HIV Diagnostics: Current Recommendations and Opportunities for Improvement

Fentogram electrochemical detection of HIV RNA based on graphene quantum dots and gold nanoparticles

This work reports the construction of an HIV-specific genosensor through the modification of carbon screen-printed electrodes (CSPE) with graphene quantum dots decorated with L-cysteine and gold nanoparticles (cys-GQDs/AuNps). Cys-GQDs were characterized by FT-IR and UV-vis spectra and electronic properties of the modified electrodes were evaluated by cyclic voltammetry and electrochemical impedance spectroscopy. The modification of the electrode surface with cys-GQDs and AuNps increased the electrochemical performance of the electrode, improving the electron transfer of the anionic redox probe [Fe(CN)6]3-/4- on the electrochemical platform. When compared to the bare surface, the modified electrode showed a 1.7 times increase in effective electrode area and a 29 times decrease in charge transfer resistance. The genosensor response was performed by differential pulse voltammetry, monitoring the current response of the anionic redox probe, confirmed with real genomic RNA samples, making it possible to detect 1 fg/mL. In addition, the genosensor maintained its response for 60 days at room temperature. This new genosensor platform for early detection of HIV, based on the modification of the electrode surface with cys-GQDs and AuNps, discriminates between HIV-negative and positive samples, showing a low detection limit, as well as good specificity and stability, which are relevant properties for commercial application of biosensors.

Reflex Human Immunodeficiency Virus (HIV) Type 1 RNA Testing Enables Timely Differentiation of False-Positive Results From Acute HIV Infection

Accurate, timely human immunodeficiency virus (HIV) diagnosis is critical. Routine HIV screening program data were examined before and after reflex HIV type 1 RNA testing. Reflex testing facilitated confirmation of reactive HIV screening assays (as true or false positives) (odds ratio, 23.7 [95% confidence interval, 6.7-83.4]; P < .0001), improving detection of acute HIV and reducing unconfirmed discordant results.

An HFman probe-based reverse transcription loop-mediated isothermal amplification (RT-LAMP) assay for HIV-1 detection

Loop-mediated isothermal amplification (LAMP) is suitable for the development of a rapid and cost-effective nucleic acid technique for point of care (POC) applications. However, LAMP methods often generate non-specific amplification, therefore inevitably resulting in false positive results especially when sequence-independent dyes are used to indirectly reflect the results. In this study, we established and optimized a reverse transcription LAMP (RT-LAMP) assay with a high-fidelity DNA polymerase-mediated fluorescent probe (HFman probe) for human immunodeficiency virus-1 (HIV-1) detection. The assay showed high sensitivity and specificity. Using 101 plasma samples with different HIV-1 viral load, we demonstrated that our assay can detect the major HIV-1 subtypes circulating in China, including CRF01_AE, CRF07_BC, CRF08_BC, CRF55_01B, and unique recombinant forms (URFs). We also compared our assay with an approved commercial real-time quantitative polymerase chain reaction (RT-qPCR) kit and found the sensitivity, specificity and consistency was 88.8%, 100% and 89.1%, respectively. The HFman probe-based RT-LAMP assay is a high specific detection method that is rapid, variant-tolerant and simple to operate, and thus is of great significance for timely disclosure of HIV status and rapid POC diagnosis.

Predicting, Diagnosing, and Treating Acute and Early HIV Infection in a Public Sector Facility in Eswatini

BACKGROUND

The lack of acute and early HIV infection (AEHI) diagnosis and care contributes to high HIV incidence in resource-limited settings. We aimed to assess the yield of AEHI, predict and diagnose AEHI, and describe AEHI care outcomes in a public sector setting in Eswatini.

SETTING

This study was conducted in Nhlangano outpatient department from March 2019 to March 2020.

METHODS

Adults at risk of AEHI underwent diagnostic testing for AEHI with the quantitative Xpert HIV-1 viral load (VL) assay. AEHI was defined as the detection of HIV-1 VL on Xpert and either an HIV-seronegative or HIV-serodiscordant third-generation antibody-based rapid diagnostic test (RDT) result. First, the cross-sectional analysis obtained the yield of AEHI and established a predictor risk score for the prediction of AEHI using Lasso logistic regression. Second, diagnostic accuracy statistics described the ability of the fourth-generation antibody/p24 antigen-based Alere HIV-Combo RDT to diagnose AEHI (vs Xpert VL testing). Third, we described acute HIV infection care outcomes of AEHI-positive patients using survival analysis.

RESULTS

Of 795 HIV-seronegative/HIV-serodiscordant outpatients recruited, 30 (3.8%, 95% confidence interval: 2.6% to 5.3%) had AEHI. The predictor risk score contained several factors (HIV-serodiscordant RDT, women, feeling at risk of HIV, swollen glands, and fatigue) and had sensitivity and specificity of 83.3% and 65.8%, respectively, to predict AEHI. The HIV-Combo RDT had sensitivity and specificity of 86.2% and 99.9%, respectively, to diagnose AEHI. Of 30 AEHI-positive patients, the 1-month cumulative treatment initiation was 74% (95% confidence interval: 57% to 88%), and the 3-month viral suppression (<1000 copies/mL) was 87% (67% to 98%).

CONCLUSION

AEHI diagnosis and care seem possible in resource-limited settings.

Machine Learning Classification of False-Positive Human Immunodeficiency Virus Screening Results

BACKGROUND

Human immunodeficiency virus (HIV) screening has improved significantly in the past decade as we have implemented tests that include antigen detection of p24. Incorporation of p24 detection narrows the window from 4 to 2 weeks between infection acquisition and ability to detect infection, reducing unintentional spread of HIV. The fourth- and fifth-generation HIV (HIV5G) screening tests in low prevalence populations have high numbers of false-positive screens and it is unclear if orthogonal testing improves diagnostic and public health outcomes.

METHODS

We used a cohort of 60,587 HIV5G screening tests with molecular and clinical correlates collected from 2016 to 2018 and applied machine learning to generate a classifier that could predict likely true and false positivity.

RESULTS

The best classification was achieved by using support vector machines and transformation of results with principle component analysis. The final classifier had an accuracy of 94% for correct classification of false-positive screens and an accuracy of 92% for classification of true-positive screens.

CONCLUSIONS

Implementation of this classifier as a screening method for all HIV5G reactive screens allows for improved workflow with likely true positives reported immediately to reduce infection spread and initiate follow-up testing and treatment and likely false positives undergoing orthogonal testing utilizing the same specimen already drawn to reduce distress and follow-up visits. Application of machine learning to the clinical laboratory allows for workflow improvement and decision support to provide improved patient care and public health.

Performance of an Alternative Laboratory-Based HIV Diagnostic Testing Algorithm Using HIV-1 RNA Viral Load

BACKGROUND

Since 2014, the recommended algorithm for laboratory diagnosis of HIV infection in the United States has consisted of an HIV-1/2 antigen/antibody (Ag/Ab) test followed by an HIV-1/2 antibody (Ab) differentiation test and, if necessary, a diagnostic HIV-1 nucleic acid test to resolve discordant or indeterminate results.

METHODS

Using stored specimens from persons seeking HIV testing who had not received a previous diagnosis or treatment, we compared the performance of a 3-step alternative algorithm consisting of an Ag/Ab test followed by a quantitative HIV-1 RNA viral load assay and, if viral load is not detected, an Ab differentiation test, to that of the recommended algorithm. We calculated the sensitivity and specificity of 5 Ag/Ab tests and the proportion of specimens correctly classified by the alternative algorithm compared with the recommended algorithm. Results were examined separately for specimens classified as early infection, established infection, and false-reactive screening.

RESULTS

Sensitivity and specificity were similar among all Ag/Ab tests. Viral load quantification correctly classified all specimens from early infection, all false-reactive screening specimens, and the majority of specimens from established infection.

CONCLUSIONS

Although cost, regulatory barriers, test availability, and the ability to differentiate early from established infection must be considered, this alternative algorithm can potentially decrease the total number of tests performed and reduce turnaround time, thereby streamlining HIV diagnosis and initiation of treatment.

Serological diagnosis and prevalence of HIV-1 infection in Russian metropolitan areas

BACKGROUND

HIV infection is a major health problem in Russia. We aimed to assess HIV prevalence in different population groups and to compare the characteristics of 4th generation immunoassays from Abbott, Bio-Rad, Vector-Best, Diagnostic Systems, and Medical Biological Unit.

METHODS

The study included 4452 individuals from the general population (GP), 391 subjects at high risk of HIV infection (HR) and 699 with potentially interfering conditions. HIV positivity was confirmed by immunoblot and by HIV RNA, seroconversion and virus diversity panels were also used. HIV avidity was employed to assess recent infections.

RESULTS

The prevalence in GP was 0.40%, higher in males (0.62%) and in people aged < 40 years (0.58%). Patients attending dermo-venereal centers and drug users had a high prevalence (34.1 and 58.8%). Recent infections were diagnosed in 20% of GP and in 4.2% of HR. Assay sensitivity was 100% except for one false negative (99,54%, MBU). Specificity was 99.58-99.89% overall, but as low as 93.26% on HR (Vector-Best). Small differences on early seroconversion were recorded. Only the Abbott assay detected all samples on the viral diversity panel.

CONCLUSION

HIV infection rate in the high-risk groups suggests that awareness and screening campaigns should be enhanced. Fourth generation assays are adequate but performance differences must be considered.