Antibody ELISA Test Research Articles

Seroprevalence of antibodies to the human immunodeficiency virus in dialysis workers: results of a multi-center study.

The Center for Devices and Radiological Health, in collaboration with the Department of Veterans Affairs Medical Center, Brooklyn, N.Y., conducted a multi-center, multi-institutional study of the seroprevalence of antibodies to the human immunodeficiency virus (HIV) among dialysis workers. Seven dialysis units and 112 dialysis workers participated in the study over a period of 2 years. Participation was limited to dialysis workers who, by questionnaire, denied non-occupational risk factors for HIV infection. The vast majority of the study participants were drawn from areas where the prevalence of HIV infection and AIDS cases are substantially greater than the national average. Study participants received the ELISA test for HIV antibodies. All 112 of the participants tested negative for HIV antibodies. These results are encouraging, as they failed to reveal unrecognized occupational transmission of HIV infection among dialysis workers.

Ten-year study comparing enzyme-linked immunosorbent assay with the immunofluorescent antibody test for detection of feline leukemia virus infection in cats

Summary Immunodetection tests for feline retroviruses are powerful tools used in modern veterinary practice. Veterinarians must fully understand the characteristics—strengths and weaknesses—of the FeLV tests so that the information gained from them can be used properly. Any FeLV elisa or immunofluorescent antibody (ifa) test is a method for detection of FeLV infection (the virus) and is not a diagnostic test for leukemia or other feline disease. From previous studies, it was determined that the most accurate test for detection of persistent FeLV infection is the ifa test, which detects FeLV antigens in cytoplasm of leukocytes in the blood of infected cats. In the study reported here, 1,142,600 FeLV ifa tests were performed between June 1972 and December 1990. During this period 19.8% of the ifa test results were positive and 78% were negative. Evaluation was not possible for the remaining 2.2% of the tests because of lack of enough leukocytes in the smears to evaluate, or nonspecific staining reactions. In 1979, 7 years after introduction of the ifa test, in-hospital FeLV elisa were introduced, which enabled veterinarians to test for FeLV in their hospitals. Ever since that time, continual discrepancies have been reported between results of FeLV elisa and ifa tests, particularly between positive elisa results and their ifa test confirmation. A 10-year comparison was made between practitioner-performed in-hospital FeLV elisa (n = 20, 240 tests) results and FeLV ifa test performed by a commercial laboratory. All samples tested by elisa were submitted (for confirmation of results) by veterinarians from the United States, Canada, Europe, Japan, and Australia. There was 86.9% agreement between negative elisa results and the ifa test result, but only 46.3% agreement between positive elisa results and the ifa test result. Overall agreement was 49.0% for all confirmatory ifa tests. However, there was bias toward confirmation of positive elisa results because 93% of confirmatory tests requested were of elisa-positive samples. It is apparent from this study that between 26 and 69% of in-hospital positive elisa results and 13% of in-hospital negative elisa results are incorrect. On the basis of these observations, we recommend that veterinarians immediately confirm all FeLV positive elisa results by ifa testing. In addition, negative elisa results in cats that the veterinarian suspects have FeLV infection or FeLV-induced disease should also be confirmed by ifa testing. We also recommend that all cats be vaccinated for FeLV and that they be tested for FeLV and the feline immunodeficiency virus at time of first vaccine dose.

Comparison of the efficacy of three commercial feline leukemia virus vaccines in a natural challenge exposure

Summary Forty-seven kittens were exposed for 31 weeks to 12 FeLV-positive carrier cats. The carrier cats were infected with 2 laboratory strains of FeLV and at least 2 strains of street virus. Eleven nonvaccinated control kittens and 12 vaccinated kittens were allotted to 3 groups. After 31 weeks of exposure, the following kittens were persistently blood FeLV positive by elisa and immunofluorescence antibody (ifa) testing: 7 of the 11 control kittens, 0 of 12 kittens inoculated with vaccine A, 5 of 12 kittens inoculated with vaccine B, and 6 of 12 kittens inoculated with vaccine C. Only the kittens inoculated with vaccine A were significantly (P < 0.05) different from the control group. After 23 weeks of exposure, culture was done to identify FeLV in the bone marrow of the kittens. Feline leukemia virus was isolated from the bone marrow of 9 of 11 control kittens. Virus was isolated from the bone marrow of 5 of 12 kittens inoculated with vaccine A, 11 of 12 kittens inoculated with vaccine B, and 10 of 12 kittens inoculated with vaccine C. Of the 17 cats that had FeLV isolated only from culture of bone marrow (negative results of blood virus isolation, elisa, and ifa testing), 13 eliminated the virus from the bone marrow by week 31 of exposure. After 31 weeks of exposure, FeLV was isolated from the bone marrow of 8 of 11 control kittens, O of 12 kittens inoculated with vaccine A, 7 of 12 kittens inoculated with vaccine B, and 7 of 12 kittens inoculated with vaccine C.

Serological Analysis of Human Tuberculosis by an ELISA with Mycobacterial Antigen 60

An ELISA method for detecting serum antibodies against A60, an antigen prepared from the cytoplasm of Mycobacterium bovis BCG, has been applied to 385 subjects, namely 197 controls (neonates, healthy adults, and tuberculin negative, nontuberculous patients), and 188 subjects at various stages of tuberculous infection and disease. Most IgM determinations gave negative results. While the neonates and normal adults had titers of IgG anti-A60 antibodies below the cut off value, wide variations in antibody titers were observed among the various types of subjects infected by M. tuberculosis. The results obtained with nontuberculous subjects were: 100% negative IgG in neonates and healthy adult individuals and 6.4% "false positive" cases among 124 non-tuberculous patients. The percentage of serologically positive cases of tuberculosis was: 5.9% in latent active primary forms, 42.8% in patent active primary forms, and 82.8% in active postprimary forms. Tuberculous infections had a positively rate of 14.7%, while inactive postprimary tuberculosis had a positivity rate of 50%. The results obtained with A60 can favourably be compared with other serum ELISA tests for tuberculous antibodies against purified or semipurified mycobacterial antigens. Anti-A60 ELISA IgG antibody test can be useful to monitor the kinetics of humoral immunological response during tuberculous infection, disease and chemotherapy. A positive IgG ELISA test may support the diagnosis of active tuberculous disease.

Acquired immunodeficiency syndrome: analysis of neurologic complications in 44 cases

We studied the clinical records of 280 patients admitted to our Hospital between 1985 and 1988, with a positive Elisa test for HIV-related antibodies: 15.71% (44) of these patients exhibited clinical abnormalities related to disease of the CNS. In 6 (13.6%) patients the neurological complication was the first manifestation of HIV-infection. Patients were mainly male homosexuals, in the 30-39 age range. Frequent chief complaints included hemiparesis, headache and behavior disturbances. Cerebral toxoplasmosis was diagnosed in 18 instances. It should be considered the first diagnostic possibility in patients presenting with mass lesions. Meningeal infections were present in 19 cases (cryptococcal in 13, tuberculous in 4, HIV-related in 2). CSF findings in these patients were non specific, except for demonstration of Cryptococcus neoformans on direct examination of CSF or culture studies. CT scans frequently displayed unique or multiple hypodense lesions. The lesions exhibited ring-enhancement in 7 instances, and were non-enhancing in 8 others. Cortical and subcortical atrophy with hydrocephalus ex-vacuum were occasionally found, and the CT scans were normal in 8 instances. Time from appearance of the various neurological complications to death or clinical resolution was almost always shorter than 6 months. Death was the most frequent outcome, usually occurring within 6 months. Survival in the most of these patients never reached the end of the first year.

Early Pregnancy Varicella and Associated Congenital Anomalies

A case of congenital anomalies following varicella infection in the 8th week of gestation is described. Though the baby demonstrated a majority of the features characteristic of the congenital varicella syndrome and had positive immunofluorescent and ELISA tests for VZ specific antibodies, no vesicles or depigmented skin areas were seen.

Observations on human echinococcosis (hydatidosis) and evaluation of transmission factors in the Maasai of northern Tanzania.

An attempt was made to estimate the prevalence of hydatid disease amongst the Maasai people of northern Tanzania and to examine the factors which would contribute to the transmission of the disease in this region. Retrospective review of hospital records revealed an annual surgical rate of hydatid disease for 1977 through 1986 of 11 per 100,000 people. Ten (1%) of 959 people screened by ultrasound scanning had hydatid cyst-like echoes, giving a prevalence estimation of 1.4%. Thirty per cent of positive ultrasound cases were also positive in an ELISA antibody test. Three of four dogs necropsied and two of six dogs purged were found to harbour patent Echinococcus infections. Quantitative man:dog contact studies, examination of soil and water samples for Echinococcus eggs and comparison of the anti-Echinococcus antibody responders revealed that there are few marked differences in exposure to infection between the Maasai and the Turkana, who have a much higher prevalence of hydatidosis and perhaps the highest prevalence in the world. Hypotheses to explain the differences in the infection rate between these two groups of pastoralists who share a similar traditional lifestyle are presented. The Maasai, like the Turkana, had no knowledge of hydatid disease, and it is suggested that the best way to control the disease in Maasailand would be by proven dog control measures, supported by a suitable, more durable, educational programme.

A serological test for the diagnosis of Strongyloides antibodies in ex Far East Prisoners of War.

This paper gives the results of an ELISA test for Strongyloides stercoralis antibodies in a group of 436 ex Far East Prisoners of War (FEPOWs). Antigen was obtained from third-stage larvae of Strongyloides cebus. Sensitivity of the test is 97%, with a specificity of 99%. The test is being investigated further as regards cross-reactions with other helminths, but initial results look promising.

Testing the homogeneity of small error rates: application to the sensitivity of different Elisa tests for aids antibodies

This note develops modifications of the chi-square and maximum likelihood tests for the homogeneity of the success probabilities p i of k binomial variables when the number of trials, n i , vary widely and all p i are small. With N = Σn i , and letting the n i / N approach fixed fractions, γ i may differ. The procedures are appied to the first licensing data on the sensitivility which includes the case where the γ i may differ. The procedures are applied to the first licensing data on the sensitivity of the ELISA tests used to screen for the AIDS virus and it is shown that one of the test kits was significantly less sensitive than the others.

Laboratory studies of acute varicella and varicella immune status.

We evaluated varicella-zoster virus (VZV) culture and serum antibody methods utilizing specimens from 620 children enrolled in protocols for prevention or treatment of varicella and samples routinely submitted to the Clinical Virology Laboratory. In a foreskin fibroblast tube culture system, we initially isolated VZV from only 29 (51%) of 57 children cultured on the first day of varicella. After modifying the method, the proportion of culture-positive children increased significantly to 36 (80%) of 45 (p less than 0.005 by corrected X2), and the median days-to-positivity were significantly shortened from 5.6 to 3.8 days (p less than 0.001, Wilcoxon rank-sum test). The Viran fluorescent antibody to membrane antigen (FAMA) assay was difficult to read and not reproducible. The standard FAMA was more sensitive than the Merck ELISA antibody test for detecting vaccine-induced antibody. The Whittaker ELISA did not detect vaccine-induced antibody but was comparable to FAMA for immune status testing (sensitivity, 95%; specificity, 92%) and for diagnosis of acute varicella.

Surveillance for naturally acquired leprosy in a nine-banded armadillo population.

Samples from 77 nine-banded armadillos (Dasypus novemcinctus) inhabiting a 16.7 km portion of the East Atchafalaya River Levee, Point Coupee Parish, Louisiana, were serologically tested and/or histopathologically examined for evidence of naturally acquired leprosy. Five of 67 (7.5%) armadillos tested sero-positive with ELISA test for IGM class antibodies to the phenolic-glycolipid-1 antigen of Mycobacterium leprae. One of 74 (1.3%) was histopathologically positive as determined by presence of acid-fast bacteria in nerves.

The causes of false-positives encountered during the screening of old-world primates for antibodies to human and simian retroviruses by ELISA

Sera from 526 old-world primates representing 50 different species were screened by ELISA for antibodies to human T-lymphotropic viruses I and III, and simian retrovirus type 1 (SRV-1). About onefourth of the sera were positive by ELISA. There was a tendency, however, for the same sera to be positive for all three human and simian retroviruses. Only about one in five of the ELISA antibodypositive sera were confirmed to be positive by Western blotting. False-positive ELISA antibody tests were particularly common among sera from mandrills, crab-eating macaques, lion-tailed macaques, African green monkeys, and DeBrazza's and moustached guenons. Sera that were falsely positive in ELISA antibody tests to the three human and simian retroviruses were found to contain antibodies that reacted at comparable intensity with feline leukemia, infectious peritonitis and panleukopenia viruses. The false anti-viral activity of these sera was found to be due to antibodies that reacted with non-viral proteins that were copurified with all five virus preparations. These proteins were present in normal cat and human cells used to grow the various viruses and in gelatin. The implications of nonspecific cell-protein antibodies in primate sera were discussed in the light of this and previous seroepidemiologic studies of man and old-world monkeys.

The cultural impact of the ‘AIDS’ test: The American experience

In March 1985 an ELISA test for serum antibodies to human T-cell leukemia/lymphotropic virus type III (HTLV-III) was licensed for use in screening commercial blood products. Controversy over the appropriate use and interpretation of this test continues, and some public health officials in the United States have advocated different counselling strategies for high and low risk individuals with the same test results. The response to AIDS illustrates that contagion has a social definition, even in the context of Western scientific medicine.

Comparative serological studies with egg drop syndrome virus

The sensitivities of five serological tests (haemagglutination inhibition, ELISA, serum neutralisation, fluorescent antibody and agar gel immunodiffusion) for detection of Egg Drop Syndrome virus antibody were compared. In experimentally inoculated birds seroconversion was first detected at five days post-inoculation using haemagglutination inhibition, ELISA, serum neutralisation and fluorescent antibody test, and at seven days post-inoculation using agar gel immunodiffusion. Sera from birds experimentally infected with two or more different fowl adenovirus serotypes gave positive reactions in some of these tests, as did a small percentage of haemagglutination inhibition negative field sera. It is concluded that only haemagglutination inhibition or serum neutralisation should be used for detection of infection in commercial birds.

ELISA tests for antibodies against mycobacterial glycolipids

ELISA tests with purified mycobacterial glycolipids and bovine heart cardiolipin are described. The possible clinical use of ELISA tests with mycobacterial glycolipids for the diagnosis of tuberculosis and other mycobacterioses is discussed.