HIV Enzyme Immunoassay Research Articles

True and false positive HIV point of care test results in a prospective multinational study of at-risk African women: implications for large-scale repeat HIV testing in HIV prevention programs.

Accurate HIV point of care testing is the cornerstone of prevention and treatment efforts globally, though false (both negative and positive) results are expected to occur. We assessed the spectrum of true and false positive HIV results in a large prospective study of HIV incidence in African women using three contraceptive methods tested longitudinally in Eswatini, Kenya, South Africa, and Zambia. HIV serologic testing was conducted quarterly using two parallel rapid HIV tests. When one or both tests were positive, additional confirmatory testing was conducted, including HIV enzyme immunoassay (EIA) and ribonucleic acid (RNA). 7730 women contributed 48,234 visits: true positive results occurred at 412 visits (0.9%) and false positives at 96 visits (0.2%). Of 412 women with HIV seroconversion, 10 had discordant (i.e., one negative and one positive) rapid tests and 13 had undetectable HIV RNA levels. Of 62 women with false positive rapid HIV results, most had discordant rapid testing but six (9.7%) had dually-positive rapid results and four (6.5%) had false positive or indeterminate EIA results. The positive predictive value of dual positive rapid results was 98.3%. Although the majority of rapid test results were accurate, false positive results were expected and occurred in this population of initially HIV seronegative individuals tested repeatedly and prospectively. When HIV infection occurred, not all cases had textbook laboratory results. Our findings highlight the importance of confirmatory testing, particularly for individuals undergoing repeat testing and in settings where the point prevalence is expected to be low.

Use of the Bio-Rad Geenius HIV-1/2 supplemental assay for the testing of oral fluids for the presence of HIV antibody

There is currently an absence of products which are cleared by the FDA to provide supplemental testing for oral fluid for HIV antibody. We created a procedure for the use of the BioRad Geenius HIV-1/2 as a supplemental antibody test for oral fluid specimens. The modified procedure was evaluated for its ability to detect HIV-1 antibody in oral fluid in specimens that were found to be repeatedly reactive for HIV-1 antibody by way of the Avioq HIV-1 enzyme immunoassay (EIA). Evaluated were oral fluid specimens analyzed at a local public health laboratory which were stored frozen and oral fluid specimens collected prospectively. Prospectively collected specimens were from patients whose HIV status was subsequently assessed through blood-based testing. For retrospective specimens found repeatedly EIA reactive, and positive by Western blot, the modified Geenius was found positive in 37/38 instances (97.4 %). Those specimens with a mean EIA signal-to-cutoff (S/CO) greater than 3.00 were found to be positive by Geenius in 34/34 (100 %) of instances. For specimens found repeated reactive by EIA and positive by Western blot with mean S/CO less than or equal to 3.00, the Geenius was positive in 4/5 instances (80 %) of instances. For prospectively collected specimens, the Geenius accurately confirmed infection in 22/24 cases (92 %) while prospective specimens found repeatedly reactive by EIA without supplemental Geenius testing were confirmed positive in 29/37 instances (78 %). A modified usage of the Geenius HIV-1/2 Supplemental Assay antibody test may provide utility in the supplementation of testing of oral fluid for the presence of HIV-1 antibody.

An approach for evaluating early and long term mother-to-child transmission of HIV (MTCT) in low and middle income countries: a South African experience

BackgroundEliminating mother-to-child transmission of HIV is a global public health target. Robust, feasible methodologies to measure population level impact of programmes to prevent mother-to-child transmission of HIV (PMTCT) are needed in high HIV prevalence settings. We present a summary of the protocol of the South African PMTCT Evaluation (SAPMTCTE) with its revision over three repeated rounds of the survey, 2010–2014.MethodsThree cross sectional surveys (2010, 2011–2012 and 2012–2013) were conducted in 580 primary health care immunisation service points randomly selected after stratified multistage probability proportional to size sampling. All infants aged 4–8 weeks receiving their six-week immunisation at a sampled facility on the day of the visit were eligible to participate. Trained research nurses conducted interviews and took infant dried blood spot (iDBS) samples for HIV enzyme immunoassay (EIA) and total nucleic acid polymerase chain reaction (PCR) testing. Interviews were conducted using mobile phones and iDBS were sent to the National Health Laboratory for testing. All findings were adjusted for study design, non-response, and weighted for number of South African live-birth in each study round. In 2012 a national closed cohort of these 4 to 8-week old infants testing EIA positive (HIV Exposed Infants) from the 2012–2013 cross-sectional survey was established to estimate longer-term PMTCT impact to 18 months. Follow-up analyses were to estimate weighted cumulative MTCT until 18 months, postnatal MTCT from 6 weeks until 18 months and a combined outcome of MTCT-or-death, using a competing risks model, with death as a competing risk. HIV-free survival was defined as a child surviving and HIV-negative up to 18 months or last visit seen. A weighted cumulative incidence analysis was conducted, adjusting for survey design effects.DiscussionIn the absence of robust high-quality routine medical recording systems, in the context of a generalised HIV epidemic, national surveys can be used to monitor PMTCT effectiveness; however, monitoring long-term outcomes nationally is difficult due to poor retention in care.

Problems encountered in conventional HIV 1/2 Algorithms: lack of necessity for immunoblot assays to confirm repeated ELISA reactive results.

The use of conventional (serologically based) HIV 1/2 diagnostic algorithms has become controversial in recent years. Sera from patients who underwent verification tests were evaluated because repeated ELISA-reactive results demonstrated a HIV1+HIV2 positive band pattern. The line immunoassay (LIA) test was used for repeated HIV enzyme immunoassays (EIA)-reactive sera in patients at three centers. The Bio-Rad Geenius™ HIV 1/2 and the HIV-1 RNA tests were used. HIV-1 and RNA HIV-2 were investigated using PCR. LIA was used to evaluate 3,224 out of 10,591 samples with repeated ELISA reactivity (30%). We found that 32 (1%) of the sera, along with HIV1 bands and HIV2 gp36 bands, were positive. Only 28 of the 32 verified serum samples with gp36 bands were repeated, and no gp36 band positivity was detected using the Bio-Rad Geenius™ HIV-1/2 confirmatory assay in these serum samples. The HIV-2 proviral DNAs were also negative. Therefore, we excluded the possibility of HIV1+2 co-infection. All samples from the 32 patients were positive for HIV-1 RNA. Our findings highlight the need to exclude confirmatory tests like the LIA test from the current diagnostic HIV algorithm and replace it with rapid HIV-1 and HIV-2 confirmatory immunochromotographic tests.

Outcomes of acutely HIV-1-infected individuals following rapid antiretroviral therapy initiation.

Few data exist on the benefits and acceptability of rapid initiation of antiretroviral treatment in acute HIV infection (AHI). We analysed a large cohort of acutely infected HIV patients starting antiretroviral therapy (ART) to determine uptake, linkage into care and time to achieve viral suppression. Case notes of all individuals diagnosed with AHI between May 2014 and October 2015 at 56 Dean Street, a sexual health clinic in London, UK were reviewed. AHI was defined through documentation of plasma HIV RNA positivity only, plasma HIV RNA and p24 antigen positivity with a negative HIV enzyme immunoassay (EIA) test or HIV EIA test switching from negative to positive within 6 weeks. Between-group comparisons of time to viral suppression according to ART chosen were performed using the log-rank test. We identified 113 individuals with AHI. Linkage to care was 95%. 77% of patients started ART at first medical appointment: all men who have sex with men, median age 35 years, median viral load (VL) log10 6.45, median CD4+ T-cell count 483 cells/mm3. Median time from diagnosis to ART initiation was 20 days. At 24 weeks, no patients had discontinued ART; 99% of patients achieved viral suppression by 24 weeks, with a median time to documented VL suppression of 74 days. Viral suppression was more rapid with integrase inhibitors compared with other regimens (median 41 versus 88.5 days, P<0.05). In acute HIV infection, individuals demonstrated high ART uptake and rapid VL suppression suggesting that early treatment with antiretrovirals is acceptable and efficacious.

Population-level effectiveness of PMTCT Option A on early mother-to-child (MTCT) transmission of HIV in South Africa: implications for eliminating MTCT.

Eliminating mother-to-child transmission of HIV (EMTCT), defined as ≤50 infant HIV infections per 100 000 live births, is a global priority. Since 2011 policies to prevent mother-to-child transmission of HIV (PMTCT) shifted from maternal antiretroviral (ARV) treatment or prophylaxis contingent on CD4 cell count to lifelong maternal ARV treatment (cART). We sought to measure progress with early (4-8 weeks postpartum) MTCT prevention and elimination, 2011-2013, at national and sub-national levels in South Africa, a high antenatal HIV prevalence setting ( ≈ 29%), where early MTCT was 3.5% in 2010. Two surveys were conducted (August 2011-March 2012 and October 2012-May 2013), in 580 health facilities, randomly selected after two-stage probability proportional to size sampling of facilities (the primary sampling unit), to provide valid national and sub-national-(provincial)-level estimates. Data collectors interviewed caregivers of eligible infants, reviewed patient-held charts, and collected infant dried blood spots (iDBS). Confirmed positive HIV enzyme immunoassay (EIA) and positive total HIV nucleic acid polymerase chain reaction (PCR) indicated infant HIV exposure or infection, respectively. Weighted survey analysis was conducted for each survey and for the pooled data. National data from 10 106 and 9120 participants were analyzed (2011-12 and 2012-13 surveys respectively). Infant HIV exposure was 32.2% (95% confidence interval (CI) 30.7-33.6%), in 2011-12 and 33.1% (95% CI 31.8-34.4%), provincial range of 22.1-43.6% in 2012-13. MTCT was 2.7% (95% CI 2.1%-3.2%) in 2011-12 and 2.6% (95% CI 2.0-3.2%), provincial range of 1.9-5.4% in 2012-13. HIV-infected ARV-exposed mothers had significantly lower unadjusted early MTCT (2.0% [2011-12: 1.6-2.5%; 2012-13:1.5-2.6%]) compared to HIV-infected ARV-naive mothers [10.2% in 2011-12 (6.5-13.8%); 9.2% in 2012-13 (5.6-12.7%)]. Pooled analyses demonstrated significantly lower early MTCT among exclusive breastfeeding (EBF) mothers receiving >10 weeks ARV prophylaxis or cART compared with EBF and no ARVs: (2.2% [95% CI 1.25-3.09%] vs 12.2% [95% CI 4.7-19.6%], respectively); among HIV-infected ARV-exposed mothers, 24.9% (95% CI 23.5-26.3%) initiated cART during or before the first trimester, and their early MTCT was 1.2% (95% CI 0.6-1.7%). Extrapolating these data, assuming 32% EIA positivity and 2.6% or 1.2% MTCT, 832 and 384 infants per 100 000 live births were HIV infected, respectively. Although we demonstrate sustained national-level PMTCT impact in a high HIV prevalence setting, results are far-removed from EMTCT targets. Reducing maternal HIV prevalence and treating all maternal HIV infection early are critical for further progress.

Population–level effectiveness of PMTCT Option A on early mother–to–child (MTCT) transmission of HIV in South Africa: implications for eliminating MTCT

BackgroundEliminating mother–to–child transmission of HIV (EMTCT), defined as ≤50 infant HIV infections per 100 000 live births, is a global priority. Since 2011 policies to prevent mother–to–child transmission of HIV (PMTCT) shifted from maternal antiretroviral (ARV) treatment or prophylaxis contingent on CD4 cell count to lifelong maternal ARV treatment (cART). We sought to measure progress with early (4–8 weeks postpartum) MTCT prevention and elimination, 2011–2013, at national and sub–national levels in South Africa, a high antenatal HIV prevalence setting ( ≈ 29%), where early MTCT was 3.5% in 2010.MethodsTwo surveys were conducted (August 2011–March 2012 and October 2012–May 2013), in 580 health facilities, randomly selected after two–stage probability proportional to size sampling of facilities (the primary sampling unit), to provide valid national and sub–national–(provincial)–level estimates. Data collectors interviewed caregivers of eligible infants, reviewed patient–held charts, and collected infant dried blood spots (iDBS). Confirmed positive HIV enzyme immunoassay (EIA) and positive total HIV nucleic acid polymerase chain reaction (PCR) indicated infant HIV exposure or infection, respectively. Weighted survey analysis was conducted for each survey and for the pooled data.FindingsNational data from 10 106 and 9120 participants were analyzed (2011–12 and 2012–13 surveys respectively). Infant HIV exposure was 32.2% (95% confidence interval (CI) 30.7–33.6%), in 2011–12 and 33.1% (95% CI 31.8–34.4%), provincial range of 22.1–43.6% in 2012–13. MTCT was 2.7% (95% CI 2.1%–3.2%) in 2011–12 and 2.6% (95% CI 2.0–3.2%), provincial range of 1.9–5.4% in 2012–13. HIV–infected ARV–exposed mothers had significantly lower unadjusted early MTCT (2.0% [2011–12: 1.6–2.5%; 2012–13:1.5–2.6%]) compared to HIV–infected ARV–naive mothers [10.2% in 2011–12 (6.5–13.8%); 9.2% in 2012–13 (5.6–12.7%)]. Pooled analyses demonstrated significantly lower early MTCT among exclusive breastfeeding (EBF) mothers receiving >10 weeks ARV prophylaxis or cART compared with EBF and no ARVs: (2.2% [95% CI 1.25–3.09%] vs 12.2% [95% CI 4.7–19.6%], respectively); among HIV–infected ARV–exposed mothers, 24.9% (95% CI 23.5–26.3%) initiated cART during or before the first trimester, and their early MTCT was 1.2% (95% CI 0.6–1.7%). Extrapolating these data, assuming 32% EIA positivity and 2.6% or 1.2% MTCT, 832 and 384 infants per 100 000 live births were HIV infected, respectively.ConclusionsAlthough we demonstrate sustained national–level PMTCT impact in a high HIV prevalence setting, results are far–removed from EMTCT targets. Reducing maternal HIV prevalence and treating all maternal HIV infection early are critical for further progress.

Field evaluation of a dual rapid diagnostic test for HIV infection and syphilis in Lima, Peru

ObjectivesScreening for HIV and syphilis in key populations is recommended by the WHO to reduce the morbidity, mortality and transmission associated with undiagnosed and untreated infections. Rapid point-of-care tests that...

Frequency of false positive rapid HIV serologic tests in African men and women receiving PrEP for HIV prevention: implications for programmatic roll-out of biomedical interventions.

BackgroundRapid HIV assays are the mainstay of HIV testing globally. Delivery of effective biomedical HIV prevention strategies such as antiretroviral pre-exposure prophylaxis (PrEP) requires periodic HIV testing. Because rapid tests have high (>95%) but imperfect specificity, they are expected to generate some false positive results.MethodsWe assessed the frequency of true and false positive rapid results in the Partners PrEP Study, a randomized, placebo-controlled trial of PrEP. HIV testing was performed monthly using 2 rapid tests done in parallel with HIV enzyme immunoassay (EIA) confirmation following all positive rapid tests.ResultsA total of 99,009 monthly HIV tests were performed; 98,743 (99.7%) were dual-rapid HIV negative. Of the 266 visits with ≥1 positive rapid result, 99 (37.2%) had confirmatory positive EIA results (true positives), 155 (58.3%) had negative EIA results (false positives), and 12 (4.5%) had discordant EIA results. In the active PrEP arms, over two-thirds of visits with positive rapid test results were false positive results (69.2%, 110 of 159), although false positive results occurred at <1% (110/65,945) of total visits.ConclusionsWhen HIV prevalence or incidence is low due to effective HIV prevention interventions, rapid HIV tests result in a high number of false relative to true positive results, although the absolute number of false results will be low. Program roll-out for effective interventions should plan for quality assurance of HIV testing, mechanisms for confirmatory HIV testing, and counseling strategies for persons with positive rapid test results.

The rise of targeted HIV oral rapid testing in Australia.

To assess the performance and acceptability of the OraQuick Advance Rapid HIV-1/2 Antibody Test (ORT) in Australia. Cross-sectional study of 1074 men who have sex with men (MSM) and individuals aged 18 years or older at high risk of acquiring HIV infection who attended five public HIV or sexual health services, two general practices and one community clinic in Sydney from 1 January to 31 December 2013. One ORT confirmed by fourth-generation HIV enzyme immunoassay (EIA). ORT sensitivity and specificity compared with EIA; acceptabiity of the ORT to participants. 83.5% of participants were MSM, 90.3% were aged under 50 years, and 9% had never been tested for HIV. There were 11 true-positive ORT results, two false-negative (non-reactive) results (both were early infections), and one false-positive (reactive) result (due to reader error). Sensitivity and specificity were 84.6% and 99.8%, respectively (compared with a sensitivity of 99.3% and specificity of 99.8% listed by the manufacturer). Three quarters of participants (74.0%; 730/987) found the ORT less stressful than venous sampling. Those who usually had tests at intervals of greater than 3 months deemed the ORT less stressful than those who had quarterly tests (77.5% v 64.8%; P<0.001). Nearly all participants (99.2%; 998/1006) would have an ORT again and 99.4% (994/1000) would recommend it to peers. Most participants (69.1%; 720/1042) felt ORT approval by Australia's Therapeutic Goods Administration (TGA) would encourage testing. ORT sensitivity is reduced in early HIV infection. The test is highly acceptable and less stressful than venous sampling. Participants are keen to be tested with the ORT in future, would recommend it to peers and would have tests more frequently if the ORT were licensed. TGA approval of this test might slow increasing HIV infection rates among MSM and others by facilitating diagnosis and treatment.

Pooled nucleic acid testing increases the diagnostic yield of acute HIV infections in a high-risk population compared to 3rd and 4th generation HIV enzyme immunoassays

ObjectivesWe compared a 3rd generation (gen) and two 4th gen HIV enzyme immunoassays (EIA) to pooled nucleic acid testing (PNAT) for the identification of pre- and early seroconversion acute HIV infection (AHI). Study Design9550 specimens from males >18 year from clinics attended by men who have sex with men were tested by Siemens ADVIA Centaur® HIV 1/O/2 (3rd gen) and HIV Combo (4th gen), as well as by Abbott ARCHITECT® HIV Ag/Ab Combo (4th gen). Third gen non-reactive specimens were also tested by Roche COBAS® Ampliprep/COBAS® TaqMan HIV-1 Test v.2 in pools of 24 samples. Sensitivity and specificity of the three EIAs for AHI detection were compared. Results7348 persons contributed 9435 specimens and had no evidence of HIV infection, 79 (94 specimens) had established HIV infection, 6 (9 specimens) had pre-seroconversion AHI and 9 (12 specimens) had early seroconversion AHI. Pre-seroconversion AHI cases were not detected by 3rd gen EIA, whereas 2/6 (33.3%) were detected by Siemens 4th gen, 4/6 (66.7%) by Abbott 4th gen and 6/6 (100%) by PNAT. All three EIAs and PNAT detected all individuals with early seroconversion AHI. Overall sensitivity/specificity for the EIAs relative to WB or NAT resolved infection status was 93.6%/99.9% for Siemens 3rd gen, 95.7%/99.7% for Siemens 4th gen and 97.9%/99.2% for Abbott 4th gen. ConclusionsWhile both 4th gen EIAs demonstrated improved sensitivity for AHI compared to 3rd gen EIA, PNAT identified more AHI cases than either 4th gen assay. PNAT is likely to remain a useful strategy to identify AHI in high-risk populations.

Reduced markers of HIV persistence and restricted HIV-specific immune responses after early antiretroviral therapy in children

Understanding the extent to which early antiretroviral therapy (ART) can limit the establishment and persistence of the HIV reservoir is an important step to designing interventions aimed at achieving HIV cure. We measured the markers of HIV persistence and HIV-specific immunity in early treated children. This is a cross-sectional study that enrolled 15 children older than 2 years of age who initiated ART before 6 months of age and had sustained viral suppression. Total and integrated HIV DNA, and 2-LTR circles in CD4 T cells, HIV antibody response by fourth generation HIV enzyme immunoassay, and CD4 and CD8 T-cell responses to gag/env peptides by intracellular cytokine staining of CD4 and CD8 T cells were measured. The median current age was 6.3 years and age at ART initiation was 17 weeks. The median duration of viral suppression was 6 years, and all had HIV RNA less than 50 copies/ml. The median CD4 T cells was 44%. The median total HIV DNA was 132 copies/10 CD4 T cells (range 11-1804) and integrated HIV DNA was 17 copies/10 CD4 T cells (range 0-516), and no one had detectable 2-LTR circles. Nine of the 15 children (60%) had undetectable or extremely low integrated HIV DNA (<20 copies/10 CD4 T cells). All except one (93%) had undetectable HIV-specific CD4/CD8 cell responses and seven (47%) had nonreactive enzyme immunoassay. Early ART resulted in very low levels of markers of HIV persistence and undetectable HIV-specific immune responses in the majority of HIV-infected children who started ART before 6 months of age.

HIV Diagnosis in Resource Constrained Setting: How Good Is the Current Algorithm?

Background: The conventional HIV testing algorithm in most of the developed countries consists of two tests: an HIV enzyme immunoassay capable of identifying HIV-1 and HIV-2 antibodies and a confirmatory HIV-1 Western blot or immunofluorescence assay. However, the current algorithm for HIV diagnosis in India uses three sequential antibody assays. There has always been doubt regarding the benefits of this algorithm. Objective: To determine the utility of the current diagnostic algorithm and to find out the proportion of indeterminate or discrepant results. Methods: Retrospective analysis of HIV antibody testing data was carried out over a period of five years after institutional ethics committee approval. The specimens positive with the screening test and negative with both the supplemental tests were labeled as discrepant. Specimens positive with any of the two tests (screening and one of the supplemental tests) and negative with the remaining supplemental test were labeled as indeterminate. These indeterminate specimens were confirmed by immunoblotting. Results: A total of 141,296 samples were tested. Of these, 71 (0.05%) samples were indeterminate and 292 (0.21%) were discrepant. Western blot was done on 60 indeterminate samples of which 10 (16.67%) were positive for HIV 1 antibodies, 14 (23.33%) were negative for HIV antibodies and 36 (60%) had indeterminate result. Conclusion: In view of the low numbers of indeterminate and discrepant results, the current algorithm appears to be appropriate in our resource constrained setting. However, the algorithm for HIV testing should also include DNA PCR testing facility to resolve western blot indeterminate results.

O15.5 Performance Characteristics of SD Bio Line Rapid HIV-Syphilis Duo Test Kit For Simultaneous Detection of HIV and Syphilis Infections

BackgroundHuman immunodeficiency virus (HIV) and Treponema pallidum share modes of transmission. Congenital syphilis is a significant cause of stillbirth, prenatal death and serious neonatal infections. We sought to evaluate rapid...

Prospective cohort study of HIV incidence and molecular characteristics of HIV among men who have sex with men(MSM) in Yunnan Province, China

BackgroundYunnan has the largest number of reported HIV/AIDS cases among all Chinese provinces, the reported prevalence of HIV among Yunnan men who have sex with men (MSM) passed 10%, while HIV incidence epidemic and molecular characteristics of new infected Yunnan MSM were not evaluated before.MethodsAn 18 months prospective followed up with a frequency of 3 month per visit were conducted among HIV seronegative MSM in Kunming cityduring 2009–2011. Interviewer-administrated questionnaires were carried out. Blood specimens were obtained to test for syphilis and HIV, in which HIV were evaluated by standard HIV enzyme immunoassay (EIA) and HIV nucleic acid amplification testing (NAAT). Near full-length regions of the HIV-1 were evaluated for subtyping, primary drug resistance mutations.ResultsDuring the follow-up 70.1% of the recruited 378 MSM retained in the cohort. Eleven MSM seroconverted to HIV and fifteen MSM seroconverted to syphilis. The HIV incidence and syphilis incidence was 3.5 (95% CI 1.8-6.2) cases /100 person year(PY) and 5.3 (95% CI 3.0-8.7) cases/100 PY, respectively. Multivariate analysis showed that baseline syphilis infection (aHR, 17.7), occupation (students vs. others [aHR, 5.7], retirees vs. others [aHR, 4.1]), bleeding experience after receptive anal intercourse (aHR,7.6), and minority ethnic(vs. Han) [aHR, 5.7] were independent risk factors for HIV seroconversion(each P<0.05). Among the 7/11 successfully amplified near full-length sequences, 71.4% (5/7) were CRF01_AE, and 28.6% (2/7) were CRF07_BC. Two HIV transmission pairs were detected among seroconverted minority ethnic MSM.ConclusionsHIV incidence was moderately high among Yunnan MSM. Yunnan province need to strengthen both HIV and syphilis screening among MSM population. Some subpopulations of MSM, such as students, retirees and minority ethnic groups require more HIV epidemic surveillance and strengthened behavior interventions. HIV subtypes and primary drug resistance should be continually monitored to track cross-group transmission of HIV strains.

HIV Surveillance in a Large, Community-Based Study: Results from the Pilot Study of Project Accept (HIV Prevention Trials Network 043)

BackgroundProject Accept is a community randomized, controlled trial to evaluate the efficacy of community mobilization, mobile testing, same-day results, and post-test support for the prevention of HIV infection in Thailand, Tanzania, Zimbabwe, and South Africa. We evaluated the accuracy of in-country HIV rapid testing and determined HIV prevalence in the Project Accept pilot study.MethodsTwo HIV rapid tests were performed in parallel in local laboratories. If the first two rapid tests were discordant (one reactive, one non-reactive), a third HIV rapid test or enzyme immunoassay was performed. Samples were designated HIV NEG if the first two tests were non-reactive, HIV DISC if the first two tests were discordant, and HIV POS if the first two tests were reactive. Samples were re-analyzed in the United States using a panel of laboratory tests.ResultsHIV infection status was correctly determined based on-in country testing for 2,236 (99.5%) of 2,247 participants [7 (0.37%) of 1,907 HIV NEG samples were HIV-positive; 2 (0.63%) of 317 HIV POS samples were HIV-negative; 2 (8.3%) of 24 HIV DISC samples were incorrectly identified as HIV-positive based on the in-country tie-breaker test]. HIV prevalence was: Thailand: 0.6%, Tanzania: 5.0%, Zimbabwe 14.7%, Soweto South Africa: 19.4%, Vulindlela, South Africa: 24.4%, (overall prevalence: 14.4%).ConclusionsIn-country testing based on two HIV rapid tests correctly identified the HIV infection status for 99.5% of study participants; most participants with discordant HIV rapid tests were not infected. HIV prevalence varied considerably across the study sites (range: 0.6% to 24.4%).Trial RegistrationClinicalTrials.gov registry number NCT00203749.

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.

Evaluation of OraQuick Advance Rapid HIV-1/2 Antibody Test as a Screening Test for HIV Infection

Background: For the diagnosis of HIV infection, enzyme immunoassay (EIA) or chemiluminescence immunoassay (CLIA) is commonly used as a screening test. Although these methods have a high sensitivity and low cost, their high false positive rate can cause confusion in the patients and clinicians until a more specific test is done. OraQuick Advance Rapid HIV-1/2 Antibody Test (OraQuick) (OraSure Technologies, USA) is a rapid test that can detect HIV-1/2 antibodies in 20 minutes. It uses oral fluid, whole blood or serum sample. In this study, we evaluated the usefulness of the OraQuick as a screening and point-of-care test for HIV infection. Methods: From Jan 2007 to Dec 2008, 45,276 samples referred to our laboratory were tested by CLIA method using the ADVIA Centaur (Bayer Healthcare LTD., USA) for HIV-1/2 antibody detection. Among them, 74 positive and 50 negative samples were tested by the Western immunoblot assay (WIB) and OraQuick test as a case-control study. Also, oral fluids from 30 HIV patients and 48 healthy persons were tested by OraQuick test. Results: The sensitivity and specificity of OraQuick test (using serum samples) were 100% and 98.8% (95% confidence interval 96.9∼100%), respectively. OraQuick tests (using oral fluid samples) were all positive for HIV patients but all negative for healthy persons. Conclusion: This study suggests that OraQuick can be used successfully as a rapid test for the early detection of HIV-1/2 antibody in patients visiting emergency departments and for the prevention of HIV infection in the health care providers. (Korean J Clin Microbiol 2009;12:116-121)

Clinical presentation and diagnosis of primary HIV-1 infection

To describe current findings concerning the clinical manifestations and diagnosis of primary HIV-1 infection. HIV-1 seroconversion can occur with a variety of clinical manifestations or without symptoms. More severe and numerous symptoms during primary HIV-1 infection predict a higher plasma HIV-1 RNA set-point and faster disease progression. While detection of primary HIV-1 infection is potentially very important for HIV-1 prevention and may offer clinical benefits, the diagnosis is often missed. Diagnosis of symptomatic individuals with antibody-negative HIV-1 infection requires recognition of the diverse signs and symptoms of this syndrome. Diagnostic tests for primary HIV-1 infection include assays for HIV-1 RNA, p24 antigen, and third generation enzyme immunoassay antibody tests capable of detecting IgM antibodies. Targeting these tests using clinical presentation alone will probably miss the diagnosis in many individuals. Consequently, increasing effort has gone into developing strategies to incorporate the use of these assays into routine HIV-1 testing algorithms. More numerous and severe primary HIV-1 infection symptoms predict more rapid disease progression. Pooled HIV-1 RNA screening and fourth generation HIV-1 enzyme immunoassay antibody tests with sensitive p24 antigen detection are beginning to be implemented in routine HIV-1 testing algorithms, but further research is needed to define optimal strategies for increasing detection of primary HIV-1 infection.

Low specificity of the Murex fourth‐generation HIV enzyme immunoassay in Tanzanian adolescents

To determine the specificity of the Abbott Murex HIV antigen/antibody combination enzyme immunoassay (EIA) for the diagnosis of HIV infection in Tanzania. A cross-sectional survey of 7333 Tanzanian adolescents and young adults was carried out. Sera testing positive by the Murex assay were further evaluated using a battery of other EIA which detect either antibody to HIV-1 or p24 antigen, and by PCR using pol primers. Of the 674 sera testing positive by the Murex assay, only 53 (7.9%) were confirmed. The specificity of the Murex assay was 91.5%. Serological tests for HIV may perform differently in different populations. New diagnostic tests should not be introduced into populations in which they have not been evaluated.