Detection of typhus antibodies by latex agglutination.

A latex test for assay of antibodies to endemic and epidemic typhus rickettsiae is simple, group-specific, sensitive, and reproducible. Cross-reactivity within the typhus group was extensive.     

Detection of rinderpest antigen by latex agglutination test

A slightly modified latex agglutination test was applied for detection of rinderpest antigen. The antigen was added to sensitized latex particles in the presence of hyperimmune antiserum to facilitate agglutination. Out of 129 samples tested by latex agglutination (LA), solid phase aggregation of coated erythrocytes (SPACE), reverse phase passive haemagglutination (RPHA) and counter immunoelectrophoresis (CIE) test, 86.0, 86.8, 84.4 and 79.8 per cent, respectively, were found positive.     

Measurement of antibodies to varicella-zoster virus by using a latex agglutination test.

We evaluated a rapid, simple-to-perform assay for detecting antibodies to varicella-zoster virus by latex agglutination (LA); dilutions of test sera were added to latex particles coated with varicella-zoster virus antigen. We tested 878 serum specimens by LA and with fluorescent antibody to membrane antigen; of these, 227 were also tested by a commercially marketed enzyme-linked immunosorbent assay (ELISA). LA was almost as sensitive as the fluorescent antibody to membrane antigen test and more sensitive than ELISA. No cross-reacting antibodies were detected by LA, and false-positive reactions were rare.     

Detection of antibodies to Babesia equi in horses by a latex agglutination test using recombinant EMA-1

A latex agglutination test (LAT) using recombinant equi merozoite antigen 1 (EMA-1) for the detection of antibodies to Babesia equi was developed. The LAT was able to differentiate very clearly between sera from B. equi-infected horses and sera from Babesia caballi-infected horses or from normal horses. The LAT results were identical to those of a previously developed enzyme-linked immunosorbent assay. These results indicate that LAT using recombinant EMA-1 might be very useful as a routine screening method for the diagnosis of B. equi infection.     

Detection of human anti-flavivirus antibodies with a west nile virus recombinant antigen microsphere immunoassay

We report a new, suspended-microsphere diagnostic test to detect antibodies to West Nile (WN) virus in human serum and cerebrospinal fluid (CSF). The microsphere immunofluorescence assay can be performed in less than 3 h on specimens of 相似文献   

Detection of rabies virus antigen in dog saliva using a latex agglutination test

Dog bites are responsible for more than 90% of human rabies deaths in Asia. We developed a simple and inexpensive test based on latex agglutination (LA) for rabies virus antigen detection in dog saliva. Rabies virus antigen could be detected by agglutination on a glass slide using latex particles coated with gamma globulin. By evaluation of paired saliva-brain specimens from 238 dogs, the LA test using saliva was 99% specific and 95% sensitive compared to the fluorescent antibody test (FAT) on brain smears. The advantages of the LA test over the standard FAT are that it is comparatively simple and there is no need to kill the animal before examination.     

Detection of Rocky Mountain spotted fever antibodies by a latex agglutination test.

A latex test for immunodiagnosis of Rocky Mountain spotted fever, using erythrocyte-sensitizing substance from Rickettsia rickettsii adsorbed to latex particles, has been developed. The test was evaluated with a total of 123 single and 118 paired human sera submitted for Rocky Mount spotted fever testing. This test is simple, sensitive, and specific. Its efficiency, relative to the reference microimmunofluorescence test, was 95.1% for single sera and approached 100% for paired sera.     

Detection of human immunodeficiency virus antigen in vitreous humor.

The vitreous humor from 11 patients with acquired immunodeficiency syndrome was obtained at postmortem examination and tested for human immunodeficiency virus antigen and antibody by using the Abbott enzyme-linked immunosorbent assay procedures. Five patients had detectable antigen, supporting the recent observation that the virus may directly infect the retina.     

Detection of cytomegalovirus antibody with latex agglutination.

Transfusion-acquired cytomegalovirus (CMV) infections should be prevented in seronegative immunocompromised patients by providing blood products from donors who are also seronegative. Latex agglutination was investigated as a simple and rapid method for detecting antibody against CMV. Latex beads were coated with CMV antigen, incubated for 8 min at room temperature with 25 microliter of sera, and examined for agglutination. The sensitivity and specificity of latex agglutination was compared with that of indirect hemagglutination (IHA, Cetus Corp., Emeryville, Calif.) and enzyme immunoassay (EIA) with sera from 604 random blood donors or patients. Of 327 serum samples shown to be seronegative by EIA and IHA, 327 had a latex agglutination titer of less than 1:4 (specificity, 100%). Of 236 serum samples with detectable antibody by EIA and IHA, 228 had a latex agglutination titer of 1:4 or greater (sensitivity, 97%). Plasma collected with EDTA, heparin, or citrate was satisfactory for latex agglutination. Latex agglutination results correlated quantitatively with those of EIA, and the test also detected fourfold or greater rises in antibody with paired sera from six patients with posttransfusion CMV infections. Latex agglutination is a sensitive and specific assay that is rapid and simple to perform and should be effective in selecting seronegative blood donors to prevent posttransfusion CMV infections in seronegative recipients.     

Detection of antibodies to opioid and glutamate receptors by latex agglutination and enzyme immunoassay

We studied adsorption capacity of 5 latexes to synthetic peptide fragments of μ- and δ-opioid receptors and to GluR1 and NR2A subunits of glutamate receptor. Levels of autoantibodies to opioid receptors in the latex agglutination test and enzyme immunoassay were in good correlation. The level of autoantibodies to opioid receptors measured by these methods was increased in patients with opium narcomania, while the content of autoantibodies to the glutamate receptor subunits was increased in epileptics.__________This revised version was published online in July 2005 with the addition of the issue titleTranslated from Byulleten’ Eksperimental’noi Biologii i Meditsiny, Vol. 139, No. 1, pp. 94–97, January, 2005     

Detection of specific human immunodeficiency virus IgM antibodies

This study was done to demonstrate whether the use of the antigen-sandwich human immunodeficiency virus (HIV) antibody-screening assays (3rd generation assays), which detect all classes of anti-HIV immunoglobulins, leads to an earlier detection of HIV IgM compared to the 2nd generation HIV antibody-screening assays. We tested sequential bleeds of three donors obtained from commercially available seroconversion panels. Anti-HIV testing was done before and after high-performance liquid chromatography separation of IgG and IgM fractions. The positive result of the first bleedings from all three panels was linked to the IgM fraction, while at that time the IgG fraction was still negative. For subsequent samples drawn 5–9 days later, a positive signal was obtained with the IgG fraction in addition to a stronger positive signal obtained with the IgM fraction. We conclude that an assay capable of simultaneously detecting different immunoglobulin classes, including IgM, will help to narrow the window period for serological detection of seroconversion to HIV by detecting anti-HIV IgM-containing samples earlier than conventional assays using only anti-human IgG enzyme conjugates (indirect anti-HIV-screening assay, 2nd generation assays).     

Evaluation of a latex agglutination test for screening antibodies to rubella virus

The performance of a commercial latex agglutination test for screening rubella antibodies was investigated, using two panels of selected serum samples especially designed for a careful evaluation of sensitivity. Three false negative results were obtained on samples with very low levels of antibody. However, the test had higher sensitivity than the hemagglutination inhibition test and fluoroimmunoassay when samples were tested undiluted. False positive results were not obtained, and prozone reactions were not observed. The test is a very practical method for screening rubella antibodies in primary health care units.     

A latex agglutination test using a recombinant nucleoprotein for detection of antibodies against avian influenza virus

A latex agglutination test (LAT) was developed for detecting antibodies against avian influenza virus. The recombinant avian influenza virus nucleoprotein expressed in Escherichia coli was purified, coupled with latex beads, and used as an antigen for the LAT. The LAT was capable of detecting anti-avian influenza virus antibodies irrespective of the avian-influenza subtype, and in most cases, the results correlated with the results of an agar gel precipitation test (AGPT). However, in comparison with the AGPT, the LAT could detect the anti-avian influenza virus antibodies for a longer period of time after the infection. The nonspecific agglutination observed in uninfected chicken sera was resolved by pretreating the sera with dried chicken-liver powder for 1 h. The LAT is easy to perform, and even after considering the time required for pretreatment of the serum, the total time required for obtaining the results is reduced in comparison to the time required in the case of the AGPT. This easy and rapid LAT is considered to be useful for monitoring avian influenza virus infection in the field.     

Elimination of false-positive serum reactivity in latex agglutination test for cryptococcal antigen in human immunodeficiency virus-infected population.

We recently tested serum from a human immunodeficiency virus-infected patient for the presence of cryptococcal antigen using the Meridian latex agglutination (LA) test (Cryptococcal Antigen Latex Agglutination System). Two pronase-treated serum specimens from the patient had LA titers of 80 and 160, but the patient had no evidence of cryptococcal disease. The serum was negative for rheumatoid factor, a well-documented cause of false-positive LA reactions. Seven blood culture supernatants from the patient were also LA positive, but were culture negative for cryptococcus. When the sera and blood culture supernatants were treated with 0.01 M 2-beta-mercaptoethanol (2-ME), the agglutinating activity was ablated. Similar results were seen when the sera were tested by two other commercial LA assays. Serum and cerebrospinal fluid specimens from patients with confirmed cryptococcal disease were treated with 2-ME, and the results were compared with those obtained after pronase (sera) or heat (cerebrospinal fluid) inactivation. The titers were identical (n = 56) or within 1 dilution (n = 3). One hundred serum specimens from human immunodeficiency virus-seropositive patients with no known history of cryptococcal disease were examined to determine the frequency of false-positive reactivity in this patient population. Of this group, three were positive following pronase treatment. One remained positive after 2-ME treatment; the remaining two were negative. These data indicate that 2-ME can be used to eliminate nonspecific reactivity in the LA test without affecting true-positive results.     

Comparison of sensitivities and specificities of latex agglutination and an enzyme-linked immunosorbent assay for detection of antibodies to the human immunodeficiency virus in African sera.

The sensitivities, specificities, and positive and negative predictive values of the Cambridge BioScience Corp. (Worcester, Mass.) human immunodeficiency virus latex agglutination assay were compared by using three different blood preparations. By using the manufacturer's standard test method with diluted sera, the sensitivity of latex agglutination was 100%, the specificity was 99.58%, and the positive and negative predictive values were 99.26 and 100%, respectively. Use of diluted whole blood or undiluted whole blood did not significantly affect the sensitivity (mean, 99.72%), specificity (mean, 99.47%), positive predictive value (mean, 99.07%), or negative predictive value (mean, 99.89%). The latex agglutination assay is a simple, rapid assay for the detection of human immunodeficiency virus that would be useful in Third World countries or other areas where enzyme-linked immunosorbent assays are not available or cannot be used.     

Diagnosis of systemic candidiasis by latex agglutination for serum antigen.

Three latex agglutination test procedures for detecting Candida antigen in human serum were compared in a retrospective study of 69 patients and 20 normal volunteers. Untreated human serum was reacted with two different latex reagents; one reagent also was reacted with serum treated with protease and heat. The test procedure with treated serum was best, detecting serum antigen in 17 of 21 patients (81%) with disseminated candidiasis. Judging by autopsy-proven cases, there was an increase in positive test results in the last 2 weeks of life. When untreated sera were tested with this reagent, only 3 (14%) of the 21 patients with disseminated candidiasis had detectable antigen in serum. A subset of these same sera was tested by a commercial latex reagent (Candida Detection System lot C001; Ramco Laboratories, Inc., Houston, Tex.) and untreated serum. Of 18 patients with disseminated candidiasis, 5 (28%) had at least one positive serum. Sera from patients with less severe clinical forms of candidiasis were usually negative regardless of the test procedure used. With one exception, sera from control patients were negative or were positive only in sera containing rheumatoid factor. Latex agglutination tests for Candida spp. in treated serum may prove to be a useful procedure for the rapid diagnosis of severe disseminated candidiasis.     

Detection of staphylococcal exfoliative toxin by slide latex agglutination.

A simple and rapid method in which slide latex agglutination was used was developed to detect the exfoliative toxin (ET) elaborated by clinical isolates. ET types A and B (ET-A and ET-B) were purified by plate gel isoelectrofocusing, and anti-ET sera were obtained by immunizing rabbits. A specific immunoglobulin G antitoxin was then prepared from the immunized rabbit sera by fast protein liquid chromatography, and latex particles were coated with the antitoxin. Of 74 staphylococcal strains isolated from patients with staphylococcal scalded skin syndrome, 61 strains were found to produce ET by the newborn mouse bioassay. All 61 strains were shown to be positive for ET-A and ET-B production by the slide latex agglutination method. The lowest concentration of ETs detected by the latex agglutination method was 0.5 microgram/ml, which was much lower than that detected by the double immunodiffusion method, with a sensitivity of 50 micrograms/ml. It is crucial to prove ET production by clinical isolates for the diagnosis and surveillance of staphylococcal scalded skin syndrome. The latex agglutination method is a sensitive, simple, and rapid test which can be used as an alternative to the newborn mouse bioassay.