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At least 541 records · Page 30Linked to original sources
PubMed1975

IgG antibody suppression of the IgM antibody response to Toxoplasma gondii in newborn rabbits.

Studies were performed in an experimental rabbit model in an attempt to explore the possibility that the absence of an IgM antibody response in human infants congenitally infected with Toxoplasma may be caused by a suppressive effect of IgG antibody passively transferred from the mother. The IgM antibody response to Toxoplasma gondii infection in newborn rabbits previously injected with IgG Toxoplasma antibody was significantly suppressed as determined by an immunofluorescent antibody assay (IgM-IFA). In newborn rabbits infected with Toxoplasma, IgM-IFA antibody was first demonstrated 15 days after infection and reached a peak titer of 1:128 in two animals on days 20 and 25. In newborn rabbits injected with IgG Toxoplasma antibody and then infected with Toxoplasma, the Igm-IFA antibody and then infected with Toxoplasma, the Igm-IFA antibody response was considerably lower; the highest titer was 1:16 and occurred 25 and 30 days after infection. The results of these studies lend support to the concept that maternally transmitted IgG may suppress the IgM antibody response in the fetus and newborn infant.

Animals↗
PubMedDate not supplied

Detection of antibody to turkey coronavirus by antibody-capture enzyme-linked immunosorbent assay utilizing infectious bronchitis virus antigen.

An antibody-capture enzyme-linked immunosorbent assay (ELISA) for detection of antibody to turkey coronavirus (TCV) utilizing infectious bronchitis virus (IBV) antigen was developed. Anti-TCV hyperimmune turkey serum and normal turkey serum were used as positive or negative control serum for optimization of the ELISA system. Goat anti-turkey immunoglobulin G (light plus heavy chains) conjugated with horseradish peroxidase was used as detector antibody. The performance of the ELISA system was evaluated with 45 normal turkey sera and 325 turkey sera from the field and the cutoff point was determined. Serum samples of turkeys experimentally infected with TCV collected sequentially from 1 to 63 days postinfection were applied to the established antibody-capture ELISA using IBV antigens. The optimum conditions for differentiation between anti-TCV hyperimmune serum and normal turkey serum were serum dilution at 1:40 and conjugate dilution at 1:1600. Of the 325 sera from the field, 175 were positive for TCV by immunofluorescent antibody (IFA) assay. The sensitivity and specificity of the ELISA relative to IFA test were 93.1% and 96.7%, respectively, based on the results of serum samples from the field turkey flocks using the optimum cutoff point of 0.18 as determined by the logistic regression method. The ELISA values of all 45 normal turkey sera were completely separated from that of IFA-positive sera. The ELISA results of serum samples collected from turkeys experimentally infected with TCV were comparable to that of the IFA assay. Reactivity of anti-rotavirus, anti-reovirus, anti-adenovirus, or anti-enterovirus antibodies with the IBV antigens coated in the commercially available ELISA plates coated with IBV antigens could be utilized for detection of antibodies to TCV in antibody-capture ELISA.

Animals↗
PubMedDate not supplied

[An immunoenzymatic technique for the detection of antinuclear antibodies].

In the present work, we propose, for the detection of the anti-nuclear antibodies (ANA) an immunoenzymatic test in simple sandwich in heterogeneous phase (ANA-EIA) allowing the screening of the antinuclear antibodies, and its assessment in comparison with the indirect immunofluorescent assay (IFA) for 292 sera of patients affected by rheumatic diseases and 40 sera of individuals presenting no pathology. The ANA-EIA test proved to have a sensitivity of 97% and a specificity of 96%. Moreover, it gives a global concordance of 96.6% and a discordance of 3.4% compared to IFA. Also, the analysis of correlation between this test and IFA for the positive individual gives a very good concordance according to homogeneous, speckled and nucleolar aspects. On the other hand, the results obtained for cytoplasmic aspect (74%), although acceptable, needs to be confirmed a second time with a more important sampling. According to the results obtained, this test could have an interesting routine application in laboratory of immunopathology given its analytic characteristics similar to those of IFA, and its great easiness of realisation.

Antibodies, Antinuclear↗
PubMed1998

Fluorescein angiography and indocyanine green videoangiography in the iris of pseudoexfoliation syndrome.

The precise evaluation of iris vascular pattern in pseudoexfoliation syndrome (PXS) may be difficult on iris fluorescein angiography (IFA) because of the frequent presence of a heavily pigmented iris and late conspicuous leakage. Thanks to its special characteristics, iris indocyanine green videoangiography (IICGV) is able precisely to visualize details of the iris vascular pattern. The aim of the study is to analyze the feasibility of IICGV in detecting microvascular changes in PXS and compare these findings with those of IFA. Twenty-eight patients affected in both eyes by PXS underwent an ophthalmologic examination including IFA and IICGV. IICGV was performed using IMAGEnet system H1024. A better visualization of iris hypoperfusion and anastomotic vessels was obtained on IICGV, whereas iris microneovascularization was far more clearly visible on IFA. Moreover, iris pigment epithelium defects were detectable on IICGV. IICGV may be considered a useful tool in the evaluation of the iris vascular pattern in PXS. Iris hypoperfusion could not play a contributory role in the development of iris microvascular changes.

Aged↗
PubMed1998

[Study on the effect of human herpesvirus 6 on replication of Epstein-Barr virus].

OBJECTIVE: To examine the effect of human herpesvirus 6(HHV-6) on the replication of Epstein-Barr virus (EBV) in cell lines. METHODS: Both EBV-infected Raji cells and EBV-transformed lymphoblastoid cell lines (LCL) were infected with HHV-6. Immunofluoresence assay (IFA) with monoclonal antibodies (MAb) against HHV-6 was applied to confirm the infection of HHV-6 in the two cell lines. Expression of EBV antigen was examined by IFA using human anti-EBV serum. RESULTS: Following HHV-6 infection, cytopathic effects (CPE) were observed in Raji cells but not in LCL. HHV-6 were detected in both cell lines by IFA with anti-HHV-6 MAb, but not in controls. EBV antigens were detected by IFA with human serum against EBV in both HHV-6 infected cell lines. CONCLUSION: Data in this study suggest that HHV-6 promotes the expression of EBV antigen and may contribute to the pathogenesis of nasopharyngeal carcinoma in cooperation with EBV.

Antigens, Viral↗
PubMed2000

[The changes in serum antibody level after immunization with HFRS vaccine].

OBJECTIVES: To observe the changes in serum antibody level after mass immunization with vaccine against hemorrhagic fever with renal syndrome (HFRS) and to evaluate its efficacy and effectiveness in the prevalent areas. METHODS: Healthy people aged 16 to 60 years in the villages were recruited as study subjects, excluding those suffered from HFRS previously, going out for more than nine months and those with contraindications, and were randomly allocated into immunization and control groups with 10,460 and 16,159 persons, respectively. Specific IgG antibody was determined with indirect immunofluorescent assay (IFA) and neutralizing antibody (NA) was determined with micro CPE method. RESULTS: Two weeks after the full-course immunization, sero-conversion rate for IFA reached 100% in those sero-negative before immunization, with a 95% confidence interval of 96.3 - 100.0%, and that for NA 44.4%, with a 95% CI of 22.0% - 69.0%. Geometric mean titer (GMT) were 72.1 and 4.6 for IFA and NA, respectively. Booster immunization was provided for them one year later. Positivity of IFA and NA was 28.6%, 83.3%, 75.0%, 53.1%, 22.6% and 14.8%, 55.6%, 35.0%, 31.3%, 26.0%, before booster immunization, two weeks, one year, one and a half years, two years after booster immunization, respectively. CONCLUSION: HFRS vaccine had good immunogenicity, but its duration of serum antibody sustenance was relatively short.

Adolescent↗
PubMed2002

The use of chosen serological diagnostic methods in Lyme disease in horses. Part I. Indirect immunofluorescence and enzyme-linked immunosorbent assay (ELISA).

The investigations aimed to establish the reliability of the chosen serological tests designed for the diagnosis of Lyme borreliosis in horses. The investigations were carried out in five Horse Breeding Centres (OHK). Statistical analysis methods were used to determine sample size for particular centres: Krasne (Kr)--49, Łack (Ł)--21, Walewice (W)--111, BogusŁawice (B)--17, Kozienice (K)--61. The experimental material comprised the chosen horses from which blood samples were collected in order to obtain sera. The test used for indirect immunofluorescence assay (IFA No 75941, Bio-Mérieux) is commercially designed for the investigation of human sera and thus needed a prior species adaptation and standardization; ELISA (MRL DIAGNOSTICS, No EL0400G) which was also species adapted and stardandized and ELISA commercially assigned for the examination of dog or horse sera (Die System Diagnostica GmbH Borrelia burgdorferi Veterinary ELISA No. 122.00 Genzyme Virotech GmbH). In the IFA test the highest share of positive results was obtained in respect of the sera from OHK in (K)--60.7% and then in (B)--52.9%, (Ł)--42.9%, (W)--40.5%, (Kr)--38.7%. In the standardized ELISA the highest percent of positive results, amounting to 33.3%, was obtained in respect of the sera from (Ł), and then from (W)--20.7%, (K)--11.5%, (Kr)--10.2% and (B)--5.9%. The percent of positive results obtained in the commercial ELISA also agreement on a high level: the sera originating from (W) were positive in 18.9%, from (K)--9.8%, (Ł)--9.5%. (B)--5.9% and (Kr)--4.1%. Both ELISAs showed high agreement although the standardized test was characterized by a greater tendency for suggesting the presence of B. burgdorferi infection and the agreement of these two ELISAs with the IFA was not so strong. The IFA showed the highest tendency for suggesting the presence of the B. burgdorferi infection, being characterized by the highest percent of false positive results.

Animals↗
PubMed2002

Role of IgM specific indirect immunofluorescence assay in diagnosing an outbreak of leptospirosis.

The study was conducted during a suspected epidemic of leptospirosis in Maharashtra. A total of 13 acute phase blood samples, collected at 5-6 days from the onset of symptoms, and 10 convalescent phase samples, colected at around 20 days from the onset of symptoms were obtained from 13 patients. Sera were separated and the samples were subjected to Microagglutination Test (MAT) and IgM-Indirect Immunofluorescence assay (IFA) to detect antibodies against leptospira. In the acute phase sera, only one sample was positive by MAT while seven were positive by IFA. In the convalescent samples, six were positive by MAT and seven were positive by IFA. IFA is a rapid test and can be used for early diagnosis of leptospirosis.

Acute Disease↗
PubMedDate not supplied

Evaluation of an indirect immunofluorescence assay for detecting Chlamydia trachomatis as a method for diagnosing tubal factor infertility in Mexican women.

UNLABELLED: To evaluate the clinical impact of the use of an indirect immunofluorescence assay (IFA) against Chlamydia as a method to identify patients with tubal factor infertility (TFI) in a population of infertile Mexican women. METHODS: This was a retrospective analysis made on 100 patients attending the infertility clinic who underwent laparoscopy. Blood and cervical samples were collected during the clinical examination. The presence of anti-Chlamydia trachomatis IgG antibodies was documented using the IFA test, and the presence of active chlamydial infection was evaluated using the nucleic acid hybridization assay. RESULTS: The sensitivity and specificity values of the IFA test to identify patients with periadnexal adhesions were 45% and 82%, respectively; and the positive predictive and negative predictive values were 42% and 84%, and the positive and negative likelihood ratios were 2.5 and 0.7, respectively. CONCLUSION: The IFA test was not usable for the identification of patients with periadnexal adhesions as a cause of infertility in this population. However, it could be useful as a screening test to decide which patients might receive laparoscopic treatment. Furthermore, it could be useful for identifying patients with active chlamydial infections in the upper genital tract, but a study with a larger sample needs to be done.

Adolescent↗
PubMed2003

[The application of indirect immuno-fluorescence assay in the diagnosis of severe acute respiratory syndrome].

OBJECTIVE: To explore the temporal profile of serum antibody against coronavirus in patients with severe acute respiratory syndrome (SARS), and to evaluate the reliability of indirect immuno-fluorescence assay (IFA) in the diagnosis of SARS. METHODS: Clinically confirmed SARS patients, suspected SARS patients, and controls were included in the study. IFA was used to detect the serum antibody against SARS coronavirus. General information about the subjects was collected using a standard questionnaire. RESULTS: The positive rates of specific IgG and IgM against SARS virus within 10 days after onset of the disease were 55.1% and 16.3% respectively and then increased up to 89.8% for IgG and 65.3% for IgM. After 25 days of the onset of the disease, 90.9% patients became positive for both IgG and IgM. Results from chi-square for trend test revealed that the positive rates of both IgG and IgM increased with time (chi(2) for trend = 16.376, P = 0.00005 for IgG; chi(2) for trend = 28.736, P = 0.00000 for IgM). Sensitivity, specificity and agreement value of IFA regarding the diagnosis of SARS were all higher than 90%. CONCLUSION: IFA can be used to assist diagnosis of SARS after 10 days of the onset of disease.

Antibodies, Viral↗
PubMed1992

Comparison of haemagglutination inhibition and indirect fluorescent antibody tests to detect certain flavivirus antibodies in equines.

Formalinized goose erythrocytes were used in haemagglutination inhibition (HI) and indirect fluorescent-antibody (IFA) tests to detect antibodies to Japanese encephalitis (JE) and West Nile (WN) viruses in equines. Paired serum samples from 31 cases having clinical symptoms of flaviviral infections (JE and WN viruses) and 45 controls were examined. For HI test, formalinized goose erythrocytes were used as such, whereas in IFA test, formalinized goose erythrocytes were first coated with respective viral antigens separately and later used to detect antibodies. By employing HI and IFA tests, paired samples having a titre same or less than two fold rise over the control sera were considered normal for both the viruses. IFA test was found to be a method of choice, due to its sensitivity over HI test.

Animals↗
PubMedDate not supplied

Development and comparison of serologic methods for diagnosing chicken anemia virus infection.

This paper describes the development of an indirect immunoperoxidase assay (IIP) and an indirect enzyme-linked immunosorbent assay (ELISA) for detecting antibodies to chicken anemia virus (VAC). The IIP assay developed used CAV-infected MDCC-MSB1 cells for detecting antibody to CAV, whereas the ELISA utilized gradient-purified immunoadsorbed CAV as the target antigen. The IIP and ELISA were compared with the standard indirect immunofluorescent antibody (IFA) assay, which is more conventionally used to screen chicken serum for antibodies against CAV. Comparative test results of 185 field samples of chicken serum by these three methods were in agreement 84% of the time. Both IFA and IIP assays yielded fewer positive tests than did the ELISA. IFA and IIP assays were in agreement 93% of the time, as compared with 91% agreement of IIP and ELISA results, or 84% agreement for comparative IFA and ELISA results.

Anemia↗
PubMed1992

Seroprevalence survey of borreliosis in children with chronic arthritis in British Columbia, Canada.

A seroprevalence survey using an indirect immunofluorescence assay (IFA) for IgG antibodies to Borrelia hermsii and Borrelia burgdorferi was conducted for varied pediatric chronic arthritis patients and a nonrheumatic control group in the province of British Columbia, Canada. Overall, a higher rate of sera with IFA titers > or = 1/256 was found for B. hermsii (36.6%) compared to B. burgdorferi (12.5%). There were no significant differences among the arthritis subgroups and controls for the distribution of IFA titers for either organism. IgG immunoblotting of selected high titered sera to either borrelia species confirmed the lack of specificity of the IFA assay. Serological tests for borreliosis should be cautiously interpreted in children with chronic arthritis.

Adolescent↗
PubMed1992

Computer algorithms to characterize individual subject EMG profiles during gait.

Three methods of precisely determining onset and cessation times of gait EMG were investigated. Subjects were 24 normal adults and 32 individuals with gait pathologies. Soleus muscle EMG during free speed level walking was obtained with fine wires, and was normalized by manual muscle test (%MMT). Linear envelopes were generated from the rectified, integrated EMG at each percent gait cycle (%GC) of each stride in individual gait trials. Three methods were used to generate EMG profiles for each tested subject. The ensemble average (EAV) was determined for each subject from the mean relative intensity of the linear envelopes. Low relative intensity or short duration EMG was removed from the ensemble average to create the intensity filtered average (IFA). The packet analysis method (PAC) created an EMG profile from the linear envelopes in successive strides whose respective centroid %GC locations were within +/- 15%GC of each other. Control values for onset and cessation times of individual gait trials were calculated after spurious outliers were removed. Mean onset and cessation times across subjects for control values and the experimental methods (EAV, IFA, and PAC) were calculated. Dunnett's test (p less than .05) was performed to compare control and experimental groups in patient and normal trials. EAV differed from control values for onsets (p less than .01), cessations (p less than .01), and durations (p less than .01) in both normal and patient trials. IFA and PAC had no significant differences from control value means. IFA was selected for clinical use as automatic analysis could be performed on all trials and a minimum number of decision rules were needed.

Adult↗
PubMedDate not supplied

Comparison of enzyme-linked immunosorbent assay and indirect immunofluorescence assay in the diagnosis of human strongyloidiasis.

BACKGROUND: An enzyme-linked immunosorbent assay (ELISA) and indirect immunofluorescence assay (IFA) were evaluated for serological diagnosis of human strongyloidiasis. METHODS: Serum specimens obtained from 46 individuals infected with Strongyloides stercoralis, 37 healthy persons and 381 persons with other parasitic infections were tested using an IgG-ELISA that used crude antigen of S. stercoralis filariform larvae and an IFA. Test sera were pre-incubated with antigens from Ascaris, Toxocara and hydatid protoscolices to remove non-specific antibodies. RESULTS: The sensitivity, specificity, positive predictive value and negative predictive value for ELISA were 93.5%, 96.1%, 72.9% and 99.2%, respectively, and those for IFA were 87%, 90.1%, 49.4% and 98.4%, respectively. Both assays showed false positivity in hydatidosis, ascariasis and toxocariasis; however, this was less common with ELISA. CONCLUSION: ELISA method using filariform larval antigen may be a sensitive and specific test for human strongyloidiasis, and may be preferable to IFA.

Enzyme-Linked Immunosorbent Assay↗
PubMed2004

A prospective evaluation of four immunodiagnotic assays for human leptospirosis.

This was a prospective evaluation of four immunodiagnostic assays for human leptospirosis, including the indirect immunofluorescence test (IFA), the microscopic agglutination test (MAT), the LEPTO dipstick, and the latex agglutination (LA) test. Four hundred ninety-two serum samples were collected from 348 patients who presented with acute fever without localizing signs. The sensitivities of the IFA, MAT, Dipstick, and LA were 91.9, 76.6, 77.4, and 83.1%, respectively. The specificities of these assays were 100.0, 100.0, 89.3, and 83.5, respectively. Even though IFA showed the highest overall sensitivity and specificity, when acute sera were considered, the LA was the most sensitive (28.7%). All 3 genus specific antibody assays had broad reactivity against various serogroups. The MAT is best suited for the reference laboratory, where it can be maintained with the battery of live antigens; the IFA is suited for a laboratory with sophisticated equipment and technical expertise; the Dipstick and LA are suitable for peripheral laboratories which lack expensive equipment and expertise.

Fluorescent Antibody Technique, Indirect↗
PubMed1991

Clinical evaluation of cats with lower urinary tract disease.

In a prospective study, 141 cats with hematuria, dysuria, urethral obstruction, or combinations of these signs were evaluated by contemporary diagnostic methods and compared with 26 clinically normal cats (controls). Specific diagnosis was established in 45% (64/141) of cats affected with lower urinary tract disease (LUTD). Crystalline matrix plug-induced urethral obstruction was diagnosed in 21% (30/141) of affected cats, uroliths were identified in 21% (30/141) of affected cats, uroliths with concomitant bacterial urinary tract infection (UTI) were identified in less than 2% (2/141) of affected cats, and bacterial UTI alone was identified in less than 2% (2/141) of cats with LUTD. Viruses, mycoplasmas, and ureaplasmas were not isolated from urine samples collected from affected or control cats. Bovine herpesvirus 4 (BHV-4)-neutralizing antibodies were not detected in any serum sample obtained from cats with LUTD or from control cats. In contrast, BHV-4 antibodies were detected by an indirect immunofluorescent antibody (IFA) test in sera obtained from 31% (44/141) of cats with LUTD and 23% (6/26) of control cats. The prevalence of positive BHV-4 IFA test results in affected cats was not significantly different from that observed in control cats. Significant association was not apparent between positive BHV-4 IFA test results and clinical diagnosis, abnormal laboratory findings, or cat age. However, the number of male cats with BHV-4 IFA titer was significantly (P less than 0.02, chi 2 test) greater than that of female cats. Detection of BHV-4 antibodies in approximately 30% of affected and control cats indicates prior virus exposure. Further investigations are warranted to clarify the specific role of BHV-4 in cats with naturally acquired LUTD.

Animals↗
PubMed2006

In situ RT-PCR can distinguish between productive and latent cytomegalovirus infection in the blood cells of bone marrow transplant recipients.

Thirty-four peripheral blood leukocyte samples from bone marrow transplant (BMT) recipients were examined for Human cytomegalovirus (HCMV) phosphoprotein 65 (pp65), DNA and late transcripts. Twenty seven samples were positive for pp65 in the cytoplasm by immunofluorescent assay (IFA). Viral DNA was confirmed in 26 samples by nested PCR (nPCR). Using in situ RT-PCR, viral late transcripts were found in 19 samples, positive also by IFA and nPCR; these samples were considered indicative of productive viral infection. Five samples, positive by nPCR but negative by IFA and in situ RT-PCR, were considered to represent latent viral infection. In 8 samples, positive by IFA and nPCR but negative by in situ RT-PCR, apparently phagocytosis of viral particles took place.

Bone Marrow Transplantation↗