Development of an antigen spot test for detection of coronavirus in bovine fecal samples.

We have developed a rapid and sensitive microimmunodot blot assay, the antigen spot test (AST), for the detection of bovine coronavirus (BCV) antigen from neonatal calf fecal samples. The AST procedure can be completed in 3.5 h, whereas the previously reported immunodot blot assays require 10 to 12 h. Ninety-six samples can be tested per membrane, and 10 membranes (960 samples) may be processed by a single technologist in 1 working day. The effects of detergents, oxidizing chemicals, chaotropic agents, and enzyme substrates in improving the sensitivity and signal-to-noise ratio of the AST were studied. Finally, the sensitivity and specificity of AST for the detection of BCV antigen were compared to those of a sandwich enzyme-linked immunosorbant assay (ELISA) and a hemagglutination assay (HA). Of 347 field samples tested by all three methods, 94.2% were positive by AST, 91.4% were positive by ELISA, and 86.7% were positive by HA. The sensitivity of the AST was determined to be 100% compared to the results of the ELISA reference method. The specificity of the AST was 67%, which reflects a lower limit of detection of 10(4) viral particles per ml in a 10% fecal suspension.     

Evaluation of a Latex Agglutination Kit (Virogen Rotatest) for Detection of Bovine Rotavirus in Fecal Samples

The performance of the Virogen Rotatest latex agglutination test (LAT) was evaluated for detection of bovine rotavirus antigen. Sixty-three fecal samples from diarrheic calves were collected from November 1999 to May 2000 and screened by LAT, the Rotazyme II enzyme-linked immunosorbent assay (ELISA), and virus isolation (VI) followed by an anti-rotavirus fluorescent-antibody (FA) test to detect the presence of group A rotavirus antigen. Of the 63 samples screened by VI-FA, 33 (58%) tested positive for rotavirus antigen. When the results from the LAT were compared to those from VI-FA, the “gold standard” for detection of bovine rotavirus in fecal samples, the sensitivity and specificity were found to be 87.8 and 73.3%, respectively. Latex agglutination compared with ELISA (the reference method) showed 100% sensitivity and 96.3% specificity, and when ELISA was compared with VI, the sensitivity was 84.8% and the specificity was 73.3%. Latex agglutination is easy to perform in a short time and does not require expensive equipment or skilled personnel, and the reagents have long shelf lives. These factors make the LAT suitable and highly efficient for use in a clinical laboratory as a rapid screening test for bovine rotavirus.     

Enzyme Immunoassay Detection of Antigen-Specific Immunoglobulin G Antibodies in Longitudinal Serum Samples from Patients with Cryptosporidiosis

Cryptosporidium parvum is a protozoan parasite that causes diarrheal illness in a wide range of mammalian hosts, including humans. Characteristic serum immunoglobulin G (IgG) antibody responses to antigens in the 27- and 17-kDa size ranges have been shown to develop after infection, and several enzyme-linked immunosorbent assay (ELISA) and Western blot assay formats have been used to measure these IgG levels in human serum. Using a collection of serial samples from laboratory-confirmed cryptosporidiosis patients, we compared the results obtained by using two new ELISAs with those obtained with two different Western blot assays. When assayed with the large-format Western blot, 97% of the 67 patients had a demonstrable antibody response on at least one occasion. The Cp23 ELISA correctly identified 93% of the samples that had a 27-kDa response by Western blot and 100% of the negative samples. The Triton antigen ELISA detected 77% of the samples that had a 17-kDa response by Western blot and 88% of the negative samples. The sensitivity of the Triton antigen assay was higher for samples collected between 16 and 92 days after the onset of symptoms (96%). The minigel-format Western blot did not compare favorably with the large-format blot for the detection of antibodies to the 27-kDa antigen (71% sensitivity). A half-life of about 12 weeks was estimated for antibodies to both the 27- and 17-kDa antigens. We believe the Cp23 and Triton antigen ELISAs will be useful in epidemiologic studies of the prevalence of Cryptosporidium infection in the population.     

Cross-protection studies between respiratory and calf diarrhea and winter dysentery coronavirus strains in calves and RT-PCR and nested PCR for their detection

Summary.  A 1-step RT-PCR assay, targeting a 730 bp fragment of the nucleocapsid (N) gene of bovine coronavirus (BCV), and a nested PCR assay, targeting a 407 bp fragment of the N gene, were developed to detect BCV in nasal swab and fecal samples of calves experimentally exposed to BCV. Both 1-step RT-PCR and nested PCR recognized cell culture passaged isolates of 10 bovine respiratory coronavirus (BRCV), 5 calf diarrhea (CD) and 8 winter dysentery (WD) strains of BCV, but not transmissible gastroenteritis coronavirus or bovine rotavirus. The sensitivity of the 1-step RT-PCR and nested PCR was compared to that of an antigen-capture ELISA. The lowest detection limit of the 1-step RT-PCR and nested PCR as determined by using tenfold serial dilutions of the BRCV 255 and 440 strains in BCV negative nasal swab suspensions from preexposure gnotobiotic calves was 2 × 10⁴ and 2 × 10² TCID₅₀/0.1 ml for each strain, respectively. The lowest detection limit of the antigen-capture ELISA as determined by using the same serially diluted samples was 1 × 10⁶ TCID₅₀/0.1 ml for each strain. Therefore, the 1-step RT-PCR and nested PCR assays were 50 and 5000 times, respectively more sensitive than the antigen-capture ELISA to detect BRCV in nasal swab suspensions. To investigate in vivo cross-protection between the BRCV and CD or WD strains of BCV and to detect nasal and fecal shedding of BCV using the 1-step RT-PCR, nested PCR and antigen-capture ELISA, 6 colostrum-deprived and two gnotobiotic calves were inoculated with a BRCV, a CD or a WD strain of BCV and then challenged 3–4 weeks later with either BRCV, CD or WD strains of BCV. All calves developed diarrhea after inoculation and BCV antigen (ELISA) or RNA (RT-PCR) was detected in the diarrheic fecal samples or the corresponding nasal swab samples. In addition, low amounts of BCV were also detected only by nested PCR in the fecal and nasal swab samples before and after diarrhea. No respiratory clinical signs were observed during the entire experimental period, but elevated rectal temperatures were detected during diarrhea in the BCV-inoculated calves. All calves recovered from infection with the BRCV, CD, or WD strains of BCV were protected from BCV-associated diarrhea after challenge exposure with either a heterologous or homologous strain of BCV. However, all calves challenged with heterologous BCV strains showed subclinical BCV infection evident by detection of nasal and fecal shedding of BCV RNA detected only by nested PCR. Such results confirm field and experimental data documenting reinfection of the respiratory and enteric tracts of cattle, suggesting that, in closed herds, respiratory or enteric tract reinfections may constitute a source of BCV transmissible to cows (WD) or neonatal or feedlot calves. In addition, the present 1-step RT-PCR and nested PCR assays were highly sensitive to detect BCV in nasal swab and fecal specimens. Therefore, these assays should be useful to diagnose BCV infections in calves and adult cows. Received Septemper 21, 2000 Accepted January 17, 2001     

Development and Applications of a Bovine Coronavirus Antigen Detection Enzyme-Linked Immunosorbent Assay

We developed a monoclonal antibody-based, antigen capture sandwich enzyme-linked immunosorbent assay (ELISA) for bovine coronavirus. We compared the ELISA with electron microscopy and the hemagglutination test and found a close correlation between them. The sensitivity of the ELISA was 10⁴ bovine coronavirus particles per ml of 10% fecal suspension. Compared with electron microscopy, bovine coronavirus ELISA had 96% specificity.     

Dot Blot Assay for Detection of Antidiacyltrehalose Antibodies in Tuberculous Patients

A simple dot blot test with diacyltrehalose (DAT) as the antigen was developed to detect anti-DAT antibodies in tuberculous patients. To enhance antigen-antibody reaction detection, rabbit serum raised against human immunoglobulins was used prior to incubation with a protein A-colloidal gold complex. With the dot blot system, it was possible to obtain a sensitivity similar to that of enzyme-linked immunosorbent assay (ELISA) and a specificity of 97.14%, versus a specificity of 94.29% by the ELISA. We conclude that this simple and fast assay could be used in places where ELISA equipment is not easy available and that it might also be applicable with other Mycobacterium tuberculosis immunogenic antigens.     

Serological Evaluation of Thin-Layer Immunoassay–Enzyme-Linked Immunosorbent Assay for Antibody Detection in Human Trichinellosis

A new immunoenzymatic test, named the thin-layer immunoassay–enzyme-linked immunosorbent assay (TIA-ELISA), was evaluated for antibody detection in human trichinellosis using excretion and secretion products prepared from Trichinella spiralis muscle larvae. Serum samples from people with positive muscle biopsies or symptoms compatible with the disease (n = 8 or 26, respectively), all reactive in enzyme-linked immunoelectrotransfer blot assay (EITB), as well as 67 serum samples from healthy, EITB-negative people, were tested in an ELISA and TIA-ELISA. TIA-ELISA was performed in polystyrene plastic petri dishes by adding dots of 10 μl each of antigen (7 μg/ml) followed by adding diluted serum and the conjugate. Finally, the substrate mixed with agar was added to develop the reaction. Enzymatic by-products were easily detected by the naked eye as defined dots. Sensitivity and specificity were 76 and 94% for ELISA, and both parameters were 91% for TIA-ELISA. The kappa correlation indices for both tests in relation to EITB were 0.73 and 0.80, respectively. The TIA-ELISA can be carried out with common laboratory equipment in 3 h and uses lower quantities of antigen than EITB and ELISA. Since TIA-ELISA is easy to perform, cheap, sensitive, and specific, the test could be an acceptable alternative to use in clinical laboratories lacking specialized equipment needed for ELISA and EITB and in field studies for antibody detection in human trichinellosis.     

Comparison of Nine Commercially Available Enzyme-Linked Immunosorbent Assays for Detection of Giardia lamblia in Fecal Specimens

Overall performance, including ease of use, total hands-on time, incubation and processing times, sensitivity, and specificity, of each of nine enzyme-linked immunosorbent assays (ELISAs) were compared by using 222 individual fecal samples submitted for the detection of Giardia lamblia. The assays evaluated were manufactured by Alexon, Inc., Cambridge Biotech Corp., Meridian, Inc., and Trend Scientific, Inc. All assays used polyclonal antibodies except the “new and improved” Microplate (direct and diluted methods) by Alexon, which is a monoclonal antibody assay. Seventy specimens were positive for G. lamblia by ELISA, ova and parasite test, and/or direct fluorescent-antibody assay. One hundred fifty two were negative by all three methods. Sensitivities and specificities ranged from 88.6 to 100% and 99.3 to 100%, respectively. The total hands-on time needed to run one specimen ranged from 1 min to 2 min 17 s per specimen. All except one commercially available ELISA were found to be rapid, sensitive, and specific for the detection of G. lamblia in fecal specimens.     

Rapid Detection of a Schistosoma mansoni Circulating Antigen Excreted in Urine of Infected Individuals by Using a Monoclonal Antibody

Schistosoma circulating antigens were used to indicate the infection intensity and to assess cure. An immunoglobulin G2a (IgG2a) mouse monoclonal antibody was used in a fast dot-enzyme-linked immunosorbent assay (ELISA; FDA) for rapid and simple diagnosis of schistosomiasis in the field. Seven hundred Egyptians were parasitologically examined for Schistosoma mansoni and other parasitic infections. A rectal biopsy was done as a “gold standard” for individuals showing no S. mansoni eggs in their feces. Egg counts were obtained by the Kato smear method for only 100 of 152 individuals with eggs in their feces. Specific anti-schistosome IgG antibodies were evaluated in sera by ELISA. Urine samples from the 700 individuals were tested by FDA for detection of the circulating antigen. The assay showed a sensitivity of 93% among 433 infected individuals and a specificity of 89% among 267 noninfected individuals. FDA showed the highest efficiency of antigen detection (91%) compared with the efficiency of antibody detection by ELISA (75%) and stool analysis (60%). In addition, FDA detected infected patients with 20 eggs/g of feces. Also, the sensitivity of FDA ranged from 90 to 94% among samples from patients with different clinical stages of schistosomiasis. All the assay steps can be completed within 30 min at room temperature for 96 urine samples. The monoclonal antibody identified a 74-kDa antigen in different antigenic extracts of S. mansoni and Schistosoma haematobium and in the urine of infected individuals. In addition, a 30-kDa degradation product was identified only in the urine samples. On the basis of these results, FDA should be used as a rapid tool for the sensitive and specific diagnosis of Schistosoma infection.     

Rapid Detection of Salmonella enterica Serovar Choleraesuis in Blood Cultures by a Dot Blot Enzyme-Linked Immunosorbent Assay

A dot blot enzyme-linked immunosorbent assay (ELISA) with a monoclonal antibody specific to phase1-c Salmonella was developed for the direct detection of Salmonella enterica serovar Choleraesuis in blood cultures. This system was applied to the identification of serovar Choleraesuis, and the results were compared with those obtained by a conventional biochemical method. It was revealed that all 12 samples identified to be infected with serovar Choleraesuis were positive on testing by the ELISA. In contrast, 77 samples infected with bacteria commonly isolated from the blood were not reactive by the ELISA. The calculated sensitivity and specificity of the established assay are 100%.     

Detection of Rubella Virus-Specific Immunoglobulin G in Saliva by an Amplification-Based Enzyme-Linked Immunosorbent Assay Using Monoclonal Antibody to Fluorescein Isothiocyanate

An immunoglobulin G (IgG)–capture enzyme-linked immunosorbent assay (ELISA) for rubella virus is described. The assay uses a fluorescein isothiocyanate (FITC)–anti-FITC amplification system. The detection limit of the ELISA was approximately 7 IU of rubella virus-specific IgG per ml of serum sample. For saliva samples the performances of the capture ELISA and previously described radioimmunoassay were assessed, and the results of those two assays were compared to the rubella virus-specific IgG result obtained by a commercial ELISA (Behring Enzygnost) with a panel of paired serum and saliva samples. This comparison showed that the capture ELISA with saliva was more sensitive than the radioimmunoassay and that the results correlated better with the serum IgG result than the results of the radioimmunoassay did, with an overall sensitivity of 82% and a rank correlation of 0.68, whereas the sensitivity and rank correlation for the radioimmunoassay were 74% and 0.45, respectively. For subjects of 10 years of age or younger, the ELISA with saliva had a sensitivity of 94% and a specificity of 100% compared to the results of the ELISA (Behring Enzygnost) for rubella virus-specific IgG with corresponding serum samples. The sensitivity was much lower for subjects ages 17 years or older. The assay may have wider epidemiological use with saliva specimens, particularly those from children.     

Peptide-Based OspC Enzyme-Linked Immunosorbent Assay for Serodiagnosis of Lyme Borreliosis

Sera from 210 patients with Lyme borreliosis (LB) were studied by an enzyme-linked immunosorbent assay (ELISA) based on a synthetic peptide (pepC10) comprising the C-terminal 10-amino-acid residues of OspC of Borrelia burgdorferi. We found that 36.3 and 45.0% of the serum samples from patients with erythema migrans (EM) and neuroborreliosis (NB), respectively, displayed immunoglobulin M (IgM) anti-pepC10 reactivities, while these samples rarely (≤8%) displayed IgG antibody reactivities. Sera from patients with acrodermatitis chronica atrophicans did not contain anti-pepC10 antibodies. The diagnostic performance of this newly developed peptide ELISA was compared with those of an ELISA based on the full-length recombinant OspC protein (rOspC) and a commercially available ELISA based on the B. burgdorferi flagellum (Fla). The sensitivity of the IgM pepC10 ELISA was slightly lower (P < 0.04) than that of the rOspC ELISA for EM patients (36.3 versus 43.8%), while there was no difference for NB patients (45.0 versus 48.0%). However, the optical density values obtained by the pepC10 ELISA were generally higher than those obtained by the rOspC ELISA, leading to a significantly better quantitative discrimination between seropositive patients with NB and controls (P < 0.008). The specificity of the pepC10 ELISA was similar to those of the rOspC ELISA and the Fla ELISA for relevant controls including patients with syphilis and mononucleosis. Although the overall diagnostic sensitivity of the Fla ELISA was superior, 8.8 and 12.0% of the EM and NB patients, respectively, were antibody positive only by the pepC10 ELISA. Thus, use of a diagnostic test for LB based on the detection of IgM antibodies to pepC10 and Fla has increased sensitivity for the diagnosis of early LB.     

Diagnosis of Human Immunodeficiency Virus Infection Using an Immunoglobulin E-Based Assay

Immunoglobulin assays that are sensitive and specific for detecting human immunodeficiency virus type 1 (HIV-1) infection are especially important in developing countries where PCR and viral culture may not be readily available. Immunoglobulin E (IgE), which is elevated in HIV-1 infection, is the only antibody that does not cross the placenta, making it potentially valuable for viral detection in both children and adults. This study developed an assay for detection of HIV specific IgE antibodies in adults. A total of 170 serum samples from 170 adults (116 HIV positive and 54 HIV negative) were analyzed. Serum or plasma samples were treated by using the protein G affinity method. The HIV status was determined by using two IgG enzyme-linked immunosorbent assays (ELISAs) and one Western blot evaluation. The IgE enzyme immunoassay test for HIV-1 correctly identified the HIV status in 98.8% of the samples (168 of 170). One false-positive and one false-negative test occurred with the IgE ELISA, as well as with the IgG ELISA test but were correctly identified by the IgE test. Analysis of the data demonstrated a high specificity (99%) and sensitivity (99%) of the IgE test, with 95% confidence intervals. The IgE assay appears to be sensitive and specific, suggesting that IgE-specific antibodies offer an effective method to detect HIV-1 infection in adults.     

Detection of Antigen in Sera of Patients with Invasive Aspergillosis: Intra- and Interlaboratory Reproducibility

The intra- and interlaboratory reproducibilities of a commercial sandwich enzyme-linked immunosorbent assay (ELISA) for the detection of Aspergillus galactomannan in serum (Platelia Aspergillus; Sanofi Diagnostics Pasteur, Marnes-La-Coquette, France) were evaluated in six laboratories of university hospitals. Twenty serum samples were obtained from 12 neutropenic patients including 6 with invasive aspergillosis. These samples were blinded and sent to each center together with eight blinded ELISA-negative serum samples spiked with known concentrations of galactomannan. The centers were provided with ELISA microtiter plates from a single batch and a detailed protocol. Ten clinical samples showed ELISA reactivity, while 10 samples were ELISA negative. The mean coefficient of variation (CV) of the optical density values was 4.24% within a single assay and 25.6% between runs. The interassay CV of the ratios for the serum samples tested was 18.6%. Analysis of ordinal interpretation of the ELISA result (i.e., negative, gray zone, or positive) showed excellent reproducibility. Recalculation of the cutoff values for positive and negative samples suggested that the cutoff level recommended by the manufacturer could be lowered from 1.0 to 0.8 for negative samples and from 1.5 to 1.0 for positive samples. The intra- and interlaboratory reproducibilities were excellent when the ELISA results were interpreted as ordinal data, but considerable variation in optical density values and, to a lesser extent, in the ratios for the serum samples tested, was observed between runs. High assay variability was also found for serum samples spiked with known concentrations of galactomannan. Therefore, antigen titers in serum samples from a single patient, measured in different runs, should be compared with caution.     

Use of Monoclonal Antibody in Diagnosis of Candidiasis Caused by Candida albicans: Detection of Circulating Aspartyl Proteinase Antigen

To develop a serological diagnosis of invasive candidiasis based on detection of circulating secreted aspartyl proteinase (SAP) antigen of Candida albicans, three different enzyme-linked immunosorbent assays (ELISAs) were compared. The first was a standard ELISA to detect anti-SAP antibodies, and the others were an antigen capture ELISA and an inhibition ELISA to detect circulating SAP antigen with monoclonal antibody (MAb) CAP1, which is highly specific for SAP. These tests were applied to 33 serum samples retrospectively selected from 33 patients with mycologically and/or serologically proven invasive candidiasis caused by C. albicans. Serum samples from 12 patients with aspergillosis and serum samples from 13 healthy individuals were also included. The sensitivities and specificities were 69.7 and 76.0% for the standard ELISA and 93.9 and 92.0% for the antigen capture ELISA, respectively. However, these values reached 93.9 and 96.0%, respectively, for the inhibition ELISA. Serum samples from 31 of 33 patients had detectable SAP antigen, with concentrations ranging from 6.3 to 19.0 ng/ml. These results indicate that the inhibition ELISA with MAb CAP1 is effective in detection of circulating SAP antigen and that this assay may be useful for diagnosis and treatment monitoring of invasive candidiasis.     

Seroprevalence of turkey coronavirus in North American turkeys determined by a newly developed enzyme-linked immunosorbent assay based on recombinant antigen

Turkey coronavirus (TCoV) causes diarrhea in young turkey poults, but little is known about its prevalence in the field. To address this, the complete nucleocapsid gene was cloned and expressed in Escherichia coli. Expressed nucleocapsid gene produced two distinct proteins (52 and 43 kDa); their specificity was confirmed by Western blotting using two different monoclonal antibodies. Recombinant N protein was purified and used as an antigen to develop an enzyme-linked immunosorbent assay (ELISA) for the serological detection of TCoV that was then validated using experimentally derived turkey serum. The N-based ELISA showed (97%) sensitivity and (93%) specificity for TCoV, which was significantly higher than an infectious bronchitis coronavirus-based commercial test for TCoV. To assess the utility of this recombinant ELISA, 360 serum samples from turkey farms in Ontario, Canada, and 81 serum samples from farms in Arkansas were tested for TCoV-specific antibodies. A high seroprevalence of TCoV was found in turkeys from the Ontario farms with 73.9% of breeders and 60.0% of meat turkeys testing seropositive using the N-based ELISA. Similarly, a high field prevalence was found in the turkeys from Arkansas, for which 64.2% of the serum samples tested seropositive.     

Dynamics of Antigenemia and Coproantigens during a Human Fasciola hepatica Outbreak

In the present study the dynamics of antigenemia and coproantigens were studied in patients with Fasciola hepatica infection during an outbreak occurring in La Palma, Pinar del Río, in the West Province of Cuba. Stool and serum samples were collected from 67 patients and 40 healthy subjects. Stool samples were studied by a simple gravity sedimentation technique and an ES78 sandwich enzyme-linked immunosorbent assay (ELISA) for observation of eggs and detection of parasite coproantigens, respectively. Serum samples were also studied by the ES78 sandwich ELISA and an indirect ELISA to detect circulating antigens and antibodies, respectively. At the beginning of the study, 8 of 67 patients had patent infections and 59 had prepatent infections, which was determined by the recent consumption of lettuce contaminated with metacercariae of F. hepatica, the presence of clinical symptoms, and the absence of Fasciola eggs in their stools. Patients with prepatent infections were monitored by all techniques until patency. Circulating antigens were not detected in patients with patent infections. However, coproantigens were clearly detected in all patients with patent infections. On the other hand, 28.8% of patients with prepatent infections tested positive for circulating antigens and 81.4% tested positive for coproantigens in the first stool sample studied. Only two other coproantigen determinations were necessary to diagnose 93.2% of the patients. While circulating antigen levels diminished in all patients during the infection, coproantigen levels increased. The present study demonstrates that the ES78 sandwich ELISA is a better tool than parasitological examination for diagnosis of active early infection, since by the combination of the circulating-antigen detection assay and the coproantigen detection assay 91% of patients were able to be diagnosed at the beginning of the study. In contrast, a coprologic analysis repeated over several weeks was necessary to diagnose 100% of the patients.     

Assessment of three commercially available serologic assays for detection of antibodies to Mycobacterium tuberculosis and identification of active tuberculosis

Tuberculosis (TB) caused by Mycobacterium tuberculosis remains a major world disease, with approximately 9 million new cases each year. Identification and treatment of active disease are essential for TB control. Serology may offer increased detection of active disease in patients with a positive tuberculin skin test (TST) or QuantiFERON-TB (QFT-G). The InBios Active TbDetect immunoglobulin G (IgG) enzyme-linked immunosorbent assay (ELISA), IBL M. tuberculosis IgG ELISA, and Anda Biologics TB ELISAs were evaluated for the ability to detect M. tuberculosis antibodies in patients with active disease. Agreement, sensitivity, and specificity for each ELISA were determined and compared to those for culture or amplified direct detection and M. tuberculosis low-risk control patients. The InBios Active TbDetect ELISA had an agreement of 96.2%, a sensitivity of 83.3%, and a specificity of 98.9%. The IBL M. tuberculosis ELISA had an agreement of 84.0%, a sensitivity of 5.6%, and a specificity of 100.0%. The agreement, sensitivity, and specificity of the Anda Biologics TB ELISA were 74.2%, 83.3%, and 72.0%, respectively. The sensitivity for detecting M. tuberculosis antibodies in human immunodeficiency virus-associated TB was 50% for both the InBios Active TbDetect ELISA and the Anda Biologics TB ELISA and 0% for the IBL M. tuberculosis ELISA. The positivity rates for InBios Active TbDetect ELISA, IBL M. tuberculosis ELISA, and Anda Biologics TB ELISA in latently infected individuals positive by TST and/or QFT-G were 5.1%, 0.0%, and 30.8%, respectively. It can be concluded that the InBios Active TbDetect IgG ELISA is superior to the other ELISAs in accurately detecting active TB.     

Immunodiagnosis of Human Fascioliasis by an Enzyme-Linked Immunosorbent Assay (ELISA) and a Micro-ELISA

Enzyme-linked immunosorbent assay (ELISA) and micro-ELISA were evaluated for their ability to detect anti-Fasciola hepatica antibodies in humans by using excretory-secretory antigen. The sensitivity of each method was 100%, but the specificity was 100% for ELISA and 97% for micro-ELISA. The micro-ELISA could be used as a screening assay and ELISA could be used as a confirmatory method for the serodiagnosis of human fascioliasis.