Comparing the performance of traditional non-treponemal tests on syphilis and non-syphilis serum samples.

The goal of the present study was to determine the performance of two traditional non-treponemal tests for syphilis. Syphilis sera (n = 209) included different stages of disease, and control sera (n = 247) were from patients with tumours, leprosy, systemic lupus erythematosus, hepatitis, pregnant women and healthy individuals. Treponema pallidum ELISA, Treponema pallidum particle agglutination and rapid treponema-specific tests were used as gold standards. Rapid plasma reagin or toluidine red unheated serum test had a sensitivity and specificity of over 95%. False-negative reactions of rapid plasma reagin and toluidine red unheated serum test were observed mainly in primary and latent syphilis cases, and false-positive reactions were present in systemic lupus erythematosus, hepatitis-infected patients. Overall, both non-treponemal tests had high sensitivities and specificities making the assays attractive as screening tests for syphilis. When examined on WHO reference serum samples and based on lower limits of detection, non-treponemal tests were less sensitive than treponema-specific tests.

A hag mutant of Moraxella catarrhalis strain O35E is deficient in hemagglutination, autoagglutination, and immunoglobulin D-binding activities.

Previous studies correlated the presence of a 200-kDa protein on the surface of Moraxella catarrhalis with the ability of this organism to agglutinate human erythrocytes (M. Fitzgerald, R. Mulcahy, S. Murphy, C. Keane, D. Coakley, and T. Scott, FEMS Immunol. Med. Microbiol. 18:209-216, 1997). In the present study, the gene encoding the 200-kDa protein (designated Hag) of M. catarrhalis strain O35E was subjected to nucleotide sequence analysis and then was inactivated by insertional mutagenesis. The isogenic hag mutant was unable to agglutinate human erythrocytes and lost its ability to autoagglutinate but was still attached at wild-type levels to several human epithelial cell lines. The hag mutation also eliminated the ability of this mutant strain to bind human immunoglobulin D. The presence of the Hag protein on the M. catarrhalis cell surface, as well as that of the UspA1 and UspA2 proteins (C. Aebi, I. Maciver, J. L. Latimer, L. D. Cope, M. K. Stevens, S. E. Thomas, G. H. McCracken, Jr., and E. J. Hansen, Infect. Immun. 65:4367-4377, 1997), was investigated by transmission electron and cryoimmunoelectron microscopy. Wild-type M. catarrhalis strain O35E possessed a dense layer of surface projections, whereas an isogenic uspA1 uspA2 hag triple mutant version of this strain did not possess any detectable surface projections. Examination of a uspA1 uspA2 double mutant that expressed the Hag protein revealed the presence of a relatively sparse layer of surface projections, similar to those seen on a uspA2 hag mutant that expressed UspA1. In contrast, a uspA1 hag mutant that expressed UspA2 formed a very dense layer of relatively short surface projections. These results indicate that the surface-exposed Hag protein and UspA1 and UspA2 have the potential to interact both with each other and directly with host defense systems.

Comparison of a recombinant-antigen enzyme immunoassay with Treponema pallidum hemagglutination test for serological confirmation of syphilis.

A recombinant-antigen enzyme immunoassay (EIA), BioSCREEN anti-Treponema pallidum, was compared favorably with the T. pallidum hemagglutination test, in the detection of specific antibodies in different groups of sera from patients with primary (n = 38), secondary (n = 10), early latent (n = 28) and congenital syphilis (n = 2), patients with leptospirosis ( n= 8), infectious mononucleosis (n = 7), hepatitis (n = 9), diabetes mellitus (n = 11), rheumatoid arthritis (n = 13), leprosy (n = 11), tuberculosis (n = 9), HIV/Aids ( n= 12), systemic lupus erythematosus (n = 4), rheumatic fever (n = 3), old-persons (n = 9), pregnant women (n = 29) and blood donors (n = 164). The coincidence between them was 95.1%. The sensitivity and specificity of the EIA were 93.3% and 95.5%, respectively. Fifteen serum specimens belonging to old-persons, pregnant women, blood donors, and patients with human leptospirosis, hepatitis, diabetes mellitus, tuberculosis and rheumatic fever gave false-positive results by Venereal Disease Research Laboratory and/or Rapid Plasma Reagin. The EIA can be used as alternative method for the serological confirmation of syphilis.

Comparison of a Recombinant-antigen Enzyme Immunoassay with Treponema pallidum Hemagglutination Test for Serological Confirmation of Syphilis

A recombinant-antigen enzyme immunoassay (EIA), BioSCREEN TM anti-Treponema pallidum, was compared favorably with the T. pallidum hemagglutination test, in the detection of specific antibodies in different groups of sera from patients with primary (n = 38), secondary (n = 10), early latent (n = 28) and congenital syphilis (n = 2), patients with leptospirosis ( n= 8), infectious mononucleosis (n = 7), hepatitis (n = 9), diabetes mellitus (n = 11), rheumatoid arthritis (n = 13), leprosy (n = 11), tuberculosis (n = 9), HIV/Aids ( n= 12), systemic lupus erythematosus (n = 4), rheumatic fever (n = 3), old-persons (n = 9), pregnant women (n = 29) and blood donors (n = 164). The coincidence between them was 95.1 percent. The sensitivity and specificity of the EIA were 93.3 percent and 95.5 percent, respectively. Fifteen serum specimens belonging to old-persons, pregnant women, blood donors, and patients with human leptospirosis, hepatitis, diabetes mellitus, tuberculosis and rheumatic fever gave false-positive results by Venereal Disease Research Laboratory and/or Rapid Plasma Reagin. The EIA can be used as alternative method for the serological confirmation of syphilis

Evaluation of enzyme-linked immunosorbent and alternative assays for detection of HIV antibodies using panels of Brazilian sera.

Sera from 472 Brazilian subjects, confirmed to be either positive or negative for HIV antibodies and comprising the total clinical spectrum of HIV infection, were utilized in the evaluation of six commercially available enzyme-linked immunosorbent assays (ELISA), as well as of four alternative assays, namely indirect immunofluorescence (IIF), passive hemagglutination (PHA), dot blot and Karpas AIDS cell test. The sensitivities ranged from 100% (Abbott and Roche ELISA) to 84.2% (PHA) and the specificities ranged from 99.3% (IIF) to 80.2% (PHA). The sensitivity and specificity of the PHA and the sensitivity of the Karpas cell test were significantly lower than those of the other tests. Although the IFF and dot blot had good sensitivities and specificities, the six ELISA were more attractive than those tests when other parameters such as ease of reading and duration of assay were considered.

PIP: 6 commercially available ELISA kits and 4 new Brazilian made methods for detecting HIV were compared on 2 panels of sera, 292 from AIDS patients, HIV-positives and negatives, and 180 sera from asymptomatic blood donors, including 90 HIV-positives. The kits tested were 5 ELISAs: Roche Diagnostica (Basel), Hoechst Enzygnostic (Sao Paulo), Virgo Electronuclionics (Columbia MD), Organon Teknika (Boxtel, Netherlands), Salck Industria e Comercio de Produtos Biologicos (Sao Paulo), and a passive hemagglutination test, (Salck Ind), and indirect immunofluorescence IIF (Virgo electronucleonics, Columbia), a dot blot (Embrabio, Empressa Brasiliera de Biotecnologia Ltda, Sao Paolo) and Karpas AIDS cell test, Fujichemical Industries Ltd (Chokeiji, Takaoka, Japan). The sensitivities ranged from 84.2% to 100% with no significant differences in sera from panel A. In panel B, the sensitivity of the PHA test was significantly lower than that of the ELISA and the AIDS cell tests. The specificities of the PHA and the AIDS cell tests were also lower than that of the ELISA. The costs of all the tests were similar, but the equipment needs varied. The simplest tests to perform were the dot blot assay, PHA and Karpas AIDS cell test. The Hoechst ELISA is simpler because it does not require dilution of the serum. The dot takes too long for use in a blood bank, 16-18 hours. Immunofluorescence tests would be practical in countries already screening blood for malaria or Changes disease. Brazil is not doing so on a large scale due to lack of political will. In countries with high incidence of malaria, Chagas disease, leishmania, hepatitis and leprosy, HIV test need to be tested on local sera because of possible B cell activation.

Instrumental variables in the evaluation of diagnostic test procedures when the true disease state is unknown.

We explore the estimation of sensitivity and specificity of diagnostic tests when the true disease state is unknown. Instrumental variables which subdivide the patient population are used. A logistic model, relating these instrumental variables to the (unknown) true disease state is proposed. It is shown that this procedure allows the goodness-of-fit to the resulting model to be tested.

A passive hemagglutination test for leprosy using a synthetic disaccharide antigen.

There is a need for a simple, sensitive, and specific test for the serodiagnosis of leprosy. A passive hemagglutination (PHA) test for leprosy was developed to meet these requirements. A synthetic disaccharide, conjugated to bovine serum albumin and specific for the phenolic glycolipid of Mycobacterium leprae, was sensitized to aldehyde preserved and tanned sheep erythrocytes (SRBC). The sensitized SRBC were used for testing sera from leprosy and tuberculosis cases and normal controls at 1: 64 and 1:128 serum dilutions. It was found that if the hemagglutination reaction at greater than or equal to 1: 128 is considered positive, the test was positive in 84.2% of 38 cases of multibacillary leprosy, 16.7% of 24 cases of paucibacillary leprosy, 16.7% of 6 contacts of multibacillary leprosy, 11.8% of 51 cases of tuberculosis, and 3.7% of 54 blood donors. If the cutoff value used was 1:64, the test was more sensitive but less specific. The results are similar to that of an ELISA for IgM antibody to the same synthetic antigen. The present PHA test is simple and sensitive, but moderately specific. Its simplicity and sensitivity make it highly suitable for large-scale screening of contacts in leprosy-endemic areas.

Non-organ specific thermostable tissue antigens.

Thermostable ethanol insoluble antigens (BE antigens) were identified that occur in all human tissues and human dispersed cells, but which are absent from normal human serum. In contradistinction to previously described organ-specific BE antigens, these antigens were referred to as non-organ-specific tissue antigens (NOST). Antisera obtained by immunization of rabbits with BE preparations of human organs had been selected for being devoid of any organ specificity and had been absorbed by BE preparations of pooled human serum. Such antisera could be used as reagents for detection of NOST BE antigens in pathological human sera. Inhibition of enzyme immunoassay proved to be a convenient procedure for these studies. Inhibition of 35% or more was only exceptionally noted in studying sera of normal subjects 20-40 years old, but inhibition exceeding 35% (positive results) was noted in 48% of sera from subjects at the age of 70 years or more. A high incidence of positive results was also encountered in sera of patients with end-stage renal disease (30%), renal graft recipients (18%), and in patients with lymphoma or leukemia (44%), but interestingly enough, no positive tests were noted in patients with lepromatous leprosy.

Thyroglobulin autoantibodies in leprosy.

Two hundred and five sera from lepromatous leprosy patients were tested for the presence of thyroglobulin autoantibodies using tanned red cell haemagglutination technique. Six out of 182 sera from LL patients and 5 out of 23 sera from LL patients with ENL gave a positive reaction for thyroglobulin autoantibodies.

Antispermatozoal antibodies in leprosy with special reference to their morphological patterns.

Sixty two male patients with polar leprosy--38 lepromatous and 24 tuberculoid types were investigated for the presence of antispermatozoal antibodies with special reference to their morphological patterns. Antibodies were detected by three different immunological techniques. Sperm agglutination was found to be the most sensitive. The incidence of antibodies was higher in patients with lepromatous leprosy and was directly proportional to the duration of the disease in both types of leprosy. Morphologically, head-to-head type of agglutination was observed in 50 percent of the patients, mixed in 41.7 percent and tail-to-tail type in 8.3 percent. There was no correlation between the number of ENL attacks and the incidence of anti-bodies. In polar tuberculoid leprosy patients the histological findings of testicular biopsy indicated cell mediated tissue damage occurring in a non-infective form.

Natural tetanus immunity in lepromatous leprosy patients.

35 lepromatous leprosy patients with recurrent trophic ulcers were analysed for tetanus antitoxin levels by passive haemagglutination test (PHA). 42.85% patients and 32% controls had protective levels of antitoxin in their serum (greater than or equal to 0.1). All the patients (100%) demonstrated measurable antitoxin levels. The findings indicate immunological protection from tetanus and support the clinical impression of it's rarity in leprosy patients.

Symposium on the immunodiagnosis of rheumatic and related diseases, Part II. Rheumatoid factors.

Human rheumatoid factors are antibodies of IgG, IgA, or IgM class that show reactions with antigenic determinants present on other immunoglobulin molecules. The most commonly measured rheumatoid factor relates to the 19S IgM type, which reacts by agglutination of latex particles coated with 7S IgG and is often measured in the standard latex fixation test. Approximately 65 to 70 per cent of patients with rheumatoid arthritis show positive serologic tests for rheumatoid factor; however, a number of other chronic disease conditions are also associated with positive rheumatoid factor reactions, including infective endocarditis, sarcoidosis, leprosy, and other hyperglobulinemic conditions. Although extensive serologic and immunochemical studies have identified a number of specific antigenic structural sites on immunoglobulin molecules that react with rheumatoid factors, recent studies have shown that a certain proportion of such antibodies may show cross-reactivity with DNA-histone complexes as well. It is still not entirely clear how rheumatoid factors fit into the pathogenesis of rheumatoid arthritis itself.

Hepatitis-B-surface antigen (HBsAg) in leprosy patients.

The detection of the presence of Hepatitis-B-Surface antigen (HBsAg) using Indirect Haemagglutination technique (IHA) was carried out in 134 Lepromatous Leprosy cases (LL), 22 Lepromatous Leprosy cases during ENL reaction (LL with ENL), 24 Borderline leprosy (BL) cases, 7 Borderline Tuberculoid cases (BT) and 31 control subjects. The maximum percentage positivity of 32% was seen in cases with LL as compared to 6.2% in controls. The difference was found to be statistically significant (P less than 0.01).