Serologic Detection of Coccidioidomycosis Antibodies in Northeast Brazil

Coccidioidomycosis is a systemic infection caused by Coccidioides spp. The disease is endemic in Brazil but its incidence is underreported as it is not a notifiable disease. This article presents the results of a serologic survey carried out with 229 volunteers in northeast Brazil by the immunodiffusion (ID) test with commercial Coccidioides spp. antigens. The commercial ID test detected 15 individuals without clinical diagnosis of the disease and two individuals in treatment for coccidioidomycosis. Regarding the epidemiological data, most of the positive individuals were male, between 18 and 65 years of age and were engaged in armadillo hunting. Three women who had never participated in armadillo hunts also displayed positive results for coccidioidal antibodies. Besides armadillo hunts, exposure to environmental dust in endemic areas may account for the serologic response detected in the study. The data from this study suggest the importance of performing epidemiological surveys for coccidioidomycosis in order to understand the prevalence of this disease in Brazil.     

Comparison of a Newly Developed Latex Agglutination Test and an Immunodiffusion Test in the Diagnosis of Systemic Candidiasis

A newly developed latex agglutination (LA) test and a modified immunodiffusion (ID) test were evaluated. The antigen used was a homogenate of Candida albicans. A total of 167 antisera were employed in the evaluation. They included 36 sera from clinically well persons; 78 from patients with various clinical forms of candidiasis; 52 from patients with proven cases of aspergillosis, blastomycosis, coccidioidomycosis, cryptococcosis, histoplasmosis, nocardiosis, paracoccidioidomycosis, sporotrichosis, and tuberculosis; and one serum from a patient with toruloposis. Use of the LA test in conjunction with the ID test permitted the detection of more than 90% of 43 proven candidiasis cases. Of all the heterologous cases and normal human sera tested, LA reactions were noted with 3 of 10 cryptococcosis case specimens, 1 of 9 tuberculosis case specimens, and with the torulopsemia case serum. In contrast, the only heterologous serum reactive in the ID test was that from the patient with torulopsemia. Torulopsis glabrata and C. albicans antisera gave identical reactions in LA and ID tests with T. glabrata or C. albicans antigens. ID tests with selected antigens, however, permitted differentiation of rabbit and human T. glabrata antibody from that of C. albicans antibody. Six different precipitins were recognized with the C. albicans antigens. The occurrence of multiple precipitin lines and high LA titers was suggestive of severe candidiasis. The LA test, in contrast to the ID test, appeared to have prognostic value. Together, the LA and ID tests provided a simple, rapid, and accurate means of detecting and monitoring infections by species of Candida.     

Reversal of coccidioidal anergy in vitro by dendritic cells from patients with disseminated coccidioidomycosis

Coccidioides immitis is a pathogenic, dimorphic fungus found in the southwestern United States and is the causative agent of coccidioidomycosis. Extrathoracic dissemination of coccidioidomycosis is associated with a lack of cellular immunity. Dendritic cells (DCs) have been shown to initiate and modulate cellular immune responses. To determine whether DCs could modulate or initiate the immune response in this disease, monocyte-derived DCs were generated from coccidioidal Ag nonresponsive patients with disseminated coccidioidomycosis and healthy nonimmune individuals. DCs generated from both groups demonstrated phenotypes characteristic of DCs and stimulated strong allogeneic MLR. DCs from patients and healthy nonimmune individuals pulsed with the coccidioidal Ag preparation T27K induced lymphocyte proliferation. Mature DCs were much more efficient than immature DCs in these stimulations. Furthermore, restimulation of T27K-primed PBMC with Ag-pulsed DCs generated a C. immitis-specific cellular immune response in PBMC from patients with disseminated coccidioidomycosis as well as healthy nonimmune individuals. These results show that 1) DCs have the capacity to stimulate specific cellular immune responses from patients with disseminated coccidioidomycosis who are nonresponsive to coccidioidal Ag and healthy nonimmune individuals in vitro; 2) DCs can be used to screen coccidioidal Ags as candidates for human vaccine development; and 3) DC therapy may be useful in the treatment of disseminated coccidioidomycosis.     

Comparative evaluation of two commercially available antigen enzyme immunoassays (EIA) for the detection of Legionella pneumophila urinary antigen in frozen non-concentrated urine samples

We evaluated two commercial enzyme immunoassay kits, Binax EIA (for detection of soluble antigen of Legionella pneumophila serogroup 1) and Biotest EIA (for detection of antigens of Legionella pneumophila serogroups and other Legionella spp.) in order to introduce this test routinely for the diagnosis of Legionnaires' disease (LD) in our Laboratory. Frozen non-concentrated urine samples belonging to 45 patients with and without LD were tested. The sensitivity of Binax EIA and Biotest EIA was 47.4% and 42.1% respectively, the specificity was 95% by both tests. Biotest did not detect antigen from a patient with culture-proven infection of L. pneumophila serogroup 6. The detection of urinary antigen by both EIA tests is a useful tool for rapid diagnosis of LD, especially when samples are unavailable for culture; the sensitivity may be increased if the assay is performed on unfrozen and concentrated samples.     

Significance of Isolated Positive IgM Serologic Results by Enzyme Immunoassay for Coccidioidomycosis

Serologic testing is important for diagnosis of coccidioidomycosis. Many methods are available for diagnostic testing. Enzyme immunoassay (EIA) can be performed quickly and locally but has the potential for false-positive results in patients manifesting a positive EIA for immunoglobulin M (IgM) antibodies and a negative EIA for immunoglobulin G (IgG). We retrospectively reviewed the charts of 405 patients with coccidioidal serologic testing performed between 1999 and 2003. Of 706 EIAs, 37 (5%) produced test results for 28 patients that showed isolated IgM positivity. Among these 28 patients, 24 (86%) had positive serologic findings by other methods (complement fixation or immunodiffusion or both), and 7 (25%) had positive microbiologic or histopathologic findings. All 4 (14%) patients without other positive serologic results had diagnostic tests with positive microbiologic or histopathologic results. No false-positive IgM assays were observed. We conclude that the false-positive rate of the EIA IgM is low, and that an isolated positive EIA IgM should prompt further follow-up and diagnostic testing. J. T. Currier was a Visiting Research Trainee at the Division of Infectious Diseases, Mayo Clinic, Scottsdale, AZ.     

Western blotting using Strongyloides ratti antigen for the detection of IgG antibodies as confirmatory test in human strongyloidiasis

The present study was conducted to evaluate the frequency of antigenic components recognized by serum IgG antibodies in Western blotting (WB) using a Strongyloides ratti larval extract for the diagnosis of human strongyloidiasis. In addition, the WB results were compared to the enzyme-linked immunosorbent assay (ELISA) and the indirect immunofluorescence antibody test (IFAT) results. Serum samples of 180 individuals were analyzed (80 with strongyloidiasis, 60 with other intestinal parasitoses, and 40 healthy individuals). S. ratti was obtained from fecal culture of experimentally infected Rattus rattus. For IFAT, S. ratti larvae were used as antigen and S. ratti larval antigenic extracts were employed in WB and ELISA. Eleven S. ratti antigenic components were predominantly recognized by IgG antibodies in sera of patients with strongyloidiasis. There was a positive concordance for the three tests in 87.5% of the cases of strongyloidiasis. The negative concordance in the three tests was 94% and 97.5%, in patients with other intestinal parasitoses and healthy individuals, respectively. In cases of positive ELISA and negative IFAT results, diagnosis could be confirmed by WB. ELISA, IFAT, and WB using S. ratti antigens showed a high rate of sensitivity and specificity. In conclusion, WB using S. ratti larval extract was able to recognize 11 immunodominant antigenic components, showing to be a useful tool to define the diagnosis in cases of equivocal serology.     

In vitro modulation of cytokine production by lymphocytes in human coccidioidomycosis

The modulation of the cytokine response to coccidioidal antigen by lymphocytes from donors with coccidioidomycosis was examined. In initial experiments, samples from 13 healthy immune donors and seven donors with active coccidioidomycosis anergic to the coccidioidal antigen T27K were assessed for CD3 lymphocyte expression of intracellular IFN-gamma using whole blood analysis. Addition of 10 ng/ml of recombinant IL-12 significantly increased response to T27K among immune and anergic subjects (p<0.05), but the percent of cells expressing IFN-gamma was still significantly greater for immune subjects. Among immune donors, the percentage of CD3 lymphocytes expressing IFN-gamma was significantly reduced with the addition of 10 ng/ml of recombinant IL-4, IL-10, TGF-beta, or their combination (for all, p<0.05). Among anergic donors, addition of 10 ng/ml of anti-IL-10 significantly increased IFN-gamma production (p<0.05), but addition of anti-IL-4 or anti-TGF-beta did not. Among immune donors, the percent of both CD3 lymphocytes and NK cells expressing IFN-gamma after 24h of T27K was increased above control (p<0.05), while the percent of NK cells producing TNF-alpha in response to T27K was not greater than control. Depletion of NK cells from peripheral blood mononuclear cells resulted in significant increases in TNF-alpha and IL-10 (for both, p<0.05) but resulted in no significant decrease in IFN-gamma or IL-2. These data demonstrate a differential response to stimulation with the coccidioidal antigen T27K among donors with coccidioidomycosis that can be manipulated by cell type and cytokine environment.     

Dot-Blot Immunoassay of Fasciola gigantica Infection using 27 kDa and Adult Worm Regurge Antigens in Egyptian Patients

The purpose of the present study was to evaluate the potential role of the 27-Kilodalton (KDa) antigen versus Fasciola gigantica adult worm regurge antigens in a DOT-Blot assay and to assess this assay as a practical tool for diagnosis fascioliasis in Egyptian patients. Fasciola gigantica antigen of an approximate molecular mass 27-(KDa) was obtained from adult worms by a simple elution SDS-PAGE. A Dot-Blot was developed comparatively to adult worm regurge antigens for the detection of specific antibodies from patients infected with F. gigantica in Egypt. Control sera were obtained from patients with other parasitic infections and healthy volunteers to assess the test and compare between the antigens. The sensitivity, specificity, positive and negative predictive values of Dot-Blot using the adult worm regurge were 80%, 90%, 94.1%, and 69.2% respectively, while those using 27-KDa were 100% which confirms the diagnostic potential of this antigen. All patients infected with Fasciola were positive, with cross reactivity reported with Schistosoma mansoni serum samples. This 27-KDa Dot-Blot assay showed to be a promising test which can be used for serodiagnosis of fascioliasis in Egyptian patients especially, those presenting with hepatic disease. It is specific, sensitive and easy to perform method for the rapid diagnosis particularly when more complex laboratory tests are unavailable.     

Reactivity of serum samples from patients with a flavivirus infection measured by immunofluorescence assay and ELISA

Flavivirus infections are a significant public health problem, since several members of the Flaviviridae family are highly pathogenic to humans. Accurate diagnosis and differentiation of the infecting virus is important, especially in areas where many flaviviruses are circulating. In this study we evaluated a newly developed commercially available immunofluorescence assay (IFA) (INDX, Baltimore, MD, USA) for the detection of IgM and IgG antibodies against dengue virus, yellow fever virus, Japanese encephalitis virus and West Nile virus. IFA was compared with standard diagnostic enzyme immunoassays (EIAs) specific for the detection of IgM and IgG antibodies against these viruses. Forty-seven serum samples from patients with a defined flavivirus infection were tested. As controls, serum samples from individuals with antibodies against tick-borne encephalitis virus and hepatitis C virus as well as healthy individuals were included. The results obtained from this study indicate that IFA showed a significantly better discrimination for flavivirus specific IgM antibodies than did the standard IgM specific EIAs (the overall cross-reactivity varied between 4 and 10% by IFA and 30-44% by EIA for the respective viruses). In contrast, the detection of flavivirus specific IgG antibodies showed high cross-reactions in both IFA and EIAs (overall cross-reactivity 16-71 and 62-84%, respectively). This study clearly stated the complexity of flavivirus diagnosis, showing that one cannot rely on one assay or search for one virus only. The flavivirus IFA is a useful tool for the identification of flavivirus infections during the acute stage of disease. In particular, IFA can be an important diagnostic tool for testing samples from travellers who have been accidentally exposed to these viruses.     

Immunochemical properties of the extracellular hydrolases (protease and alkaline phosphatase) of Coccidioides immitis]

Extracellular hydrolases (protease and alkaline phosphatase) of the coccidioidal fungus possessed antigenic properties and caused production of the corresponding antibodies. Phosphatase-antiphosphatase-substrate system apparently has future prospects for the elaboration of immunobiochemical methods for the diagnosis of coccidioidomycosis.     

Measurement of Cellular Immunity in Human Coccidioidomycosis

Measurement of cellular immune response in human coccidioidomycosis, a disease of the Western Hemisphere caused by the soil-dwelling fungus Coccidioides, began more than 75 years ago. Numerous studies have shown that measurement of coccidioidal cellular immunity is a useful epidemiologic and clinical tool. The first widely used coccidioidal skin-test reagent, coccidioidin, was derived from a filtrate of cultured mycelia of Coccidioides by Smith and colleagues in the 1940's. It remained the standard until the 1970's, when spherulin, obtained from the spherule form of the fungus, was found to be more sensitive. Both reagents are specific indicators of coccidioidal cellular immunity. Since then, other coccidioidal antigens have been identified and in vitro tests of cellular immunity have been shown to yield comparable results to skin testing. In vitro assays have also begun to open a window on the specific immunologic events of coccidioidal cellular immunity. Persistent expression of coccidioidal cellular immune response appears to augur an improved clinical outcome. Despite this, a study of a coccidioidal vaccine failed to demonstrate efficacy. Current and future studies are focused on modulating the coccidioidal immune response in vitro and in vivo and on developing an improved vaccine.     

丙型肝炎病毒核壳蛋白抗原的化学合成及其在血清学诊断中的应用

选取丙型肝炎病毒(HCV)核壳蛋白区两个可能含有优势抗原表位的19和16氨基酸的肽殴(C-19肽和C-16肽),利用固相多肽合成技术进行了化学合成。经用反相高压液相层析(HPLC)及脉冲液相多肽测序技术检定合成肽产品的纯度及序列后,以C-19和C-16肽作为包被抗原组装成检测HCV血清抗体的ELISA诊断试剂。用所组装的合成肽试剂检测中国药品生物制品检定所提供的HCV标准参比血清,并比较利用该试剂和美国Abbott实验室生产的HCV第二代EIA诊断试剂平行检测109份献血员血清的结果,表明C-19肽能够特异、重复、灵敏地检出HCV血清抗体,可以作为我国第一代HCV诊断试剂的合成肽抗原。     

An Archived Lot of Coccidioidin Induces Specific Coccidioidal Delayed-type Hypersensitivity and Correlates with in vitro Assays of Coccidioidal Cellular Immune Response

No test for assessing cellular immune response in coccidioidomycosis is currently available in the United States. In the present study, we tested 49 healthy subjects living in the coccidioidal endemic region with a 1:55.8 dilution of a single lot of coccidioidin archived since the 1970s. In this group, 23 evaluable subjects demonstrated ≥5 mm of induration at 24, 48 or 72 h, with a mean±SEM maximum induration of 18.4±4.0 mm. The induration results among 14 subjects reactive at 24 h were compared to those from 179 individuals in an historical cohort studied in the 1980s using a reference lot of coccidioidin. Results were within 5% and not significantly different (P=0.924). The maximum induration response of all evaluable subjects correlated significantly with the results of in vitro tests of coccidioidal cellular immunity using supernatant interferon-gamma concentration and CD69 expression on T cells (Spearman rank correlation coefficients 0.69 and 0.68, respectively; P<0.01 for both). These data suggest that archived coccidioidin retains its potency and specificity and that in vitro test of coccidioidal immunity may have utility in the measurement of coccidioidal cellular immunity.     

Humoral response to selected antigens of Yersinia enterocolitica and Yersinia pseudotuberculosis in the course of yersiniosis in humans. I. Occurrence of antibodies to Yersinia lipopolisacharydes and Yop proteins by ELISA

The antibodies against the somatic antigens of Y. enterocolitica O3, O8, O9, O5,27,Y. pseudotuberculosis I, and released proteins Yop were detected using the ELISA in 1634 serum samples and 84 synovial fluids collected from 1290 persons suspected for yersiniosis, as well as 200 serum samples from healthy individuals (blood donors). The presence of antibody in diagnostically significant titres for somatic antigens of Yersinia were detected by ELISA in 20.5% and 50.6%, antibodies for released proteins Yop in 11.5% and 28.4% respectively of blood donors and patients suspected for yersiniosis. The antibody against the O3 antigen of Y. enterocolitica was the most frequently detected antibody while the most infrequent was the antibody for the antigen from the 08 serologic group. The results of the study showed that the humoral response picture to Yersinia antigens in the course of yersiniosis in humans is dependent on the age and sex of the patient, duration of the infection, and clinical manifestations. Most frequently the elevated antibody levels were detected among patients with erythema nodosum and patients with gastrointestinal symptoms. The frequency of occurrence of antibodies for most antigens of Yersinia, together with age increased reaching its peak, on the average, among individuals aged 21 - 40 years. Analysis of individual cases showed that by the end of the first week of infection, elevated levels of antibodies for somatic antigens of Yersinia are evident. On the other hand, antibodies for released proteins Yop as a matter of rule appear in the second week from the onset of clinical symptoms. Within this early phase of infection immunoglobulins of the A and M classes dominate reaching their highest level in the second to third week of the infection. In majority of the individuals studied antibodies of the IgG class reached their highest level much later in relation to those of the IgA and IgM classes. Significant differences were found in IgA antibody detection among individuals with clinical manifestations of stomachaches and arthritis. Nevertheless, among individuals with clinical symptoms of stomachaches, these immunoglobulins as a matter of principle disappear with a period of 2-3 months from the onset of clinical symptoms. In individuals with arthritis however the aforementioned immunoglobulins maintained at considerable levels even after a year. In joint-fluid samples obtained from patients with arthritis antibodies for Yersinia antigens were detected in similar levels just as obtained simultaneously serum from those individuals.     

Further observations on the specificity of antigen 5 of Echinococcus granulosus.

The presence of IgE antibodies to antigen 5 of Echinococcus granulosus was detected by means of radioimmunoelectrophoresis in the sera of two of six patients infected with E. multilocularis. Sera from three of these patients gave a precipitin band in gel diffusion tests identical to that produced by a monospecific rabbit anti-E. granulosus antigen 5 serum, when tested against whole hydatid fluid. Sera from 19 individuals infected with Fasciola hepatica, 20 with Schistosoma mansoni, and 5 with with Taenia saginata showed no detectable antibodies against antigen 5 of E. granulosus, The monospecific rabbit anti-E. granulosus antigen 5 serum did not react in immunodiffusion with homologous antigen when absorbed with either 4 mg/ml of whole hydatid fluid or with 200 mg/ml of a soluble E. multilocularis extract. Absorption of the monospecific antiserum with crude antigens of either F. hepatica, Onchocerca volvulus, S. mansoni, or T. saginata did not abolish the reaction with antigen 5. It appears, therefore, that antigen 5 can no longer be considered specific for E. granulosus, but is also present in E. multilocularis. In the light of this observation, some reevaluation of immunodiagnostic tests in hydatid disease will be necessary.     

LIPS arrays for simultaneous detection of antibodies against partial and whole proteomes of HCV, HIV and EBV

For many infectious agents, the detection of antibodies is critical for diagnosing, monitoring and understanding vaccine responses. To facilitate the highly quantitative and simultaneous analysis of antibodies against multiple proteins from infectious agents, we have developed Luciferase Immunoprecipitation Systems (LIPS) arrays. By configuring microtiter plates with multiple antigens and testing control and infected serum samples at one time in solution, LIPS arrays provided highly reproducible antibody titers to panels of antigens with a wide dynamic range of detection. While all serum samples showed similar positive and negative immunoreactivity with internal control antigens derived from Influenza and Renilla luciferase-alone protein, respectively, antibody titers to many HCV and HIV antigens were generally 10 to over 400-fold higher in the infected versus uninfected samples. Additional screening of 18 proteins from the EBV proteome with serum samples from healthy EBV-infected individuals showed statistically significant antibody titers to 50% of the proteins tested. Antibody titers for the different EBV antigens in the healthy EBV-infected individuals were markedly heterogeneous highlighting the complexity of host humoral responses. These results suggest that LIPS arrays offer a highly discriminating platform for simultaneously profiling a wide spectrum of antibodies associated with many infectious agents.     

Serological detection of Plasmodium vivax malaria using recombinant proteins corresponding to the 19-kDa C-terminal region of the merozoite surface protein-1

BACKGROUND: Serological tests to detect antibodies specific to Plasmodium vivax could be a valuable tool for epidemiological studies, for screening blood donors in areas where the malaria is not endemic and for diagnosis of infected individuals. Because P. vivax cannot be easily obtained in vitro, ELISA assays using total or semi-purified antigens are rarely used. Based on this limitation, we tested whether recombinant proteins representing the 19 kDa C-terminal region of the merozoite surface protein-1 of P. vivax (MSP119) could be useful for serological detection of malaria infection. METHODS: Three purified recombinant proteins produced in Escherichia coli (GST-MSP119, His6-MSP119 and His6-MSP119-PADRE) and one in Pichia pastoris (yMSP119-PADRE) were compared for their ability to bind to IgG antibodies of individuals with patent P. vivax infection. The method was tested with 200 serum samples collected from individuals living in the north of Brazil in areas endemic for malaria, 53 serum samples from individuals exposed to Plasmodium falciparum infection and 177 serum samples from individuals never exposed to malaria. RESULTS: Overall, the sensitivity of the ELISA assessed with sera from naturally infected individuals was 95%. The proportion of serum samples that reacted with recombinant proteins GST-MSP119, His6-MSP119, His6-MSP119-PADRE and yMSP119-PADRE was 90%, 93.5%, 93.5% and 93.5%, respectively. The specificity values of the ELISA determined with sera from healthy individuals and from individuals with other infectious diseases were 98.3% (GST-MSP119), 97.7% (His6-MSP119 and His6-MSP119-PADRE) or 100% (yMSP119-PADRE). CONCLUSIONS: Our study demonstrated that for the Brazilian population, an ELISA using a recombinant protein of the MSP119 can be used as the basis for the development of a valuable serological assay for the detection of P. vivax malaria.     

Use of microcapsular leptospiral antigens for detecting specific antibodies

The sensitivity of microcapsular leptospiral antigens, produced by Japan Lyophilization Laboratory and intended for use in tests for the detection of antibodies to leptospires in the sera of experimentally immunized laboratory animals, were studied. The comparative study of the microcapsular agglutination (MCA) test and other serological tests, such as the microagglutination (MA) test and the indirect enzyme immunoassay (EIA), was made. The leptospiral antigens under study were found to actively react with serospecific and group-specific antibodies. In infected guinea pigs and rabbits specific antibodies could be detected from days 3-4 in the MCA test and only from days 5-7 in the MA test. The average antibody level determined by titration in the MCA test was 3.3 times higher and in indirect EIA, 4.3 times higher than that determined by titration in the MA test. These data make it possible to recommend the use of microcapsular leptospiral antigens for the early diagnosis of leptospirosis.     

Evaluation of the enzyme-linked immunosorbent assay for the serodiagnosis of tularemia

The usefulness of the ELISA using as antigen prepared in our laboratory supernatant obtained after centrifugation of sonicated F. tularensis cell suspension was compared with the tube agglutination test with commercial available antigen. Paired serum specimens obtained from 6 patients with ulceroglandular syndrome of tularemia were tested in both tests. The cut-off limit of serum antibodies was set at mean antibody titre determined in the sera of 115 blood donors exceeded by three standard deviations. Antibodies to F. tularensis in diagnostically significant titre were detected in all 12 serum samples by both tests. However the titres obtained in ELISA were several times higher than in tube agglutination test. In the second serum sample the level of IgA and IgM was lower but the level of IgG higher than in the first sample. We could not observe any difference in the level of antibodies between paired serum specimens in tube agglutination test.     

DIAGNOSIS OF PULMONARY COCCIDIOIDAL INFECTIONS

A wide variety of pulmonary lesions may be caused by coccidioidomycosis. Suspicion of coccidioidomycosis may be substantiated by careful clinical-epidemiological histories. The first laboratory procedure should be a coccidioidin skin test. If the reaction to the test is positive, serological tests are next. Also, if there is no reaction to coccidioidin, serological tests are still indicated if dissemination is suspected. The more severe the infection, the greater the probability of establishing a diagnosis serologically. In only three-fifths of patients with coccidioidal cavities can the diagnosis be fixed serologically. In such patients if differential skin tests are not conclusive, attempt should be made to recover the fungus. However, this is accompanied by great risk of laboratory infection. Eosinophilia and accelerated erythrocyte sedimentation are only circumstantial items of evidence, as is the appearance of the pulmonary roentgenogram.