Review of HIV Self Testing Technologies and Promising Approaches for the Next Generation

A handheld HIV detection platform using paper-based sample preparation and real-time isothermal amplification

Early and accurate diagnosis of human immunodeficiency virus (HIV) infection is essential for timely initiation of antiretroviral therapy (ART) and prevention of new infections. However, conventional nucleic-acid-based tests for HIV detection require sophisticated laboratory equipment and trained personnel, which are often unavailable at the point-of-care (POC) or unaffordable in resource-limited settings. We report our development of a low-cost, integrated platform for POC testing of HIV. The platform integrates viral nucleic acid extraction on a paper substrate and reverse transcription loop-mediated isothermal amplification (RT-LAMP) in a portable, battery-powered heating device with real-time detection. The platform does not require laboratory infrastructure such as power outlets. The assay showed a detection limit of 30 copies/mL of HIV RNA in 140 μL human serum or 4 copies/reaction using 50 μL human serum, with no cross-reactivity with hepatitis C virus (HCV). We validated the platform using both plasma samples spiked with HIV and clinical samples from HIV-positive individuals, and compared it with standard laboratory assays based on polymerase chain reaction (PCR). These results demonstrate the feasibility of our platform for HIV testing at the POC.

Challenges and Opportunities with at-Home Blood Collection for HIV-1 Viral Load Monitoring among Sexual Minoritized Men who use Stimulants

Sexually minoritized men (SMM) with HIV who use stimulants experience difficulties achieving and maintaining an undetectable viral load (VL). Home-based VL monitoring could augment HIV care by supporting interim, early identification of detectable VL. We describe implementation challenges associated with a home-collection device for laboratory-based VL testing among SMM with HIV who use stimulants. From March-May 2022, cisgender SMM with HIV reporting moderate-to-severe stimulant use disorder and suboptimal (< 90%) past-month antiretroviral therapy (ART) adherence were recruited via a consent-to-contact participant registry. Eligible men completed teleconference-based informed consent and were mailed a HemaSpot-HD blood collection device (volume capacity 160 µL; lower limit of detection 839 copies/mL) with detailed instructions for home blood self-collection and return shipment. Implementation process measures included estimated blood volume and VL quantification. Among 24 participants, 21 (88%) returned specimens with a median duration of 23 days (range: 10-71 days) between sending devices to participants and receiving specimens. Of these, 13/21 (62%) included enough blood (≥ 40 µL) for confidence in detectable/undetectable results; 10/13 (77%) had detectable VL, with 4/10 (40%) were quantifiable at ≥ 839 copies/mL. The remaining 8/21 had low blood volume (< 40 µL), but 3/8 (38%) still had detectable VL, with 1/3 (33%) quantifiable at ≥ 839 copies/mL. Home blood collection of ≥ 40 µL using HemaSpot-HD was feasible among this high-priority population, with > 50% having a VL detected. However, interim VL monitoring using HemaSpot-HD among those experiencing difficulties with ART adherence may be strengthened by building rapport via teleconferencing and providing detailed instructions to achieve adequate sample volume.

Self-swabbing versus assisted swabbing for viral detection by qRT-PCR: the experience from SARS-CoV-2 based on a meta-analysis of six prospectively designed evaluations conducted in a UK setting

PURPOSE

In April 2020, the UK Government implemented NHS Test and Trace to provide SARS-CoV-2 quantitative reverse transcription polymerase chain reaction (qRT-PCR) testing for the public, with nose-and-throat swabbing for samples performed by trained staff. Self-swabbing (SS) would allow rapid scale-up of testing capacity and access. Six studies were undertaken to determine whether SS was as effective for detecting SARS-CoV-2 as swabbing performed by trained staff.

METHODS

Six prospective studies were conducted between April-October 2020, using six swab/media combinations. Differences between assisted swabbing (AS) and SS were evaluated for concordance, positivity, sensitivity, cycle threshold (Ct) values and void rates. Statistical analysis was performed using 95% confidence intervals (CIs), paired t-tests and model-based methods.

RESULTS

Overall, 3,253 individuals were recruited (median age 37 years, 49% female), with 2,933 having valid paired qRT-PCR results. Pooled concordance rate was 98% (95% CI: 96%, 99%). Positivity rate differences for SS (8.1%) and AS (8.4%) and differences in pooled sensitivities between SS (86%; 95% CI: 78%, 92%) and AS (91%; 95% CI: 78%, 96%) were nonsignificant. Both types of swabbing led to pooled void rates below 2% and strongly correlated Ct values. Age, sex and previous swabbing experience did not have a significant impact on concordance or sensitivity.

CONCLUSION

The UK adopted a policy to promote self-testing for SARS-CoV-2 based on data demonstrating equivalence of SS versus AS. Positive outcomes with SS are likely generalisable to testing for other respiratory pathogens, and we consider self-sampling and self-testing essential for future pandemic preparedness.

Cancer Methylation Biomarker Detection in an Automated, Portable, Multichannel Magnetofluidic Platform

Early detection of cancer is critical to improving clinical outcomes, especially in territories with limited healthcare resources. DNA methylation biomarkers have shown promise in early cancer detection, but typical workflows require highly trained personnel and specialized equipment for manual and lengthy processing, limiting use in resource-constrained areas. As a potential solution, we introduce the Automated Cartridge-based Cancer Early Screening System (ACCESS), a compact, portable, multiplexed, automated platform that performs droplet magnetofluidic- and methylation-specific qPCR-based assays for the detection of DNA methylation cancer biomarkers. Development of ACCESS focuses on esophageal cancer, which is among the most prevalent cancers in low- and middle-income countries with extremely low survival rates. Upon implementing detection assays for two esophageal cancer methylation biomarkers within ACCESS, we demonstrated successful detection of both biomarkers from esophageal tumor tissue samples from eight esophageal cancer patients while showing specificity in paired normal esophageal tissue samples. These results illustrate ACCESS's potential as an amenable epigenetic diagnostic tool for resource-constrained areas toward early detection of esophageal cancer and potentially other malignancies.

Awareness and willingness to use HIV self-testing among people who inject drugs in Iran

BACKGROUND

Most people who inject drugs (PWID) in Iran have not undergone recent HIV testing. While PWID face barriers when seeking HIV testing at health facilities, HIV self-testing (HIVST) could be a promising approach to improve HIV testing uptake. We examined the awareness and willingness to use HIVST among PWID in Iran. We also identified participants' characteristics associated with a higher willingness to use HIVST.

METHODS

PWID were recruited in 11 cities using a respondent-driven sampling method. Willingness to use HIVST was defined as a binary variable (very low/low willingness vs. high/very high willingness). We performed multivariable modified Poisson regression to examine associated factors and report adjusted prevalence ratios (aPR) and 95% confidence intervals (CI).

RESULTS

Of 2,252 PWID, 362 (16.2%; 95% CI 14.7, 17.8) had ever heard of HIVST; however, 1,658 (73.6%; 95% CI 71.7, 75.4) reported high/very high willingness to use HIVST. Willingness to use HIVST was higher among PWID who reported having a high/moderate HIV risk perception (aPR 1.22; 95% CI 1.09, 1.37), ever experiencing homelessness (aPR 1.15; 95% CI 1.03, 1.28), > 10 years of injecting history (aPR 1.16; 95% CI 1.00, 1.34), and high injection frequency in the last three months (aPR 1.18; 95% CI 1.05, 1.32).

CONCLUSION

Most PWID in Iran, particularly those experiencing homelessness, have a longer injecting history, engage in more frequent injection practices, and possess a heightened perception of HIV risk would be willing to adopt HIVST. Enhancing HIVST awareness through increased access to HIVST and health education programs are needed. Additionally, conducting implementation science studies to effectively design and run HIVST programs in Iran can also increase PWID's access to HIV testing.

Biosensor Design for the Detection of Circulating Tumor Cells Using the Quartz Crystal Resonator Technique

A new mass-sensitive biosensing approach for detecting circulating tumor cells (CTCs) using a quartz crystal resonator (QCR) has been developed. A mathematical model was used to design a ring electrode-based QCR to eliminate the Gaussian spatial distribution of frequency response in the first harmonic mode, a characteristic of QCRs, without compromising the sensitivity of frequency response. An ink-dot method was used to validate the ring electrode fabricated based on our model. Furthermore, the ring electrode QCR was experimentally tested for its ability to capture circulating tumor cells, and the results were compared with a commercially available QCR with a keyhole electrode. An indirect method of surface immobilization technique was employed via modification of the SiO₂ surface of the ring electrode using a silane, protein, and anti-EpCAM. The ring electrode successfully demonstrated eliminating the spatial nonuniformity of frequency response for three cancer cell lines, i.e., MCF-7, PANC-1, and PC-3, compared with the keyhole QCR, which showed nonuniform spatial response for the same cancer cell lines. These results are promising for developing QCR-based biosensors for the early detection of cancer cells, with the potential for point-of-care diagnosis for cancer screening.