The use of simple, rapid tests to detect antibodies to human immunodeficiency virus types 1 and 2 in pooled serum specimens.

BACKGROUND: The use of pooled specimens has been proposed as a means of expanding testing for human immunodeficiency virus (HIV) antibodies in population studies and in blood screening, while reducing laboratory costs. OBJECTIVES: To develop a strategic specimen pooling method to be used with rapid HIV antibody assays to detect positive specimens and to evaluate its performance in comparison with testing with commercial EIA and WB. STUDY DESIGN: Two lateral flow rapid HIV antibody assays, Seroz*Strip HIV-1/2(1) and Determine HIV-1/2, were evaluated for their ability to detect HIV-1 antibodies in serum and/or plasma specimens pooled in sizes ranging from two to 20 following the respective manufacturers' protocols. One thousand prospectively collected specimens and 55 seroconversion specimens were prepared in pools of five for evaluation by the two rapid HIV assays. RESULTS: Optimal detection and discrimination of HIV-1 antibody-positive and HIV-1 antibody-negative specimens was observed in pool sizes of five to ten for both assays. The ability of the two rapid assays to detect HIV-1 antibody-positive samples from commercial HIV-1 seroconversion panels contained in the pools was equivalent to that of commercial enzyme immunoassays (EIAs) and Western blot (WB) to detect HIV-1 antibody in the non-pooled samples. Application of the pooling method in prospectively collected specimens yielded excellent concordance with EIA/WB results in both sensitivity (98.88% for Seroz*Strip HIV-1/2, 100% for Determine HIV-1/2) and specificity (99.56% for Seroz*Strip HIV-1/2, 99.45% for Determine HIV-1/2). CONCLUSION: Use of a pooling strategy with either assay reduced the number of tests required by almost 50% and could provide substantial cost reductions for HIV screening in settings where HIV-1 prevalence is less than 10%.     

Synthetic-peptide-based enzyme-linked immunosorbent assay for screening human serum or plasma for antibodies to human immunodeficiency virus type 1 and type 2.

A synthetic-peptide-based enzyme-linked immunosorbent assay (EIA) capable of screening for antibodies to both human immunodeficiency virus type 1 (HIV-1) and HIV-2 has been developed for use in blood banks and diagnostic laboratories. Microtiter wells are coated with two synthetic peptides, one corresponding to the highly conserved envelope region of HIV-1 and another corresponding to the conserved envelope region of HIV-2. Overall, sensitivity was 100% in 303 individuals diagnosed with AIDS and 96 individuals diagnosed with AIDS-related complex, 14.8% in a study of 500 high-risk group members, 99.9% in 600 EIA repeatedly reactive (RR)-HIV-1 Western blot (WB)-positive repository specimens, and 100% for 222 geographically diverse HIV-1 specimens and 216 confirmed HIV-2-positive specimens evaluated. The specificity was determined to be 99.72% for a total of 13,004 serum and plasma samples from random volunteer donors evaluated across five blood banks. Forty donors who were found to be EIA RR-WB indeterminate but nonreactive on the United Biomedical, Inc., test (UBI HIV 1/2 EIA) were prospectively followed as an additional measure of specificity. None of the 40 low-risk cases evolved into a positive WB pattern at follow-up. The sensitivity and specificity of this new assay are comparable to those of other Food and Drug Administration-licensed HIV-1 and HIV-1-HIV-2 assays that are currently available in the United States. The UBI HIV 1/2 EIA affords laboratories another choice in the detection of antibodies for HIV-1 and HIV-2 with a test based on an alternative antigen format.     

Field Evaluation of the Determine Rapid Human Immunodeficiency Virus Diagnostic Test in Honduras and the Dominican Republic

Rapid detection of human immunodeficiency virus (HIV) infection can result in improved patient care and/or faster implementation of public health preventive measures. A new rapid test, Determine (Abbott, Abbott Park, Ill.), detects HIV type 1 (HIV-1) and HIV-2 antibodies within 15 min by using 50 microl of serum or plasma. No specialized equipment or ancillary supplies are required, and results are read visually. A positive result is noted by the appearance of a red line. An operational control (red line) indicates proper test performance. We evaluated the Determine rapid HIV detection test with a group of well-characterized serum samples (CD4 counts and viral loads were known) and serum samples from HIV-positive individuals at field sites in Honduras and the Dominican Republic. In the field evaluations, the results obtained by the Determine assay were compared to those obtained by local in-country HIV screening procedures. We evaluated serum from 100 HIV-positive patients and 66 HIV-negative patients. All samples gave the expected results. In a companion study, 42 HIV-positive samples from a Miami, Fla., serum bank were tested by the Determine assay. The samples had been characterized in terms of CD4 counts and viral loads. Fifteen patients had CD4 counts <200 cells/mm(3), while 27 patients had CD4 counts >200 cells/mm(3). Viral loads ranged from 630 to 873,746 log(10) copies/ml. All samples from the Miami serum bank were positive by the Determine test. Combined results from the multicenter studies indicated that the correct results were obtained by the Determine assay for 100% (142 of 142) of the HIV-positive serum samples and 100% (66 of 66) of the HIV-negative serum samples. The Determine test was simple to perform and the results were easy to interpret. The Determine test provides a valuable new method for the rapid identification of HIV-positive individuals, especially in developing countries with limited laboratory infrastructures.     

Performance of two commercial immunochromatographic assays for rapid detection of antibodies specific to human immunodeficiency virus types 1 and 2 in serum and urine samples in a rural community-based research setting (Rakai, Uganda)

Rapid detection of human immunodeficiency virus (HIV) antibodies is of great importance in developing and developed countries to diagnose HIV infections quickly and at low cost. In this study, two new immunochromatographic rapid tests for the detection of HIV antibodies (Aware HIV-1/2 BSP and Aware HIV-1/2 U; Calypte Biomedical Corporation) were evaluated in rural Africa to determine the tests' performance and comparability to commercially available conventional enzyme immunoassay (EIA) and Western blot (WB) tests. This prospective study was conducted from March 2005 through May 2005 using serum and urine from respondents in the Rakai Community Cohort Survey. Nine hundred sixty-three serum samples were tested with the Aware blood rapid assay (Aware-BSP) and compared to two independent EIAs for HIV plus confirmatory Calypte WB for any positive EIAs. The sensitivity of Aware-BSP was 98.2%, and the specificity was 99.8%. Nine hundred forty-two urine samples were run using the Aware urine assay (Aware-U) and linked to blood sample results for analysis. The sensitivity of Aware-U was 88.7% and specificity was 99.9% compared to blood EIAs confirmed by WB analysis. These results support the adoption of the Aware-BSP rapid test as an alternative to EIA and WB assays for the diagnosis of HIV in resource-limited settings. However, the low sensitivity of the Aware-U assay with its potential for falsely negative HIV results makes the urine assay less satisfactory.     

Field evaluation of a rapid human immunodeficiency virus (HIV) serial serologic testing algorithm for diagnosis and differentiation of HIV type 1 (HIV-1), HIV-2, and dual HIV-1-HIV-2 infections in West African pregnant women

We evaluated a two-rapid-test serial algorithm using the Determine and Genie II rapid assays, performed on-site in four peripheral laboratories during the French Agence Nationale de Recherches sur le SIDA (ANRS) 1201/1202 Ditrame Plus cohort developed for prevention of mother-to-child transmission of human immunodeficiency virus (HIV) infection in Côte d'Ivoire. A total of 1,039 specimens were retested by two commercial enzyme-linked immunosorbent assays (ELISAs). The following specimens were tested: 315 specimens found on-site to be infected with HIV type 1 (HIV-1), 8 specimens found on-site to be infected with HIV-2, 71 specimens found on-site to be infected with both HIV-1 and HIV-2, 40 specimens found on-site to have indeterminate results for HIV infection, and 605 specimens taken during a quality assurance program. For HIV discrimination, 99 positive serum samples (20 with HIV-1, 8 with HIV-2, and 71 with HIV-1 and HIV-2 on the basis of our rapid test algorithm) were retested by the Peptilav test, Western blot (WB) assays, and homemade monospecific ELISAs. Real-time DNA PCRs for the detection of HIV-1 and HIV-2 were performed with peripheral blood mononuclear cells from 35 women diagnosed on-site with HIV-1 and HIV-2 infections. Compared to the results of the ELISAs, the sensitivities of the Determine and Genie II assays were 100% (95% lower limit [95% LL], 99.1%) and 99.5% (95% confidence interval [95% CI], 98.2 to 99.9%), respectively. The specificities were 98.4% (95% CI, 96.9 to 99.3%) and 100% (95% LL, 99.3%), respectively. All serological assays gave concordant results for infections with single types. By contrast, for samples found to be infected with dual HIV types by the Genie II assay, dual reactivity was detected for only 37 samples (52.1%) by WB assays, 34 samples (47.9%) by the Peptilav assay, and 23 samples (32.4%) by the monospecific ELISAs. For specimens with dual reactivity by the Genie II assay, the rates of concordance between the real-time PCR assays and the serological assays were 25.7% for the Genie II assay, 82.9% for the Peptilav assay, 74.3% for WB assays, and 80% for the homemade ELISAs. Our algorithm provided high degrees of sensitivity and specificity comparable to those of ELISAs. Even if they are rare, women identified by the Genie II assay as being infected with HIV-1 and HIV-2 mostly appeared to be infected only with HIV-2.     

Evaluation of three rapid tests for detection of antibodies to HIV-1 non-B subtypes

Three rapid tests were evaluated for the detection of antibodies to HIV in 111 plasma specimens (81 HIV-1 non-B subtypes, including 4 coinfections with HIV-2, 30 HIV negative). The Determine HIV-1/2, Equipar HIV, and Multispot HIV-1/2 tests were 100% sensitive and specific for the detection of HIV-1 antibodies. Multispot showed 92.7% specificity for HIV-2.     

A simple semi-rapid HIV-1&2 confirmatory immunoassay using magnetic particles

The Bionor HIV-1&2 Confirmatory Test is a semi-rapid simple immunoassay based on magnetic particles for the confirmation of serological status to human immunodeficiency virus (HIV). The specificity and sensitivity of this assay was evaluated by comparison with the Diagnostic Biotechnology HIV-1 Western blot (WB) 2.2 and the HIV-2/SBL-6669 WB. Bionor's confirmatory test demonstrated 98% specificity when testing sero-negative blood donors and false positive sera in screening tests compared to 81.5 and 71.6%, respectively, using the HIV-1 WB. The sensitivity of this assay for HIV-1 antibody positive sera was 97.9% compared to the WB which was 99.5%. When testing confirmed HIV-2 antibody positive samples, 2/100 scored negative using this confirmatory test similar to other HIV-2 peptide-based line immunoassays available commercially, whilst 8/100 were indeterminate reacting to HIV-2 membrane antigens only. Bionor's confirmatory test detected HIV-1 seropositivity earlier than the WB in longitudinal seroconversion panels and could discriminate between HIV-1 and -2 infection. The number of indeterminate responses was generally reduced significantly using Bionor's confirmatory test compared to the HIV-1 WB. The greater specificity, speed and ease of interpretation of Bionor's confirmatory test renders it an attractive and cost effective alternative to the WB for confirming HIV serological status worldwide.     

The fourth generation AlereTM HIV Combo rapid test improves detection of acute infection in MTN-003 (VOICE) samples

BackgroundEarly and accurate detection of HIV is crucial when using pre-exposure prophylaxis (PrEP) for HIV prevention to avoid PrEP initiation in acutely infected individuals and to minimize the risk of drug resistance in individuals with breakthrough infection.ObjectiveTo determine if fourth-generation antigen/antibody (Ag/Ab) rapid diagnostic tests (RDT) would have detected HIV infection earlier than the third-generation RDT used in MTN-003 (VOICE).Study design5029 VOICE participants were evaluated with third-generation Alere Determine™ HIV-1/2, OraQuick ADVANCE^® Rapid HIV-1/2, Uni-Gold™ Recombigen^® HIV-1/2 and Bio-Rad GS HIV-1/2 + O EIA; and fourth-generation Alere Determine™ HIV-1/2 Ag/Ab Combo, Conformité Européene (CE)-Marked Alere™ HIV Combo and Bio-Rad HIV Combo Ag/Ab EIA. Multispot^®, GS HIV-1 Western Blot (WB) and Geenius™ (Bio-Rad) were also evaluated.ResultsOf 57 antibody-negative pre-seroconversion plasma samples with HIV RNA >20 copies/mL identified, 16 (28%) were reactive by CE-Marked Alere™ HIV Combo (1 Ab; 9 Ag; 6 Ag/Ab reactive) and 4 (7%) by Alere Determine™ HIV-1/2 Ag/Ab Combo (2 Ab; 2 Ag; 0 Ag/Ab reactive) (p = 0.0005). Multispot^® confirmed only 1 of 16 acute infections while WB and Geenius™ confirmed none. GS HIV Combo Ag/Ab EIA identified 27 of 57 (47%) pre-seroconversion RNA-positive samples.ConclusionIn VOICE, 28% of infections missed by current third-generation RDT would have been identified with the use of CE-Marked Alere™ HIV Combo. Geenius™, Multispot^® and WB were all insensitive ( < 10%) in confirming infections detected by fourth-generation assays. An improved diagnostic algorithm that includes a fourth-generation RDT with HIV RNA testing will be essential for efficiently identifying seroconverters on PrEP.     

Performance of a rapid immunochromatographic screening test for detection of antibodies to human immunodeficiency virus type 1 (HIV-1) and HIV-2: experience at a tertiary care hospital in South India

The performance characteristics of a rapid immunochromatographic-screening test, SD Bioline HIV-1/2 3.0 (Standard Diagnostics Inc., Kyonggi-do, South Korea) on 23,754 sera and 30 plasma samples are reported. The sensitivity and specificity for the assay on serum samples are 100% and 99.4%, respectively. The assay detected antibodies in individuals infected with human immunodeficiency virus type 1 (HIV-1) genotypes A and C and HIV-2. This straightforward assay is a reliable diagnostic tool for screening HIV in resource-poor settings.     

Molecular epidemiology of HIV in Ghana: dominance of CRF02_AG

Recent studies showed the importance of CRF02_AG in West Africa, although the clinical relevance of these recombinant forms of HIV remains unknown. The present study aimed at determining the molecular diversity of HIV in Ghana and investigating the possible epidemiologic advantage of recombinant HIV-1. Plasma samples collected in 1999-2002 from two populations of HIV infected individuals (144 asymptomatic candidate blood donors and 169 AIDS patients) were studied and 249 of them were molecularly characterised in gag, pol, and env regions. Five molecular groups were identified: strains clustering with CRF02_AG in all regions (147/249 or 59%), recombinant strains clustering with CRF02_AG in one or two regions (50/249 or 20%), other subtypes, pure or recombinant, but not involving CRF02_AG (37/249 or 15%), HIV-2 (11/249 or 4.5%), and double infections (4/249 or 1.5%). There was no significant difference in the distribution of HIV-1 recombinant strains according to clinical presentation. No evidence of a significant increase in CRF02_AG prevalence between 1999 and 2002 was found. Irrespective of clinical condition, CRF02_AG is the predominant molecular form of HIV-1 in Kumasi, Ghana.     

Diagnostic challenges for rapid human immunodeficiency virus assays. Performance using HIV-1 group O, HIV-1 group M, and HIV-2 samples

OBJECTIVE: We sought to determine the ability of seven rapid assays for human immunodeficiency virus (HIV) to detect antibodies in a panel of sera from individuals infected with different types and groups of HIV. STUDY DESIGN/METHODS: Sixty-eight well-characterized samples, including HIV-1 group O (24), several HIV-1 group M clades (21), HIV-1/2 (10), HIV-2 (10), and samples with indeterminate results (3), were tested by the following rapid HIV assays: HIV-Spot, HIVCHEK System 3, A/Q Rapid HIV, Genie II HIV-1/HIV-2, Quix HIV-1-2-O, ImmunoComb II HIV-1+2 BiSpot, and the Serodia HIV-1+2. RESULTS: All tests successfully detected the HIV-1 group M clades and the HIV-1/2-positive samples. Of the HIV-2 stand-alone samples, four tests missed the same sample, and three tests missed another sample. Of the HIV-1 group O samples, four samples were missed by at least one test, and another sample was missed by three tests. The sensitivity of the seven rapid assays in detecting each group of sera was between 83% and 100%, with only one test having a sensitivity of 100% for all groups of sera. Three samples proved to be problematic because they were misclassified by more than one assay. CONCLUSIONS: The performance of rapid HIV assays is variable when testing sera from individuals infected with HIV-1 group O and HIV-2.     

Assessment of a rapid HIV test strategy during labor: a pilot study from Rio de Janeiro, Brazil

OBJECTIVES: To use two rapid human immunodeficiency virus (HIV) tests at labor, measure test acceptance and performance, and measure HIV prevalence in these women. METHODS: Between February and October 2000, two rapid tests (Determine; Abbott, Chicago, IL, U.S.A. and Double Check; Orgenics, Yavne, Israel) were used in three public maternities in Rio de Janeiro, Brazil. Enzyme-linked immunosorbent assay (ELISA) and Western blot (WB) analysis confirmed positive and discordant results. RESULTS: Of the 858 patients who were enrolled, the mean gestational age was 36 weeks (median = 39, mode = 40) and 17 (2%) refused testing. Of the 841 patients tested, 13 were positive by both tests, which represents a 1.5% prevalence (95% confidence interval: 0.7%-2.3%); all were confirmed by ELISA and WB analysis. Seven samples gave discordant results by the rapid tests; of these, six were ELISA-negative/WB-negative and one was ELISA-negative/WB-indeterminate. The positive predictive value for samples that were positive by both rapid tests simultaneously was 100%. CONCLUSIONS: Two rapid HIV tests used at labor were well accepted (98%). When the combined results of the two rapid tests (but not a single rapid test) were analyzed, this strategy was as efficient as the standard ELISA and WB HIV strategy for correctly classifying individuals.     

Rapid Assay for Simultaneous Detection and Differentiation of Immunoglobulin G Antibodies to Human Immunodeficiency Virus Type 1 (HIV-1) Group M, HIV-1 Group O, and HIV-2

A rapid immunodiagnostic test that detects and discriminates human immunodeficiency virus (HIV) infections on the basis of viral type, HIV type 1 (HIV-1) group M, HIV-1 group O, or HIV-2, was developed. The rapid assay for the detection of HIV (HIV rapid assay) was designed as an instrument-free chromatographic immunoassay that detects immunoglobulin G (IgG) antibodies to HIV. To assess the performance of the HIV rapid assay, 470 HIV-positive plasma samples were tested by PCR and/or Western blotting to confirm the genotype of the infecting virus. These samples were infected with strains that represented a wide variety of HIV strains including HIV-1 group M (subtypes A through G), HIV-1 group O, and HIV-2 (subtypes A and B). The results showed that the HIV genotype identity established by the rapid assay reliably (469 of 470 samples) correlates with the HIV genotype identity established by PCR or Western blotting. A total of 879 plasma samples were tested for IgG to HIV by a licensed enzyme immunoassay (EIA) (470 HIV-positive samples and 409 HIV-negative samples). When they were tested by the rapid assay, 469 samples were positive and 410 were negative (99.88% agreement). Twelve seroconversion panels were tested by both the rapid assay and a licensed EIA. For nine panels identical results were obtained by the two assays. For the remaining three panels, the rapid assay was positive one bleed later in comparison to the bleed at which the EIA was positive. One hundred three urine samples, including 93 urine samples from HIV-seropositive individuals and 10 urine samples from seronegative individuals, were tested by the rapid assay. Ninety-one of the ninety-three urine samples from HIV-seropositive individuals were found to be positive by the rapid assay. There were no false-positive results (98.05% agreement). Virus in all urine samples tested were typed as HIV-1 group M. These results suggest that a rapid assay based on the detection of IgG specific for selected transmembrane HIV antigens provides a simple and reliable test that is capable of distinguishing HIV infections on the basis of viral type.     

Long-term highly suppressed HIV-infected children and adolescents with negative rapid HIV tests due to significant antibody loss

BackgroundRapid HIV test devices are widely used throughout the world and are important as diagnostic tools with relatively high sensitivity and specificity. Loss of HIV specific antibodies in late-stage AIDS patients has previously been reported in patients with advanced disease (i.e., AIDS).ObjectiveTo study rate of antibody loss that may lead to false negative HIV-antibodies results in children and adolescents who received long term antiretroviral (ARV) treatment with persistently undetectable viral loads.Study designFive FDA approved rapid HIV test kits including Trinity Uni-Gold Recombigen HIV-1, OraQuick Advance HIV-1/2, Reveal G3 HIV-1, Clearview STAT-PAK HIV-1/2, and Clearview COMPLETE HIV-1/2 were used to test 98 stored samples from 27 patients. Samples were tested at baseline and at least twice in 6–14 years post initiation of ARV treatment and full viral load suppression.ResultsOf the 403 tests, 43 (10.7%) were found to be false-negative using rapid HIV kits. Loss of positivity was correlated with decrease of HIV antibody titer.ConclusionsThere is a slow but persistent loss of HIV specific antibodies in highly suppressed HIV infected children and adolescents that may lead to false-negative results in rapid HIV antibody tests. The temporal loss of signal is dependent on the baseline level of antibodies and the type of HIV rapid test kit used.     

中国HIV-1 B'/C亚型感染者对异体病毒中和作用与疾病进展关系研究

目的 探讨中国HIV-1 B'/C亚型感染者对异体病毒中和作用与疾病进展的关系.方法 根据CD4 T淋巴细胞数量和有尤临床症状将HIV-1 B'/C亚型感染者分为HIV慢性感染组和AIDS组.将HIV-1感染者血清稀释(1/10～1/320)后,与在基因结构特点上同源性很低的3株HIV-1作用,以检测其中和作用.同时以正常人血清加病毒悬液为对照孔,能够抑制对照孔50%病毒复制的血清为中和作用阳性.将某个HIV-1感染者血浆能够中和异体病毒的个数占3个异体病毒的百分率定义为HIV-1感染者中和异体病毒的宽度;将某个HIV-1感染者血浆中和3个异体病毒抗体滴度的几何平均滴度定义为HIV-1感染者中和异体病毒的强度.结果 HIV-1慢性感染组与AIDS组之间中和异体病毒的宽度和强度差异有统计学意义,HIV-1慢性感染组显著高于AIDS组.HIV-1慢性感染组中和异体病毒的宽度和强度与病毒载量呈正相关,而AIDS组巾和异体病毒的宽度和强度与病毒载量没有显著的相关性.HIV-1慢性感染组和AIDS组中和异体病毒的宽度和强度与CD4 T淋巴细胞数均没有显著的相关性.结论 中国HIV-1B'/C亚型感染者不同疾病进展阶段针对异体病毒中和作用能力不同,HIV慢性感染组显著高于AIDS组,当疾病进展到AIDS期时,失去对异体病毒的中和作用,提示针对异体病毒的中和抗体与疾病进程有关.     

Evaluation of rapid prenatal human immunodeficiency virus testing in rural cameroon

Pregnant women (n = 859) in rural Cameroonian prenatal clinics were screened by two rapid human immunodeficiency virus (HIV) antibody tests (rapid tests [RT]) (Determine and Hema-Strip) using either whole blood or plasma. One additional RT (Capillus, HIV-CHEK, or Sero-Card) was used to resolve discordant results. RT results were compared with HIV-1 enzyme immunoassay (EIA) and Western blot (WB) results of matched dried blood spots (DBS) to assess the accuracy of HIV RTs. DBS EIA/WB identified 83 HIV antibody-reactive, 763 HIV antibody-nonreactive, and 13 indeterminate specimens. RT results were evaluated in serial (two consecutive tests) or parallel (two simultaneous tests) testing algorithms. A serial algorithm using Determine and Hema-Strip yielded sensitivity and specificity results of 97.6% and 99.7%, respectively, whereas a parallel RT algorithm using Determine plus a second RT produced a sensitivity and specificity of 100% and 99.7%, respectively. HIV RTs provide excellent alternatives for identifying HIV infection, and their field performance could be monitored using DBS testing strategies.     

Sero-diagnosis of tuberculosis with A60 antigen enzyme-linked immunosorbent assay: failure in HIV-infected individuals in Ghana

In order to assess the diagnostic usefulness of the A60 (ANDA Biologicals, Strassbourg, France) sero-diagnostic enzyme-linked immunosorbent assay (ELISA) kit for tuberculosis in Africa, sera of 53 pulmonary smear-positive tuberculosis (TB) patients, 30 apparently healthy control subjects and 6 AIDS suspects were sampled in Agogo Hospital in the forest area of Ghana. These sera were analyzed for antibodies to HIV-1 and HIV-2, and IgG-antibodies to the A60 BCG-antigen, while the non-HIV individuals were tested for total IgG levels. One healthy control subject, all of 6 AIDS suspects and 7 of the TB patients has HIV infections. In the non-HIV TB group, the sensitivity and specifity of the A60 ELISA was 78% and 86%, respectively, which was much poorer than expected from published reports about the A60 test. The A60 test failed, completely however, to discriminate between TB and non-TB in the HIV-positive group. In the non-HIV groups, total IgG levels were significantly higher in TB patients than in controls. It seems that the usefulness of the A60 ELISA test to diagnose tuberculosis is very limited in this high-incidence area, and that it seems to be of no value in patients infected with HIV.     

Evaluation of Rapid Prenatal Human Immunodeficiency Virus Testing in Rural Cameroon

Pregnant women (n = 859) in rural Cameroonian prenatal clinics were screened by two rapid human immunodeficiency virus (HIV) antibody tests (rapid tests [RT]) (Determine and Hema-Strip) using either whole blood or plasma. One additional RT (Capillus, HIV-CHEK, or Sero-Card) was used to resolve discordant results. RT results were compared with HIV-1 enzyme immunoassay (EIA) and Western blot (WB) results of matched dried blood spots (DBS) to assess the accuracy of HIV RTs. DBS EIA/WB identified 83 HIV antibody-reactive, 763 HIV antibody-nonreactive, and 13 indeterminate specimens. RT results were evaluated in serial (two consecutive tests) or parallel (two simultaneous tests) testing algorithms. A serial algorithm using Determine and Hema-Strip yielded sensitivity and specificity results of 97.6% and 99.7%, respectively, whereas a parallel RT algorithm using Determine plus a second RT produced a sensitivity and specificity of 100% and 99.7%, respectively. HIV RTs provide excellent alternatives for identifying HIV infection, and their field performance could be monitored using DBS testing strategies.     

Evaluation of the Recombigen HIV-1 Latex Agglutination Test.

The Recombigen HIV-1 Latex Agglutination (LA) Test was recently licensed by the U.S. Food and Drug Administration for use as a rapid screening assay for human immunodeficiency virus type 1 (HIV-1) antibodies. However, its performance in various settings and in different populations has not been firmly established. Consequently, we evaluated the test in the Cleveland Clinic Retrovirus Laboratory, a regional reference laboratory for HIV diagnostic testing and a testing laboratory for the Ohio Department of Health Anonymous HIV Testing and Counseling Program. Serum samples from 93 individuals presumed to be at high risk for HIV infection were evaluated. The sera were initially tested for HIV antibodies by enzyme-linked immunosorbent assay (ELISA). All repeatedly reactive sera were subjected to confirmatory Western blot (WB; immunoblot) testing. Of 97 serum specimens tested (5 were from one seroconverter), 44 were repeatedly reactive by ELISA and 53 were nonreactive. Of the reactive serum specimens, 31 were confirmed positive and 12 were indeterminate by WB. All of the sera were coded and then retested by the LA test. Of 53 serum specimens nonreactive by ELISA, 51 were also nonreactive in the LA test. Of the 44 serum specimens reactive by ELISA, 16 were nonreactive by LA; however, 3 of the latter were WB positive. No serum specimen with an ELISA ratio (specimen optical density/cutoff optical density) of less than 2.1 scored reactive in the LA test. The LA test was positive for only two of five consecutive serum specimens from a seroconverter despite the fact that all but the earliest of these were ELISA reactive and WB positive. Although the LA test appears to be an adequate first-line screening test when appropriately used according to the directions of the manufacturer, our data suggest that occasional sera with low levels of reactivity by ELISA may not be readily detected as reactive by the LA test.     

Indeterminate human immunodeficiency virus Western blot profiles in ethiopians with discordant screening-assay results.

The Western blot (WB) assay is the most widely accepted confirmatory assay for the detection of antibodies to human immunodeficiency virus type 1 (HIV-1). However, indeterminate WB reactivity to HIV-1 proteins may occur in individuals who do not appear to be infected with HIV. The profiles of WB reactivity among Ethiopians are hardly known. Here, we describe the profiles of indeterminate WB reactivity in Ethiopians with discordant screening assays. Between 1996 and 2000, a total of 12,124 specimens were tested for HIV-1 antibodies. Overall, 1,437 (11.9%) were positive for HIV-1 antibody. Ninety-one ( approximately 0.8%) gave equivocal results because of discordant results among the various screening assays and indeterminate WB profiles by the American Red Cross (ARC) criteria. Most (30.4%) of these indeterminate WB results were due to p24 reactivity. However, 12 samples (13.2%) displayed reactivity to p24 and gp41 or to p24 and gp120/160 proteins (positive by Centers for Disease Control and Prevention [CDC] criteria). Only two samples (2.2%) were reactive to both env glycoproteins gp41 and gp120/160 (positive by the World Health Organization [WHO] criteria). Of 31 WB assays initially indeterminate by the ARC criteria and with follow-up samples, 29 (93.5%) became negative when retested subsequently while 2 (6.5%) remained indeterminate for more than a year and were thus considered negative. Using CDC and WHO criteria, 6 (19.4%) and 2 (6.5%), respectively, of these WB assays would have been considered falsely positive. In addition, 17 indeterminate samples were negative when assessed by a nucleic acid-based amplification assay for HIV-1 viremia. In general, there was 97.8% concordance between the ARC and WHO criteria and 85.7% concordance between the ARC and CDC criteria for an indeterminate WB result. The ARC criteria best met the specified objectives for diagnosis in our setting.