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Query: UMLS:C0021051 (immunodeficiency)
 71,517 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Unlike test sensitivity and specificity, the false positive and negative predictive values (probabilities of mislabeling an individual being tested) depend heavily on the prevalence of the infection of the human immunodeficiency virus (HIV) as well as the quality of the kit. A consequence of this dependence is that the false positive predictive value can reach a high magnitude such as 0.9; that is, 90% of the positive tests are false. This raises many important issues pertaining to the current practice of HIV screening such as to how to control these misclassification errors, how to interpret test results, and how to estimate prevalence using test results. These issues are examined in detail here by considering the factors that dictate the quality of a screening program. Some real data examples are used to illustrate the importance of this consideration in designing programs to achieve the desired goals. The rationale behind the common two-step sequential protocol in HIV screening is examined to point out its limitations under practical situations. Finally, the use of entropy in evaluating the informativeness of a screening program is discussed.
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PMID:Issues in human immunodeficiency virus (HIV) screening programs. 141 46

The dot immunobinding assay (DIA), a modified enzyme immunoassay (EIA), has been demonstrated to be a highly sensitive and specific assay for the detection of antibody to a number of viruses. Different laboratory procedures are available for detecting antibody to the immunodeficiency viruses; however, these procedures require a certain amount of sophisticated equipment and trained personnel. Further, commercial kits for detecting antibody to human immunodeficiency virus, as now available, are not easy to use in the nonlaboratory setting. The DIA, as described herein, may be formatted to test up to 30 serum samples and is designed to be used in the absence of laboratory equipment. To determine the effectiveness of the DIA as a test kit for the detection of HIV and human T-cell leukemia virus type I (HTLV-I) antibodies, the kit was compared with commercial EIA and Western blot (WB; immunoblot) kits. Testing approximately 1,000 human serum samples for HIV antibody by DIA and EIA revealed a total agreement of 98.1%, a specificity of 99.0%, and a sensitivity of 95.9%. For 804 serum samples tested (200 were tested independently in two laboratories), eight results were discrepant: four DIA negatives which were EIA borderline positive and four DIA positives which were EIA negative. Testing the eight discrepant sera by immunofluorescence assay and WB resulted in their being either negative or indeterminate. The four DIA positives were indeterminate by WB. Close agreement was obtained when the remaining sera were compared by DIA, EIA, and WB. Of interest was finding that the DIA results compared favorably with those obtained by WB. Twenty-six suspect HTLV-I-positive serum samples tested by DIA also gave results comparable to those obtained by EIA and WB.
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PMID:Detection of antibody to immunodeficiency viruses by dot immunobinding assay. 157 88

A mycobacterial DNA probe (designated X) was recently developed to help identify Mycobacterium avium complex (MAC) isolates that are nonreactive with probes specific for M. avium or Mycobacterium intracellulare. The prevalence of X probe-positive mycobacteria in clinical specimens and their role in causing disease is unknown. Using a DNA probe kit that includes the X probe, we characterized 100 consecutive clinical MAC isolates as M. avium, M. intracellulare, or X. Lysates from 81 of the isolates reacted with the M. avium probe, 13 with the M. intracellulare probe, 3 with the X probe, and 3 failed to hybridize with any of the probes. All three X-positive isolates were recovered from sputa of patients who were recent immigrants to the United States and who presented with hemoptysis. One isolate was from a Hispanic man infected with human immunodeficiency virus type 1 (HIV-1) and the other 2 were from Filipino patients with no HIV-1 risk factors. This study also showed a higher than expected number of M. intracellulare isolates from blood and cerebrospinal fluid of HIV-1-infected patients.
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PMID:Use of DNA probes to detect Mycobacterium intracellulare and "X" mycobacteria among clinical isolates of Mycobacterium avium complex. 160 95

In May 1988, the Centers for Disease Control's Model Performance Evaluation Program (Atlanta, Ga) surveyed 1092 laboratories that performed enzyme immunoassays and Western blot tests for human immunodeficiency virus type 1 antibody on mailed plasma samples of known human immunodeficiency virus type 1 antibody reactivity and that described their laboratory characteristics and testing practices. The study objective was to evaluate the quality of laboratory performance in testing for human immunodeficiency virus type 1 antibody. After identifying relevant variables in univariate analyses, multivariate analyses were performed using stepwise logistic models. Human immunodeficiency virus type 1 antibody test performance was independently associated with analytic variables such as commercial test kit used and with nonanalytic variables such as experience, training, and degree requirements of laboratory personnel. These results validate the importance of nonanalytic variables to the quality of outcomes in laboratory testing.
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PMID:Quality of laboratory performance in testing for human immunodeficiency virus type 1 antibody. Variables associated in multivariate analyses. 174 26

Two algorithms for screening sera for antibody to human immunodeficiency virus type 1 were compared for their efficiency in identifying a true-positive sample in a population with heterogeneous risk factors, using the criteria of specificity and positive predictive value (PPV). In the first algorithm, all sera were screened by using a single enzyme immunoassay (EIA) kit, and a specificity of 98.6% and a PPV of 69.3% was calculated for true-positive sera. The second algorithm employed two different EIA kits in parallel to screen each sample. In the first instance, a specificity and a PPV of 100% was calculated if a positive sample was defined as reactive by both EIA kits; in the second, a specificity of 99.97% and a PPV of 99.4% was obtained if this criterion was extended to include a combination of one reactive and one equivocal result obtained with the two EIA kits.
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PMID:Predicting human immunodeficiency virus type 1-positive sera by using two enzyme immunoassay kits in a parallel testing format. 177 56

Twenty-two human immunodeficiency virus 1 (HIV-1) enzyme immunoassay (EIA) reactive and two non-reactive patient specimens were analyzed using five commercially available HIV-1 Western blot kits. The percentage of HIV-1 bands detected by each kit was recorded. The differences between pairs of kits were not found to be statistically significant at the 0.05 level. All EIA reactive specimens were reconfirmed as reactive by each Western blot kit tested.
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PMID:Comparison of five commercial western blot kits for detection of human immunodeficiency virus 1. 187 52

The incidence of circulating-immune complexes (CICs) and their human immunodeficiency virus (HIV) antigen and antibody content and isotopes are described in 214 healthy, HIV-infected seropositive individuals from Pune, India. The subjects were commercial blood donors, sexually transmitted disease (STD) clinic patients, foreign students, prostitutes, hemophiliacs and suspected acquired immunodeficiency syndrome (AIDS) cases. Controls were seronegative persons from similar groups and employees of the research institution. Immune complexes were precipitated, dissolved, and tested for Clq binding with a commercial with a commercial enzyme immunoassay kit (DiaMedix, Florida). Specific HIV-anti HIV immune complexes, HIV-antigens in the CICs, and HIV- antibodies in CICs were determined with EIA and ELISA techniques. 44 of the 214 seropositive subjects had Clq binding above control levels of 20 mcg, and 6 were borderline. Positive values ranged from 20-120 mcg. All controls were normal. 33 of the 44 positives had specific HIV- anti-HIV CICs on solid-phase EIA. 31 persons had detectable HIV antigen in hydrolyzed CIC supernatant solutions. The antibody isotopes in CICs, assessed by single radial immunodiffusion were IgG and IgA immunoglobulins, with IgGs predominating at 250 mg/dl and IgAs measuring 200 mg/dl compared to normal healthy controls. The IgM levels in seropositive subjects did not differ from controls.
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PMID:Circulating immune complexes in healthy, HIV-antibody positive subjects. 190 33

We have demonstrated the use of a radioimmunoassay to quantitate the peptidolytic activity of human immunodeficiency virus, type 1 (HIV-1) protease using a tetradecapeptide substrate of porcine renin, Asp-Arg-Val-Tyr-Ile-His-Pro-Phe-His-Leu-Leu-Val-Tyr-Ser. HIV-1 protease catalyzes cleavage of this substrate at the same Leu-Leu bond as does porcine renin, resulting in the formation of authentic angiotensin-I. The angiotensin-I product is then detected by use of a commercially available renin plasma assay kit, which constitutes the basis of the RIA. The radioimmunoassay provides detection of the protease-catalyzed formation of angiotensin-I at picomolar concentrations in vitro. We demonstrate the use of this assay in determining IC50 values for two HIV-1 protease inhibitors present in cell culture media and in standard assay buffer. An example of the potential development of this assay for the quantitation of these inhibitors present in ex vivo plasma samples is also presented.
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PMID:Adaptation of the plasma renin radioimmunoassay for use with HIV-1 protease. 195 69

Testing saliva for the detection of human immunodeficiency virus (HIV) antibodies has many potential advantages for epidemiologic surveillance. A commercial ELISA kit and a standardized in-house immunoblot (IB) system were slightly modified to enhance antibody detection in saliva. Frozen saliva specimens from Toronto Sexual Contact Study participants (including sequential saliva specimens collected during seroconversion) were tested as were fresh saliva samples collected from a population of street-based intravenous drug users (IVDUs). HIV antibody results on saliva were compared with HIV serostatus determined by ELISA and IB on serum or dried blood spots. The overall sensitivity was 98.3% (117/119) for the kit and 99.2% (118/119) for IB; the specificity was 100% (429/429). In the IVDU population, compliance in the voluntary submission of specimens increased from 69% agreeing to provide blood samples to 89% agreeing to provide blood, saliva, or both. Saliva specimens can be easily collected under difficult field conditions with minimal training and provide a valuable alternative to testing blood for HIV-seroprevalence studies.
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PMID:Comparison of saliva and blood for human immunodeficiency virus prevalence testing. 201 Jun 25

Detection of antibodies to the human immunodeficiency virus (HIV) in recently infected donors is crucial to prevent the transmission of HIV infection via blood products. To determine whether specific antibodies of the IgA or IgM class are present as markers of recent infection in donor specimens that have borderline reactivity on routine enzyme immunoassay (EIA) screening, 15 specimens that were positive by immunoblot were tested for IgA and IgM HIV antibodies. All 15 had detectable IgA HIV antibodies, and 14 had IgM HIV antibodies. The 15 specimens were tested further, each by two independent laboratories, with nine licensed EIAs. Two of the nine EIAs found all 15 units positive in both laboratories; seven EIAs found 1 to 5 of the 15 units negative, for a total of 31 false-negative results. The results indicated a difference between the sensitivity of EIA kits using only anti-IgG reagents and of kits using multispecific reagents that react with IgG and other classes of antibody. In a modified procedure, the addition of enzyme-conjugated anti-IgA or anti-IgM to the kit's enzyme-conjugated reagent increased the optical density values of most false-negative specimens to the positive range. It was concluded that licensed kits vary in reactivity with IgA and IgM HIV antibodies and that sensitivity could be increased by improved detection of these classes of antibody.
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PMID:IgA and IgM human immunodeficiency virus antibodies in weakly reactive or false-negative blood donors. 204 77


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