Journal of acquired immune deficiency syndromes (1999), Jan 15, 2014
CD4⁺ T-cell counts are used to screen and follow-up HIV-infected patients during treatment. As pa... more CD4⁺ T-cell counts are used to screen and follow-up HIV-infected patients during treatment. As part of the World Health Organization prequalification program of diagnostics, we conducted an independent multicenter evaluation of the FACSCount CD4 and the Pima CD4, using the FACSCalibur as reference method. A total of 440 paired capillary and venous blood samples were collected from HIV-infected patients attending the HIV outpatient clinic in Antwerp, Belgium, and the HIV care and treatment center in Dar es Salam, Tanzania. Capillary blood was run on Pima analyzer, whereas venous blood was analyzed on FACSCount, Pima, and FACSCalibur instruments. Precision and agreement between methods were assessed. The FACSCount CD4 results were in agreement with the FACSCalibur results with relative bias of 0.4% and 3.1% on absolute CD4 counts and an absolute bias of -0.6% and -1.1% on CD4% in Antwerp and Dar es Salam, respectively. The Pima CD4 results were in agreement with the FACSCalibur result...
A new anti-human immunodeficiency virus type 1 and 2 (anti-HIV 1 and 2) test is described. It use... more 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.
The enzyme-linked immunosorbent assay (ELISA) is currently being used as a sensitive screening te... more 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-HIVinfected 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.
To evaluate the performance of 22 assays for the detection of antibodies to HIV. Twenty-two assay... more To evaluate the performance of 22 assays for the detection of antibodies to HIV. Twenty-two assays for the combined detection of antibodies to HIV-1 and HIV-2, were evaluated on the same panel of serum specimens of diverse origin. Eight of the assays were ELISAs and the remaining 14 were simple, assays read visually. The specimen panel consisted of anti-HIV positive and negative samples from Africa (n=192), Europe (n=206), Asia (n=99) and Latin America (n=98). In addition to estimations of sensitivity and specificity, the assays were assessed, using a novel scoring system, for their ease of performance and for their suitability for use in small laboratories and clinics. The sensitivities of the assays in terms of seroconversion were assessed using series of specimens collected from nine individuals undergoing seroconversion. Eight ELISAs and eight of 14 simple assays had sensitivities and specificities of >99 and 95%, respectively. The results of these evaluations will be of assistance to those responsible for the selection of appropriate anti-HIV assays according to laboratory circumstances, the purpose of the testing and the population being tested.
Three hundred seventy-seven prostitutes from Kinshasa, Zaire, were enrolled in a study to determi... more 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.
A total of 152 sera from African subjects were tested for presence of antibody to human immunodef... more 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 immunofluorescenee 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.
European Journal of Clinical Microbiology & Infectious Diseases, 1991
An anti-HIV-1/HIV-2 line immunoassay (LIA), using peptides and recombinant antigens was evaluated... more 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 % (9%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 (Z 2 = 29.30; p < 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.
Infection with HIV results in a progressive depletion of CD4+ T cells and leads to significant in... more 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-I -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 HIVinfected 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 HIVnegative 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.
Archives of Ophthalmology, a monthly professional medical journal published by the American Medic... more Archives of Ophthalmology, a monthly professional medical journal published by the American Medical Association, publishes peer-reviewed, original articles on all aspects of ophthalmology.
To define the rate of HIV infection and associated risk factors among heterosexual partners of HI... more 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.
Journal of acquired immune deficiency syndromes (1999), Jan 15, 2014
CD4⁺ T-cell counts are used to screen and follow-up HIV-infected patients during treatment. As pa... more CD4⁺ T-cell counts are used to screen and follow-up HIV-infected patients during treatment. As part of the World Health Organization prequalification program of diagnostics, we conducted an independent multicenter evaluation of the FACSCount CD4 and the Pima CD4, using the FACSCalibur as reference method. A total of 440 paired capillary and venous blood samples were collected from HIV-infected patients attending the HIV outpatient clinic in Antwerp, Belgium, and the HIV care and treatment center in Dar es Salam, Tanzania. Capillary blood was run on Pima analyzer, whereas venous blood was analyzed on FACSCount, Pima, and FACSCalibur instruments. Precision and agreement between methods were assessed. The FACSCount CD4 results were in agreement with the FACSCalibur results with relative bias of 0.4% and 3.1% on absolute CD4 counts and an absolute bias of -0.6% and -1.1% on CD4% in Antwerp and Dar es Salam, respectively. The Pima CD4 results were in agreement with the FACSCalibur result...
A new anti-human immunodeficiency virus type 1 and 2 (anti-HIV 1 and 2) test is described. It use... more 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.
The enzyme-linked immunosorbent assay (ELISA) is currently being used as a sensitive screening te... more 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-HIVinfected 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.
To evaluate the performance of 22 assays for the detection of antibodies to HIV. Twenty-two assay... more To evaluate the performance of 22 assays for the detection of antibodies to HIV. Twenty-two assays for the combined detection of antibodies to HIV-1 and HIV-2, were evaluated on the same panel of serum specimens of diverse origin. Eight of the assays were ELISAs and the remaining 14 were simple, assays read visually. The specimen panel consisted of anti-HIV positive and negative samples from Africa (n=192), Europe (n=206), Asia (n=99) and Latin America (n=98). In addition to estimations of sensitivity and specificity, the assays were assessed, using a novel scoring system, for their ease of performance and for their suitability for use in small laboratories and clinics. The sensitivities of the assays in terms of seroconversion were assessed using series of specimens collected from nine individuals undergoing seroconversion. Eight ELISAs and eight of 14 simple assays had sensitivities and specificities of &amp;amp;amp;amp;gt;99 and 95%, respectively. The results of these evaluations will be of assistance to those responsible for the selection of appropriate anti-HIV assays according to laboratory circumstances, the purpose of the testing and the population being tested.
Three hundred seventy-seven prostitutes from Kinshasa, Zaire, were enrolled in a study to determi... more 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.
A total of 152 sera from African subjects were tested for presence of antibody to human immunodef... more 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 immunofluorescenee 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.
European Journal of Clinical Microbiology & Infectious Diseases, 1991
An anti-HIV-1/HIV-2 line immunoassay (LIA), using peptides and recombinant antigens was evaluated... more 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 % (9%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 (Z 2 = 29.30; p < 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.
Infection with HIV results in a progressive depletion of CD4+ T cells and leads to significant in... more 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-I -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 HIVinfected 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 HIVnegative 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.
Archives of Ophthalmology, a monthly professional medical journal published by the American Medic... more Archives of Ophthalmology, a monthly professional medical journal published by the American Medical Association, publishes peer-reviewed, original articles on all aspects of ophthalmology.
To define the rate of HIV infection and associated risk factors among heterosexual partners of HI... more 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.
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Papers by G. Vercauteren