Clinical Evaluation of Plasma Separation Cards as a Tool to Collect, Store, and Test Blood Samples for Hepatitis B and C Serological Markers

Dried Spot Paradigm: Problems and Prospects in Proteomics

The analysis of biological fluids plays a crucial role in biomarker discovery, disease diagnostics, and precision medicine. Dried sample carriers-such as dried blood spots, dried plasma, serum, saliva, tears, and urine-have emerged as powerful tools, offering advantages in sample collection, storage, and transport, particularly in remote and resource-limited settings. Recent advances in proteomic methodologies have expanded the potential of these dried matrices, yet challenges related to protein stability, sensitivity, and standardization persist. This review critically examines the current state of proteomic investigations using dried biological fluids. Furthermore, we compare proteomics' progress in this field with other omics approaches, such as metabolomics, to contextualize its development and integration potential. While dried fluid proteomics is promising for non-invasive diagnostics and large-scale epidemiological studies, addressing technical limitations will be essential for its broader adoption in clinical and translational research.

Clinical evaluation of patterned dried plasma spot cards to support quantification of HIV viral load and reflexive genotyping

Quantifying viral load, a key indicator required to achieve control and elimination of the HIV epidemic, requires cell-free plasma or serum to ensure measurements are not biased by proviral DNA contained in infected CD4 T lymphocytes. Plasma separation cards (PSC) collect and preserve a dried specimen, which makes them practical solutions for decentralized sample collection and transport in limited-resource settings. However, physiological variations in hematocrit levels can introduce significant variability in the quality of plasma generated by commercial PSCs and can lead to inaccurate test results and clinical decisions. In addition to hematocrit-dependent sampling, the Roche PSC, a standard for dried plasma collection, is known to induce considerable hemolysis, which further impacts specimen quality, concordance with liquid plasma, and the overall benefit of microsampling. We address these gaps with a patterned dried plasma spot (pDPS) card, which generates plasma with improved hematocrit independence and minimal hemolysis. This study directly compares pDPS cards to the Roche PSC to measure HIV viral load. Analysis of viral load from 75 donors revealed strong agreement in sensitivity, specificity, overall accuracy, and viral load band placement between devices, with quantitative metrics suggesting improved performance for pDPS cards. In reflexive genotyping, remnant dried blood from pDPS cards exhibited greater success than Roche PSC in amplification and sequencing (71% vs. 62%) and detecting drug resistance mutations (63% vs. 42%). Based on this performance, pDPS cards can be versatile across multiple analytical platforms, integrate seamlessly into existing clinical laboratory workflows, and aid clinicians in making accurate treatment decisions.

Community-based screening enhances hepatitis B virus linkage to care among West African migrants in Spain

BACKGROUND

Chronic infection with HBV is responsible for >50% of all hepatocellular cancer cases globally and disproportionately affects sub-Saharan African (sSA) countries. Migration from these countries to Europe has increased substantially in recent years, posing unique challenges to health systems. The aim of this study was to carry out a community-based intervention to increase HBV screening, vaccination, and linkage to care among sSA migrants in Catalonia, Spain.

METHODS

This was a prospective cohort study. Participants ≥18 years were offered community-based HBV screening between 20/11/20 and 21/01/22. Rapid HBV testing and blood sample collection utilizing plasma separation cards were carried out and linkage to care was offered to all participants. HBV vaccination and post-test counseling were performed at a second visit in the community. The main outcome was the odds of those with current HBV infection being successfully linked to hepatology. Rates of completing the care cascade of this model were analyzed.

RESULTS

In the present study, 444 people undergo screening, with 50.6% of participants showing evidence of past or current HBV infection, including an HBsAg prevalence of 9.2%. Migrants with current HBV infection exhibit 5.2 times higher odds of successful linkage to care compared to those in need of post-test counseling or vaccination. The study achieves a successful linkage to care rate of 72% for all participants, with specialist appointments arranged within 15.5 days.

CONCLUSIONS

This community-based HBV screening program provides evidence of a successful model for identifying and providing care, including vaccination, to west African migrants at high risk of HBV infection who may otherwise not engage in care.

Prospective Laboratory Evaluation of the cobas Plasma Separation Card for HIV and Treponema pallidum Antibody Analysis

BACKGROUND

The cobas Plasma Separation Card (PSC; Roche Diagnostics) was developed for HIV viral load testing. This study evaluates the performance of HIV and Treponema pallidum (Tp) antibody (Ab) detection on PSCs as an alternative to dried blood spots (DBSs).

METHODS

EDTA whole blood samples were collected from HIV-positive (n = 100), HIV-negative (n = 50), Tp-positive (n = 100), and Tp-negative patients (n = 50) and spotted on DBS and PSC. Antibody detection performance was evaluated for HIV Ab using the Genscreen ULTRA HIV Ag-Ab test (Bio-Rad) and for Tp Ab using the Syphilis Total Ab test (Bio-Rad). Plasma was used as a reference specimen.

RESULTS

Receiver operating characteristic curve analysis for DBS and PSC generated areas under the curve (AUC + 95% confidence interval) of 0.985 (0.960-1.000) and 0.987 (0.973-1.000) for HIV Ab and 1.000 (1.000-1.000) and 0.996 (0.983-1.000) for Tp Ab, respectively. Receiver operating characteristic areas under the curve were not significantly different between DBS and PSC for HIV or TP Ab. At selected cutoff values rendering at least 99% sensitivity for HIV Ab detection, the specificity was 96% on DBS and 68% on PSC. For Tp Ab detection at 90% sensitivity, 100% specificity is reached on both DBS and PSC (exceeding the required 95%). However, the median quantitative HIV and Tp Ab signal of positive samples significantly decreased in PSC compared with DBS and plasma.

CONCLUSIONS

Although receiver operating characteristic analysis does not seem to indicate significant differences in performance between DBS and PSC, the significant reduction in quantitative Ab detection signal dictates card composition optimization before its use for HIV and Tp Ab detection can be advised.