首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 93 毫秒
1.
Jiang T  Gong D  Ma LA  Nie H  Zhou Y  Yao B  Zhao J 《Veterinary parasitology》2008,158(1-2):51-56
The entire gene encoding microneme protein 3 (MIC3) from Toxoplasma gondii was cloned into the plasmid pGEX-KG and subsequently expressed in Escherichia coli as a glutathione-S-transferase (GST) fusion protein. The recombinant MIC3 (rMIC3) was purified and evaluated in a latex agglutination test (LAT) as the diagnostic antigen for the detection of antibodies to T. gondii in pig sera. The specificity, stability, and reproducibility of the test were examined. No agglutination was found when the sensitized latex beads were mixed with phosphate-buffered saline (PBS), borate-buffered saline (BBS), normal saline, and negative serum samples. There was no cross-reactivity with the standard positive sera of other pathogens. But intense agglutination occurred with T. gondii antibody positive serum samples. In our study, the coincidence rate of tested positive-sera of the LAT with rMIC3-sensitized latex particles and the ELISA with rSAG1 was up to 92.8%, T. gondii specific antibodies were detected by the LAT in all piglets that were experimentally infected with T. gondii tachyzoites from 8 to 42 days after infection. Our results indicated that the rMIC3 based latex agglutination test appears to be suitable for the detection of T. gondii antibodies at the early stage of infection.  相似文献   

2.
R K Gast  C W Beard 《Avian diseases》1990,34(3):721-728
The antibody response of laying hens to experimental Salmonella enteritidis infection was evaluated in microagglutination, tube agglutination, and rapid whole-blood plate agglutination assays. Hens of three different ages were infected by either oral inoculation or horizontal contact transmission. Blood was collected at weekly intervals, and the presence of specific antibodies was assessed by reaction with antigens prepared from strains of S. enteritidis and S. pullorum. The sensitivity of detection of infected hens did not vary significantly between the assays, as all three tests effectively identified most exposed hens as seropositive. Within each test, however, variation was observed in the detection sensitivity when different antigens were used. The microagglutination titers of serum samples were determined by serial dilution. Antibody titers peaked at 1 to 2 weeks postinoculation and declined steadily, although most birds were still identified as seropositive at 10 weeks postinoculation. The mean microtest titers obtained with S. enteritidis antigens were higher than with an S. pullorum antigen, indicating greater test sensitivity. However, use of the S. pullorum antigen resulted in fewer false positives when sera from uninfected control hens were tested. The titers of contact-exposed hens peaked later and at lower values than did those of inoculated hens, but these two groups of hens had similar antibody titers after the third week postinoculation.  相似文献   

3.
重组M蛋白-乳胶凝集试验检测PRRS病毒血清抗体的研究   总被引：19，自引：0，他引：19  
利用纯化的 PRRS病毒重组 M蛋白致敏乳胶制成乳胶抗原 ,成功地建立了一种检测 PRRS病毒血清抗体的乳胶凝集试验 (L AT)诊断方法。用制备的乳胶 M抗原分别检测猪瘟、猪伪狂犬病、猪细小病毒病、猪弓形体病、猪衣原体病、猪乙型脑炎阳性血清 ,结果均为阴性 ,无交叉反应 ,说明建立的 L AT方法具有良好的特异性。用建立的乳胶凝集试验方法与国外IDEXX公司 PRRS病毒抗体检测试剂盒同时对 76份猪血清样本进行检测 ,结果表明建立的 L AT方法的特异性和敏感性均为 95 % ,两种方法的总符合率为 87% ,检出率基本一致。研究结果表明 L AT方法具有操作简便、快速、敏感性高、特异性强、价格低廉且可用于现场检测等优点 ,是一种适合基层兽医单位用于 PRRS病毒血清抗体检测的新方法  相似文献   

4.
Eight pregnant goats were inoculated orally with 10 to 1,000 oocysts of Toxoplasma gondii at 83 to 102 days of gestation. Serum samples from the goats and from the kids born to them were analyzed, using the Sabin-Feldman dye test (DT), a commercially available modified agglutination test (MAT), and a latex agglutination test. Six of the does were observed for greater than 1 year; during this time, they delivered twice. All does developed DT and MAT antibody titers of greater than or equal to 1:2,048 within 29 days after inoculation, and the high titers persisted through the 2nd pregnancy; therefore, serologic results alone should not be relied on for the diagnosis of T gondii-induced abortion in does. On the other hand, all transplacentally infected kids had DT or MAT antibody titers of 1:2,048 before ingesting colostrum, indicating the usefulness of serologic evaluation of the fetus or stillborn kid in the diagnosis of abortion. Antibody was not found in the sera of noninfected kids born to Toxoplasma-infected does. The passively acquired colostral antibody declined by 5 months. Therefore, specific antibody found in adult goats is probably actively acquired. The commercially available MAT was simple, sensitive, and reliable for the diagnosis of caprine toxoplasmosis. The latex agglutination test needs further improvement, as titers rarely exceeded 1:256.  相似文献   

5.
The sensitivity, specificity, accuracy and predictive values of counter immunoelectrophoresis (CIE), latex agglutination (LA) and coagglutination (CoAg) tests were compared for detection of pneumococcal antigen in cerebrospinal fluid (CSF) of patients suspected of meningitis. A total of 95 CSF samples comprising 15 culture proven, 47 clinically suspected but culture negative cases of meningitis and 33 controls were screened by above tests. Among three tests, LA was found to have high sensitivity and moderately high negative predictive value than CIE and CoAg tests. However, CIE had slightly better specificity than LA and CoAg tests. Accuracywise CIE and LA tests were comparable than CoAg test. CIE and LA tests had high positive predictive value than CoAg test.  相似文献   

6.
Nineteen pregnant (45 to 90 days of gestation) and 9 nonpregnant ewes were inoculated orally with 1,000 or 10,000 oocysts of Toxoplasma gondii. Pregnant ewes were euthanatized at days 14 (2 ewes), 21 (1 ewe), 23 (1 ewe), 28 (2 ewes), 35 to 42 (6 ewes), and 49 to 62 (6 ewes), and antibody titers in fetal and maternal sera were assayed, using the modified agglutination, latex agglutination, indirect hemagglutination, and dye tests. Although all ewes developed antibody titers of greater than or equal to 1,024 within 28 days after inoculation, fetuses were seronegative up to 28 days, using the modified agglutination test. Toxoplasma gondii antibodies were found in fetuses, using the modified agglutination and dye tests 35 days after ewes were inoculated. Latex agglutination and indirect hemagglutination tests were insensitive for detection of T gondii antibodies in ovine fetal sera. Toxoplasma gondii antibody titers in nonpregnant ewes were similar to those in pregnant ewes. Passively acquired T gondii antibodies from the colostrum decreased from 1,024 to less than 16 between 49 and 56 days of age in 1 lamb and between 62 and 106 days in its twin.  相似文献   

7.
The attenuated SA14-14-2 strain of Japanese encephalitis virus (JEV) was cultured in BHK-21 cells. The viral supernatant was purified and concentrated with PEG (MW 20 000). A suitable concentration of JEV antigen was used to sensitize latex to prepare the latex antigen. The specificity, sensitivity and stability of the antigen were assessed. A latex agglutination test (LAT) was developed for rapidly detecting antibody against JEV infection. The LAT and haemagglutination inhibition (HI) assay were compared by simultaneously testing 35 porcine serum samples from five farms. Ninety per cent (20/23) of the samples were seropositive by both assays. No significant difference was found between the two methods (p > 0.05). Furthermore, when 1613 porcine sera from 120 farms were tested by LAT, the number of positive sera was 652, while that of negative sera was 961, ranging from 20% to 50% positive throughout the year. These results indicate that LAT is an appropriate candidate method for epidemiological surveys for and diagnosis of Japanese encephalitis.  相似文献   

8.
Latex beads agglutination (LA) for the detection of the antibody against virus infection-associated (VIA) antigen of foot-and-mouth disease (FMD) virus was estimated using experimentally infected animals. The VIA antibody titer by the LA test were compared with the neutralization titer and the titer by agarose gel diffusion (AGD) test, which has been used as a standard method for VIA antibody titration. The latex beads were coated with VIA antigen in carbonate buffer solution (0.5 M, pH 9.6) for the test. The sensitivity of the LA test was clearly higher than that of the AGD test in the results for cattle and swine infected experimentally. The antibody was detected in the bovine serum obtained at the 13th week after inoculation by the LA but not by the AGD test. The LA test appears to be simple, rapid and sensitive for the detection of the antibody of FMD virus in the surveillance of FMD and the FMD quarantine of imported animals.  相似文献   

9.
Enzyme-linked immunosorbent assay (ELISA) is compared with the indirect fluorescent antibody test (IFAT), the indirect haemagglutination test (IHAT) and the latex agglutination (LA) test for the detection of toxoplasma antibodies in swine sera. The 100 swine sera examined represent ELISA values from greater than 0 to 154 EIU. The agreement was highest (0.67) between ELISA and IFAT with an ELISA cut-off value of 30 EIU, and between ELISA and the LA test with an ELISA cut-off value of 50 EIU (0.74). All sera giving less than 10 EIU were negative in the other tests, and all those with greater than 70 EIU were positive in 1, 2 or all of the reference tests. In order to avoid false positive results with ELISA, all sera giving 10-70 EIU should be confirmed with a test which has a good specificity, e.g. IFAT. ELISA is a sensitive test and is highly suitable for the screening of large amounts of samples, but it may be too complicated for screening toxoplasma antibodies in the laboratories of abattoirs.  相似文献   

10.
A commercial cryptococcal antigen latex agglutination test was used to evaluate sera from 20 cats with cryptococcosis and 184 cats without cryptococcosis. Cryptococcal antigen was detected in the sera from 19 of 20 cats with cryptococcosis. Antigen was not detected in sera from any of the cats without cryptococcosis. The test had sensitivity of 95% and specificity of 100%.  相似文献   

11.
A 0.8 kb DNA fragment encoding the major epitope domain of glycoprotein E (gE) of pseudorabies virus (PRV) was inserted downstream of the T7 promoter of an expression vector, pET-28b, to yield the recombinant plasmid pETgE804. After induction by isopropy1-β-D-thiogalactopyranoside (IPTG), a high level expression of fusion protein was obtained. SDS-PAGE and western immunoblotting analysis showed that the fusion protein was 38 kDa and could bind with antisera against PRV. The protein existed mainly in the form of the inclusion body. After being denatured and renatured, the protein was used to prepare the latex antigen. The concentration of antigen, temperature and time for sensitization were optimized. The latex agglutination test (LAT) was able to differentiate sera of PRV-infected pigs from those of gE-deletion vaccine-immunized pigs. The diagnostic specificity and sensitivity of the developed gE latex agglutination test (gE-LAT) were also evaluated by using sets of sera. The diagnostic specificity and diagnostic sensitivity of the gE-LAT were 96.77% and 95.76%, respectively. For comparison between gE-LAT and a commercial blocking enzyme-linked immunosorbent assays (ELISA), 260 serum samples were tested. The coincidence frequency of both assays was 96.94% (252/260). No significant difference was found between the two methods (p>0.05). For comparison between the abilities of gE-LAT and gE-ELISA to detect sera with low titres of gE-specific antibody, 66 sera from 22 pigs were tested. The data indicate that the gE-LAT is of similar sensitivity to gE-ELISA. These results indicate that gE-LAT using recombinant gE might be very useful as a routine screening method for the differential diagnosis of PRV infection.  相似文献   

12.
Latex agglutination test for canine parvovirus   总被引：1，自引：0，他引：1  
Canine parvovirus (CPV) was detected in faeces from dogs with diarrhoea by a specific slide agglutination test using latex particles coated with anti-CPV monoclonal antibody (LA-anti-CPV). The agglutination of LA-anti-CPV with CPV on a glass slide was evident macroscopically within 2 min. The sensitivity of the latex agglutination (LA) test was similar to that of the hemagglutination test. The LA test is available for the rapid diagnosis of CPV infection at an animal hospital.  相似文献   

13.
An agglutination test with the use of formalin-killed antigen of the cell carrying the capsule was developed and used for the detection of antibody in swine naturally infected with Bordetella bronchiseptica. Under optimum antigen concentration and reaction temperature 210 or 60% of 342 serum samples tested from 42 conventional swine herds were positive for Bordetella infection. In contrast, only 34 or 10% of 342 nasal swabs from the same animals were positive for Bordetella by culture technique. The test was relatively free of cross-reactivity to related organism. However, 2.7 and 13.0% of sera from growing pigs and mature hogs, respectively, reacted with antigen of Pasteurella multocida. Because of this, only agglutinin reactions in 1:20 dilutions or higher to Bordetella were considered positive. The bulk of the antibody activity of selected sera tested from various age ranges of swine was mercaptoethanol sensitive, suggesting that serum antibody in Bordetella infection may be associated with immunoglobulin IgM. Because of the high agglutinability and stability of formalin-killed antigen the test may be useful as an auxiliary aid for the diagnosis of Bordetella infection where the organism cannot be identified by culture means.  相似文献   

14.
Comparison was made among results of cloacal specimen culture, and cloacal swab specimen (cytologic) peroxidase-antiperoxidase (PAP), serum latex agglutination (LA), and tissue PAP assays for diagnosis of chlamydiosis in 144 birds. Swab specimen PAP findings correlated poorly with LA results and failed to predict the LA test result in any bird. Only 1 cloacal swab specimen was regarded as PAP-positive and was from the cloaca of a bird from which chlamydiae were isolated in culture. The sensitivity of swab specimen PAP, compared with culture results, was 33%, whereas specificity was 94%. In this study, swab specimen PAP was a less sensitive test, compared with culture, than was reported in a previous study. The sensitivity of LA in identifying birds that were cloacal culture-positive was poor; true-positive results were not detected, compared with culture results. The specificity of the LA method was 93%, compared with culture results. Results of the tissue PAP method correlated with culture results in the 3 birds for which both tests were performed.  相似文献   

15.
Thirty 5-month-old red-legged partridges (Alectoris rufa) reared in battery were divided into five groups: 4 birds in group A, 14 birds in group B, 4 birds in group C, 4 birds in group D and 4 birds in group E, and were inoculated orally with 10, 50, 10(2), 10(3) and 10(4) oocysts of the OV-51/95 strain of Toxoplasma gondii, respectively. During the experiment, blood samples from all birds were drawn every 3-7 days and at necropsy. Serologic response was measured by the modified agglutination test (MAT) and the latex agglutination test (LAT). One bird from each group was killed at 44, 58, 65 and 72 days after inoculation (DAI). From 72 DAI to the end of the experiment, surviving partridges from group B were killed at weekly intervals. The last partridges were sacrified 100 DAI. MAT was the most sensitive and specific test for detecting T. gondii antibodies in the birds. First positive titers were detected by MAT in all sera on 7 DAI, but titers by LAT did not appear until 13 DAI. Antibody titers detected by MAT on 7 DAI were higher in the partridges with the largest inocula (10(3) or 10(4) oocysts) than those inoculated with 10, 50 or 10(2) oocysts. All surviving birds developed a serologic response to T. gondii, with maximum titers of 512-32,768 in the MAT on 13-17 DAI, and positive titers persisted at least until 100 DAI. To the contrary, LAT reveals only very low antibody titers even in partridges inoculated with the highest dose of T. gondii.  相似文献   

16.
A simple lated agglutination test (LAT) for the diagnosis of Babesia bovis and Anaplasma marginale infection in cattle was developed using cell culture-derived soluble antigens to sensitize latex particles. The conditions to perform the test were established as follows: a 2% suspension of polystyrene latex particles (0.8 μm diameter) in 0.15 M glycine buffer pH 8.3 containing 0.2% disodium-EDTA was used to sensitize an equal vlume of antigen at a final antigen concentration between 0.625×–1.25× of the original antigen concentration of the supernatant culture medium. The latex particles were sensitized for 15 min at 56°C, The test, which uses heat-inactivated sera, was performed at room temperature by mixing one drop of each antigen and serum on a glass slide. T he LAT showed a high degree of specificity and sensitivity when compared with the babesiosis indirect fluorescent antibody (IFA) and anaplasmosis capillary tube-agglutination (CA) tests. The LAT possesses appropriate stability and simplicity suitable for field purposes.  相似文献   

17.
Antibody to smooth Brucella abortus lipopolysaccharide antigen on the surface of polystyrene tubes was detected with peroxidase-labeled antibody against bovine immunoglobulin G. The enzyme-labeled antiglobulin test (ELAT) activity of samples was expressed in arbitrary units/0.01 ml by reference to a standard curve based on tests of dilutions of a positive serum pool. Reactions greater than 3.0 U/0.01 ml were classified positive because specificity at this level was 99.8% (417/418 samples correctly classified negative) with agglutination test-negative sera from 33 Brucella-free herds. Results of the ELAT were compared with results of agglutination tests and the complement-fixation test (CFT), using 430 sera from cattle in 7 infected herds. Activity of greater than 5.0 ELAT U/0.01 ml was detected in all 54 sera classified as positive (titer greater than 1:10) by the CFT, including 5 sera classified as negative by the tube agglutination test. Sera from 8 nonvaccinated cows in the infected herds reacted only by the ELAT, whereas reactions were obtained with 25 and 5 sera by only agglutination tests and the CFT, respectively. The ELAT and CFT results were in agreement for 25 of 26 sera from agglutination test-reactor cattle in herds of unknown status. Comparisons of milk ring and whey agglutination tests with the whey ELAT on 146 quarter samples from cows in an infected herd revealed no ELAT activity greater than or equal to 1.0 U/0.01 ml in the 73 samples considered negative by the 2 other tests. Samples (n = 47) that contained greater than or equal to 1.0 ELAT U/0.01 ml included all (n = 40) samples with milk ring or whey agglutination titers greater than or equal to 1:16 and greater than or equal to 32, respectively, and 7 samples that gave weaker reactions to the latter tests.  相似文献   

18.
A latex agglutination test for detecting Echinococcus multilocularis coproantigen in definitive hosts was developed using latex beads sensitized with EmA9 monoclonal antibody raised against somatic antigens of adult E. multilocularis. A primary test (LA 1) was performed on 82 fecal samples of necropsied foxes, of which 46 were infected, and resulted in 61% sensitivity and 86% specificity. To increase the sensitivity, 4 ng/mL of excretory/secretory antigens of adult worms was added to the samples in a secondary test (LA 2), resulting in 91% sensitivity and 61% specificity. The positive predictive value of the LA 1 test and the negative predictive value of the LA 2 test were both 85%. The combination of the LA 1 and LA 2 tests is applicable and practical for use in situations that require quick diagnosis or screening based on the following interpretation: the samples that are positive in the LA 1 test are positive; the samples that are negative in the LA 2 test are negative; and the samples that are negative in the LA 1 test and positive in the LA 2 test are classified as suspicious.  相似文献   

19.
A rapid recombinant antigen-based latex agglutination test (LAT) has been developed to detect specific anti-leptospiral antibodies from human and dog sera. The recombinant LipL32 antigen developed and used for detecting the antibodies is specific in detection of the pathogenic serovars of Leptospira as the expression of the LipL32 antigen is restricted only to the pathogenic leptospires. The sensitized latex beads are stable and could be stored at 4°C for more than three months without showing loss of activity for both weakly and strongly positive samples. The test is found to be sensitive, specific and accurate as compared to the standard microscopic agglutination test (MAT). Moreover, the recombinant antigen-coated latex beads could detect the specific anti-leptospiral antibodies in the acute phase of the illness. The test is simple and inexpensive, and is rapid in the management of large numbers of patients.  相似文献   

20.
Goats housed in microbiologically secure facilities were experimentally endobronchially infected with Mycoplasma capricolum subsp. capripneumoniae (Mccp), causal agent of contagious caprine pleuropneumonia (CCPP). The animals were monitored over an 8-week period post-infection (p.i.). Elevated temperatures were observed 2-7 days p.i., reaching a maximum of 41.5 degrees C in one animal (1884). By 8 weeks p.i. the infection was successfully cleared, with no Mccp being recovered from the lungs, serum or nasal passages. Mccp was not isolated from serum throughout the experiment, either directly by culture or indirectly via polymerase chain reaction (PCR). Humoral immune responses against Mccp capsular polysaccharide (CPS) were generally poor when measured by ELISA. CPS antigen was present in the serum of all infected animals early in the infection (day 14 p.i.), although in one animal (1855) CPS antigen persisted throughout. This was the only animal to exhibit a serious cough (day 5-19 p.i.). Successful diagnosis of CCPP was achieved using two different types of latex agglutination test (CPS antibody and CPS antigen detection test), immunoblotting and a blocking ELISA, although the latter lacked sensitivity until later in the infection (35-40 days p.i.). Only a single animal (1855) was detected positive using the current complement fixation test (CFT). Strong immune responses to protein antigens were detected by IgG and IgM immunoblotting from the first time point at day 14 p.i. IgM immunodominant bands of 220, 85, 62 and 40kDa were observed in the 3 infected animals and from CFT-positive CCPP field sera. Band intensity gradually diminished throughout the experiment. IgG immunodominant bands of 108, 70, 62, 44, 40 and 23kDa were shared between experimentally-infected and field sera, with band intensity either remaining unchanged or increasing from day 14 p.i. These bands were not present using pre-infection sera. Of the diagnostic tests used, only the CPS antibody detection latex agglutination test and IgG immunoblotting gave positive diagnoses throughout the entire period post-infection (days 14-53 p.i.).  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号