Use of glycopeptidolipid core antigen for serodiagnosis of mycobacterium avium complex pulmonary disease in immunocompetent patients

We report the development of a serodiagnostic method for Mycobacterium avium complex (MAC) disease with an enzyme immunoassay (EIA) with the MAC-specific glycopeptidolipid (GPL) core as the antigen. In this study, we confirmed by EIA that the GPL core antibody was in the sera of immunocompetent patients with MAC disease. The EIA for quantifying the GPL core antibody was evaluated as a clinical tool for serodiagnosis of pulmonary MAC disease. A significant increase in GPL core antibodies (immunoglobulins G, A, and M) was detected in sera of patients with MAC pulmonary diseases when they were compared to patients who were colonized with MAC, patients with Mycobacterium kansasii disease or tuberculosis, and healthy subjects. The sensitivities and specificities of the GPL core-based EIA for diagnosis of MAC pulmonary disease were 72.6% and 92.2%, respectively, for IgG, 92.5% and 95.1%, respectively, for IgA, and 78.3% and 91.0%, respectively, for IgM. The best sensitivity and specificity were obtained by measuring immunoglobulin A antibodies against GPL core antigen. The level of GPL core antibodies reflected disease activity, since it decreased in cured MAC patients who had responded to chemotherapy. Measurement of serum antibodies against GPL core is useful for both diagnosis and assessment of disease activity in MAC disease of the lung.     

Mycobacterium avium complex disease in patients with AIDS: seroreactivity to native and recombinant mycobacterial antigens.

Antibodies to Mycobacterium avium complex (MAC) antigens were measured by enzyme-linked immunosorbent assays and immunoblot analyses in sera from 20 patients with AIDS and disseminated MAC disease, 5 human immunodeficiency virus-seronegative patients with pulmonary MAC infections, and 20 healthy controls. Whereas enzyme-linked immunosorbent assay titers for healthy controls and patients with AIDS and MAC disease were comparable, human immunodeficiency virus-seronegative patients with MAC disease had higher anti-MAC antibody titers (P less than 0.01). Immunoblot analysis with the same sonic extracts indicated that each of the three groups had a limited heterogeneous response to M. avium antigens. No significant differences in immunoblot reactivities were detected. However, immunoblot studies with recombinant nontuberculous mycobacterial antigens revealed that sera from over 90% of the patients with MAC disease and only 25% of controls recognized a recombinant protein derived from a 35-kDa mycobacterial antigen. Although sonic extracts did not permit adequate discrimination of antibody reactivity in patients with MAC disease, recombinant antigens may be useful as indicators of disease.     

Measurement of sputum antibodies in the diagnosis of acute and chronic respiratory infections associated with Chlamydia pneumoniae.

The aim of this study was to develop methods for the measurement of sputum antibodies in the laboratory diagnosis of acute and chronic lower respiratory tract infections caused by Chlamydia pneumoniae. Paired serum specimens, sputum specimens, and pharyngeal or nasopharyngeal swabs were obtained from 97 patients; 51 of them had community-acquired pneumonia, and 46 had chronic obstructive pulmonary disease (COPD). C. pneumoniae-specific serum immunoglobulin G (IgG), IgA, and IgM antibodies were measured by the microimmunofluorescence (micro-IF) test. For sputa, specific IgA and IgG antibodies were measured by the micro-IF test and secretory IgA (sIgA) was measured by enzyme immune assay (EIA) with C. pneumoniae elementary bodies as the antigen. Sputum IgA and sIgA antibodies to C. pneumoniae were found, respectively, in 52 and 51% of the COPD patients. Elevated levels of stable serum IgG and IgA antibodies (IgG titer of > or = 128 and IgA titer of > or = 40), suggesting chronic infection, were found in 54% of the COPD patients. The sensitivity for the sputum IgA micro-IF test compared with elevated serum antibody levels was 87.5%, and that for the sputum sIgA EIA was 88%; the respective specificities were 90 and 95%. Acute C. pneumoniae infection was diagnosed in seven pneumonia patients, and two (29%) of these patients were positive by sputum EIA antibody measurements. Two pneumonia patients without acute infection had stable elevated IgG and IgA levels in their sera, and both of them were sputum antibody positive. We conclude that the measurement of IgA antibodies to C. pneumonia in sputum is a useful additional diagnostic tool for chronic C. pneumoniae infections.     

Dextran and antidextran antibodies in the sera of patients with liver diseases

Dextran and antidextran antibodies were examined by enzyme immunoassay (EIA) and immunodiffusion in sera of 108 patients with various liver diseases. In EIA, IgG class antidextran antibody was detected in 16 patients (14.8%), mostly with chronic liver diseases such as liver cirrhosis (26.9%) and chronic hepatitis (22.2%). IgM class antibody was detected in 10 patients (9.2%). Results obtained by EIA inhibition revealed that dextran antigen was present mostly in sera of patients with acute liver diseases such as fulminant hepatitis (75.0%) and acute hepatitis (17.2%). Identity of the dextran antigen in the liver diseases serum and the dextran preparation recognized by an antibody-containing serum was demonstrated. These results suggest that the damaged hepatocytes in the process of the liver disease may release the dextran antigen into the patient's circulation which is responsible for the formation of antidextran antibodies by the patients with liver diseases.     

A 38-kD Mycobacterium tuberculosis antigen associated with infection. Its isolation and serologic evaluation.

To identify antigens that could be specifically associated with tuberculosis infection, the antibody response to Mycobacterium tuberculosis antigens of patients with pulmonary tuberculosis and of healthy individuals were compared by immunoblot. In healthy individuals, serum antibodies were found in the majority of cases. Bands of 60 and 32-31 kilodaltons (kD) were the antigens more frequently recognized by antibodies of normal sera (55.8 and 64.7%, respectively). In patients with pulmonary tuberculosis, the number and intensity of the developed antigen bands were much higher than in normal individuals. Antigens reacting preferentially with tuberculosis sera were also identified. Furthermore, a unique disease-associated protein antigen of 38 kD was found to react with 57% of patients' sera but with none of the controls. This antigen was isolated by elution from nitrocellulose membranes and tested as an ELISA reagent in the serodiagnosis of pulmonary tuberculosis. A specificity of 0.96 and sensitivity of 0.68 were obtained.     

Naturally occurring antibodies against Mycobacterium avium complex

Serum obtained from 57 healthy individuals and patients admitted to the hospital owing to diverse pathological causes, as well as serum from seven patients with AIDS and disseminated Mycobacterium avium complex (MAC) infection, were studied to determine the prevalence of IgG and IgM antibodies against surface proteins of M. avium complex. Immunodot assay to detect serum positivity against MAC and Western Blot technique in order to determine the MAC antigens eliciting antibody production were performed. Sera from 89 percent and 81 percent of the non-AIDS population had IgG and IgM antibodies against MAC antigens, respectively. In contrast, 43 percent and 71 percent of the AIDS population had IgG and IgM antibodies against MAC antigens, respectively, in the serum. To define further the antigens recognized by these naturally occurring antibodies, the serum of 14 non-AIDS and four acquired immunodeficiency syndrome (AIDS) patients were studied. Multiple antigens of MAC, with molecular weight ranging from 10 to 95 kilodaltons were recognized by IgG and IgM antibodies present in the sera. The IgM type antibodies were shown to react mainly against 10 kilodalton and 31 kilodalton antigenic protein, while the IgG type antibodies were produced mainly against the 10, 31, and 65 kilodalton proteins. Although the pattern of reaction was consistent between non-AIDS and AIDS populations, IgM antibodies were not detected against the 10 kilodalton protein nor were IgG antibodies detected against the 31 kilodalton protein in the AIDS population.     

Analysis of the immunological humoral response toMycobacterium tuberculosis glycolipid antigens (DAT,PGLTb1) for diagnosis of tuberculosis in HIV-seropositive and -seronegative patients

Using an enzyme immunoassay (EIA) test, the concentrations of IgG antibodies against 2,3 diacyl trehalose (DAT) and phenolic glycolipid Tb1 (PGLTb1) were measured in the sera of 153 patients with active tuberculosis, 50 of whom were coinfected with HIV, and in the sera of 152 healthy blood donors, 149 asymptomatic HIV-seropositive patients, 12 HIV-seronegative patients with conditions simulating tuberculosis, 23 HIV-seropositive patients with disseminated infection caused by mycobacteria other than tuberculosis and 24 HIV-seropositive patients with pulmonary disease from whom mycobacteria was not isolated in culture. A slightly lower percentage (74 %) of the HIV-seropositive than the HIV-seronegative (77 %) tuberculosis patients were positive for anti-DAT and antiPGLTb1 IgG antibodies, with a specificity ranging from 91 to 95 %. There was no significant difference between EIA sensitivity in smear-positive and smear-negative patients with pulmonary tuberculosis for all HIV immune statuses and sites of disease (pulmonary vs. extrapulmonary). In HIV-seropositive patients, however, sensitivity was always lower for disseminated tuberculosis than for localized tuberculosis. Combining data for both the smear test and the EIA maximized sensitivity. The main value of the EIA test could be to provide early complementary information by antibody detection in patients with tuberculosis, particularly those with a negative smear test.     

Cellular immune responses to ESAT-6 discriminate between patients with pulmonary disease due to Mycobacterium avium complex and those with pulmonary disease due to Mycobacterium tuberculosis.

ESAT-6 (for 6-kDa early secreted antigenic target) is a secreted antigen found almost exclusively in organisms of the Mycobacterium tuberculosis complex. We compared in vitro gamma interferon (IFN-gamma) responses by peripheral blood mononuclear cells to this antigen in patients with pulmonary disease due to either Mycobacterium avium complex (MAC) or Mycobacterium tuberculosis with those in healthy, skin test-negative, control subjects. Significant IFN-gamma responses to ESAT-6 were detected in 16 (59%) of 27 M. tuberculosis pulmonary disease patients, 0 (0%) of 8 MAC disease patients, and 0 (0%) of 8 controls. Significant IFN-gamma responses to M. tuberculosis purified protein derivative were detected in 23 (85%) of 27 M. tuberculosis disease patients, 2 (25%) of 8 MAC disease patients, and 5 (63%) of 8 healthy controls. M. avium sensitin was recognized in 24 (89%) of 27 M. tuberculosis disease patients, 4 (50%) of 8 MAC disease patients, and 1 (13%) of 8 controls. IFN-gamma responses to ESAT-6 are specific for disease due to M. tuberculosis and are not observed in patients with MAC disease or in healthy controls.     

Cellular Immune Responses to ESAT-6 Discriminate between Patients with Pulmonary Disease Due to Mycobacterium avium Complex and Those with Pulmonary Disease Due to Mycobacterium tuberculosis

ESAT-6 (for 6-kDa early secreted antigenic target) is a secreted antigen found almost exclusively in organisms of the Mycobacterium tuberculosis complex. We compared in vitro gamma interferon (IFN-γ) responses by peripheral blood mononuclear cells to this antigen in patients with pulmonary disease due to either Mycobacterium avium complex (MAC) or Mycobacterium tuberculosis with those in healthy, skin test-negative, control subjects. Significant IFN-γ responses to ESAT-6 were detected in 16 (59%) of 27 M. tuberculosis pulmonary disease patients, 0 (0%) of 8 MAC disease patients, and 0 (0%) of 8 controls. Significant IFN-γ responses to M. tuberculosis purified protein derivative were detected in 23 (85%) of 27 M. tuberculosis disease patients, 2 (25%) of 8 MAC disease patients, and 5 (63%) of 8 healthy controls. M. avium sensitin was recognized in 24 (89%) of 27 M. tuberculosis disease patients, 4 (50%) of 8 MAC disease patients, and 1 (13%) of 8 controls. IFN-γ responses to ESAT-6 are specific for disease due to M. tuberculosis and are not observed in patients with MAC disease or in healthy controls.     

Association of hepatitis C virus carrier state with the occurrence of hepatitis C virus core antibodies.

An enzyme immunoassay (EIA) was developed for the determination of antibodies against the "putative" core protein of hepatitis C virus (HCV). Antigens used were recombinant fragments (amino acids 6-77 or 6-143) of the HCV core protein, produced in Escherichia coli with truncated hepatitis B core (HBc) as fusion protein. Evaluation of 385 sera positive for HCV antibodies by first generation EIA, revealed 98 (25.4%) with HCV core antibodies. HCV-RNA, determined by the polymerase chain reaction (PCR), was exclusively found in the sera positive for HCV core antibodies (89 PCR positives). In random screening of 3,708 sera, 3 sera with HCV core antibodies were found PCR positive. Only 2 of these sera were positive in the first generation EIA. It is concluded that HCV core antibody determination is a reliable test for identifying HCV carriers among blood donors.     

Immunological studies on Kawasaki disease. I. Appearance of Hanganutziu-Deicher antibodies

Sera of patients with Kawasaki disease were studied for heterophile antibodies by means of enzyme immunoassay (EIA) with enzyme conjugated antisera to human IgM, IgG, IgA and IgE. Antibodies of IgM (43%), IgG (3%), IgA (11%) and IgE (49%) classes were demonstrated that combined with high molecular weight glycoprotein (HMWGP) of bovine red blood cells (BRBC) one of the antigenic preparations of the Hanganutziu-Deicher (H-D) heterophile system. Studies on sequential sera of the patients revealed that HMWGP antibodies of IgM and IgE classes began to appear in the second week, reached their peaks in the third week of the disease and declined gradually thereafter. Absorption studies on the positive sera showed that the HMWGP antibody activities were abolished by BRBC, sheep red blood cells and guinea-pig kidney tissues, confirming H-D specificity of these antibodies. EIA inhibition studies showed that the antibody activity was inhibited by HMWGP and partially by asialo-HMWGP and NGNA ganglioside rich preparation of BRBC but not by purified Paul-Bunnell or Forssman antigens. These results indicate that the H-D antibodies under investigation consist of antibodies of two different specificities; one directed against asialo-HMWGP and the other NGNA ganglioside of BRBC. Circulating immune complexes (IC) were demonstrated in 23% of the patients by means of anti-antibody inhibition test. Evidence was presented that IC in the sera of five patients were composed of H-D (HMWGP) antigen and its corresponding antibodies.     

Serodiagnosis of Mycobacterium avium Complex and Mycobacterium abscessus Complex Pulmonary Disease by Use of IgA Antibodies to Glycopeptidolipid Core Antigen

An enzyme immunoassay kit that detects serum IgA antibody reacting to glycopeptidolipid core antigen derived from Mycobacterium avium complex (MAC) was not useful for differentiating MAC pulmonary disease (PD) from Mycobacterium abscessus complex PD (MAB-PD). However, this assay could be useful for differentiating MAC- and MAB-PD from pulmonary tuberculosis. (This study has been registered at ClinicalTrials.gov under registration no. {"type":"clinical-trial","attrs":{"text":"NCT00970801","term_id":"NCT00970801"}}NCT00970801.)     

Changes in Avidity and Level of Immunoglobulin G Antibodies to Mycobacterium tuberculosis in Sera of Patients Undergoing Treatment for Pulmonary Tuberculosis

Much is known about specific antibodies and their titers in patients with tuberculosis. However, little is known about the avidity of these antibodies or whether changes in avidity occur during the progression of the disease or during treatment. The aims of this study were to determine the avidity of antibodies to Mycobacterium tuberculosis in patients with pulmonary tuberculosis, to explore the value of avidity determination for the diagnosis of tuberculosis, and to study changes in levels of antibodies and their avidity during treatment. Antibody avidity was measured by an enzyme-linked immunosorbent assay with thiocyanate elution. Avidity indices and serum levels of immunoglobulin G to M. tuberculosis were determined for 22 patients with pulmonary tuberculosis before and during treatment and for 24 patients with other pulmonary diseases. Antibody levels and avidity were both significantly higher in untreated tuberculosis patients than in the controls. Avidity determination had more diagnostic potential than determination of the antibody levels. Tuberculosis patients with a long duration of symptoms had higher antibody avidity than those with a recent onset of symptoms, indicating affinity maturation of specific antibodies during active disease. In the early phase of treatment, a decrease in antibody avidity was observed for 73% of all tuberculosis patients, accompanied by an initial increase in antibody levels in 36% of these patients. These phenomena could be explained by an intense stimulation of the humoral response by antigens released from killed bacteria, reflecting early bactericidal activity of antituberculous drugs leading to the production of low-affinity antibodies against these released antigens.     

Enzyme immuno assay for the detection of virus specific IgG and IgM antibody in patients with Haemorrhagic Fever with Renal Syndrome

Summary Consecutive serum samples collected from 235 patients with Haemorrhagic Fever with Renal Syndrome (HFRS), between two days and two years after onset of disease, have been analysed for the presence of IgG and IgM type of antibodies specific for Hanta-viruses. The sera were screened in parallel by a newly developed indirect Immuno Enzyme Assay (EIA) in parallel with Indirect Immunofluorescent Antibody Assay (IFA). In both tests the Hantaan virus strain 76–118 was used as the antigen. The EIA was much more sensitive than the IFA test for the detection of IgM type antibodies. With the indirect EIA IgM type antibodies against Hantaan virus 76–118 have been detected in HFRS patient's sera from the second day of illness indicating the usefulness of this test for the early serological diagnosis of this disease.     

Immunodiagnosis of Human Granulocytic Ehrlichiosis by Using Culture-Derived Human Isolates

Human granulocytic ehrlichiosis (HGE) is an emerging infection caused by an Ehrlichia species closely related to Ehrlichia equi and Ehrlichia phagocytophila. Recent advances in the isolation and cultivation of this organism have allowed us to develop an immunofluorescence assay (IFA), enzyme immunoassay (EIA), and Western immunoblotting (WB) using HL-60 cell culture-derived human isolates. Antibody was detected in sera from culture-confirmed HGE patients by IFA and EIA, and these samples were reactive when analyzed by immunoblot analysis. HGE patient sera had high antibody titers and did not react with uninfected HL-60 cells. When IFA, EIA, and WB were used to analyze sera from healthy donors or those with a range of other disorders, including infections caused by Ehrlichia chaffeensis, Rickettsia rickettsii, and Coxiella burnetti, no significant cross-reactivity could be detected by EIA or immunoblot analysis with the exception of two of four serum samples from R. rickettsii-infected patients that were reactive by IFA only. Sera from HGE patients did not significantly cross-react in serologic tests for Borrelia burgdorferi. Using sera from patients previously enrolled in two clinical trials of treatment for early Lyme disease, we evaluated a two-step approach for estimation of the seroprevalence of antibodies reactive with the etiologic agent of HGE. On the basis of the immunoblot assay results for sera from culture-confirmed HGE patients, WB was used to confirm the specificity of the antibody detected by EIA and IFA. EIA was found to be superior to IFA in the ability to detect WB-confirmed antibodies to the HGE agent. When EIA and WB were used, 56 (19.9%) patients with early Lyme disease (n = 281) had either specific immunoglobulin M (IgM) or IgG antibodies; 38 patients (13.5%) had IgM only, 6 (2.1%) had IgG only, and 12 (4.3%) had both IgM and IgG. Therefore, Lyme disease patients are at high potential risk for exposure to Ehrlichia. Analysis by immunoblotting of serial samples from persons with culture-confirmed HGE or patients with Lyme disease and antibodies to the agent of HGE revealed a reproducible pattern of the immune response to specific antigens. These samples confirmed the importance of the 42- to 45-kDa antigens as early, persistent, and specific markers of HGE infection. Other significant immunogenic proteins appear at 20, 21, 28, 30, and 60 kDa. Use of the two-test method of screening by EIA and confirming the specificity by WB appears to offer a sound approach to the clinical immunodiagnosis of HGE.     

Comparison of a monoclonal antibody-blocking enzyme-linked immunoassay and a strip immunoblot assay for identifying type-specific herpes simplex virus type 2 serological responses

Detection of herpes simplex virus type 2 (HSV-2)-specific antibodies by a monoclonal antibody (MAb)-blocking enzyme-linked immunoassay (EIA) was compared with detection by a strip immunoblot assay (SIA) in a sexually transmitted disease (STD) clinic population. The study population consisted of 1,683 genitourinary medicine clinic attendees (582 women and 1,101 men). Sera were tested for the presence of HSV-2 antibody by use of the blocking EIA, in which binding of the MAb AP-1 to HSV-2 glycoprotein G-2 (gG-2) is blocked by HSV-2-specific antibody. The Chiron RIBA HSV-1 and -2 strip immunoassay (SIA) utilizes HSV-1- and HSV-2-specific or cross-reactive antigens immobilized on nitrocellulose strips (HSV gB-1 and HSV gG-1 peptide bands specific for HSV-1 antibody, HSV-2 gG-2 band specific for HSV-2 antibody, and HSV gD-2 band cross-reactive for HSV-1 and HSV-2 antibodies). A total of 1,612 sera were tested by MAb-blocking EIA for HSV-2 antibody and by SIA for HSV-1 and HSV-2 antibodies. By EIA, 541 (33.6%) sera were positive for HSV-2 antibody and 1,068 sera were negative for HSV-2 antibody; 3 sera gave equivocal results. HSV-2 antibody was detected in 555 (34.4%) sera by SIA; 144 (26%) of these sera possessed only HSV-2 antibody, and 411 (74%) sera contained both HSV-1 and HSV-2 antibodies. SIA detected HSV-1 antibody in 1,155 (71.6%) sera; 744 (64%) of these sera contained HSV-1 antibody alone. Sixteen sera contained antibody against HSV but could not be typed by SIA. A total of 512 sera were positive for HSV-2 antibody by both the EIA and SIA. We concluded that the blocking EIA and SIA showed a high level of agreement in detecting HSV-2 antibody in this population. In contrast to the SIA, the blocking EIA is a useful tool for large epidemiological studies, though the SIA proved to be slightly more sensitive once sera with discrepant results were further tested.     

HIV-1/2抗体和P24抗原联合检测试剂盒的研制与评价

目的研制HIV-1／2抗体和P24抗原联合检测酶免疫试剂盒并评价其实用性。方法联合使用基因工程HIVI／2型抗原和抗HIVP24单克隆抗体包被酶联反应板，以辣根过氧化物酶标记的HIVI／2型抗原和生物素化的兔抗HIVP24抗体作为标记物，研制了联合检测HIVI／2抗体和P24抗原的ELISA诊断试剂，并对其特异性、敏感性、稳定性等进行评价和临床考评。结果检测P24抗原质控品的灵敏度可达0．2ng／ml；与雅培公司试剂比较检测78份AIDS患者血清和85份正常人血清、对照检测中国药品生物制品检定所研制的HIV参比血清，特异度和灵敏度均为100％。临床考核检测12051份各种血清，灵敏度为100％（543／543），特异度为99．48％（11448／11508）。试剂在37℃放置6d后，试验结果无明显差异。结论本试剂盒具备特异度强、敏感度高、稳定性好、操作简便等优点，可以一步检出HIV特异性抗体和HIVP24抗原，缩短了HIV感染的检测窗口期，适用于HIV感染的实验室诊断和流行病学调查。     

Serodiagnosis of tuberculosis and leprosy by enzyme immunoassay

Objective: To evaluate the use of serodiagnosis for tuberculosis and leprosy using mycobacterial antigen 38 kDa, with kits from Omega laboratories, to detect IgG by enzyme immunoassay (EIA).
Method: The study population consisted of 58 patients with evidence of tuberculous infection (culture of Mycobacterium tuberculosis complex or microscopic evidence), of whom 23 had pulmonary and 35 had extrapulmonary disease. There were six subjects who had recently been treated for tuberculosis, 11 patients on treatment for leprosy and 137 patients suspected of having tuberculosis on clinical or radiologic grounds (without laboratory evidence). A control group comprised 35 healthy individuals or patients suffering from diseases other than tuberculosis.
Results: The tests showed that there was a significant difference in antibody levels between the patients with active pulmonary disease, extrapulmonary tuberculosis and leprosy in comparison with the control group ( p <0.001). The sensitivities of the two tests together for proven pulmonary tuberculosis were 100% and 95.7% at 1.0–1.5 and >1.6 EIA cut-off points respectively, while the specificities were 88.5% and 100% at the same cut-off points. The sensitivities for extrapulmonary tuberculosis were 71.4% and only 51.4% at 1.0–1.5 and >1.6 EIA cut-off points. The test was positive in 30 (21.9%) of the 137 suspected patients, while 43 (31.4%) had an equivocal result and the remaining 64 (47.7%) suspects were definitely negative. There was again a significant difference in positivity rates between suspects and the control group.
Conclusions: Omega IgG test is useful in the serodiagnosis of active pulmonary tuberculosis and leprosy, but less sensitive in extrapulmonary disease, particularly in children. Equivocal results may only add to the evidence of tuberculosis in early or minimal disease.     

Evaluation of specificity of EIA kit (ED-007)

EIA (Eitest: Eisai) and Gelatin Particle Agglutination: PA (SERODIA: Fujirebio) assays were performed for the detection of HTLV-I antibodies with 10,780 sera from patients since 1986. Eleven point five percent were reactive by both EIA and PA, while 1.1% was PA(+), EIA(-), these PA false positive occurred on low titer. Conversely 0.2% on EIA positive seems PA false negative because of Western blot (WB) positivity. Zero point nine percent was EIA(+), PA(-), of these 80.6% were not inhibited by EIA confirmatory test. The main cause of EIA false positive was due to reactivity of auto antibody with MT-2 cell lysate. We used new EIA (ED-007: Eisai) coated with HTLV-I antigen purified from supernatant of culture medium of MT-2 cell. The results completely matched with EIA confirmatory test and WB. Cut off index value of sera from SLE patients were down to 0.2 (mean +/- SD) from 0.7 +/- 0.4 of Eitest ATL. EIA (ED-007) are probably useful and more specific assays for the detection of HTLV-I antibodies, especially, the sera of patients with autoimmune diseases.     

Early diagnosis of typhoid fever by an enzyme immunoassay usingSalmonella typhi outer membrane protein preparations

An enzyme immunoassay (EIA) for detection of serum antibodies in patients with typhoid fever was developed usingSalmonella typhi outer membrane protein (OMP) preparations as antigen. Acute phase (first week) sera from adult typhoid fever patients were tested as well as sera from the following control groups: adult travellers with diarrhea caused by enterotoxigenicEscherichia coli, children infected withCampylobacter jejuni, healthy Mexican adult blood donors, and adults with septicemia caused by other organisms. At a 1:3,125 serum dilution, the mean absorbance values were 1.41 in the typhoid fever patients, and 0.57, 0.55, 0.51 and 0.52 in the respective control groups. Inhibition EIA studies using OMP preparations or lipopolysaccharide (LPS) as free antigen indicated that proteins can play an important role in the detection of antibodies in early typhoid fever. This EIA may be useful for the diagnosis of typhoid fever since results were obtained within about five hours and in an endemic area antibodies againstSalmonella typhi OMP preparations appear early in the course of the disease.