Enzyme-linked immunosorbent assay (ELISA) for the detection of antibodies to Angiostrongylus cantonensis

The enzyme-linked immunosorbent assay (ELISA) was employed for the sero-diagnosis of Angiostrongylus cantonensis infections in rats and man. Metabolic and 'purified' antigens of adult or juvenile A. cantonensis were evaluated by ELISA and compared against Toxocara canis antigen for sensitivity and specificity. Sera and cerebrospinal fluid (CSF) from both rats and man gave higher ELISA values against antigens of A. cantonensis than those obtained from negative control samples. The results showed that cross reaction occurred between T. canis and A. cantonensis. Of four A. cantonensis antigens tested, a Sephacryl S-300 'purified' fraction was shown to be superior in the ELISA to determine angiostrongyliasis.     

酶联免疫斑点技术在结核病诊断中的应用

酶联免疫斑点技术（ELISPOT）是一种从单细胞水平检测分泌抗体或细胞因子细胞的免疫学新技术,Lalvani等首先将ELISPOT用于结核病的诊断后,相关报道日益增多。ELISPOT技术以其敏感、特异、简便的优点被应用于结核病的诊断,在欧美已被批准用于临床。我科将该项技术应用于结核病的辅助诊断,现与结核抗体检测及PPD试验作对比,探讨ELISPOT在结核病诊断中的价值。     

The enzyme-linked immunosorbent assay (ELISA)

The enzyme-linked immunosorbent assay “ELISA” developed in recent years represents a significant addition to existing serological tools. Encouraging preliminary results obtained through its application to a number of parasitic diseases during the last two years indicate the value of further investigations and trials which will permit a true evaluation.     

Enzyme-linked immunosorbent assay in the diagnosis of kala-azar in Bhadohi (Varanasi), India

An enzyme-linked immunosorbent assay (ELISA) developed using Leishmania donovani promastigote soluble antigen gave positive responses in practically all the clinically and parasitologically diagnosed patients with kala-azar in a preliminary study. Healthy control subjects from non-endemic and endemic areas gave negative results. No cross-reaction was observed with patients having leprosy, filariasis, malaria, tuberculosis, or amoebiasis. Blood samples collected on filter paper were adequate for the test. The test appears promising in the diagnosis of kala-azar.     

Enzyme-linked immunosorbent assay of nicotine metabolites

Introduction  

The level of cotinine in biological specimens, such as serum, urine, and saliva, measured by gas or liquid chromatography is the most validated and reliable indicator of exposure to tobacco smoke. However, chromatographic methods are not always suitable for all types of situations.     

Serodiagnosis of pulmonary tuberculosis in Argentina by enzyme-linked immunosorbent assay (ELISA) of IgG antibody to Mycobacterium tuberculosis antigen 5 and tuberculin purified protein derivative

IgG antibody to Mycobacterium tuberculosis antigen 5 and tuberculin purified protein derivative (PPD) was measured, by enzyme-linked immunosorbent assay (ELISA), in serum samples from 86 patients with active pulmonary tuberculosis and 91 non-tuberculous control subjects from Santa Fé, Argentina. The geometric mean titre for the tuberculosis patients was 74.6 with antigen 5 and 99.5 with PPD. In 91 control subjects the geometric mean titres were 3.6 and 15.6 respectively. Titres were not related to tuberculin reactor status or prior BCG vaccination. At a serum dilution end-point of 1:40, ELISA with antigen 5 had a sensitivity of 81.4% and a specificity of 93.4% for tuberculosis. At 1:40, ELISA with PPD showed a sensitivity of 82.6% and a specificity of 54.9% for tuberculosis. Applied at a serum dilution of 1:40 to a hypothetical model population with a tuberculosis prevalence of 2%, ELISA using antigen 5 would correctly classify 93.2% of persons and ELISA with PPD, 55.5%. At a dilution of 1:80, accuracy is increased to 99.3% with antigen 5 and 83.3% with PPD, but sensitivity decreases to 64.0% with antigen 5 and 72.1% with PPD. Thus, antigen 5 is more accurate than PPD for the diagnosis of tuberculosis using ELISA.     

Enzyme-linked immunosorbent assay (ELISA) for the detection of antibodies against foot-and-mouth disease virus. III. Evaluation of antibodies after infection and vaccination

Investigations using a liquid-phase blocking sandwich enzyme-linked immunosorbent assay (ELISA) for the measurement of antibodies against foot-and-mouth disease virus (FMDV) in sera from sheep and from cattle are reported, and results compared with those obtained by virus neutralization (VN) tests. Serum antibody titres in sheep after primary vaccination and in cattle challenged with a natural aerosol after vaccination were similar by ELISA and VN. However, the antibody levels detected in sera of cattle during early infection and of vaccinated cattle after intradermolingual challenge were clearly greater by ELISA than by VN. The ELISA titres in cattle sera following synthetic peptide vaccination indicated some relationship to protection and were clearly different from those recorded by VN. On the other hand, the antibody levels following conventional vaccination showed that ELISA and VN titres in cattle sera were related to protection. Although there was a good agreement between the ELISA antibody titre and protection for the four vaccines used, by VN the titre which afforded protection varied depending on the vaccine used. The ELISA was considered therefore to be more reliable than the VN and may prove useful for evaluating the immunological response of animals following infection and following vaccination.     

Evaluation of the enzyme-linked immunosorbent assay (ELISA) and other serological tests for the diagnosis of toxoplasmosis

The enzyme-linked immunosorbent assay (ELISA) was evaluated in human toxoplasmosis in three laboratories using their own procedures. The same batch of serum samples was investigated in the three laboratories. ELISA results were compared by statistical analysis both with one another and with those of the dye test (DT), immunofluorescence (IF), complement fixation test (CFT), and indirect haemagglutination (IHA).     

Detection of antibodies in strongyloidiasis by enzyme-linked immunosorbent assay (ELISA)

Detection of IgG antibodies to Strongyloides stercoralis in sera of 29 patients with strongyloidiasis was attempted by the enzyme-linked immunosorbent assay (ELISA) using an extract of filariform larvae of S. stercoralis. The antibodies were found with a high degree of sensitivity in almost all patients. The ELISA values, however, did not correlate with the intensity of the infection or with differences in clinical and laboratory parameters. When the ELISA values of persons with Strongyloides were compared with those showing no S. stercoralis by faecal examinations, a significant difference was obtained between these two groups. The cross reactions with other helminth infections were significantly weaker than the reaction with Strongyloides infection. It was concluded that the antibodies are strongly elicited in human strongyloidiasis and that the assay provides a sensitive and specific method for diagnosis of strongyloidiasis.     

Specificity of the enzyme-linked immunosorbent assay (ELISA) for Toxoplasma IgG antibody

An ELISA developed for Toxoplasma IgG antibody was demonstrated to be more sensitive than the current reference tests, the indirect haemagglutination antibody test (IHAT) and the indirect immunofluorescence test (IIFT). No additional cross reactions were found in the ELISA with sera from patients with other parasitic infections, and there was no interference due to the presence of either rheumatoid factor or antinuclear antibodies.     

Estimation of cercarial antigen efficiency by enzyme-linked immunosorbent assay (ELISA)

Cercariae were collected, hemogenized and the amount of protein was measured. ELISA was preformed by using 3 concentrations of cercarial Ag(2.5 ug/ml; 5 ug/ml and 10 ug/ml) also two types of sera were used; immune and non immune. Two dilutions (1:500 and 1:2000) of the conjugate were used in this test. The degree of absorbance was measured after 24 H by spectrophotometer, where the results showed that, the degree of absorbance was increased in the presence of immune sera and also in the presence of 1:500 conjugate concentration, but there was no difference in the degree of absorbance with the use of different Ag concentrations. It is obvious that 2.5 ug/ml of Ag could give very high ELISA readings with infected mice sera.     

Enzyme linked immunosorbent assay (ELISA) for determination of Staphylococcus aureus enterotoxin type B.

Determination of Staphylococcus aureus enterotoxin type B using ELISA is described. The ELISA is more sensitive than the micro-slide technique. The specificity of the determination of enterotoxin B depends on the specificity of the antisera used. Application of this new assay is evaluated and discussed.     

Evaluation of a 200-kDa amastigote-specific antigen of L. donovani by enzyme-linked immunosorbent assay (ELISA) for the diagnosis of visceral leishmaniasis

A purified 200-kDa antigenic fraction from Leishmania donovani axenic amastigotes was evaluated by ELISA for the detection of antibody response in visceral leishmaniasis (VL) patients, post kala-azar dermal leishmaniasis (PKDL) patients and controls, for the diagnosis of visceral leishmaniasis. A positive antibody response to the 200-kDa amastigote fraction and to Leishmania amastigote soluble antigen (LASA) was found in 29 (96.6%) and 30 ((100%) confirmed VL patients, respectively, by the use of ELISA. However, only 1 (10%) out of 10 PKDL patients had detectable antibody response to 200-kDa fraction while all the 10 (100%) PKDL patients exhibited an immune response to LASA. Therefore, use of the 200-kDa antigenic fraction for the detection of antibody response in an ELISA follow-up (post treatment) of VL patients may have prognostic significance, and it may also be useful for differentiating active VL and PKDL.     

活动性肺结核的影像诊断价值探讨

目的分析活动性肺结核的影像学特征及鉴别诊断方法,提高其影像诊断水平。方法回顾性分析63例经确诊的活动性肺结核的胸部X线平片及CT影像资料,并作对照分析。结果X线胸片及胸部CT提示活动性肺结核好发部位为两肺上叶尖后段、下叶背段（47例）;病灶多呈不规则斑片状影（34例）,边界不清,密度不均;X线胸片22例可见病灶内钙化,呈散在斑片状或宽点状,而CT显示为36例;X线胸片9例存在薄壁或厚壁空洞,CT可见19例;X线胸片显示病灶周围有支气管播散灶者6例,CT可见14例;CT显示肺门或（和）纵隔淋巴结增大15例,淋巴结钙化19例,而X线胸片只分别显示9例和12例;CT显示胸腔积液16例,胸膜增厚、粘连或钙化27例,而X线胸片只分别显示8例和18例。结论胸部X线检查是评价肺结核的主要和常用方法,CT在发现细小、隐匿病灶,鉴别可疑病灶,确定病灶是否活动方面有着不可替代的重要作用,可明显提高诊断准确率。     

Application of enzyme-linked immunosorbent assay (ELISA) to identification of Anopheles mosquito bloodmeals

The microplate method of the ELISA described by Volleret al. (1974) was manipulated for identification of Anopheles bloodmeals. Blood samples collected from man and from laboratory animals were put in small amounts (1 to 2 μl) on filter paper.Also bloodmeals from A. stephensi fed on human volunteers and guinea-pig were smeared on filter paper one, six 12, 24 and 48 hours after ingestion. The samples were tested by a modified microplate ELISA, using alkaline phosphatase anti-human IgG conjugate.Results showed that ELISA is a quite specific and sensitive technique for the detection of a small amount of human blood, even 24 hours after ingestion by anopheline mosquitoes. The ELISA seems to be a more practical and reproducible method than the precipitin test for identification of arthropod blood-meals, and could also be used for identification of blood spots in forensic laboratories.The anthropophilic index of anopheline mosquitoes is an important factor in the role of different Anopheles mosquitoes in malaria transmission. The technique which has been most commonly used for determination of the source of Anopheles bloodmeals is the precipitin test which was first employed by Uhlenhuthet al. (1908) as a medicolegal procedure for the identification of human blood stains. Later it was used and modified for determining the sources of bloodmeals in mosquitoes and other insects (King & Bull, 1923; Rice & Barber, 1935).Although the precipitin test is quite a specific and reliable test, the microplate indirect method of enzyme-linked immunosorbent assay (ELISA) developed by Volleret al. (1974) may be more practical for the identification of human blood in engorged anopheline mosquitoes. The ELISA test has, therefore, been modified for mosquito bloodmeal identification in this study.     

Further evaluation of lectin affinity purified glycoprotein (GP90) in the enzyme linked immunosorbent assay (ELISA) for diagnosis of Trypanosoma cruzi infection

Sera from 143 patients considered to be infected with Trypanosoma cruzi on the basis of epidemiological, clinical and standard serological evidence gave positive results in the enzyme-linked immunosorbent assay (ELISA) using a lectin affinity purified 90,000 molecular weight glycoprotein (GP90) antigen preparation. Levels of antibody did not discriminate between clinically classified groups of patients in the chronic phase of infection. The GP90 preparation was found to be heterogeneous.     

Application of the enzyme linked immunosorbent assay (ELISA) for the serodiagnosis of Schistosoma mansoni infections in St. Lucia

As part of our search for a serodiagnostic assay to replace the expensive and tedious stool examination in the diagnosis of Schistosoma mansoni infection, we have studied the sensitivity, specificity and quantitative features of an enzyme linked immunoassay (ELISA) using crude S. mansoni egg antigen preparation.Results of studies carried out in both London and St. Lucia indicate that the assay can give useful serodiagnostic information ranging from 82 to 99·5% sensitivity, depending on level of infection intensity and method of blood collection and 100% specificity in St. Lucian/St. Vincent populations. The St. Lucia study also showed that the assay could be operated in a qualitative form in an endemic area.