Spectrum of false positivity for the fourth generation human immunodeficiency virus diagnostic tests

False-Reactive Fourth-Generation Human Immunodeficiency Virus Testing in Cancer Patients

BACKGROUND

The fourth-generation (4th-gen) human immunodeficiency virus (HIV)-1/2 antibody/antigen (Ab/Ag) combination immunoassay currently used for HIV screening offers greater sensitivity than previous assays, but false-reactive results occur in up to 20% of patients. Large-scale observations in cancer patients are lacking.

METHODS

We conducted a retrospective study of cancer patients seen at the University of Texas MD Anderson Cancer Center (March 2016-January 2023) who had reactive 4th-gen ARCHITECT HIV-1/2 Ab/Ag combination immunoassay results. We analyzed characteristics of patients with true-reactive and false-reactive results, defined based on Centers for Disease Control and Prevention criteria.

RESULTS

A total of 43 637 patients underwent 4th-gen HIV screening, and 293 had reactive 4th-gen HIV test results. Twenty-one patients were excluded because they did not have cancer. Among the remaining 272 patients, 78 (29%) had false-reactive results. None of these patients experienced delays in their cancer treatment, but 26% experienced mental distress. Multivariate logistic regression analysis identified 5 predictors of having false-reactive results: age >60 years (adjusted odds ratio [aOR], 6.983; P < .0001), female sex (aOR, 6.060; P < .0001), race/ethnicity (Black: aOR, 0.274; Hispanic: aOR, 0.236; P = .002), syphilis coinfection (aOR, 0.046; P = .038), and plant alkaloids therapy (aOR, 2.870; P = .013).

CONCLUSIONS

False-reactive 4th-gen HIV test results occur in almost one-third of cancer patients. Physicians should be aware of the high rates of false-reactive HIV screening results in this patient population. These findings may have implications for counseling regarding testing, especially among those at low risk for HIV infection.

A case of a false positive HIV antigen/antibody screen in a pregnant woman at delivery and the clinical importance of reviewing signal-to-cutoff ratio values

We present a unique case not previously touched upon in the literature, and its ensuing management, of a falsely reactive HIV (human immunodeficiency virus) screening test which resulted in a woman during active labor, hours after rupture of membranes. The patient was screened for HIV using the ARCHITECT 4th generation HIV 1 and 2 Antigen/Antibody (Ag/Ab) Combo assay, and the results were repeatedly reactive. A cesarean delivery was recommended, and the patient received intrapartum antiretroviral therapy. Due to rapid progression of labor, the infant was delivered vaginally and received multiple doses of antiretroviral therapy. For confirmation, a viral load PCR test was obtained which resulted undetectable, and it was concluded that the screening results were falsely positive. While the cause of the inaccurate screening result is still unclear, a COVID-19 vaccination in close proximity to the delivery remains suspicious. Four months after delivery, the patient's screening test was no longer reactive.

Increased risk of false-positive HIV ELISA results after COVID-19

OBJECTIVE

From the first-generation options available in 1985, tests to detect HIV-1 specific antibodies have increased its sensitivity and specificity. HIV-1 and SARS-CoV-2 surface glycoproteins present a certain degree of homology and shared epitope motifs, which results of relevance as both pandemics coexist. Here, we aimed to evaluate the rate of false-positive HIV serology results among individuals with COVID-19 diagnosis and in vaccinated individuals.

DESIGN

A retrospective analysis of the samples stored at the Infectious Disease Biobank in Argentina from donors with previous COVID-19 diagnosis or anti-SARS-CoV-2 vaccination.

METHODS

Plasma samples were analyzed using Genscreen Ultra HIV Ag-Ab. In those with a positive result, the following assays were also performed: ELISA lateral flow Determine Early Detect; RecomLine HIV-1 & HIV-2 IgG and Abbott m2000 RealTime PCR for HIV-1 viral load quantification. In all samples, the presence of anti-SARS-CoV-2 IgG antibodies was evaluated by ELISA using the COVIDAR kit. Statistical analysis was done using Pearson's and Fisher's exact chi-squared test; Mann-Whitney and Kruskal-Wallis tests.

RESULTS

Globally, the false-positive HIV ELISA rate was 1.3% [95% confidence interval (95% CI) 0.66-2.22; χ2  = 4.68, P  = 0.03, when compared with the expected 0.4% false-positive rate]. It increased to 1.4% (95% CI 0.70-2.24, χ2  = 5.16, P  = 0.02) when only samples from individuals with previous COVID-19 diagnosis, and to 1.8% (95% CI 0.91-3.06, χ2  = 7.99, P  = 0.005) when only individuals with detectable IgG SARS-CoV-2 antibodies were considered.

CONCLUSION

This higher occurrence of HIV false-positive results among individuals with detectable antibodies against Spike SARS-CoV-2 protein should be dispersed among virology testing settings, health providers, and authorities.

False-Positive Human Immunodeficiency Virus Results in COVID-19 Patients

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus, which causes coronavirus disease 2019 (COVID-19) disease, was first described in 2019 and became a pandemic in 2020. Although it is possible for two viruses to co-infect together, a rarer phenomenon of false-positive results due to cross-reactivity between viruses is also possible. Herein, we present two cases of the false-positive human immunodeficiency virus (HIV) results in those infected with COVID-19. Both patients were screened for HIV and were initially found to be positive with the fourth-generation test. A subsequent blood test revealed no viral load, and an enzyme-linked immunosorbent assays (ELISA) test indicated no reactivity to HIV, thus the false initial screening test. SARS-CoV-2 is an enveloped RNA virus with its outer surface containing a spike-like glycoprotein, which allows it to recognize host cells and invade. HIV-1 gp41 and SARS-CoV-2 share several structural sequences and motifs. These similarities could explain cross-reactivity and false-positive results when screening for HIV in the presence of COVID. The presence of HIV must be confirmed through more specific laboratory tests such as ELISA.

Utility of the Signal-to-Cutoff Ratio and Antigen Index from Fourth- and Fifth-Generation HIV-1/HIV-2 Antigen/Antibody Assays for the Diagnosis of Acute HIV Infection: Applicability for Real-Time Use for Immediate Initiation of Antiretroviral Therapy

Identification of individuals with acute HIV infection (AHI) and rapid initiation of antiretroviral therapy (ART) are priorities for HIV elimination efforts. Fourth- and fifth-generation HIV-1/HIV-2 antigen (Ag)/antibody (Ab) combination assays can quickly identify patients with AHI, but false-positive results can occur. Confirmatory nucleic acid amplification testing (NAAT) may not be rapidly available. We reviewed the data for 127 patients with positive fourth-generation ARCHITECT and fifth-generation Bio-Plex immunoassay results who had negative or indeterminate confirmatory Ab testing results, which yielded 38 patients with confirmed AHI and 89 patients with false-positive results. The receiver operating characteristic (ROC) curves showed excellent discriminatory power, with an area under the curve (AUC) for the signal-to-cutoff (S/CO) ratio of 0.970 (95% confidence interval [CI], 0.935 to 1.00) and an AUC for the Ag index (AI) of 0.968 (95% CI, 0.904 to 1.00). A threshold of 3.78 for the S/CO ratio would maximize the sensitivity (96.3%) and specificity (93.4%). The threshold for AI was 2.83 (sensitivity of 100% and specificity of 96.4%). The S/CO ratio was significantly correlated with the viral load (Spearman correlation coefficient, 0.486 [P = 0.014]), but the AI was not. The viral loads were all high, with a median of >2.8 million copies/mL. Two false-positive results with AI and S/CO ratio values markedly higher than the medians were observed, indicating that biological false-positive results can occur. Review of the S/CO ratio or AI may be used to improve the accuracy of AHI diagnosis prior to confirmatory NAAT results being available.

A fatal SARS-coronavirus-2 induced bone marrow aplasia complicated with invasive fungal infection and severe neutropenic enterocolitis

Background

Immunization against the coronavirus disease 2019 (COVID-19) began in January 2021 in Iran; nonetheless, due to a lack of vaccination among children under 12, this age group is still at risk of SARS-CoV-2 infection and its complications.

Case presentation

SARS-CoV-2 infection was diagnosed in a 6-year-old girl who had previously been healthy but had developed a fever and pancytopenia. The bone marrow aspiration/biopsy demonstrated just hypocellular marrow without signs of leukemia. She was worked up for primary and secondary causes of pancytopenia. Except for a repeated reactive HIV antibody/Ag P24 assay, all test results were inconclusive. After a thorough diagnostic investigation, the cross-reactivity of the HIV antibody/Ag P24 test with SARS-CoV-2 antibodies was confirmed. The patient did not develop any COVID-19-related signs and symptoms, but she did get a severe invasive fungal infection and neutropenic enterocolitis. She died as a result of disseminated intravascular coagulopathy.

Conclusion

It is critical to recognize children infected with SARS-CoV-2 who exhibit atypical clinical manifestations of COVID-19, such as persistent pancytopenia. SARS-CoV-2 infection can cause severe and deadly consequences in children; thus, pediatricians should be aware of COVID-19’s unusual signs and symptoms mimicking other conditions such as aplastic anemia.

Exploring community enabling factors associated with recent HIV testing in a regional sample of gay, bisexual, and other men who have sex with men

HIV testing and diagnosis are the gateway into treatment and eventual viral suppression. With gay, bisexual, and other men who have sex with men (GBMSM) persistently over-representing new HIV diagnoses in Canada, combined with the evolving nature of community social connection, an exploration of factors associated with recent HIV testing is warranted. As most studies of GBMSM rely on samples obtained from larger metropolitan regions, examining HIV testing from an under-researched region is necessary. With data collected from an online survey of LGBTQ+ persons 16 or older living, working, or residing in the Region of Waterloo, Ontario, Canada, we used multinomial logistic regression to explore socio-demographic, behavioural, and psychosocial factors associated with recent HIV testing for GBMSM. In the final multivariate multinomial logistic regression model: sense of belonging was associated with more recently testing, as was having an increasing proportion of LGBT friends, app use to find sex partners in the past 12 months, access to the local AIDS service organization, and general sense of belonging to local community, among other. This analysis highlights the continued importance of enabling and need factors when accessing testing, and suggests areas for further testing promotion in physical and virtual spaces frequented by GBMSM.

Clinical Application Evaluation of Elecsys® HIV Duo Assay in Southwest China

Background

HIV/AIDS continues to be a serious health concern of morbidity and mortality globally, and novel HIV testing is still an important component of diagnosing HIV earlier and reducing the spread of HIV. The Elecsys^® HIV Duo assay is a 4th generation assay that can detect both HIV-1 p24 antigen (Ag) and HIV-1/2 antibody (Ab) in parallel and show the subresults for the Ab and Ab units.

Objectives

To evaluate the clinical performance of the Elecsys^® HIV Duo assay on the new cobas E 801 analyzer using a large number of clinical samples from a population in southwest China.

Methods

We collected testing results and information from all patients in a large general hospital. All eligible clinical specimens were first analyzed using the Elecsys^® HIV Duo assay. The test results are given either as reactive or nonreactive as well as in the form of a cutoff index (COI). All initially reactive specimens were retested in duplicate with a 3rd-generation kit. Supplementary tests were divided into Ab confirmation tests and HIV-1 nucleic acid tests. GraphPad Prism and Python were used for plotting, and SPSS 21.0 software was used for statistical analysis.

Results

A total of 186391 specimens were received, and 436 patients were confirmed to be positive for HIV. Among the 86 cases with contact history available, there were more males than females, and heterosexual transmission was the most common route of HIV infection. The Elecsys^® HIV Duo assay displayed 99.94%, 99.93% and 99.98% specificity for inpatient, outpatient and physical examination patients, respectively. The median COI ratios of the false-positive group were significantly lower than those of the true-positive group.

Conclusions

The Elecsys^® HIV Duo test (Cobase801 analyzer) differentiates the detection of HIV-1 p24 Ag and HIV-1/2 Ab with high specificity and facilitates the diagnosis of patients with early HIV infection. Therefore, the Elecsys^®HIV Duo test is used for differentiation of antigen and antibody reactivity, making it suitable for routine clinical diagnosis.

How HIV Clients Find Their Way Back to the ART Clinic: A Qualitative Study of Disengagement and Re-engagement with HIV Care in Malawi

Retention in antiretroviral therapy (ART) services is critical to achieving positive health outcomes for individuals living with HIV, but accumulating evidence indicates that individuals are likely to miss ART appointments over time. Thus, it is important to understand why individuals miss appointments and how they re-engage in HIV care. We used in-depth interviews with 44 ART clients in Malawi who recently missed an ART appointment (> 14 days) but eventually re-engaged in care (within 60 days) to explore reasons for missed appointments and barriers and facilitators to re-engagement. We found that most individuals missed ART appointments due to unexpected life events such as funerals, work, and illness for both clients and their treatment guardians who were also unable to attend facilities. Several reasons differed by gender-work-related travel was common for men, while caring for sick family members was common for women. Barriers to re-engagement included continued travel, illness, and restricted clinic schedules and/or staff shortages that led to repeat facility visits before being able to re-engage in care. Strong internal motivation combined with social support and reminders from community health workers facilitated re-engagement in HIV care.

Evaluation of serological assays for the diagnosis of HIV infection in adults

Serological tests based on the enzyme immunoassay (EIA) are the primary tool for the diagnosis of human immunodeficiency virus (HIV) in adults and have rapidly evolved to quicker, affordable and more accurate test formats to detect early HIV infection. Second- and third-generation HIV rapid tests detect the immunoglobulin G (IgG) and immunoglobulin M (IgM) antibodies to the HIV and are used at the point of care and in HIV self-testing. The tests are affordable and accessible in state and private diagnostic laboratories. The present-day fourth- and fifth-generation EIAs can detect both p24 antigen and IgG and IgM HIV antibodies and thereby diagnose early HIV infection at approximately 2 weeks. The fourth- and fifth-generation EIAs also report sensitivity and specificity of more than 99%. The correct interpretation of HIV diagnosis of false-positive and false-negative EIA test results requires collaborative scrutiny of patient factors and laboratory test methodologies.

False-positive HIV serology, Candida lusitaniae pneumonia, and a novel mutation in the CYBB gene

BACKGROUND

Chronic granulomatous disease (CGD) presents with a myriad of clinical manifestations pertaining to both immunodeficiency and hyperinflammation. Although Candida infection is a signature organism for patients with CGD, C. lusitaniae pneumonia in CGD has rarely been reported. C. lusitaniae is a ubiquitous ascomycete predominantly infecting immunocompromised hosts and has the potential to rapidly develop multi-drug resistance during therapy. Additionally, C. lusitaniae is recognized for its variable resistance against amphotericin B. To date, C. lusitaniae infections in patients with CGD have not been reviewed in detail. False-positive HIV serology, resulting from polyclonal hypergammaglobulinemia, has been reported in association with several infections, auto-immune diseases, and malignancies. Although CGD is often associated with hypergammaglobulinemia, a false-positive HIV serology in CGD has not been reported previously.

PROCEDURE

We report a combination of unique findings in a child with CGD - a false-positive HIV serology, Candida lusitaniae pneumonia, and a novel CYBB mutation. We also provide a detailed review of C. lusitaniae infections in patients with CGD.

RESULTS

In patients with CGD, C. lusitaniae has been reported to cause lymphadenitis (cervical, abdominal), fungemia, meningoencephalitis, or abscesses in the liver and spleen. Many CGD patients with C. lusitaniae infection have associated inflammatory complications of the gut (inflammatory bowel disease, colitis). Additionally, almost all C. lusitaniae infections in CGD have been reported in young infants or in patients receiving long-term immunosuppressive therapy. This reflects that further immunocompromise (in addition to the underlying immune deficiency in CGD) may specifically predispose to C. lusitaniae infection (unlike other candidal infections). Most of the CGD patients with documented C. lusitaniae infection have X-linked form of the disease which generally has been postulated to have a more severe clinical phenotype than the autosomal recessive forms of the disease.

CONCLUSIONS

HIV serology may be positive in patients with CGD and other inborn errors of immunity as a result of hypergammaglobulinemia. C. lusitaniae, which may have peculiar and evolving antimicrobial sensitivity patterns, needs to be considered in patients with CGD and pneumonia. Lastly, to reiterate, CGD should to be considered in patients with proven C. lusitaniae infection.

Shift in HIV/AIDS Epidemic and Factors Associated with False Positives for HIV Testing: A Retrospective Study from 2013 to 2018 in Xi'an, China

BACKGROUND

In China, although quite a few bold programmes have been made for HIV/AIDS, the epidemic has still shown an increasing trend.

OBJECTIVES

The study was aimed to investigate the characteristics of new HIV/AIDS and the major factors of false positives (FP) for HIV testing.

METHODS

A retrospective review was performed in a teaching hospital in Xi'an between 2013 and 2018. The overall characteristics and trends of new HIV/AIDS were described. Moreover, the major factors of FP were determined by the Pareto analysis.

RESULTS

A total of 469 new HIV/AIDS were diagnosed, with an increasing prevalence of the new HIV/AIDS from 0.0626% (41/65503) in 2013 to 0.0827% (115/139046) in 2018. Of them, the majority occurred in the males (88.50%), people aged 21-50 years (76.97%), migrants (60.98%), and sexual contact route (88.70%). There was a rapid increase in the annual number of new HIV/AIDS and increasing trends in groups of young individuals, students, and homosexual mode; however, a downward trend in the percentage of injecting drug use was also observed. Over 50 years old and patients from oncology, obstetrics, hepatobiliary surgery, nephrology, cardiology, and infectious disease constituted the major factors of FP.

CONCLUSION

The HIV/AIDS epidemic in Xi'an is still evolving, therefore, effective strategies, appropriate education and scaling up HIV testing should be developed. In addition, old adults and specific departments were associated with FP.

High risk sexual behaviours associated with traditional beliefs about gender roles among men interested in medical male circumcision in South Africa

BACKGROUND

Beliefs about gender roles and high-risk sexual behaviours underlie the human immunodeficiency virus (HIV) epidemic in South Africa. Yet, there is limited information on the relationships between beliefs about gender roles and risky sexual behaviours. Few studies have explored the association between beliefs about gender roles, high risk sexual behaviour, and health-seeking behaviour among men.

METHODS

We investigated associations between gender beliefs (dichotomised as traditional or progressive) and high-risk sexual behaviour among South African men presenting for medical male circumcision (Apr 2014 to Nov 2015).

RESULTS

Of 2792 enrolled men, 47.4% reported traditional gender beliefs. Participant ages ranged between 18-46 years (median age 26 years; interquartile range, 21-31 years). Most participants had at least one sex partner over the last 12 months (68.2%). Younger men (18-24 years old vs. 25-46 years old) (odds ratio [OR], 1.5 [95% confidence interval (CI) 1.0-2.0]), those with multiple partners ([OR], 1.5 (CI) 1.3-1.8]) and participants unsure of their last partner's HIV status (OR, 1.4 [95% CI 1.1-1.7]) were more likely to have traditional beliefs on gender roles.

CONCLUSION

Young men with traditional beliefs on gender roles may be more likely to engage in high-risk sexual behaviour and could be good candidates for HIV prevention programmes. N = 206 (max 350) Trial registration Name of registry: Clinicaltrials.gov; Trial registration number: NCT02352961; Date of registration: 30 January 2015 "Retrospectively registered"; URL of trial registry record: https://www.clinicaltrials.gov/.

False reactive HIV-1 diagnostic test results in an individual from Kenya on multiple testing platforms-A case report

Background

Rapid diagnostic tests (RDT) are routinely used in screening for HIV infection. More complex diagnostic algorithms incorporating fourth-generation screening and confirmatory HIV-1/HIV-2 differentiation immunoassays (IA) may be used to confirm HIV infection. Co-infections and autoimmune diseases may lead to falsely reactive HIV diagnostic test results.

Case presentation

A Kenyan man with asymptomatic schistosomiasis and low risk factors for HIV infection demonstrated an inconsistent and discordant pattern of reactivity on HIV RDT, repeated reactivity on fourth-generation IA and positive at a single time-point for HIV-1 on the Geenius HIV1/HIV2 confirmatory assay during the course of a prospective cohort study with HIV repeat testing. The individual initiated antiretroviral therapy following HIV diagnosis. However, his bi-annual behavioral questionnaire suggested low-risk factors for infection. Supplementary confirmatory serologic and nucleic acid tests were performed and gave discordant results. The participant was determined to be HIV uninfected using cell-associated HIV-1 DNA/RNA testing and antiretroviral therapy was discontinued.

Discussion and conclusions

Sole reliance on diagnostic test results may result in misdiagnosis of HIV infection, social harm and potential antiretroviral induced drug toxicity. Interpretation of HIV test results should incorporate multiple parameters.

Assessing donor suitability for blood donation: Utility of Geenius HIV 1/2 confirmatory assay

BACKGROUND

Blood donor care and blood safety require a quick and accurate decision on the presence or absence of Human Immunodeficiency Virus (HIV) infection, based on the proper selection of blood donors, serological and molecular HIV testing as well as western blot test. The aim was investigating the possibility of inclusion of Geenius HIV 1/2 Confirmatory Assay in blood donor testing algorithm in order to shorten test time and decrease the number of indeterminate results.

METHODS

A total of 75 archived serum/plasma samples were tested. Their previous serological and molecular HIV results were: 3 negative samples, 7 positive samples, 65 serological indeterminate or positive but confirmatory testing and NAT negative samples.

RESULTS

Geenius assay confirmed the presence of antibodies in all blood donors with HIV positive serology and Nucleic Acid Testing (NAT). HIV-1 gp160 and gp41 antibodies were detected in these donors, while p31 and p24 antibodies were not detected in two and three donors, respectively. HIV-2 antibodies gp36 and gp140 were not found. Blood donor with HIV indeterminate or positive serology but negative confirmatory testing and NAT, were negative in Geenius assay. Conclusion The results obtained are consistent with western blot results. The assay proved simple and quick to perform. Studies have confirmed the possibility of introducing Bio-Rad Geenius into a routine blood donor testing protocol.

The evaluation of low cut-off index values of Elecsys® HIV combi PT assay in predicting false-positive results

Objective

To analyze the results of different cut‐off index (COI) values of Elecsys^® HIV combi PT assay and to assess the role of COI in reducing the frequency of false‐positive results.

Methods

We conducted a retrospective study of samples analyzed by Elecsys^® HIV combi PT assay, a 4th‐generation ECLIA, between 2016 and 2017. A total amount of 379 122 samples were collected for HIV (Human Immunodeficiency Virus) screening.

Results

A total of 379 122 samples were analyzed. 2528 (0.67%) were positive by Elecsys^® HIV combi PT. Of these, 468 were false‐positive results, and most of them (94.87%) were in samples with 1 < COI < 15. The false‐positive rate was 0.12%. Patients with false‐positive samples were more distributed in elder (P < .001) and female (P < .001) than true‐positive specimens. The median COI in true‐positive specimens was (385.20), which is significantly higher than false‐positive specimens (2.08). The consistency between Elecsys^® HIV combi PT assay and 3rd‐generation and positive predictive value (PPV) increased with higher COI values. Cancer, infection, and neurological diseases were considered the potential confounding factors of HIV false‐positive results (19.44%, 11.11%, and 6.62%, respectively).

Conclusion

Samples with low COI values, especially those contain confounding factors, need to be further scrutinized to determine whether the confounding factors may cause false‐positive problem. In addition, the hypothesis that low COI values may predict false‐positive results is valid.

High positive HIV serology results can still be false positive

The consequences of falsely reactive HIV test results can be significant, for patients and healthcare providers. This case describes a diagnostic investigation of a patient with pronounced discordant HIV serological results, to determine HIV status. The fourth generation serological screening assay (Roche COBAS Elecsys HIV combiPT) had high positive results but confirmatory testing was negative (Abbott HIV Ag/Ab Combo). Five separate samples over 13 days were tested using multiple fourth generation HIV immunoassays and molecular tests for HIV-1 and HIV-2. Potential causes of falsely reactive serological results were investigated. Samples were sent to the manufacturer for analysis.

The screening assay was positive on all samples with a very high signal to cut-off ratio (S/CO) of greater than 400. However, multiple serological and molecular assays did not detect HIV-1 or HIV-2 specific antibodies, antigen or nucleic acid. A recombinant immunochromatographic assay had faint reactivity to gp41 peptide and the manufacturer investigation reported cross-reactivity to one of the screening assay’s synthetic peptides. Possible causes of the false positive result include cross reactivity to other antigens, including prior schistosomiasis infection, or the patient’s previously excised ameloblastoma (a rare germ cell tumor of the jaw). This is a rare case of false high positive results on fourth-generation HIV serology testing due to high level non-specific reactivity to an isolated synthetic peptide component of the assay. It highlights the need for confirmatory testing even in settings with HIV high prevalence and awareness that false-positive serological results may have a high S/CO.

Evaluation of the diagnostic performance and optimal cutoff value of a fourth-generation ELISA, VIDAS HIV-1/2 Duo Ultra assay, in a low-prevalence country

In this study, we described the largest analysis to date conducted with VIDAS® HIV Duo Ultra assay. Additionally, we analyzed the diagnostic performance and cutoff values (TV) of HIV Duo Ultra assay and total cost analysis for HIV testing. Of 11,642 enzyme-linked immunosorbent assay (ELISA)-positive samples referred to our center for confirmation, 2000 were positive with HIV Duo Ultra, and of these, 87% were HIV-1 positive and 0.6% were HIV-1 indeterminate with the confirmatory test. Overall, the false-positivity rate was 1.75% for HIV Duo Ultra assay. The sensitivity and specificity were 100% and 99.1%, respectively, when the TV was set at the recommended cutoff value. Even increasing the cutoff value four times, sensitivity and specificity remained high, pointing out that a TV of 0.99 is highly indicative of HIV positivity. Retesting samples with HIV Duo Ultra assay decreased 80% of the confirmatory tests, revealing a significant decrease of 78% in the total costs and reporting time.

Repeated false reactive ADVIA centaur® and bio-rad Geenius™ HIV tests in a patient self-administering anabolic steroids

Background

An individual is considered HIV positive when a confirmatory HIV-1/HIV-2 differentiation test returns positive following an initial reactive antigen/antibody combination screen. Falsely reactive HIV screens have been reported in patients with various concomitant infectious and autoimmune conditions. Falsely positive confirmatory HIV differentiation assays are seen less frequently, but have been observed in cases of pregnancy, pulmonary embolism, and malaria.

Case presentation

A healthy 27 year-old man was referred after a reactive ADVIA Centaur® HIV Ag/Ab screen and positive Bio-Rad Geenius™ HIV 1/2 Confirmatory assay, suggesting HIV-1 infection. The patient’s HIV viral load was undetectable prior to initiation of antiretroviral therapy, and remained undetectable on subsequent testing after initiation of antiretroviral therapy. Both Centaur® and Geenius™ tests were repeated and returned reactive. As this patient was believed to be at low risk of acquiring HIV infection, samples were additionally run on Genscreen™ HIV-1 Ag assay and Fujirebio Inno-LIA™ HIV-1/2 score, with both returning non-reactive. For confirmation, the patient’s proviral HIV DNA testing was negative, confirming the initial results as being falsely positive. The patient disclosed that he had been using a variety of anabolic steroids before and during the time of HIV testing.

Discussion and conclusions

The erroneous diagnosis of HIV can result in decreased quality of life and adverse effects of antiretroviral therapy if initiated, hence the importance of interpreting the results of HIV testing in the context of an individual patient. This reports suggests a potential association between the use of anabolic steroids and falsely-reactive HIV testing.

False-positive fourth-generation HIV test associated with autoimmune hemolytic anemia. Case report

Introduction: The fourth-generation ELISA human immunodeficiency virus (HIV) screening test has a high sensitivity and specificity >99% to detect both antigens and antibodies. Estimates are that only 0.5% yield false positive results.Case description: 61-year-old female patient with a clinical picture consisting of malaise, unquantified fever, asthenia and adynamia. Laboratory tests revealed anemia, so a Coombs test was performed, obtaining a positive result along with other findings of mixed autoimmune hemolytic anemia. Two fourth-generation ELISA HIV screening tests were performed obtaining positive results. Given the national recommendations on the diagnosis of HIV infection, a viral load was performed, which turned out to be negative, so the result was considered a false positive.Discussion: Clinical and biological factors are related to false positive results. There are descriptions about autoimmunity phenomena, such as systemic lupus erythematosus or autoimmune hemolytic anemia, with few cases in older adults.Conclusions: Rapid tests have changed the diagnosis of HIV infection worldwide; however, like any other diagnostic test, they may yield false positive results with differential diagnoses, including autoimmune hemolytic anemia.

Application of case study to introduce medical students to molecular biology techniques used in HIV diagnostics

Diagnostic molecular biology is a fast developing discipline of laboratory medicine widely used in numerous medical branches such as oncology, hematology, immunology, internal medicine, or infectious diseases, which will certainly have a major impact on clinical medicine in the near future. Nowadays, educational process is forced to face the quickly growing overflow of easily accessible data and properly guide the students not to be lead astray in the information chaos. Hence, in view of the foregoing, it appears obvious that modern medical education should put particular stress on selective acquiring, interpreting, and applying integrated multidisciplinary knowledge rather than on just absorbing and memorizing huge amount of scattered information. The presented case study aims at familiarizing the students with basic molecular biology techniques such as enzyme-linked immunosorbent assay, Western blot, and quantitative reverse transcription-polymerase chain reaction. Importantly, it is not limited only to discussing and learning the principles of the assays mentioned earlier, but it also shows their practical application in a particular diagnostic process and give the guidelines on how to explain and interpret exemplary results. In parallel, the way the case study is constructed allows a tutor to lead students into discussion on clinical aspects related to HIV infection what should eventually create complete picture of a HIV diagnostic process, thereby integrating basic knowledge of molecular biology laboratory techniques, HIV biology, and immunological response. © 2019 International Union of Biochemistry and Molecular Biology, 47(3):355-360, 2019.

False positive fourth generation HIV test in a patient with severe malaria

Severe malaria is an uncommon diagnosis in the United States. However, awareness of signs, symptoms, and treatment options is imperative in order to promptly initiate optimal therapy. False positive human immunodeficiency virus (HIV) results are rare in the setting of acute malaria infection and with the introduction of newer fourth-generation immunoassays. The Centers for Disease Control algorithms assist in confirming true HIV infection (Branson et al. 2014).

A multicentre evaluation of the Elecsys® HIV Duo assay

BACKGROUND

Fourth generation HIV assays, which detect both HIV p24 antigen and HIV antibodies are widely used in HIV screening. The combination of markers enables the fourth generation assays to shorten the window of detection, which is important in real-world testing scenarios. The Elecsys^® HIV Duo assay is a fourth generation assay, which provides an overall result based on both the detection of the p24 antigen and HIV antibodies, and lists the sub-results for the antibody and antigen units.

OBJECTIVES AND STUDY DESIGN

The performance of the Elecsys^® HIV Duo assay was assessed at five international centres and compared with other available fourth generation assays.

RESULTS

The specificity of the Elecsys^® HIV Duo assay in 13,328 blood donor samples was 99.87% (95% confidence interval [CI] 99.80-99.93) and was 100% (95% CI 99.63-100) in 1000 routine diagnostic samples. Sensitivity was assessed in 139 seroconversion panels; the Elecsys^® HIV Duo assay detected a greater number of positive samples/number of bleeds compared with other assays investigated. An individual analysis of those seroconversion panels also shows that the Elecsys^® HIV Duo assay compared to other fourth generation assays detected HIV up to 2 days earlier than other assays. The Elecsys^® HIV Duo assay also detected 125/130 'early seroconversion' samples assessed, which was greater than the number detected with comparator fourth generation assays.

CONCLUSION

These results indicate that the Elecsys^® HIV Duo assay is appropriate for use in the diagnosis of HIV and for screening of blood donations and is sensitive for the early detection of HIV.

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.

Heterophilic interference in specimens yielding false-reactive results on the Abbott 4th generation ARCHITECT HIV Ag/Ab Combo assay

BACKGROUND

False-reactivity in HIV-negative specimens has been detected in HIV fourth-generation antigen/antibody or 'combo' assays which are able to detect both anti-HIV-1/HIV-2 antibodies and HIV-1 antigen.

OBJECTIVES

We sought to characterize these specimens and determine the effect of heterophilic interference.

STUDY DESIGN

Specimens previously testing as false-reactive on the Abbott ARCHITECT HIV Ag/Ab combo assay and re-tested on a different (Siemens ADVIA Centaur HIV Ag/Ab) assay. A subset of these specimens were also pre-treated with heterophilic blocking agents and re-tested on the Abbott assay.

RESULTS

Here we report that 95% (252/264) of clinical specimens that were repeatedly reactive on the Abbott ARCHITECT HIV Ag/Ab combo assay (S/Co range, 0.94-678) were negative when re-tested on a different fourth generation HIV combo assay (Siemens ADVIA Centaur HIV Ag/Ab). All 264 samples were subsequently confirmed to be HIV negative. On a small subset (57) of specimens with available volume, pre-treatment with two different reagents (HBT; Heterophilic Blocking Tube, NABT; Non-Specific Blocking Tube) designed to block heterophilic antibody interference either eliminated (HBT) or reduced (NABT) the false reactivity when re-tested on the ARCHITECT HIV Ag/Ab combo assay.

CONCLUSIONS

Our results suggest that the Abbott ARCHITECT HIV Ag/Ab combo assay can be prone to heterophilic antibody interference.