Testing for HIV at home: what are the issues?
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HIV Infections↗
Biomedical subjects
G Vercauteren
Publications and source records attributed to G Vercauteren.
Evaluation of an agglutination HIV-1 + 2 antibody assay.
Studies have shown that an HIV (HIV-PA) agglutination assay (Serodia) for the detection of antibody to human immunodeficiency virus (HIV) can be as sensitive and as specific as enzyme-linked immunosorbent assay (ELISA). However, since this HIV assay was designed to detect antibody to the HIV-1 virus, a substantial number of HIV-2 positive sera are missed by this assay. Since the HIV-2 has now been found throughout the world this test is becoming less suitable. The new HIV-1 + 2 assay version (HIV-1 + 2 PA) was evaluated in 300 sera, which contained 50 HIV-1, 40 HIV-2 and 10 HIV-1/HIV-2 antibody positive samples, and a sensitivity and specificity of 100% and 99%, respectively, was obtained. Whereas all HIV-2 positive sera were detected by the new HIV-1 + 2 version, 26% (13/50) were missed by the old version of the agglutination test. It is concluded that the HIV-1 + 2 PA assay is a promising instrument free assay which can be used for screening purposes in areas where both HIV-1 and HIV-2 are present.
AIDS Serodiagnosis↗
Selective increase of activation antigens HLA-DR and CD38 on CD4+ CD45RO+ T lymphocytes during HIV-1 infection.
Infection with HIV results in a progressive depletion of CD4+ T cells and leads to significant in vivo lymphocyte phenotype changes. In this regard, the expression of HLA-DR and CD38 on CD8+ T cells has been shown to increase dramatically with disease progression. We investigated the expression of both activation markers on CD4+ T cells in HIV-1-infected subjects at different clinical stages of infection and compared the in vivo activation of CD4+ T cells with parameters of viral activity and CD8+ T cell activation. Fresh peripheral venous blood was obtained from 54 HIV-infected subjects and from 28 uninfected healthy controls. Three-colour immunophenotyping of the CD4+ T cell subset showed that the proportion of CD4+ T cells expressing HLA-DR (10% in HIV-negative controls) or CD38 (62% in HIV-negative controls) was higher in asymptomatic (P < 0.05 for CD38) and symptomatic (P < 0.001 for HLA-DR and CD38) HIV-infected subjects than in controls, whereas the proportion of CD4+ T cells expressing CD45RO (54% in controls) remained relatively unchanged. Simultaneous expression of HLA-DR and CD38 on CD4+ T cells increased from 2.3% in controls to 11% (P < 0.001) in asymptomatic and 22% (P < 0.001) in symptomatic HIV-infected subjects. This relative increase of CD38 and HLA-DR expression occurred mainly on CD4+ T cells co-expressing CD45RO. Changes in expression of HLA-DR and CD38 on CD4+ T cells correlated with similar changes on CD8+ T lymphocytes, with the presence of HIV antigen in the circulation, and with the disease stage of HIV infection.
ADP-ribosyl Cyclase↗
Diagnosis of human immunodeficiency virus (HIV) infection: multicenter evaluation of a newly developed anti-HIV 1 and 2 enzyme immunoassay.
A new anti-human immunodeficiency virus type 1 and 2 (anti-HIV 1 and 2) test is described. It uses recombinant p24 and peptides covering gp32, gp41, and gp120 to identify HIV-1 and HIV-2 infections. This test has been shown to be specific (99.5%) and sensitive (99.8%). In this respect, the assay was equal or superior to anti-HIV 1 and 2 tests run as references. The test was able to discriminate sera from patients with HIV infections from those from uninfected individuals with excellence; it also exerted high intra- and interassay precisions. The "modular" concept of the test allows the use of single components (gp32 or gp41) to separate between HIV-2 and HIV-1 infections, respectively.
Diagnosis, Differential↗
Human T-cell lymphotropic virus type 1 infection and tropical spastic paraparesis in Belgian expatriates.
A case of HTLV-1 associated tropical spastic paraparesis is described in a Belgian nun who had been working as a midwife in Central Africa. Occupational exposure was the only risk factor identified. Among 2,482 Belgian expatriates in tropical countries, 92% of whom had resided in sub-Saharan Africa for an average of 15.5 years, only one Belgian-born man was found seropositive for HTLV-1. He was married to an African woman and living in Central Africa for 23 years. The risk of HTLV-1 infection is low in Belgian expatriates and on its own does not support generalised anti-HTLV screening in autochthonous Belgian blood donors.
Belgium↗
Alternative confirmatory strategy for anti-HIV antibody detection.
Enzyme immuno assays for simultaneous screening of antibodies to HIV-1 and HIV-2 (EIA HIV-1 + HIV-2) have recently been developed. Confirming all reactive EIA HIV-1/2 screening results by Western blot (WB) for HIV-1 and HIV-2 antibodies is expensive. Six different EIA HIV-1/2 screening assays and one supplemental Line immuno assay (INNO-LIA HIV-1/HIV-2 Ab (LIA)) for confirmation of reactive EIA HIV-1/2 screening assay results were carried out on a panel of 400 sera of which 13% were HIV-1- and 2.5% were HIV-2-positive. The LIA was used as the 'gold standard'. Retrospectively, the results of the six EIA HIV-1/2 were evaluated in pairs (A and B), applying B to those sera reactive in A. A+B+ results were reported as positive. A+B- were either interpreted as negative or the LIA result of A+B- was accepted as the final result. At least seven of the EIA HIV-1/2 pairs gave rise to no false-positive or -negative results. This strategy was 5 times faster and resulted in a budget on average 50% lower than that of the conventional strategy. Further investigation of these alternative confirmatory strategies, in which the proposed algorithms are applied in sequential use of the different screening assays, are needed under field conditions in developing countries.
Costs and Cost Analysis↗
HIV screening and confirmation: a simplified and less expensive testing algorithm.
In this study we investigated the performance of fourteen different assays capable of simultaneously detecting antibodies to HIV-1 and HIV-2, referred to as combined screening assays (CSAs), on a panel of 371 sera, with a prevalence of 51.5% and 1.3% for HIV-1 and HIV-2 antibodies respectively. The geographic distribution of the sera was as follows; Europe (121), Africa (203) and Latin America (47). These sera were collected from different clinical groups of patients; Asymptomatic (36), AIDS-Related Complex/AIDS patients (18), infected individuals with generalised lymphadenopathy (12), blood donors (149), and subjects with unknown clinical status (156). The Dupont Western blot (WB) kit for detection of HTLV-III antibodies and the Pasteur new Lav-Blot II kit were used for the confirmation of HIV-1 and HIV-2 infection respectively. Of the 14 tests studied, 9 were enzyme linked immunosorbent assays (ELISAs), and 5 were non-Elisa tests requiring visual reading. An alternative approach for HIV antibody testing was studied restrospectively, whereby sera positive in an initial CSA (A) were retested on a second CSA (B), that was different from the first. The use of WB was limited to sera that gave discrepant (A+B-) results in the two CSAs. A positive result in both CSAs was reported as anti-HIV positive. A negative result in the first CSA was reported anti-HIV negative. Sensitivity, specificity, cost, and the delta (delta) values (delta values of the ELISA assays) were taken into consideration when selecting suitable pairs of assays. All the ELISAs scored 100% sensitivity, but for the non-ELISAs, the sensitivity ranged from 96.0% to 100%. The specificity for the ELISAs and non-ELISAs varied from 87.4% to 100% and from 51.4% to 100% respectively. Delta (delta) values for the ELISAs ranged from 3.82 to 136.68 and from -1.15 to -3.08 for the anti-HIV positive and anti-HIV negative populations respectively. Of the 121 test combinations studied, 9 (7.4%) pairs yielded 100% sensitivity and specificity and 61 (50.4%) pairs of CSAs required further testing on WB. This implies 100% positive predictive value, at a cost that was on average 6 times less, and a testing time that was 5 times faster than the conventional algorithm. We conclude that there are several combinations of pairs of CSAs that can be used in the alternative algorithm that can provide accurate results at a much lower cost than the conventional algorithm requiring confirmation by WB of all initially reactive CSA results.(ABSTRACT TRUNCATED AT 400 WORDS)
AIDS Serodiagnosis↗
Evaluation of a line immunoassay for simultaneous confirmation of antibodies to HIV-1 and HIV-2.
An anti-HIV-1/HIV-2 line immunoassay (LIA), using peptides and recombinant antigens was evaluated against commercially available Western blot tests for HIV-1 and HIV-2 antibodies. Two thousand one hundred and ten sera of European, African, and South American origin were used in the evaluation. The panel included 1066 sera with antibodies to HIV-1, 192 sera with antibodies to HIV-2, and 64 sera with antibodies to both. Using Western blot results interpreted according to the WHO criteria as a reference standard, the overall specificity obtained by this LIA was 100% and the sensitivity was 99.77% (97.51-100% for 95% confidence limits) when sera dually reactive in Western blot were included. Of the three sera negative in the LIA but positive in HIV-1 WB, two could be retested in a radioimmunoprecipitation assay and were negative. When dually reactive sera in the Western blot (WHO) were included, the LIA yielded 9.9% indeterminate results as compared with 15.5% for both assays (chi 2 = 29.30; p less than 0.001). Although only one HIV-2 specific peptide antigen (gp36) was used, the LIA yielded a specificity of 100% and a sensitivity of 100% as compared with the HIV-2 Western blot assay. When indeterminate results were included, the overall agreement between the LIA and the HIV-1 and HIV-2 Western blot (WHO criteria) was 89.9% and 90.1% respectively. These results indicate that the LIA provides reliable simultaneous detection of antibodies to HIV-1 and HIV-2, and at a cost which is substantially lower than the cost of Western blot tests.
Blotting, Western↗
Seroconversion rate, mortality, and clinical manifestations associated with the receipt of a human immunodeficiency virus-infected blood transfusion in Kinshasa, Zaire.
To evaluate the consequences of receiving human immunodeficiency virus type 1 (HIV-1)-seropositive blood, 90 HIV-1-seronegative recipients of HIV-1-seropositive blood (case patients) and 90 HIV-1-seronegative recipients of HIV-1-seronegative blood, matched for age, sex, number of transfusions, diagnosis, and severity of illness (controls), were followed for 12 months after transfusion at Mama Yemo Hospital in Kinshasa, Zaire. Of case patients and controls, 72% were children transfused for anemia caused by malaria. Of the 46 case patients case patients alive 6 months after transfusion and for whom HIV-1 serologic results were obtained, 44 (96%) had seroconverted. Significantly more case patients (47%) than controls (16%) died within 1 year after transfusion (P less than .001). In the first 3 months after transfusion, fatigue, diarrhea, fever, cough, pruritus, pallor, oral candidiasis, polyadenopathy, hepatosplenomegaly, and rhinorrhea were observed more often among seroconverters than controls (P less than .04). Six percent of case patients and no controls had developed clinical AIDS after 12 months of follow-up. These findings underscore the urgent need for appropriate HIV screening facilities in transfusion centers worldwide.
Adolescent↗
Comparison of five commercial enzyme-linked immunosorbent assays and Western immunoblotting for human immunodeficiency virus antibody detection in serum samples from Central Africa.
Detection by five different enzyme-linked immunosorbent assays (ELISAs) of antibody to human immunodeficiency virus (HIV) in sera from three Zairian populations consisting of 1,998 individuals with various risks for HIV infection was evaluated. Sera that were reactive by at least one assay and 10% of the nonreactive serum samples were analyzed by Western blot (immunoblot) by using U.S. Public Health Service interpretation criteria. Sera which were positive by ELISA for detection of antibody to HIV-1 and HIV-2 and negative or indeterminate by HIV-1 Western blot were also analyzed by HIV-2 Western blot. Overall, 443 (22.2%) serum specimens were HIV-1 Western blot positive, 390 (19.5%) had indeterminate HIV-1 Western blot patterns, and no samples were HIV-2 Western blot positive. The sensitivity of the ELISAs ranged from 97.5 to 99.8%, and the specificity ranged from 51.7 to 98.4%. By population group, the negative predictive value ranged from 97.1 to 100%, in contrast to the positive predictive value, which varied from 6.6 to 100%. Follow-up results for sera which were indeterminate for antibody to HIV-1 documented only four seroconversions (6.0%) among 67 individuals at high risk for HIV-1 infection and no seroconversions among 202 individuals at relatively low risk for HIV-1 infection. This study demonstrates the importance of evaluating commercial ELISAs with sera from appropriate geographical regions in order to select the most cost-effective and practical assay for use in that region. Furthermore, the high frequency of indeterminate Western blots for African sera emphasizes the continual need for improved confirmatory assays and interpretation criteria.
Blotting, Western↗
Simplified and less expensive confirmatory HIV testing.
The conventional approach to human immunodeficiency virus (HIV) antibody testing, which relies on confirmation of all initially positive screening results using a Western blot assay, is expensive. In an alternative approach, we retested sera that were positive in an initial screening assay using a second screening assay, which differed from the first, and limited the use of Western blot to those sera that gave discrepant results in the two screening assays. This resulted in 100% sensitivity and specificity at a cost that was, on average, 6.1 times less than that of the conventional approach. This level of sensitivity and specificity was also achieved at a cost that was 9.0 times less than the conventional approach if the Western blot was replaced by a third screening assay that differed from the previous two. Retesting positive sera using the same assay did not increase the accuracy of the results obtained by testing the sera only once.
AIDS Serodiagnosis↗
Comparative evaluation of 36 commercial assays for detecting antibodies to HIV.
Summarized are the results of an assessment of the major operational characteristics of 36 commercially available assays for detection of antibodies to human immunodeficiency virus type 1 (HIV-1) and/or type 2 (HIV-2). For this purpose, 20 enzyme-linked immunosorbent assays (ELISAs), 11 simple immunoassays with visual reading, four supplemental assays, and one discriminatory assay were assessed using a panel of 537 sera (65% of which were of African, 26% of European, and 9% of South American origin); the prevalence of HIV-1 was 39.1% and of HIV-2, 15.7%. The following operational parameters of the assays were investigated: ease of performance; suitability for use in small blood collection centres; sensitivity and specificity; positive predictive values at different prevalences; inter-reader variability for simple assays whose results were read visually; the proportion of indeterminate results; and, for some of the ELISA assays, delta-values, as quantitative measures of sensitivity and specificity. The results will be of use to health policy decision-makers, managers of national AIDS prevention and control programmes, directors of blood banks, and laboratory specialists in the selection of appropriate HIV antibody assays.
AIDS Serodiagnosis↗
Human T cell lymphotropic virus type I (HTLV-I) among female prostitutes in Kinshasa, Zaire.
Three hundred seventy-seven prostitutes from Kinshasa, Zaire, were enrolled in a study to determine associated risk factors for human immunodeficiency virus type 1 (HIV-1) and human T cell lymphotropic virus type I (HTLV-I) infection. Twelve samples (3.2%) were seropositive for HTLV-I; results for HIV-1 (101 [26.8%]) are reported elsewhere. HTLV-I prevalence increased with age, and seven of the seropositive women originated from the Equateur region, a remote area in northwestern Zaire. The prevalence among women from Equateur (7.2%) was higher than that of women from all other regions (1.8%, P = .02). Presence of HTLV-I antibodies was not associated with frequency or type of sex practice. In a subsequent study, 350 serum samples were obtained from a variety of subjects in the Equateur region in 1986. Nineteen (5.4%) showed antibodies to HTLV-I. These data and a recent report of a cluster of patients with tropical spastic paraparesis from this region suggest that HTLV-I is endemic in the Equateur region of Zaire.
Adult↗
[Retinitis in an infant infected with HIV].
A 7 month-old HIV-infected infant of African origin was admitted to the hospital. A routinely performed fundoscopy showed the presence of an unilateral left retinitis. Urine culture was positive for cytomegalovirus (CMV). Treatment with AZT (3.5 mg/kg/6 hr) was started concomitantly with monthly 350 mg/kg gammaglobulin intravenous administration. The retinitis resolved after 3 weeks and no recurrence was observed after 4 months of follow-up. The difficulties in establishing a diagnosis and in evaluating a response to treatment are briefly discussed.
Cytomegalovirus Infections↗
Evaluation of two enzyme immunoassays for detection of human immunodeficiency virus antigen in African and European sera.
The performance of two HIV antigen enzyme immunoassays (EIAs), the HTLV-III antigen EIA (Abbott) and the Innotest HIV antigen EIA (Innogenetics), was assessed using 276 HIV-1 antibody positive and 42 HIV antibody negative sera from European and African individuals. On the initial screening 16% (51/318) of the sera were reactive in the Abbott EIA and 21.4% (68/318) in the Innotest EIA. The Innotest detected significantly more confirmed HIV antigen positive sera (55/58, 94.6%) than the Abbott EIA (41/58, 70.7%). The presence of free detectable HIV antigen in African and European sera was strongly associated with the clinical classification CDC IV and with low p24 antibody levels.
Africa↗
Advanced immunodeficiency as a risk factor for heterosexual transmission of HIV.
To define the rate of HIV infection and associated risk factors among heterosexual partners of HIV-infected individuals, 80 partners and 77 index cases were examined for clinical, behavioural and virological variables. The study population included 61 male and 16 female index cases, of whom 40 were European and 37 African. Multiple sexual partners in central Africa was the risk factor for HIV infection in 83%. The overall infection rate among the contact cases was 45%, 53% among female partners and 13% among male partners (P less than 0.001). Variables significantly associated with HIV infection in the partners included advanced clinical stage (AIDS-related complex or AIDS), a low concentration of T4 lymphocytes and African nationality of the index case, young age of the partner, and more than 50 instances of sexual contact with the index cases. In a logistic regression analysis, a low concentration of T4 lymphocytes, clinical stage ARC/AIDS and African nationality of the index case but not number of sexual contacts, remained as independent risk factors for HIV transmission. Our data indicate that there is a significant biological heterogeneity in sexual transmission of HIV and that advanced clinical stage and severe T cell depletion of the index case are major determinants of infectivity.
Acquired Immunodeficiency Syndrome↗
Comparison of enzyme immunoassays and an immunofluorescence test for detection of antibody to human immunodeficiency virus in African sera.
A total of 152 sera from African subjects were tested for presence of antibody to human immunodeficiency virus using four enzyme immunoassays (EIA) marketed by Abbott Diagnostics, Organon Teknika, Wellcome and Diagnostics Pasteur respectively, an indirect immunofluorescence assay (IFA) and an immunoblot assay (IBA) as reference test. The sensitivity (95% confidence limits, CL) of the EIAs and the IFA ranged between 80.9% and 99.1%. The specificity of the Abbott EIA was lower (95% CL: 38.1-72%) than that of the other assays (95% CL: 83.5-100%). The use of an IFA or the Wellcome competitive EIA as confirmatory test on initially EIA positive sera yielded a specificity of 85.5-100% (95% CL) compared with the IBA. The costs of screening by an EIA, followed by confirmatory testing of reactive sera with IFA or the Wellcome EIA and IBA on discrepant test results was similar for all combinations with the exception of initial screening with the Abbott EIA which was more expensive. Using a limited number of sera from African subjects no one test system yielded a significantly superior degree of specificity or sensitivity.
Acquired Immunodeficiency Syndrome↗
Immunofluorescence tests for HIV antibody and their value as confirmatory tests.
The enzyme-linked immunosorbent assay (ELISA) is currently being used as a sensitive screening test for HIV antibody. The immunoblot assay (IBA) and indirect immunofluorescence (IF) techniques are two recommended confirmation tests for EIA-positive sera. An indirect IF test has been developed by various laboratories using acetone fixed mixtures of uninfected and HIV-infected cells, which facilitated the reading, since nonspecific reactions were easily differentiated from specific staining. Similar results have been obtained with H9-, CEM-, and HUT78-HIV-infected and uninfected cells. Anti-nuclear antibodies and auto-antibodies resulting in false-positive EIA results, could easily be differentiated by the IF test. Aspecific fluorescence can be removed by absorption of the specimens with non-infected cells. However, IF is not suitable for the screening of large series of specimens. IF is especially well suited for quantitative analysis of serum antibody levels. Whereas serum antibody titers rise initially after infection, they decrease as AIDS develops. Heat inactivation of sera did not affect reactivity in IF, in contrast to a high rate of false-positive results obtained with heat inactivated sera in some ELISAs. A well characterized serum from an AIDS patient can be used to perform IF in order to monitor HIV infection of susceptible cells. It has been claimed that titers of neutralizing antibodies significantly correlate with the levels of IF anti-HIV antibodies. An overall correlation of 99% between IF and IBA was reported by different laboratories, when HIV ELISA-reactive European and North American sera were tested. The concordance with IBA was 97% when HIV ELISA-reactive African sera were tested.(ABSTRACT TRUNCATED AT 250 WORDS)
Antibodies, Viral↗