Carbon immunoassay--a simple and rapid serodiagnostic test for feline toxoplasmosis

A serodiagnostic test, simpler and more rapid to perform than traditional methods, was sought to identify Toxoplasma gondii antibody in research cats. The reliability and sensitivity of the direct and indirect carbon immunoassay (CIA) tests were compared to each other and to the indirect immunofluorescent antibody (IFA) test. The three tests were used to detect the presence or absence of T. gondii antibody in the sera of 94 cats. The results of this study show that the CIA tests correlate with one another and the IFA test nearly 99%, indicating they are highly reliable. Comparison of titers of the positive sera indicate a high degree of sensitivity as well.     

Rapid dot sputum and serum assay in pulmonary tuberculosis

A rapid direct sputum (Sp.) and/or antibody assay, based on immunoblotting and enzyme immunoassay is described. The test can detect mycobacterial antigens or antibodies in clinical specimens from pulmonary tuberculosis (TB) patients. In this study, 87 sputa, 87 sera and 40 paired sputa and sera were utilized from smear-positive and smear-negative, culture-positive patients; 59 sputa, 37 sera and 22 paired sputa and sera from nontuberculosis respiratory disease patients and 68 sera from healthy controls. The antigen detection in sputum by dot assay has 86.1% sensitivity on active tuberculosis patients, 92.9% specificity, 91.6% positive predictive value (PPV), 88.2% negative predictive value (NPV) and 10.3% error. The antibody assay has 83.6% sensitivity, 95.4% specificity, 94.4% positive predictive value, 85.6% negative predictive value and 11% error. The test performed on paired sputum and serum (Sr.) samples has a sensitivity of 93.3%, which rose to 96.1% on smear-positive and culture-positive patients, but the specificity decreased to 83% in sputum, whereas in serum it was 92%. The results of the assay, combined with clinical and radiological data, could form the basis for starting an earlier course of treatment for tuberculosis.     

Assessment of the serodiagnostic potential of nine novel proteins from Mycobacterium tuberculosis

To identify antigens that would improve the accuracy of serological diagnosis of active tuberculosis, we cloned the genes encoding nine potentially immunogenic secreted or surface-associated proteins of Mycobacterium tuberculosis. Recombinant proteins were reacted with sera from HIV-negative individuals with extrapulmonary tuberculosis (EP-TB) or HIV-positive individuals with pulmonary tuberculosis (TBH). Specific and high level antibody responses were obtained for four recombinant proteins, of which antigen GST-822 was recognized by 60% of EP-TB and 42% of TBH and antigen MBP-506 was recognized by 45% of EP-TB and 61% of TBH. These results suggest that these proteins are strong candidates as subunits in a polyvalent serodiagnostic test.     

结核杆菌可溶性细胞壁抗原与重组38Kd蛋白用于结核病血清学诊断的价值

目的探讨结核杆菌CW抗原和rTPA38蛋白用于结核病血清学诊断的价值。方法以CW和rTPA38蛋白为抗原,LAM为对照,用DICFA检测血清中的抗结核抗体。结果191例肺结核病人血清,用CW、rTPA38和LAM检测的敏感性分别为78．0％、65．5％和72．3％,特异性分别为95．9％、98．4％和95．9％。统计分析显示CW和rTPA38检测肺结核病人血清抗结核抗体的敏感性差异有非常显著性（χ^2=16．230,P〈0．01）。两者检测健康人和非结核组病人血清的特异性差异有显著性（χ^2=3．972,P〈0．05）。检测痰涂片阳性血清86例,发现CW和rTPA38与痰阳的一致率分别为84．9％和69．8％,CW抗原与痰涂片的阳性反应明显高于rTPA38。结论CW抗原有较好的敏感性和特异性,且与痰涂片有较高的符合率,有助于结核病的血清学诊断。     

结核分枝杆菌CysA2抗原的基因克隆、表达及在血清诊断中的应用

目的 克隆并构建结核分枝杆菌CysA2基因原核表达系统,建立基于rCysA2的ELISA并检测rCys A2-ELISA在肺结核患者血清学诊断中的敏感性和特异性.方法 采用PCR扩增CysA2基因,构建CysA2基因原核表达系统.采用SDS-PAGE检测目的重组蛋白rCysA2表达情况,Ni-NTA亲和层析法提纯rCysA2,免疫印迹鉴定rCysA2的免疫反应性.以rCysA2为包被抗原,建立rCysA2-ELISA并用于检测132例血清抗体,其中涂片阳性和阴性肺结核患者血清分别占96例和36例,非肺结核肺部疾病病人血清抗体30例,健康对照血清50例.结果 克隆的CysA2基因与GenBank中相关序列相似性为100％.rCysA2表达量为细菌总蛋白的25.4％.提纯的rCysA2在SDS-PAGE后显示为单一的蛋白条带.rCysA2-ELISA检测涂片阳性和涂片阴性的肺结核患者血清抗体检出率分别为63.5％和61.1％,50例健康对照全部阴性、30例非肺结核肺部疾病患者1例呈现阳性,此方法的灵敏度为62.9％(83/132),特异性为98.8％ (79/80).结论 本研究成功地克隆并构建了结核分枝杆菌CysA2基因及其原核表达系统.以rCysA2为包被抗原的rCysA2-ELISA方法有较高的灵敏度和很好的特异性,能有效检测涂片阴性患者血清抗体,rCysA2有望成为结核病血清诊断的有效候选抗原之一.     

Rapid biochemical test for seed germinability.

Sugar and aminoacids were investigated in sterile distilled water after Pinus pinea seeds had been soaked in it during 24 hours at 37 degrees C. Germination viability decreased with the ageing of the seeds and was accompanied by sugar and aminoacids increase in the exudate. The sugar content from seeds with loss of germinability was about 50 to 80 times greater than that from seeds with good germinability. Paper chromatography showed that there was an increase in mono, di, oligosaccharides and amino-acids in seeds without germinability, but these substances were only found as trace quantities in viable seeds. The methods already described by TKAYANAGI and MURAKAMI to determine germinability could be applied with some modifications to Pinus pinea seeds. The presence of sugar in the exudate could be detected by urine sugar test after 24 hours at 37 degrees C. It was necessary to concentrate the exudate till a final volume of 2 ml.     

Rapid test for determination of urea hydrolysis

A urease test for the rapid determination of urea hydrolysis is described in which diluted urea agar concentrate was used in small amounts with dense inoculum of the test organisms. The method was evaluated and compared with Christensen's urea agar slants by using 728 clinical isolates of gram-negative bacteria. Of the 325 strains of urease-positive Proteus-Providencia-Morganella, 282 (87%) gave positive results within 5 min with the rapid test. Urease activity of 97% of these organisms became evident within 30 min. All 287 isolates which showed no urease activity on Christensen's urea agar also remained negative by this test.     

Development and clinical evaluation of a rapid serodiagnostic test for toxoplasmosis of cats using recombinant SAG1 antigen

Rapid serodiagnostic methods for Toxoplasma gondii infection in cats are urgently needed for effective control of transmission routes toward human infections. In this work, 4 recombinant T. gondii antigens (SAG1, SAG2, GRA3, and GRA6) were produced and tested for the development of rapid diagnostic test (RDT). The proteins were expressed in Escherichia coli, affinity-purified, and applied onto the nitrocellulose membrane of the test strip. The recombinant SAG1 (rSAG1) showed the strongest antigenic activity and highest specificity among them. We also performed clinical evaluation of the rSAG1-loaded RDT in 182 cat sera (55 household and 127 stray cats). The kit showed 0.88 of kappa value comparing with a commercialized ELISA kit, which indicated a significant correlation between rSAG1-loaded RDT and the ELISA kit. The overall sensitivity and specificity of the RDT were 100% (23/23) and 99.4% (158/159), respectively. The rSAG1-loaded RDT is rapid, easy to use, and highly accurate. Thus, it would be a suitable diagnostic tool for rapid detection of antibodies in T. gondii-infected cats under field conditions.     

Rapid test for distinguishing membrane-active antibacterial agents

In the search for antibacterial agents with a novel mode-of-action (MOA) many targeted cellular and cell-free assays are developed and used to screen chemical and natural product libraries. Frequently, hits identified by the primary screens include compounds with nonspecific activities that can affect the integrity and function of bacterial membrane. For a rapid dereplication of membrane-active compounds, a simple method was established using a commercially available Live/Dead(R) Bacterial Viability Kit. This method utilized two fluorescent nucleic acid stains, SYTO9 (stains all cells green) and propidium iodide (stains cells with damaged membrane red) for the drug-treated bacterial cells. The cells were then either examined visually by fluorescence microscopy or their fluorescence emissions were recorded using a multi-label plate reader set to measure emissions at two different wavelengths. The ratio of green versus red was compared to a standard curve indicating the percentage of live versus dead bacteria. Nine known antibiotics and 14 lead compounds from various antibacterial screens were tested with results consistent with their MOA.