Frequency, causes, and new challenges of indeterminate results in Western blot confirmatory testing for antibodies to human immunodeficiency virus

HIV serologically indeterminate individuals: Future HIV status and risk factors

BACKGROUND

Indeterminate HIV test results are common, but little is known about the evolution of indeterminate serology and its sociodemographic and behavioral correlates. We assessed future HIV serological outcomes for individuals with indeterminate results and associated factors in Rakai, Uganda.

METHODS

115,944 serological results, defined by two enzyme immunoassay (EIAs), among 39,440 individuals aged 15-49 years in the Rakai Community Cohort Study were assessed. Indeterminate results were defined as contradictory EIAs. Modified Poisson regression models with generalized estimating equations were used to assess prevalence ratios (PRs) of subsequent HIV serological outcomes and factors associated with HIV indeterminate results.

RESULTS

The prevalence of HIV serologically indeterminate results was 4.9%. Indeterminate results were less likely among women than men (adjPR 0.76, 95% CI 0.71,0.81), in unmarried participants than married participants (adjPR 0.92, 95% CI 0.85,99), and in individuals with primary (adjPR 0.90, 95% CI 0.80,1.02), secondary (adjPR 0.83, 95% CI 0.73,0.96) and post-secondary (adjPR 0.75, 95% CI 0.60,0.94) education, relative to no education. The proportions of persons with indeterminate results progressing to HIV positive, negative or indeterminate results in subsequent visits was 5%, 71% and 24%, respectively.

CONCLUSION

HIV serologically indeterminate results were associated with gender and marital status. HIV surveillance programs should develop a protocol for reporting individuals with mixed or persistently indeterminate HIV results on multiple follow-up visits. Most indeterminate results became HIV-negative over time, but follow-up is still needed to detect positive serologies.

Human immunodeficiency virus in cadavers: A review

Millions of people are infected with human immunodeficiency virus (HIV); however, limited research focuses on post-mortem HIV detection. Post-mortem HIV testing is vital because medical records are not always available, and the HIV status can be unknown. The aims of this study were to review the available literature and determine the most efficient HIV test for post-mortem samples, the optimal tissue or bodily fluid to be tested, and the duration that HIV remains reliably detectable. A literature search was conducted using PubMed and Google Scholar. Terms were related to HIV (HIV detection, HIV testing, HIV prevalence) and deceased individuals (post-mortem, cadaver, deceased, organ donor). Inclusion criteria included English studies, or articles with at least an English abstract, while review articles were excluded. From this literature search, 43 studies were applicable. These studies most commonly used enzyme-linked immunosorbent assay and Western blot as screening and confirmation tests, respectively. As for the optimal tissue or bodily fluid, serum remained the golden standard, while testing skin seemed promising. HIV remains detectable in the body up to 58 days after death, although few studies tested samples after 48 h. Knowledge of the HIV status can be beneficial in the case of accidental exposure and can create a range of possible research opportunities on the effects of HIV in different organ systems. This review outlined several gaps in the current literature and future studies should investigate these gaps because this information can be relevant to numerous professions. Clin. Anat. 32:603-610, 2019. © 2019 Wiley Periodicals, Inc.

Comparative evaluation of the Geenius HIV 1/2 Confirmatory Assay and the HIV-1 and HIV-2 Western blots in the Japanese population

Accurate diagnosis of earlier HIV infection is essential for treatment and prevention. Currently, confirmation tests of HIV infection in Japan are performed using Western blot (WB), but WB has several limitations including low sensitivity and cross-reactivity between HIV-1 and HIV-2 antibodies. To address these problems, a new HIV testing algorithm and a more reliable confirmation and HIV-1/2 differentiation assay are required. The Bio-Rad Geenius HIV-1/2 Confirmatory Assay (Geenius) has recently been approved and recommended for use in the revised guidelines for diagnosis of HIV infection by the Center for Disease Control and Prevention (USA). We made comprehensive comparison of the performance of Geenius and the Bio-Rad NEW LAV BLOT 1 and 2 (NLB 1 and 2) which are WB kits for HIV-1 and HIV-2, respectively, to examine if Geenius is a suitable alternative to these WB assays which are now being used in HIV testing in Japan. A total of 166 HIV-1 positive samples (146 from patients with established HIV-1 infection and 20 from patients with acute infection), five HIV-1 seroconversion panels containing 21 samples and 30 HIV-2 positive samples were used. In addition, a total of 140 HIV negative samples containing 10 false-positives on screening tests were examined. The sensitivity of Geenius and NLB 1 for HIV-1 positive samples was 99.3% and 98.6%, respectively. Geenius provided more positive results in the samples from acute infections and detected positivity 0 to 32 days earlier in seroconversion panels than NLB 1. NLB 2 gave positive results in 12.3% of HIV-1 positive samples. The sensitivity of both Geenius and NLB 2 for HIV-2 positive samples was 100%. The specificity of Geenius, NLB 1 and NLB 2 was 98.5%, 81.5% and 90.0%, respectively. Geenius is an attractive alternative to WB for confirmation and differentiation of HIV-1 and HIV-2 infections. The adaptation of Geenius to the HIV testing algorithm may be advantageous for rapid diagnosis and the reduction of testing costs.

Babesiosis as a cause of false-positive HIV serology

This is a case of a 71-year-old homosexual man who presented with a 4-day history of fever, weakness and headaches, near syncope, nausea and poor oral intake. The patient denied recent travel or sick contacts but had significant tick bites in the last 4 weeks. A peripheral blood smear showed 0.5% parasitaemia with signet ring appearance organisms consistent with Babesia microti. Serology testing for HIV 1 and 2 by ELISA and western blot were positive. Treatment for Babesia was started and the patient improved. Repeat serology testing for HIV was negative. To the best of our knowledge, this is the first case of false-positive HIV serology that is associated with active babesiosis. In this case, the positive HIV serology turned negative after successful treatment of babesiosis.

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

BACKGROUND

The use of conventional (serologically based) HIV 1/2 diagnostic algorithms has become controversial in recent years.

OBJECTIVES

Sera from patients who underwent verification tests were evaluated because repeated ELISA-reactive results demonstrated a HIV1+HIV2 positive band pattern.

METHODS

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.

RESULTS

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.

CONCLUSION

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.

The characteristics of screening and confirmatory test results for HIV in Xi'an, China

OBJECTIVES

Individuals with recent or acute HIV infection are more infectious than those with established infection. Our objective was to analyze the characteristics of detection among HIV infections in Xi'an.

METHODS

A 4th-generation kit (Architect HIV Ag/Ab Combo) and three 3rd-generationEIA kits (WanTai, XinChuang and Livzon) were used for HIV screening. Overall, 665 individuals were identified as positive and were tested by western blotting (WB). The characteristics of the screening and confirmatory tests were analyzed, including the band patterns, the early detection performance and the false-positive rates.

RESULTS

In total, 561 of the 665 patients were confirmed as having HIV-1 infection, and no HIV-2 specific band was observed. Among these 561 WB-positive cases, reactivity to greater than or equal to 9 antigens was the most commonly observed pattern (83.18%), and the absence of reactivity to p17, p31 and gp41 was detected in 6.44%, 5.9% and 2.86% of the cases, respectively. Two cases were positive by the 4th-generation assay but negative by the 3rd-generation assay for HIV screening and had seroconversion. The false-positive rate of the Architect HIV Ag/Ab Combo (22.01%) was significantly higher than those of WanTai (9.88%), XinChuang (10.87%) and Livzon (8.93%), p<0.05.

CONCLUSION

HIV infection in Xi'an is mainly caused by HIV-1, and individuals are rarely identified at the early phase. Although the false-positive rate of the 4th-generation assay was higher than that of the 3rd-generation assay, it is still recommended for use as the initial HIV screening test for high-risk individuals. In Xi'an, a 3rd-generation assay for screening could be considered.

High rate of missed HIV infections in individuals with indeterminate or negative HIV western blots based on current HIV testing algorithm in China

It remains unclear if China's current HIV antibody testing algorithm misses a substantial number of HIV infected individuals. Of 196 specimens with indeterminate or negative results on HIV western blot (WB) retrospectively examined by HIV-1 nucleic acid test (NAT), 67.57% (75/111) of indeterminate WB samples, and 16.47% (14/85) of negative WB samples were identified as NAT positive. HIV-1 loads in negative WB samples were significantly higher than those in indeterminate WB samples. Notably, 86.67% (13/15) of samples with negative WB and double positive immunoassay results were NAT positive. The rate of HIV-1 infections missed by China's current HIV testing algorithm is unacceptably high. Thus, China should consider using NAT or integrating fourth generation ELISA into current only antibodies-based HIV confirmation. J. Med. Virol. 88:1462-1466, 2016. © 2016 Wiley Periodicals, Inc.

HIV testing patterns for United States Air Force personnel, 2008-2012

OBJECTIVE

This study evaluated 3rd generation human immunodeficiency virus (HIV) test patterns and HIV infection rates in the United States Air Force (USAF).

STUDY DESIGN

Retrospective database study.

METHODS

HIV enzyme-linked immunoassay (ELISA) and Western blot tests were analysed for all USAF personnel from 2008 to 2012. For new HIV cases, unadjusted and adjusted annual rates were calculated per 100,000 persons.

RESULTS

In total, 1,608,665 tests were performed in 626,298 individuals, with a reactive ELISA observed in 809 (0.001%) persons. Western blot (n = 1949) results included 378 (19.4%) positive, 1283 (65.8%) negative, and 288 (15.0%) indeterminate (WBi). Unadjusted annual HIV rates were between 16.7 and 20.6 per 100,000 persons during the study period. The overall age-adjusted rate was 14.8 cases per 100,000 persons tested. Blacks/African Americans had the highest risk of HIV (risk ratio 7.9 [95% confidence interval 5.78, 9.95] compared to Whites).

CONCLUSIONS

WBi results, which can cause delays in determining HIV status, were relatively common with the 3rd generation assay. However, this will be mitigated by a planned transition to a 4th generation assay. Although the overall rate of HIV in the USAF is lower than US civilian adults, HIV prevention efforts targeting young Blacks/African Americans may help to reduce HIV incidence in the USAF.

Luminex xMAP combined with Western blot improves HIV diagnostic sensitivity

Currently, Western blot is used to confirm the initial serodiagnosis of HIV infection by antibody detection. However, a major deficiency of the Western blot relates to a lack of sufficient sensitivity in detecting HIV antibodies. This report describes a simple, sensitive and inexpensive bead-based assay for detection of early HIV infection. A panel of 138 positive specimens including 105 blood donors and 33 MSM with known Western blot results were evaluated using Luminex xMAP at Tianjin Centers for Disease Control and Prevention (CDC). We demonstrate a superior sensitivity of Luminex xMAP compared with Western blot. Of the 87 confirmed HIV positive blood donors, Western blot only confirmed 65 cases with 74.7% (65/87) sensitivity while Luminex xMAP identified 72 cases with 82.8% (72/87) sensitivity (p<0.05). Western blot and Luminex xMAP verified 13 and 19 of 33 MSM specimens, respectively. The sensitivity was 39.4% (13/33) for Western blot and 57.6% (19/33) for Luminex xMAP (p<0.1). Luminex xMAP combined with Western blot improves the diagnostic sensitivity of HIV infection at an early stage, and reduces the chances of missed diagnosis.

Evaluation of the Aspergillus Western blot IgG kit for diagnosis of chronic aspergillosis

Immunoprecipitin detection (IPD) is the current reference confirmatory technique for anti-Aspergillus antibody detection; however, the lack of standardization is a critical drawback of this assay. In this study, we evaluated the performance of the Aspergillus Western blot (Asp-WB) IgG kit (LDBio Diagnostics, Lyon, France), a recently commercialized immunoblot assay for the diagnosis of various clinical presentations of chronic aspergillosis. Three hundred eight serum samples from 158 patients with aspergillosis sensu lato (s.l.) were analyzed. More specifically, 267 serum samples were derived from patients with Aspergillus disease, including 89 cases of chronic pulmonary aspergillosis, 10 of aspergilloma, and 32 of allergic bronchopulmonary aspergillosis, while 41 samples were from patients with Aspergillus colonization, including 15 cystic fibrosis (CF) and 12 non-CF patients. For blood donor controls, the Asp-WB specificity was 94%, while the kit displayed a sensitivity for the aspergillosis s.l. diagnosis of 88.6%, with a diagnostic odds ratio (DOR) of 119 (95% confidence interval [CI], 57 to 251). The DOR values were 185.22 (95% CI,78.79 to 435.45) and 43.74 (95% CI, 15.65 to 122.20) for the diagnosis of Aspergillus disease and Aspergillus colonization, respectively. Among the patients, the sensitivities of the Asp-WB in the diagnosis of Aspergillus colonization were 100% and 41.7% in CF and non-CF patients, respectively. The Asp-WB yielded fewer false-negative results than did IPD. In conclusion, the Asp-WB kit performed well for the diagnosis of various clinical presentations of aspergillosis in nonimmunocompromised patients, with an enhanced standardization and a higher sensitivity than with IPD, which is the current reference method.

Evaluation of the Bio-Rad Geenius HIV-1/2 test as a confirmatory assay

OBJECTIVES

We have evaluated the recently Conformité Européenne (CE)-marked Bio-Rad Geenius human immunodeficiency virus (HIV)1/2 as a rapid and simple alternative to western blot for confirmation of HIV screening results.

METHODS

A total of 160 serum samples were tested: 44 HIV-1 reactive samples by a fourth-generation Murex HIV Ag/Ab and/or Vidas HIV Duo Ultra, five HIV-2 reactive samples, 15 HIV-1 non-B subtype samples and 11 confirmed HIV-1 early seroconversion samples, 72 nonreactive samples, eight indeterminate samples by MP HIV BLOT 2.2 confirmed negative after follow-up and five low-reactive samples by enzyme immunoassay (EIA) negative by MP HIV BLOT 2.2. The samples were tested according to the manufacturer's guidelines.

RESULTS

The overall sensitivity for Bio-Rad Geenius HIV1/2 assay was 92%. Five out of 11 early seroconversion samples were tested positive, four negative and two indeterminate. All HIV-1 non-B subtype samples were tested positive. Two out of the five HIV-2 reactive samples were tested positive HIV-2, two positive HIV-2 with HIV-1 cross-reaction and one HIV positive untypable. After excluding early seroconversion samples, the sensitivity of Bio-Rad Geenius HIV1/2 assay reached 100%. Overall specificity was 96%. All HIV negative serums by fourth-generation EIA were tested negative. All five low-reactive samples by EIA, negative by HIV BLOT 2.2 were tested negative by Bio-Rad Geenius HIV1/2. Two out of the eight indeterminate samples by MP HIV BLOT 2.2 that were confirmed negative after follow-up were tested indeterminate and one invalid, the other five were negative. After excluding these last 13 samples, the specificity of Bio-Rad Geenius HIV1/2 assay reached 100%. In comparison with MP HIV BLOT 2.2, the Bio-Rad Geenius HIV1/2 assay was markedly time saving, allowed full traceability, automatic reading and interpretation.

CONCLUSIONS

The Bio-Rad Geenius HIV1/2 confirmatory system represents a reliable alternative to other confirmatory assays in HIV testing algorithms and provides clear improvement in quality management.

Use of rapid HIV assays as supplemental tests in specimens with repeatedly reactive screening immunoassay results not confirmed by HIV-1 Western blot

BACKGROUND

An alternate HIV testing algorithm has been proposed which includes a fourth-generation immunoassay followed by an HIV-1/HIV-2 antibody differentiation supplemental test for reactive specimens and a nucleic acid test (NAT) for specimens with discordant results.

OBJECTIVE

To evaluate the performance of five rapid tests (Alere Clearview, Bio-Rad Multispot, OraSure OraQuick, MedMira Reveal, and Trinity Biotech Unigold) as the supplemental antibody assay in the algorithm.

STUDY DESIGN

A total of 3273 serum and plasma specimens that were third-generation immunoassay repeatedly reactive and Western blot (WB) negative or indeterminate were tested with rapid tests and NAT. Specimens were classified by NAT: (1) HIV-1 infected (NAT-reactive; n=184, 5.6%), (2) HIV-status unknown (NAT nonreactive; n=3078, 94.2%) or by Multispot, (3) HIV-2 positive (n=5), and (4) HIV-1 and HIV-2 positive (n=6). Excluding HIV-2 positive specimens, we calculated the proportion of reactive rapid tests among specimens with reactive and nonreactive NAT.

RESULTS

The proportion of infected specimens with reactive rapid test results and negative or indeterminate WB ranged from 30.4% (56) to 47.8% (88) depending on the rapid test. From 1% to 2% of NAT-negative specimens had reactive rapid test results.

CONCLUSIONS

In these diagnostically challenging specimens, all rapid tests identified infections that were missed by the Western blot, but only Multispot could differentiate HIV-1 from HIV-2. Regardless of which rapid test is used as a supplemental test in the alternative algorithm, false-positive algorithm results (i.e., reactive screening and rapid test in uninfected person) may occur, which will need to be resolved during the baseline medical evaluation.

Establishing benchmarks and metrics for disruptive technologies, inappropriate and obsolete tests in the clinical laboratory

Benchmarks and metrics related to laboratory test utilization are based on evidence-based medical literature that may suffer from a positive publication bias. Guidelines are only as good as the data reviewed to create them. Disruptive technologies require time for appropriate use to be established before utilization review will be meaningful. Metrics include monitoring the use of obsolete tests and the inappropriate use of lab tests. Test utilization by clients in a hospital outreach program can be used to monitor the impact of new clients on lab workload. A multi-disciplinary laboratory utilization committee is the most effective tool for modifying bad habits, and reviewing and approving new tests for the lab formulary or by sending them out to a reference lab.

•

Laboratory test overutilization is 2.9% to 56% of all lab tests ordered.

•

Guidelines may have a positive publication bias.

•

Choosing Wisely is 35 medical subspecialty groups targeting overused tests or therapies.

•

Utilization of disruptive technologies requires time for appropriate use to be established.

•

Client test utilization by speciality can help predict needs to meet future outreach growth.

Social problems of indeterminate and false positive hiv test results among clients attending a nigerian hiv treatment clinic

Increased availability of Human Immunodeficiency Virus (HIV) screening test and more public enlightenment have resulted in more people coming forward to access counseling and testing at the HIV counseling and testing centers in Nigeria. Some of the clients however obtained indeterminate and false positive results leading to emotional disturbance and occasionally, dilemma to the attending physician. This article/case series looked at some of these situations and discussed how they were attended to.

Syphilis with HIV in Florence, 2003–2009: a 7-year epidemiological study

The aims of this study were to describe the trend of acquired syphilis in the city of Florence and its province over a 7-year period, to investigate sexual behaviours in the syphilis-infected population and to analyse syphilis/HIV co-infection. A total of 259 patients were classified according to age, sex and HIV infection. We estimated that from 2004 to 2008 cases increased by 248%. Most patients with concurrent HIV infection were male (31–45 years), but 40- to 60-year-old men who had sex with men predominated in both male and HIV-positive patients. Oral sex was identified as the most significant route of transmission, although most patients did not consider it so. Late-presenters with HIV accounted for 33% of HIV-positive patients: they were unaware of their HIV status and showed syphilis lesions only. In these cases, syphilis heralded the presence of HIV infection and allowed earlier diagnosis.

Performance of parallel screening of Brazilian blood donors with two human immunodeficiency virus immunoassays: implications for sequential immunoassay testing algorithms in other countries

BACKGROUND

In Brazil it is mandatory to screen donors for human immunodeficiency virus (HIV) antibodies using two immunoassays (IAs) in parallel. Confirmatory testing is performed only on reactive donors who return for counseling. The goal of this analysis was to determine if concordant IA reactivity accurately predicts infection and can be used for HIV incidence and/or prevalence analyses.

STUDY DESIGN AND METHODS

We reviewed HIV screening and confirmatory results obtained for 307,407 donations in the first year of the REDS-II study in Brazil (2007) and for 2,304,755 donations collected from 1996 to 2006 in one of the REDS-II sites (São Paulo, Brazil).

RESULTS

In the São Paulo site, 11,410 (0.50%) HIV IA-reactive donations were discarded, but only 2095 (0.09%) were reactive to both IAs. Western blot was positive on 1002 (48%) dual-IA-reactive donors who returned for counseling. Only four HIV-infected donors were detected who had been missed at screening by one of the IAs; all occurred before 2002. The positive predictive value (PPV) of dual-IA reactivity varied from 45.8 to 100%, with 80% to 90% PPVs when using IAs from different manufacturers. If both assays yielded signal-to-cutoff (S/C) values of 3.0 or more, PPVs ranged from 91% to 99%, with approximately 99% sensitivity for true HIV seropositivity.

CONCLUSION

Parallel testing of all donations has limited efficacy when highly sensitive IAs are used. Reactivity by two sequential IAs is useful for prevalence studies if the assays are from different manufacturers and especially if high S/C values are considered.

No evidence for transmission of SIVwrc from western red colobus monkeys (Piliocolobus badius badius) to wild West African chimpanzees (Pan troglodytes verus) despite high exposure through hunting

BACKGROUND

Simian Immunodeficiency Viruses (SIVs) are the precursors of Human Immunodeficiency Viruses (HIVs) which have led to the worldwide HIV/AIDS pandemic. By studying SIVs in wild primates we can better understand the circulation of these viruses in their natural hosts and habitat, and perhaps identify factors that influence susceptibility and transmission within and between various host species. We investigated the SIV status of wild West African chimpanzees (Pan troglodytes verus) which frequently hunt and consume the western red colobus monkey (Piliocolobus badius badius), a species known to be infected to a high percentage with its specific SIV strain (SIVwrc).

RESULTS

Blood and plasma samples from 32 wild chimpanzees were tested with INNO-LIA HIV I/II Score kit to detect cross-reactive antibodies to HIV antigens. Twenty-three of the samples were also tested for antibodies to 43 specific SIV and HIV lineages, including SIVwrc. Tissue samples from all but two chimpanzees were tested for SIV by PCRs using generic SIV primers that detect all known primate lentiviruses as well as primers designed to specifically detect SIVwrc. Seventeen of the chimpanzees showed varying degrees of cross-reactivity to the HIV specific antigens in the INNO-LIA test; however no sample had antibodies to SIV or HIV strain- and lineage-specific antigens in the Luminex test. No SIV DNA was found in any of the samples.

CONCLUSIONS

We could not detect any conclusive trace of SIV infection from the red colobus monkeys in the chimpanzees, despite high exposure to this virus through frequent hunting. The results of our study raise interesting questions regarding the host-parasite relationship of SIVwrc and wild chimpanzees in their natural habitat.

Immunoassays for the diagnosis of HIV: meeting future needs by enhancing the quality of testing

Immunoassays for detecting HIV infection perform better than other serological assays. HIV immunoassays are presented in a number of different formats: instrument-based, plate, rapid assays and as immunoblots. HIV immunoassays for screening and diagnosis are now in their fourth generation; an assay generation meaning that significant modifications to the assay format have led to a significant enhancement in quality. Although still not perfect, they are now of exceptionally high quality if conducted properly. Most problems relate to how the assays are performed. Many laboratories, especially in high human development index (HDI) countries, manage testing within functioning quality-management systems, but this is not true of laboratories in low HDI countries or in many medium HDI countries. Simple rapid tests for HIV are being used increasingly, and create special challenges for assuring quality. Users of HIV immunoassays are learning that a poorer assay used well has better outcomes than a splendid assay performed poorly. Experience highlights the importance of conducting HIV testing within quality-managed systems and according to international standards, but testing quality and laboratory quality management must be funded adequately.

Performance characteristics of a new rapid immunochromatographic test for the detection of antibodies to human immunodeficiency virus (HIV) types 1 and 2

Diagnostic kits for the detection of human immunodeficiency virus (HIV) antibodies have reached an unprecedented number. But choice of an ideal, cost-effective, and rapid test for HIV infection is of immense value for use in developing countries like India, where resources are limited. In this study we have evaluated the performance characteristics of the rapid immunochromatographic HIV test kit First Response HIV 1-2.O. First, the laboratory archived 450 characterized plasma/serum specimens, which were tested on First Response HIV 1-2.O. Second, a total of 134 consecutive voluntary counseling and testing (VCT) specimens were also tested and positive specimens were further confirmed with HIV TRI-DOT. All these VCT specimens were cross-checked with HIV double-enzyme-linked immunosorbent assay (ELISA) (Murex and Vironostika), and the results were matched. The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and efficiency of First Response HIV 1-2.O with the 450 characterized specimens was 100% for HIV-1 with reference assay. The results in the VCT algorithm were correlating with double-ELISA. In the HIV-2 analysis, five HIV-2-positive specimens in First Response HIV 1-2.O were found to be HIV-2-indeterminate on Western blot. HIV TRI-DOT was unable to pick up two HIV-2 Western blot-positive specimens. First Response HIV 1-2.O has several advantages: low-cost (U.S. $0.70); only 10 microL of specimen; involves only two steps; room temperature storage; ability to differentiate HIV-1 and 2; and use of whole blood specimen. Hence this test kit could be suitable for initial screening in the HIV testing algorithm in resource-limited settings. J. Clin. Lab. Anal. 22:178-185, 2008. (c) 2008 Wiley-Liss, Inc.