Human Immunodeficiency Virus Enzyme Immunoassay Research Articles

Development and Evaluation of a Modified Fourth-Generation Human Immunodeficiency Virus Enzyme Immunoassay for Cross-Sectional Incidence Estimation in Clade B Populations.

Accurate methods for cross-sectional incidence estimation are needed for HIV surveillance and prevention research. We developed an avidity assay based on the fourth-generation Genetic Systems HIV Combo Ag/Ab EIA (Bio-Rad Combo assay) and evaluated its performance. The Bio-Rad Combo assay was modified incubating samples with and without 0.025 M diethylamine (DEA). The avidity index (AI) was calculated as the ratio of the DEA-treated to untreated result for a specific sample. We analyzed 2,140 samples from 808 individuals from the United States with known duration of HIV infection. The mean duration of recent infection (MDRI) and the false-recent rate (FRR, fraction of samples from individuals known to be infected >2 years misclassified as recent) were calculated for AI cutoffs of 20%-90% for the avidity assay alone and in combination with a viral load assay (VL, limit of detection 400 copies/ml). Factors associated with misclassification of samples collected ≥2 years after infections were also evaluated. The MDRI for the Bio-Rad Combo Avidity assay ranged from 50 days using an AI cutoff of 20% to 276 days using an AI cutoff of 90%; the FRR ranged from 0% to 9%. When samples with a VL <400 copies/ml were classified as nonrecent, the FRRs were reduced approximately twofold and the MDRI estimates were reduced by ∼20%. An AI cutoff of 50% provided an MDRI of 135 days with an FRR of 2.1%. All samples from elite suppressors had an AI >80%. In adjusted analysis, viral suppression and low CD4 cell count were significantly associated with misclassification among individuals infected >2 years. This modified Bio-Rad Combo Avidity assay may be a useful tool for cross-sectional HIV incidence estimation. Further research is needed to evaluate use of this assay in combination with other assays to accurately estimate population-level HIV incidence.

Multisite Laboratory Evaluation of a Dual Human Immunodeficiency Virus (HIV)/Syphilis Point-of-Care Rapid Test for Simultaneous Detection of HIV and Syphilis Infection.

Background. Recently, test developers have created rapid point-of-care tests that can simultaneously detect multiple infections within the same specimen using a single device. The SD BIOLINE Duo HIV/Syphilis rapid point-of-care test uses a solid-phase immunochromatographic assay to detect immunoglobulin (Ig)G, IgM, and IgA antibodies to human immunodeficiency virus (HIV)-specific antigens (HIV-1 gp41, sub O, HIV-2 gp36) and recombinant Treponema pallidum antigen (17 kDa) in human serum. This study was a multisite laboratory-based evaluation of the performance of SD BIOLINE HIV/Syphilis Duo test using previously characterized sera in 6 countries.Methods. Laboratories in Ghana, Mexico, Laos, Togo, Kenya, and Myanmar participated in the evaluation during 2012–2013. Each site characterized sera using T pallidum particle agglutination assay or T pallidum hemagglutination assay and HIV enzyme immunoassay, Western blot, and/or HIV antibody rapid tests. Those gold standard test results were compared with SD BIOLINE Duo test results. We calculated the sensitivity and specificity of test performance and used the exact binomial method to calculate 95% confidence intervals (CIs).Results. The sensitivity and specificity for the HIV antibody test component (n = 2336) were estimated at 99.91% (95% CI, 99.51% and 100%) and 99.67% (95% CI, 99.16% and 99.91%), respectively. For the T pallidum test component (n = 2059), the sensitivity and specificity were estimated at 99.67% (95% CI, 98.82% and 99.96%) and 99.72% (95% CI, 99.29% and 99.92%), respectively.Conclusions. The sensitivity and specificity of the SD BIOLINE HIV/Syphilis Duo test were consistently high across sera specimens from 6 countries around the world. Dual rapid tests should be considered for improved HIV and syphilis screening coverage.

Severe Myelosuppression and MRSA Infection as the Presentation of Perinatal HIV Infection

Severe Myelosuppression and MRSA Infection as the Presentation of Perinatal HIV Infection

False-positive human immunodeficiency virus enzyme immunoassay results in pregnant women.

ObjectiveExamine whether false-positive HIV enzyme immunoassay (EIA) test results occur more frequently among pregnant women than among women who are not pregnant and men (others).DesignTo obtain a large number of pregnant women and others tested for HIV, we identified specimens tested at a national laboratory using Genetic Systems HIV-1/HIV-2 Plus O EIA from July 2007 to June 2008.MethodsSpecimens with EIA repeatedly reactive and Western blot-negative or indeterminate results were considered EIA false-positive. We compared the false-positive rate among uninfected pregnant women and others, adjusting for HIV prevalence. Among all reactive EIAs, we evaluated the proportion of false-positives, positive predictive value (PPV), and Western blot bands among indeterminates, by pregnancy status.ResultsHIV prevalence was 0.06% among 921,438 pregnant women and 1.34% among 1,103,961 others. The false-positive rate was lower for pregnant women than others (0.14% vs. 0.21%, odds ratio 0.65 [95% confidence interval 0.61, 0.70]). Pregnant women with reactive EIAs were more likely than others (p<0.01) to have Western blot-negative (52.9% vs. 9.8%) and indeterminate results (17.0% vs. 3.7%) and lower PPV (30% vs. 87%). The p24 band was detected more often among pregnant women (p<0.01).ConclusionsFalse-positive HIV EIA results were rare and occurred less frequently among pregnant women than others. Pregnant women with reactive EIAs were more likely to have negative and indeterminate Western blot results due to lower HIV prevalence and higher p24 reactivity, respectively. Indeterminate results may complicate clinical management during pregnancy. Alternative methods are needed to rule out infection in persons with reactive EIAs from low prevalence populations.

Low Prevalence Rate of Indeterminate Serological Human Immunodeficiency Virus Results among Pregnant Women from Burkina Faso, West Africa

Rapid human immunodeficiency virus (HIV) antibody tests have been adopted into national guidelines for HIV testing in many countries in sub-Saharan Africa. One goal of HIV rapid testing is to minimize the occurrence of indeterminate results. From January 2005 to December 2007, plasma (or serum) samples from pregnant women in Bobo-Dioulasso (Burkina Faso, West Africa) were screened for HIV by using two rapid tests (the Determine HIV1/2 test [Abbott] and Genie II HIV-1/HIV-2 [Bio-Rad]) through a sequential algorithm prior to enrollment of HIV-1-infected women in a prevention of mother-to-child transmission (PMTCT) trial (WHO/ANRS 1289 Kesho Bora trial). Samples exhibiting indeterminate results (Determine positive and Genie II negative) were further tested with a fourth-generation HIV enzyme immunoassay (EIA) (Murex HIV Ag/Ab combination in 2005 and 2006 and Vironostika HIV Uni-Form II Ag/Ab in 2007). If positive, they were finally assessed for HIV-1 RNA (Generic HIV-1 RNA viral load assay; Biocentric). From a total of 44,653 samples tested, 597 (1.3%) showed indeterminate results. Of these, 367 could be analyzed by EIA. Only 15 (15/367, 4.1%) samples were found EIA reactive. Of these, 11 could be tested for HIV-1 RNA. All were HIV-1 RNA negative. In our clinical practice, pregnant women with such indeterminate results are now reassured during posttest counseling that they are very unlikely to be infected with HIV-1. As a consequence, such women with indeterminate results can reliably be considered negative when urgent clinical decisions (such as providing PMTCT prophylaxis) need to be taken.

Failure of Human Immunodeficiency Virus Enzyme Immunoassay to Rule Out Infection Among Polymerase Chain Reaction-Negative Vietnamese Infants at 12 Months of Age

: Previous studies have demonstrated that >90% of HIV-uninfected infants serorevert, as seen in the results of enzyme immunoassay (EIA) testing by 12 months of age, making it feasible to confirm or rule out infection. We assessed the reliability of EIA in a cohort of Vietnamese infants. : HIV-exposed, uninfected infants enrolled in a parent diagnostic and monitoring study from February 2005 through August 2006 were eligible for inclusion in a prospective cohort study of HIV-EIA performance. Testing using 2 standard assays (Genscreen HIV 1/2 version 2, Bio-Rad; Murex 1.2.0, Murex Biotech) was initiated at 12 months of age. Infants were categorized as EIA-negative (seroreverted; negative Genscreen), EIA-indeterminate (positive Genscreen, negative Murex), or EIA-positive (Genscreen and Murex positive). : Of 273 infants included in the study, 59 (22%) were EIA-negative at 12 months, 131 (48%) were indeterminate, and 83 (30%) were EIA-positive; specificity 21.6 (95% confidence interval: 16.6, 26.3). Infants with positive EIAs at 12 months were 74% more likely than EIA-indeterminate infants to test indeterminate or positive at 18 months (risk ratio, 1.74, 95% confidence interval: 1.15, 2.64; P = 0.03). : Expectations regarding infant seroreversion by standard EIAs should be reassessed to reflect potential cross-regional differences in their performance.

Benefits of a rapid HIV test for evaluation of the source patient after occupational exposure of healthcare workers

Rapid human immunodeficiency virus (HIV) testing for the management of occupational exposure of healthcare workers significantly decreased the number of anti-retroviral post-exposure prophylaxis regimens started whilst awaiting HIV test results. The study confirmed an equivalent performance of the rapid test in comparison with HIV enzyme immunoassay, and suggests it is cost-effective. In addition, two other potential benefits emerged: reducing the number of source patients who remain untested and increasing the number of occupational exposures reported.

Combining pooling and alternative algorithms in seroprevalence studies

Data from two seroprevalence studies and one comparative study of confirmatory algorithms were used to compare the costs and sensitivities of six algorithms for determining seropositivity to human immunodeficiency virus (HIV). We evaluated confirmatory strategies by using the CBC Recombigen HIV enzyme immunoassay (EIA; Cambridge BioScience, Worcester, Mass.) and immunoblotting followed by radioimmunoprecipitation assay to confirm indeterminate immunoblotting results with and without pooling of samples during screening. The least expensive algorithm was that in which sera were pooled during screening and EIA was used to confirm positive test results. The cost savings associated with this confirmatory test were greater when the prevalence of HIV infection was higher. Savings from pooling of sera for screen testing diminished as HIV prevalence increased. The sensitivity and specificity of EIA with respect to immunoblotting and radioimmunoprecipitation assay were estimated to be 0.9992 and 0.9977, respectively. We found that the implementation of pooling during screening and the use of EIA as the confirmatory test do not affect the statistical reliability of estimates of seropositivity but do result in considerable cost savings.

Association of human immunodeficiency virus (HIV) p24 antigenemia with decrease in CD4+ lymphocytes and onset of acquired immunodeficiency syndrome during the early phase of HIV infection

Human immunodeficiency virus (HIV) p24 antigenemia was assessed in a longitudinal study of 52 homosexual men who developed serum antibody to HIV. Antibody seroconversion to HIV as defined by a positive HIV enzyme immunoassay (EIA) confirmed by Western (immuno-) blot was associated with three major patterns of HIV antigenemia. In the first pattern, a transient antigenemia was noted 6 (six subjects) and 12 (one subject) months prior to detection of antibody by HIV EIA and Western blot in 7 (13.5%) of the 52 men. Use of an EIA employing a recombinant envelope protein (ENV9) was able to detect antibody in four of these seven men at the time of this early antigenemia. In the second pattern, HIV p24 antigenemia occurred in 8 (15.4%) of the 52 subjects within the first 12 months after HIV antibody seroconversion. No p24 antigen was detected in the 37 (71.1%) remaining subjects. CD4+ cell numbers were lower in antigen-positive men before and after antibody seroconversion. Development of acquired immunodeficiency syndrome (AIDS) or AIDS-related complex was strongly associated with evidence of persistent p24 antigenemia during the early, postseroconversion period. HIV p24 antigenemia may be of value in determining appropriate cohorts for drug therapy trials for subjects with early-phase HIV infection.