双抗原夹心法检测抗HIV-1/2总抗体方法的建立和评价

目的 进一步提高HIv感染诊断试剂的敏感性。方法 以人工合成的HIv—1 gp41．1(sP1)、gp41．2(sP2)、gp120(sP3)、P24(sP4)和HIV—2gp36(sP5)5条多肽，采用双抗原夹心酶链免疫吸附试验(ELISA)原理，以sP1、sP3、sP4和sP5混合包被酶标板作为因相抗原，辣根过氧化物酶标记sp1、sp2、sP4和sP5多肽为标记物，建立了检测抗HIV—1／2总抗体的双抗原夹心ELISA法。结果 检测卫生部药品生物制品检定所第2代40份质控参比血清，其特异性和灵敏度均为100％，高于间接ELISA法(特异性为90％，灵敏度为65％)。检测210份其他病种患者血清均为阴性，与雅培HIVAB试剂比较检测如份健康献血员血清和88份HIv感染者血清，符合率为100％。结论 本方法特异性强、敏感性高，操作简便，适用于献血员的筛选和临床HIv感染的检测。     

Development of a sensitive solid-phase radioimmunoassay technique for quantification of class-specific Escherichia coli antibodies

A specific and sensitive, quantitative solid-phase radioimmunoassay (RIA) has been developed for the detection of Escherichia coli antibodies in serum and secretions. Preparation of affinity-purified anti-E. coli standards allows accurate quantification of G, M and A classes of antibody down to 10 ng/ml using only 20 microliters of sample. This technique has considerable advantages over indirect haemagglutination in sensitivity and accuracy of immunoglobulin class detection. RIA also compares favourably with ELISA in sensitivity and sample size required. Affinity-purified standards may also be used to quantify the ELISA test.     

Dot-based ELISA and RIA: Two rapid assays that screen hybridoma supernatants against whole live cells

Two assays are described that are suitable for the screening of large numbers of hybridoma supernatants as well as for the screening of a wide range of tissues for the distribution of a given cell surface antigen. These assays use whole live cells as targets, avoiding fixation or extraction, which could alter the antigenic structural profile. The assays are rapid, simple and inexpensive. Their advantages and applications are discussed.     

检测抗HIV-1/2型抗体的双抗原夹心方法的建立及其试剂盒的研制

目的 建立更敏感的检测人免疫缺陷病毒（HIV）抗体的方法,并研制检测试剂盒。方法 根据HIV－1／2型的基因序列及其所编码氨基酸结构,采用固相法合成了HIV－1型的gp41.1、gp41.2、gp120、p24和HIV－2型的gp36五条多肽,混合包被酶标板作为固相抗原。用辣根过氧化物酶标记以上多肽抗原作为标记物,建立检测血清中抗HIV－1／2抗体的双抗原夹心ELISA法。同时,应用该方法制备检测HIV抗体的试剂盒,并检测三批中国卫生中药品和生物制品检定所HIV诊断试剂国家参比品。结果 建立了检测HIV－1／2抗体的双抗原夹心法。用检定所参比品检测,该方法特异性、灵敏度均为100％,变异系数小于10％。与间接法相比较其灵敏度、特异性均高于间接法（P＜0．05）。检测210份其他病种患者血清均为阴性。与GBI公司的HIV抗体诊断试剂比较,检测40份卫生部药品和生物制品检定所提供的质控参比品（阳性20份,阴性20份）,GBI试剂阴、阳性符合率及总符合率分别为100%(20/20)、85％（17／20）及92．5％（37／40）,而应用该方法所研制的诊断试剂盒、阳性符合率及总符合率为100％。该试剂已通过国家卫生部质检。与雅培公司HIV诊断试剂比较检测90份献血员血清和88份HIV－1／2型感染者血清,符合率为100％。试剂盒于37℃放置4d后的检测结果的阴、阳性判定不受影响。结论 本法特异性强、灵敏度高、稳定性好,适用于献血员的筛选和临床HIV感染的检测。     

Hepatic microsomal alterations during chronic trypanosomiasis in the field vole, Microtus montanus

The field vole, Microtus montanus, was used as a model system to evaluate the chronic effects of infection by Trypanosoma brucei gambiense on hepatic mixed-function oxidase activity. At day 28 post inoculation there was a 97% increase in liver wet weight per g body weight. A portion of the increase (21%) was accounted for by tissue edema which occurred after day 14 of infection. Total hepatic cytochrome P-450 content and related total tissue mixed-function oxidase activities were decreased to about 60% of control levels at day 28 post inoculation. The decrease in total tissue mixed-function oxidase activity was partly due to a small decrease in microsomal protein per cell, and partly to a large decrease in cytochrome P-450 concentration in the endoplasmic reticulum. Although the decrease in total liver monooxygenase activity in several substrates roughly paralleled the loss in cytochrome P-450 content, several other microsomal enzyme markers not related to cytochrome P-450 monooxygenation were elevated in proportion to total liver microsomal protein content. The results suggest that in M. montanus during trypanosomiasis, there is proliferation of hepatic cells with normal content of endoplasmic reticulum. Furthermore, there appears to be selective toxicity for hepatic cytochrome P-450 and related monooxygenase activities. This may compromise the animals' ability to metabolize and dispose of other drugs to which the animal may be exposed in the course of infection.     

Characterisation of monoclonal antibodies to adrenocorticotrophin

We have produced 8 monoclonal antibodies to adrenocorticotrophin (ACTH) derived from immunisation with ACTH (1-24) conjugated to bovine serum albumin or ACTH (1-39) linked to chicken immunoglobulin by a novel method. Antibody specificity was assessed by studying the binding of purified human ACTH, synthetic ACTH (1-24), fragments of ACTH and peptides from the ACTH precursor molecule which have sequence homology. A wide range of specificities was demonstrated. Thus antibody 3H9 recognises the extreme N-terminal sequence (ACTH 4-10), antibody 1A12 is specific for residues 10-18 including alpha MSH, antibody 1D1 is specific for the mid N-terminal sequence but not alpha MSH, and antibody 2A3 is specific for the C-terminal portion (ACTH 18-39). These monoclonal antibodies can be easily purified and labelled and their defined specificities make it possible to select antibody combinations which provide the basis for 2-site immunometric assays for ACTH.     

Both nicotinic and muscarinic receptors mediate catecholamine secretion by isolated guinea-pig chromaffin cells

We have studied the roles of nicotinic and muscarinic receptors in the acetylcholine-evoked secretion of catecholamine from guinea-pig chromaffin cells. Isolated guinea-pig chromaffin cells secrete catecholamine in response to acetylcholine, nicotine, and a variety of muscarinic agonists. Optimal concentrations of acetylcholine (50-200 microM) induce the release of 10-25% of the catecholamine content of the cells in 10 min. Maximal secretion evoked by nicotine or by muscarinic agonists is 5-12% of the catecholamine content of the cells. Secretion evoked by optimal concentrations of nicotine (50 microM) and muscarine (200 microM) are additive, and together these agonists cause catecholamine release equivalent to that produced by optimal concentrations of acetylcholine. Atropine causes a biphasic inhibition of acetylcholine-induced catecholamine secretion; low concentrations of atropine (0.02-0.01 microM) inhibit by 35-45% the catecholamine secretion evoked by 100 microM acetylcholine. Increasing the atropine concentration from 0.1 to 5 microM causes no further decrease in acetylcholine-evoked release, but at concentrations above 5 microM, a second distinct phase of inhibition appears. At 100 microM, atropine reduces acetylcholine-evoked secretion by 85%. At 0.1 microM, atropine significantly inhibits secretion induced by muscarinic, but not nicotinic, agonists. Tubocurarine (50 microM) does not block muscarinic stimulation of release, but inhibits acetylcholine- and nicotine-evoked release by 70 and 80%, respectively. Our experiments indicate that nicotinic and muscarinic stimulation represent distinct mechanisms for the activation of catecholamine release from guinea-pig chromaffin cells.(ABSTRACT TRUNCATED AT 250 WORDS)     

Somatostatin and substance P inhibit catecholamine secretion from isolated cells of guinea-pig adrenal medulla

Chromaffin cells isolated from guinea-pig adrenal glands secrete catecholamines in response to acetylcholine, nicotine, pilocarpine, veratridine, and high [K⁺]. Both substance P and somatostatin inhibit acetylcholine-induced catecholamine secretion. The maximal inhibition of acetylcholine-induced catecholamine secretion produced by substance P and by somatostatin is approximately 60%: the concentrations of the peptides required for half-maximal inhibition of secretion are approximately 0.8 and 2 μM. respectively. The maximal inhibition of catecholamine secretion produced by somatostatin and that caused by substance P are not additive. The effects of the peptides on secretion are readily reversible. Somatostatin and substance P also inhibit nicotine-induced catecholamine secretion, but they do not inhibit catecholamine secretion stimulated by pilocarpine, veratridine, or high [K⁺]. Thus, these peptides specifically inhibit catecholamine secretion linked to stimulation of nicotinic receptors. The inhibition of acetylcholine-induced catecholamine secretion by somatostatin is noncompetitive with respect to acetylcholine, Na⁺ or Ca²⁺.Immunoreactive somatostatin and substance P are present in guinea-pig adrenal glands. It is suggested that these peptides may play a role in the regulation of catecholamine secretion from the adrenal medulla.     

A potential radioimmunoassay system for detection of Hanganutziu-Deicher type heterophile antigen(s) and antibodies in tissues and fluids

A relatively simple, specific and sensitive radioimmunoassay system has been developed for the detection of heterophile Hanganutziu-Deicher (H-D) antigen(s) and antibodies. The 125I-labeled H-D antigen-active molecule used for the assay is a bovine erythrocyte major glycoprotein previously found to have a strong H-D antigen potency. The antigen-antibody complex was precipitated with normal human serum as the carrier protein, followed by the addition of rabbit anti-human IgG F(ab')2 serum. With this method, different H-D antigen-active molecules were compared for heterophile H-D antigen potency with reasonable sensitivity detecting about 0.3 ng of cold glycoprotein. 8 different lung cancer tissues were assayed for H-D antigen. The sera from the 8 lung cancer patients were also screened by ELISA and RIA in an attempt to correlate expression of H-D antigen on tissues with elevation of H-D antibodies. The results showed that all patients' tissues expressed the antigen(s) but only 3 of them had abnormal levels of H-D antibodies. This could have been due to excess antigens in circulation or immune complexes.     

An enzyme immunoassay for the detection of staphylococcal protein A in affinity-purified products

Rabbit antiserum, specific for protein A from Staphylococcus aureus, was conjugated to alkaline phosphatase and used in a double antibody solid-phase enzyme immunoassay. The assay was developed to monitor eluate from a large-scale protein A-Sepharose affinity column used to purify monoclonal antibodies for human clinical trials. The assay detected soluble protein A in the presence of immunoglobulin at concentrations as low as 4 ng/ml. Analysis of the product purified by affinity chromatography revealed the presence of protein A at ng/ml concentrations. The assay developed here can provide a reliable and convenient method for detecting soluble protein A.     

Simple solid-phase radioimmunoassay for human leukemia-associated cell membrane antigens

In the present study, a simple solid-phase radioimmunoassay was developed to determine detergent-extracted human leukemia-associated cell membrane antigens. In the assay, 96-well microtiter plates are coated with human leukemia cell membrane antigens containing a T cell leukemia or a non-T cell leukemia antigen in the presence of a detergent, and treated with 1.6% bovine serum albumin solution. The coated antigens were reacted with an appropriate murine monoclonal antibody (mAb), i.e., SN2 or SN3, which defines a T leukemia antigen or a non-T leukemia antigen, respectively. The bound mAb is determined by a second reaction with 125I-labeled F(ab')2 of goat anti-mouse Ig. The effect of the following detergents on the assay was investigated: Nonidet P-40 (NP-40), Renex 30, deoxycholate, 3-[(3-cholamidopropyl)-dimethylammonio]-1-propanesulfonate (CHAPS) and taurocholate. The best antigen dose-dependent antibody binding results were obtained using the plates coated with antigens in the presence of taurocholate, a rarely used detergent, whereas no significant antibody binding was observed in the assays using 2 nonionic detergents, i.e., NP-40 and Renex 30. In addition, the usefulness of the present assay with taurocholate during the purification of the antigens was demonstrated. It is very likely that the present solid-phase radioimmunoassay using taurocholate will also be useful in determining other non-leukemia cell membrane antigens.     

ELISA法和RT-PCR法在麻疹病毒检测中的应用比较分析

目的 探讨酶联免疫吸附试验(enzyme linked immunosorbent assay,ELISA)和实时荧光定量PCR(quantitative real-time PCR,RT-PCR)对疑似麻疹病例的麻疹病毒的检测,为疾病的尽早确诊及治疗提供实验依据.方法 以上海市宝山区2014年4月至2015年12月的250例疑似麻疹病例为研究对象,采集其血清标本和咽拭子标本,分别应用ELISA法检测患者血清中的麻疹特异性的免疫球蛋白M(immunoglobulin M,IgM)抗体和RT-PCR法检测咽拭子中麻疹病毒的核酸.结果 250例疑似麻疹病例,排除风疹病毒阳性的34例病例,其中麻疹病毒(measles virus,MV) IgM抗体呈阳性的有80例,阳性率为37.04％;MV RT-PCR呈阳性的有128例,阳性率为59.26％.RT-PCR的检测阳性率显著高于IgM检测(x2=41.14,P＜0.001).结论 RT-PCR法可快速诊断麻疹病毒的病原学,且对出疹初期麻疹IgM呈阴性的病例可进～步确诊,是一种有效可靠的方法.     

Sensitive detection of hydrophobic antigens using a novel lipid-aggregate based ELISA

Antibodies against hydrophobic antigens are common in several autoimmune diseases. However, detection of such antibodies by standard immune-assays, such as ELISA, is problematic, in part because of the problems with coating hydrophobic molecules onto polystyrene multi-well plates. We describe a novel method of stably associating hydrophobic antigens to ELISA plates. By mixing the antigen with a hydrophobic molecule containing a hydrophilic anchor, we generate mixed lipid aggregates that can attach to ELISA plates, and are resistant to detergent wash. Using the ganglioside GM-1 and phosphatidylethanolamine conjugated to the hapten DNP (dinitrophenyl) as model antigens, we show that hydrophobic antigens incorporated into mixed lipid aggregates expose their antigenic determinants in a correct configuration. The detection limit of both GM-1 and DNP-PE was considerably improved compared to when these antigens were coated on ELISA plates using organic solvents. Furthermore GM-1 incorporated into mixed lipid aggregates can be detected by specific antibodies in patient serum. The method of incorporating hydrophobic antigens into mixed lipid aggregates for stable association to ELISA plates can presumably be applied to a vast array of hydrophobic antigens, and may well be developed into a large scale screening system for serum reactivity towards different hydrophobic antigens.     

Dissociation of antibodies bound to surface-immobilized antigen

The dissociation of antibodies bound to surface-immobilized antigen was investigated by the ELISA, using a hapten (TNP) as antigen. Antibody binding was found to be stable, and no half-time of dissociation could be defined within 69 h. The role of the bivalence of antibodies and the difference between a homogeneous and a heterogeneous reaction was investigated by comparing the dissociation rate of antigen-antibody complexes formed by monovalent Fab fragments from surface-immobilized antigen and the dissociation rate of TNP-lysine from antibodies in a homogeneous liquid phase. Fab fragments were found to dissociate with a half-time value of about 16 h, whereas the homogeneous binding of TNP-antibody dissociated with a half-time of less than 4 h, indicating that both the bivalence of antibodies and the solid phase contributed to the stability of surface-bound antigen-antibody complexes. Qualitative differences between antibodies produced by different clones in a polyclonal antibody response to TNP was investigated by a spot assay. The results indicated that a minority of the antibodies produced had the capacity of binding practically irreversibly to solid-phase-immobilized antigen. The impact of the results on the interpretation of data from solid-phase assays is discussed together with the biological importance of the findings.     

Purine and pyrimidine metabolizing activities in Trichomonas vaginalis extracts

Sixty-one purine and pyrimidine metabolizing activities were assayed in extracts of Trichomonas vaginalis. Of these, 43 were detected and quantitated. The only phosphoribosyltransfer activity observed was with uracil. No such activity was observed with adenine, guanine, hypoxanthine, xanthine or orotic acid. The rate of nucleoside cleavage was increased dramatically by the addition of inorganic phosphate. In addition, the extracts could catalyze the synthesis of ribonucleosides from the bases adenine, hypoxanthine, guanine and uracil but not cytosine, thymine or orotic acid, in the presence of ribose 1-phosphate. These data suggest that T. vaginalis contains primarily nucleoside phosphorylases instead of nucleoside hydrolases. Adenosine, deoxyadenosine, guanosine, deoxyguanosine, inosine, uridine, thymidine and GMP were phosphorylated in the presence of ATP. No nucleoside phosphotransferase activity was detected. Deamination of guanine, adenosine, deoxyadenosine, cytidine and deoxycytidine but not adenine was observed. These data suggest that salvage of adenine and guanine for ribonucleotide synthesis in T. vaginalis occurs via a phosphorylase/kinase pathway instead of through a phosphoribosyltransferase pathway which predominates in mammalian cells. In contrast, the pyrimidine base uracil can be converted to UMP via both a phosphoribosyltransferase or a phosphorylase/kinase pathway, analogous to that in mammals.     

A method of membrane preparation for immunoassay

Membranes prepared from a variety of solid tissues were used as solid-phase antigens for ELISA or RIA after fixation onto polylysine-primed 96-well plates. The preservation of antigens in these membrane preparations was tested by reactivity in ELISA using 2 monoclonal antibodies: W6/32, which recognizes an HLA framework antigen (a protein antigen) and anti-SSEA-1, directed to a carbohydrate antigen carried on glycoproteins. Levels of antigen deposition and usefulness as solid-phase antigens were assessed for ELISA as compared to RIA. Coated plates may be frozen for many months with preservation of antigenic activity. This method is relatively simple, rapid, and is useful for preparation of tissue antigens for immunoassay, especially for screening monoclonal antibodies.     

An enzyme-linked immunosorbent assay (ELISA) for the measurement of antibodies to different parts of the gram-negative lipopolysaccharide core region

Bovine serum albumin was complexed with the core antigens of either Escherichia coli J5 LPS, Salmonella minnesota R595 LPS or E. coli lipid A. These core-BSA complexes were used for solid-phase coating in ELISAs for anti-core antibodies. Antibodies, binding to various parts of the core region were easily quantified in a single experimental set-up, which was hitherto not possible. The ELISA has only 3 incubation steps and is not costly as only moderate amounts of the core antigens (i.e., 1 microgram per test) were needed for coating. The sensitivity proved to be excellent and the complexes were biologically fully active (compared to native, smooth LPS), which make them suitable for the screening (after fusion) of monoclonal anti-core antibodies. Another possible application is the large-scale screening of blood-bank sera in order to find samples with a high anti-core antibody content.     

A sensitive radioimmunoassay for the determination of antibodies to mouse hepatitis virus

A solid-phase radioimmunoassay is described for the detection of antibodies to mouse hepatitis virus. Viruses were purified by velocity and isopycnic gradient centrifugation and 96-well plastic plates were coated with viral antigens. To allow the detection of most serotypes of low titered antisera, a pool of antigens from several viral serotypes were employed. The second antibody, an affinity-purified goat antimouse immunoglobulin, detects IgG, IgM and IgA antibodies. This assay is more sensitive than either the plaque reduction assay or the commercially available enzyme-linked immunosorbant assay and proved to be useful for screening mouse colonies for the presence of mouse hepatitis virus, following seroconversion in experimental animals and in the production of monoclonal antibodies to both structural and nonstructural proteins.     

Epitopic analysis of detergent-solubilized HLA molecules by solid-phase radioimmunoassay

A solid-phase radioimmunoanalysis of plasma membrane molecules solubilized in the presence of detergent was developed. From a crude cell lysate, membrane molecules were specifically immobilized by solid-phase adsorbed monoclonal antibodies. Analysis of these molecules was easily performed with radiolabeled monoclonal antibodies of different specificities. This technique was used to analyze the HLA-DR and HLA-A,B,C molecules expressed by RAJI cells. It was possible (a) to determine which epitopes are expressed on the same molecules; (b) to define subsets of HLA molecules according to the epitopes which they express, and (c) to perform quantitative analysis of HLA molecules on a crude cell lysate.     

Comparison of a chemiluminescence immunoassay and an enzyme immunoassay for detection of IgM antibodies against measles,mumps, rubella,cytomegalovirus (CMV), Epstein Barr virus (EBV), and human herpes virus (HHV) -1 and -2 infections

PurposeOutbreaks of vaccine-preventable viral diseases have been increasingly reported globally over the past few years. The burden of congenital viral infections, their impact on physical and mental development and the resulting economic loss to the family and the community are also well known. IgM antibody detection has been convenient in the diagnosis of acute viral infections, particularly in settings with limited resources where molecular tests are not feasible.MethodsThis is a comparative study between a chemiluminescence immunoassay (Liaison, DiaSorin, Saluggia, Italy) and an enzyme linked immunosorbent assay (ELISA) (Euroimmun, Lubeck, Germany) for the detection of IgM antibody against measles, mumps, rubella, CMV, EBV and HHV-1 and -2 viruses using a total of 345 samples. Results are expressed as agreement using kappa statistics.ResultsIn this study, CLIA is perfectly comparable to ELISA for the detection of IgM antibodies against measles (0.86) and mumps (0.92) with a moderate agreement for rubella (0.52), CMV (0.57), EBV (0.50), and HHV-1 and -2 (0.47) assays. However, a PABAK (prevalence-adjusted bias-adjusted kappa) showed improved agreement for rubella (0.64), CMV (0.65), EBV (0.60), and HHV-1 and -2 (0.88) assays.ConclusionsIgM antibody assays (CLIA and ELISA) against measles and mumps virus can be comparably used depending on the laboratory setup, throughput and expertise.