ELISA法测定牛奶和鸡肌肉中四环素类药物残留

以本实验室研制的四环素类药物多残留检测试剂盒为基础，建立了牛奶和鸡肉中四环素、土霉素、金霉素药和多西环素的ELISA检测方法。该方法对牛奶和鸡肉中四环素的检测限为7μg／L（μg／kg）左右。在牛奶和鸡肉中，4种四环素类药物100μg／L（μg／kg）浓度的添加回收率范围为43．6％～101．4％，批内变异系数小于25％，批间变异系数在30％以内。牛奶的临界值为39．5μg／L，鸡肉的临界值为35.3μg／kg。     

鸡蛋中四环素类药物残留量测定的高效液相色谱法研究

建立了鸡蛋中土霉素、四环素、金霉素、多西环素残留量测定的高效液相色谱法。样品经弱酸性缓冲液提取后,HLB固相萃取柱净化后,反相液相色谱分离测定,本方法的检出限为10μg／kg,定量限为50μg／kg。四种四环素类药物在50～1000ng／mL范围内呈线性相关。在100～400ng／g添加浓度范围内,平均回收率为60％～110％,批内变异系数在3．2％～13．7％之间（n=5）,批间变异系数在0．9％-5．3％之间（n=4）。结果表明,该法简单、灵敏、特异性强,适用于鸡蛋中土霉素、四环素、金霉素、多西环素残留量的测定。     

猪、牛、鱼组织中四环素类药物残留的测定

以本实验室研制的四环素类药物多残留检测试剂盒为基础，建立了猪、牛、鱼组织中四环素、土霉素、金霉素和多西环素4种药物残留的酶联免疫检测方法。该方法在猪、牛、鱼组织中的检测限均低于13μg/kg，4种四环素类药物最高残留限量浓度添加回收率范围为47．5％～119．4％，批内、批间变异系数在25％以内。检测各种组织中四环素类药物的临界值分别为猪肉49．2μg／kg、猪肝138．7μg／kg、牛肉52．1μg／kg、牛肝124．4μg／kg、鱼肉44．1μg／kg。     

直接竞争ELISA法快速检测动物源性食品中磺胺嘧啶残留

采用重氮化-偶联法将磺胺嘧啶（SD）与人血清白蛋白（HSA）相连制备了免疫抗原SD—HSA,与卵清白蛋白（OVA）相连制备了包被抗原SD—OVA,用过碘酸钠法将SD—OVA与辣根过氧化物酶（HRP）连接制备了酶标抗原（SD—OVA—HRP）。用SD—HSA免疫BALB／c小鼠,经融合、筛选和克隆化制备了单克隆抗体,利用单抗建立了直接竞争ELISA方法。该方法具有好的特异性,在1—729ng／mL浓度范围标准曲线方程Y=12．05x＋2．2538,R^2=0．995,IC50为41．7ng／mL,在猪肉、鸡肉、鸡肝、鸡蛋、牛奶中的检测限分别为20、20、20、5、5μg/kg。在20μg／kg和100μg／kg水平猪肉、鸡肉、鸡肝、牛奶、鸡蛋样品中添加,回收率为82．78％-104．6％。与高效液相色谱方法比较,二者的阳性符合率为81．3％,阴性符合率为83．3％,总符合率为88．9％;与同类英国RANDOX试剂盒比较,二者符合率为100％。     

牛奶中四环素类药物残留的确证方法--液质联用法

为了确证牛奶中土霉素、四环素、金霉素的残留，建立了电喷雾高效液相色谱／串联质谱法，采用正离子检测，选择离子方式扫描。牛奶样品经Mcllvaine-EDTA缓冲溶液提取离心后，上清液过C18小柱净化后甲醇洗脱，然后氮气吹干，甲醇-水（30：70）溶解（以去甲金霉素为内标）后进行分析。结果表明，牛奶中土霉素、四环素和金霉素的检测限（LODs）为0．01mg／L，定量限（LOQs）为0．025mg／L。3种药物在0．05～0．5mg／L范围内均呈良好线性关系，并且3个添加浓度的平均回收率范围为70．0％～87．6％，批内变异系数不大于10％，以最大残留限量浓度添加后所测得回收率的批间变异系数小于15％。本方法特异性强、灵敏度高、准确可靠，可作为牛奶及其他动物组织中四环素类药物残留的确证方法。     

进出口植物产品中甲胺磷残留量酶联免疫检测试剂盒的研究

采用直接竞争酶联免疫吸附试验(ELISA)对进出口植物产品中甲胺磷残留量进行快速筛选检测。将O,S-二甲基硫代磷酰氯与牛血清白蛋白偶联作为免疫原,免疫试验兔获得特异性抗体,并成功建立了甲胺磷残留直接竞争ELISA检测方法及检测试剂盒。结果:检测线性范围0.95~500μg/mL,检测低限为1μg/mL;大米、青菜、苹果、西红柿和黄瓜的加标回收率为72.6%~94.3%;重现试验变异系数为5.4%;试剂盒贮藏在4℃5个月和30℃7d质量稳定。表明本试剂盒具有操作简便、准确、快速、灵敏等特点。     

猪肉中四环素类抗生素残留的ELISA检测

采用间接竞争ELISA检测猪肉及内脏组织中土霉素、四环素、金霉素的残留量,在50~300μg/kg浓度范围内,标准添加样品回收率81.3%~122.4%,变异系数2.7%~11.1%。本方法的建立为四环素类抗生素残留的快速检验试剂盒的研制奠定了基础。     

动物组织中磺胺二甲嘧啶残留检测ELISA试剂盒的研制

在建立竞争ELISA方法的基础上，首次研制出检测磺胺二甲嘧啶的单克隆抗体快速检测试剂盒，并对其检测限、精密度、检测范围以及鸡肌肉组织中的添加回收实验做了详细研究。本试剂盒的检测限为1．0ng／m1，检测范围为1．0-81．0ng／m1，批内变异系数＜8．9％，批间变异系数＜9．5％，在10、60和200ng／m1水平鸡肌肉组织中添加，回收率为64．5％-85．5％，变异系数为6．0％-18．6％。与同类相关德国产试剂盒相比较，阳性符合率为100％。     

液相色谱-串联质谱法检测牛奶中的四环素类药物

本文以液相色谱-串联质谱法检测牛奶中的四环素类药物残留,试料中残留的四环素、土霉素、金霉素和多西环素经Mcllvaine-Na2EDTA缓冲液提取,HLB柱净化。用液相色谱-串联质谱法测定,外标法定量。经实验,制得10、20、50、100、200、500 ng/m L的系列标液。以系列标液浓度为横坐标,对应峰面积为纵坐标进行线性回归,四环素、土霉素、金霉素和多西环素在10~500 ng/m L范围内呈现良好的线性关系,R2均大于0.990。四环素、土霉素、金霉素和多西环素在牛奶中的检测限为5 ng/g,定量限为10 ng/g。在10~200 ng/g添加浓度的回收率为70%~120%。批内变异系数≤20%,批间变异系数≤20%。     

多西环素人工抗原的合成与鉴定

将多西环素（doxycycline,DOX）进行化学修饰引入羧基或氨基等活性基团,然后与牛血清白蛋白（BSA）和卵清蛋白（OVA）偶联合成人工免疫原DOX—PABA—BSA、DOX—BSA和包被原DOX—PABA—OVA、DOX～OVA,并用紫外吸收（UV）、凝胶电泳（SDS—PAGE）和EUSA方法对人工抗原进行鉴定;将合成的人工抗原DOX—PABA—BSA、DOX—BSA分别免疫BALB／C小鼠,用间接ELISA方法测定多抗（pAb）效价,用竞争ELISA方法鉴定其敏感性,用交叉反应试验鉴定其特异性。结果表明,二个免疫组6只小鼠血清抗体效价均在1：6400以上,DOXpAb对DOX的50％抑制浓度（IC50）在39．79～53．13μg/L,抗血清与四环素类药物交叉反应很低。本实验为建立多西环素ELISA残留免疫学检测方法和并制备多西环素试剂盒奠定了基础。     

牛奶中替米考星间接竞争酶联免疫吸附检测法的建立

本研究通过棋盘法优化替米考星抗体、包被原浓度,并考察了最佳包被条件,最佳反应温度、时间和酶标二抗最佳反应时间等,建立了替米考星残留的间接竞争酶联免疫吸附试验(ELISA)并应用到牛奶样本的检测。建立的间接竞争ELISA方法半数抑制浓度(IC₅₀)为2.1 ng/mL,牛奶中替米考星的最低检测限(LOD)为2 μg/L。在5、10和20 μg/L添加浓度下,回收率为79.2%~90.1%,变异系数不高于9.0%。与其他常见的大环内酯类药物无交叉反应。本研究建立的替米考星间接竞争ELISA方法灵敏度达到了残留限量标准要求,为开发可用于牛奶中替米考星的快速检测试剂盒奠定基础。     

Establishment of Indirect Competitive Enzyme-linked Immunosorbent Assay for Tilmicosin in Milk

An indirect competitive enzyme-linked immunosorbent assay (ELISA) for detecting tilmicosin residue in milk was developed and applied to milk samples after the determination of dilution of coating antigen and antibody to timicosin by using checkerboard method,and the optimization of coating condition,reaction time and temperature,and reaction time of enzyme-labled secondary antibody.The results showed that the 50% inhibition concentration (IC₅₀) of the indirect competitive ELISA was 2.1 ng/mL and the limit of detection (LOD) of tilmicosin in milk was 2 μg/L.The recoveries of tilmicosin added in milk at 5,10 and 20 μg/L ranged from 79.2% to 90.1% with the coefficients of variation (CV) not higher than 9.0%.The indirect competitive ELISA would not react with other common macrolide drugs.The sensitivity of indirect competitive ELISA developed in the study complied to the maximum residue limit of tilmicosin set by China,and laid the foundation for the test kit of the rapid detection of tilmicosin in milk.     

Technical note: Development of an enzyme-linked immunosorbent assay for the determination of florfenicol and thiamphenicol in swine feed

One polyclonal antibody against florfenicol and thiamphenicol was produced and a competitive ELISA was developed for the detection of florfenicol and thiamphenicol in swine feed. The ELISA gave a 50% inhibiting concentration of 1.02 ng/mL for florfenicol. For swine feed fortified with 0.05 to 3.0 mg/kg, the interassay recoveries of florfenicol and thiamphenicol ranged from 86.4 to 118.6%, whereas intraassay recoveries of both drug ranged from 90.1 to 126.5% with less than 15% CV. Results obtained from HPLC-tandem mass spectrometry indicated this ELISA procedure could be used as a convenient method for rapid screening of florfenicol and thiamphenicol in swine feed.     

Development of a monoclonal antibody against deoxynivalenol for magnetic nanoparticle-based extraction and an enzyme-linked immunosorbent assay

Monoclonal antibody (mAb, NVRQS-DON) against deoxynivalenol (DON) was prepared. DON-Ag coated enzyme linked immunosorbent assay (ELISA) and DON-Ab coated ELISA were prepared by coating the DON-BSA and DON mAb. Quantitative DON calculation ranged from 50 to 4,000 ng/mL for DON-Ab coated ELISA and from 25 to 500 ng/mL for DON-Ag coated ELISA. 50% of inhibitory concentration values of DON, HT-2, 15-acetyl-DON, and nivalenol were 23.44, 22,545, 5,518 and 5,976 ng/mL based on the DON-Ab coated ELISA. Cross-reactivity levels of the mAb to HT-2, 15-acetyl-DON, and nivalenol were 0.1, 0.42, and 0.40%. The intra- and interassay precision coefficient variation (CV) were both <10%. In the mAb-coated ELISA, mean DON recovery rates in animal feed (0 to 1,000 µg/kg) ranged from 68.34 to 95.49% (CV; 4.10 to 13.38%). DON in a buffer solution (250, 500 and 1,000 ng/mL) was isolated using 300 µg of NVRQS-DON and 3 mg of magnetic nanoparticles (MNPs). The mean recovery rates of DON using this mAb-MNP system were 75.2, 96.9, and 88.1% in a buffer solution spiked with DON (250, 500, and 1,000 ng/mL). Conclusively we developed competitive ELISAs for detecting DON in animal feed and created a new tool for DON extraction using mAb-coupled MNPs.     

猪肉和鸡肉中脱氧雪腐镰刀菌烯醇和T-2毒素酶联免疫吸附检测方法的建立

为保障动物源性食品安全,本研究建立了分别检测猪肉和鸡肉中脱氧雪腐镰刀菌烯醇(deoxynivalenol,DON)和T-2毒素残留的间接竞争酶联免疫吸附法.结果显示,该方法在猪肉和鸡肉样本中DON的检测限分别为34.9和43.5 μg/kg,添加回收率为72.7%~97.1%,变异系数小于8.7%;T-2毒素的检测限分别为33.7和28.7 μg/kg,添加回收率为72.1%~95.0%,变异系数小于11.3%.该方法灵敏度高、准确、简便,适用于猪肉和鸡肉中DON和T-2毒素残留的快速检测.     

动物源性食品中齐帕特罗一步法ELISA试剂盒的研制

本研究依据直接竞争ELISA原理建立了齐帕特罗一步法ELISA试剂盒。以齐帕特罗与载体蛋白偶联物作为免疫原免疫新西兰大白兔制得齐帕特罗多克隆抗体,棋盘包被法确定其最佳抗体包被浓度、酶标抗原工作浓度、包被条件、反应时间、底物显色时间等,并对试剂盒的各项技术指标进行确认。结果表明,成功组装了齐帕特罗一步法ELISA试剂盒,并建立了尿液、饲料、奶粉和奶汁,以及组织等样品的前处理方法,检测限均远低于1 μg/kg。该试剂盒线性检测范围为0.15～10 ng/mL,IC₅₀浮动范围0.43～0.79 ng/mL,样品板内、批内、批间的变异系数均小于15%,平均回收率在70%～110%之间,与其同类药物的交叉反应率均小于0.1%。提示,本试验研制的试剂盒重复性、特异性、稳定性等各项指标均符合技术要求,可用于动物源性食品中齐帕特罗药物残留的检测。     

Investigations on the usefulness of the dry chemistry blood anaylsis system SPOTCHEM SP-4410in laboratory diagnosis of cattle

The usefulness of the dry-chemistry blood analyzer, SPOTCHEM SP-4410, for analysis of bovine blood chemistry was studied in a veterinary clinic. The control serum Precipath-U, Boehringer-Mannheim, was used to measure precision within each run and between days. The coefficients of variation (CV) ranged between 1.54% and 4.86%, with the exception of albumin and creatine phosphokinase showing a CV of 6.3% and 10.03% for between-day precision. For methodological comparison bovine serum samples were assayed with both the SPOTCHEM SP-4410 and the automated blood analyzer HITACHI 705, which served as a wet-chemistry reference system. The following analytes were measured: glucose, urea, creatinine, total protein, albumin, total bilirubin and the enzymes AST, CPK and gamma-GT. For hemoglobin, which was measured in heparinized whole blood, the CO oximeter 855, CIBA-CORNING, was used as a reference system. The comparative analysis showed very good correlation in eight of ten parameters and their correlation coefficients (r) ranged between 0.962 and 0.998. Only the correlation coefficients of the analysis of total bilirubin (r = 0.903) and albumin (r = 0.771) were less satisfactory. The recovery test was carried out with the two parameters glucose and blood urea. The recovery of glucose was 93.7% and of urea 98.8%. The SPOTCHEM SP-4410 is easy to use and proved to be reliable and accurate, and therefore it seems to be useful for analysis of bovine blood samples.     

Development and validation of an enzyme-linked immunosorbent assay for feline trypsin-like immunoreactivity

OBJECTIVE: To develop and validate an ELISA for quantitative analysis of feline trypsin-like immunore-activity (fTLI). SAMPLE POPULATION: Purified feline cationic trypsin (fCT) and rabbit anti-fCT antiserum; blood samples from 63 healthy cats. PROCEDURES: A sandwich capture ELISA was developed, using anti-fCT antiserum purified by affinity chromatography that underwent biotinylation. Purified fCT was used for standards. The assay was validated by determination of sensitivity, working range, linearity, accuracy, precision, and reproducibility. A reference range was established by assaying serum samples from the 63 healthy cats. RESULTS: Sensitivity was 1.23 microg/L; working range was 2 to 567 microg/L. Ratios of observed versus expected results for 4 samples tested at various dilutions ranged from 90.0 to 120.7%. Ratios of observed versus expected results for 5 samples spiked with various concentrations of fCT ranged from 82.0 to 101.8%. Intra- and inter-assay coefficients of variability ranged from 9.9 to 11.1% and from 10.2 to 21.7%, respectively. The reference range for serum fTLI measured with this ELISA was 12 to 82 microg/L. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that an ELISA can be used to measure serum fTLI in cats. The ELISA was sufficiently sensitive, linear, accurate, precise, and reproducible for clinical use.     

Protein electrophoresis of psittacine plasma

BACKGROUND: Although protein electrophoresis (EPH) has been widely applied in human and veterinary medicine, it has only recently been implemented in the analysis of avian samples. OBJECTIVE: The purpose of this study was to examine the application of protein EPH to the analysis of psittacine plasma samples. Our goals were to describe protein fraction mobility, establish reference intervals for some common species, determine the coefficient of variation (CV) of the chosen method, and examine the effects of sample handling and sample condition. METHODS: Heparinized plasma samples from several common psittacine species (minimum sample size 50 each) were examined using the Beckman Paragon system and SPEP-II gels. Total protein was measured by refractometry. Reference intervals (95%) were calculated by the rank methods. RESULTS: Fraction migration patterns were found to vary among common psittacine species. Day-to-day CV for the EPH fractions ranged from 2.2% to 10.5%; within-run CV ranged from 4.8% to 10.8%; and total CV ranged from 3.2% to 14.8%. The highest CV was noted for the poorly defined alpha-globulin fraction. Prolonged refrigeration, repeated freeze-thawing, hemolysis, and lipemia altered the results. CONCLUSIONS: Protein fractions from psittacine species were variable in terms of migration pattern and protein concentration, which necessitates the use of species-specific reference intervals. Avian protein electrophoretic patterns and values should be interpreted based on knowledge of the CV associated with the technique as well as on the effects of sample handling and condition.     

Effect of immunotherapy on the serum concentrations of allergen-specific IgG antibodies in dog sera

An ELISA assay which uses horseradish peroxidase conjugated anti-canine IgG and polystyrene microtiter wells for detection of allergen-specific IgG in the serum of dogs is described. Individual allergen blanks were used to account for the variable nonspecific binding among various allergens, and the results observed in milliunits of absorbance were normalized using four reference sera. The coefficients of variation for the intraassay and interassay variability ranged from 1.34 to 12.50% and 4.62 to 9.77%, respectively. The relationship between ELISA results and serum concentrations of allergen-specific IgG was quantified. IgG antibodies with specificity for various allergens were found in the majority of non-atopic individuals and in all atopic subjects. Specific immunotherapy resulted in a rise in the serum concentration of allergen-specific IgG.