agglutination test, the complement fixation test, the hemolysis-in-gel test and the indirect enzyme immunoassay were diagnostically evaluated. Test data consisted of results from 1208 cattle in brucellosis-free herds, 1578 cattle in reactor herds of unknown infection status and 174 cattle from which Brucella abortus had been cultured. The complement fixation test had the highest specificity in both nonvaccinated and vaccinated cattle. The indirect enzyme immunoassay, if interpreted at a high threshold, also exhibited a high specificity in both groups of cattle. The hemolysis-in-gel test had a very high specificity when used in nonvaccinated cattle but quite a low specificity among vaccinates. With the exception of the complement fixation test, all tests had high sensitivities if interpreted at the minimum threshold. However, the sensitivities of the standard tube agglutination test and indirect enzyme immunoassay, when interpreted at high thresholds were comparable to that of the complement fixation test. A kappa statistic was used to measure the agreement between the various tests. In general the kappa statistics were quite low, suggesting that the various tests may detect different antibody isotypes. There was however, good agreement between the buffered plate antigen test and standard tube agglutination test (the two agglutination tests evaluated) and between the complement fixation test and the indirect enzyme immunoassay when interpreted at a high threshold. With the exception of the buffered plate antigen test, all tests were evaluated as confirmatory tests by estimating their specificity and sensitivity on screening-test positive samples.(ABSTRACT TRUNCATED AT 250 WORDS)     

Diagnosis of taenia saginata cysticercosis by immunohistochemical test on formalin-fixed and paraffin-embedded bovine lesions.

A new method of diagnosing cysticercus or larval stage of the human tapeworm, Taenia saginata, also known as Cysticercus bovis, in formalin-fixed bovine tissue was developed using a monoclonal antibody to T. saginata and avidin-biotin complex immunohistochemistry. Grossly recognizable viable and degenerate cysts were identifiable after immunohistochemical staining and could be differentiated from Sarcocystis, Actinobacillus, or non-cyst, normal bovine structures. Thenew test should permit laboratory confirmation of suspected T. saginata cysticercus lesions.     

An evaluation of the anamnestic test for brucellosis in cattle of the northern pastoral area

SUMMARY An investigation of the anamnestic test for brucellosis using Brucella abortus 45/20 vaccine was carried out in 3 groups of weaner cattle on 2 farms in western Queensland. Each group originally consisted of about 500 cattle. They were bled before and at 6 or 10 weeks after vaccination and again in the following year. The serums were tested by the complement fixation (CFT), Rose Bengal (RBT) and indirect haemolysis tests (IHLT). Most of the cattle reacting to one or more of the tests were killed and selected tissues were subjected to bacteriological examination for B. abortus. B. abortus was isolated from 19 of 30 (63%) pre-vaccinal reactors, 23 (24%) of 96 cattle reacting at 6 or 10 weeks after vaccination (the anamnestic test) and 1 (2%) of 50 cattle reacting one year after vaccination. The reactor found to be infected the year after vaccination had high serological titres in each of the 3 serological tests: RBT of 3, CFT of 128 and IHLT of 256. A subsequent test showed the group to be brucellosis-free. The CFT was the most efficient test. In the pre-vaccination tests 17 of 19 infected animals were positive in the CFT compared with 11 positive in the IHLT and 17 in the RBT. In post vaccination tests 22 of 23 infected animals were positive in the CFT compared with 18 in the IHLT and 19 in the RBT. At the pre-vaccinal and anamnestic tests (6 or 10 weeks after vaccination) 19 of 57 (33%) cattle with CF titre of 4 or 8 yielded B. abortus on culture compared with none of 26 cattle with similar titres in the year after vaccination. The interpretation of CF titres in cattle following 45/20 vaccination needs to be re-examined.