Diagnostic Accuracy of Dried Plasma Spot Specimens for HIV-1 Viral Load Testing: A Systematic Review and Meta-analysis

Evaluating the sensitivity and specificity of dried blood spots for serological testing of HIV, syphilis, hepatitis B and C Elecsys assays on the Roche Cobas system

This study was performed to validate a dried blood spot (DBS) method for the serological screening of HIV, syphilis, hepatitis B and C. It included 250 paired DBS and serum samples and 116 unpaired DBS samples from 366 unique patients from two laboratories between 8 October and 2 November 2021. As determined by original test request, these were tested using a DBS method for HIV Ag/Ab (n=216), anti-treponemal Ab (n=166), hepatitis B sAg (n=100), and hepatitis C Ab (n=100) Elecsys assays on the Roche Cobas automated platform. Using the manufacturer's (serum) cut-off for reactivity ('positivity'), the sensitivity and specificity of DBS testing compared with serum were: for HIV Ag/Ab 100% and 100%, for anti-treponemal Ab 68.3% and 100%, for hepatitis B sAg 95.9% and 100%, and for hepatitis C Ab 84.0% and 100%, respectively. Adjusting the assay cut-off using receiver operator curve analysis increased sensitivity of DBS testing for anti-treponemal Ab to 90.0%, hepatitis B sAg to 97.9% and hepatitis C Ab to 94.0% whilst maintaining specificity of 98.8%, 100% and 100%, respectively. With optimisation of assay cut-off, DBS can perform comparably with serum for serological testing for HIV, syphilis, hepatitis B and C and may be a valuable tool in increasing access to testing in New Zealand.

The plasma separation card as a novel solution for enhancing central laboratory capability for HIV-1 viral load monitoring in limited-access settings

Measurement of HIV-1 viral load (VL) is essential for monitoring antiretroviral treatment (ART) efficacy. The preferred specimen type for VL is plasma, but in remote settings where collection and preservation of plasma many not be possible, dried blood spots (DBS) are often used instead. A new specimen collection matrix, the cobas plasma separation card (PSC, Roche Diagnostics Solutions), enables specimen preparation from a finger prick or venous blood, using a multi-layer absorption and filtration design that results in a specimen similar to dried plasma. We sought to confirm the correlation between VL results obtained using PSC prepared from venous blood to those from plasma or DBS, as well as PSC prepared with capillary blood from a finger prick. PSC, DBS and plasma were prepared with blood from HIV-1 infected persons attending a primary care clinic in Kampala, Uganda. VL in PSC and plasma was measured using cobas HIV-1 (Roche Diagnostics), while VL in DBS was measured with RealTime HIV-1 (Abbott Diagnostics). The correlation between VL from plasma and PSC made from capillary or venous blood was high (regression coefficient of determination r2 between 0.87 and 0.91), and there was good agreement based on mean bias (-0.14 to 0.24 log10 copies/mL) and classification of VL above or below 1000 copies/mL (91.4% agreement). In contrast, VL from DBS was lower than plasma or PSC (mean bias 0.51 to 0.63 log10 copies/mL) and not as well correlated (r2 0.78 to 0.81, 75.1-80.5% agreement). These results confirm the utility of PSC as an alternative specimen type for HIV-1 viral load measurement in areas where preparation and optimal storage or shipment of plasma is an obstacle to provision of treatment and care of HIV-1 infected people.

Technologies for HIV-1 drug resistance testing: inventory and needs

PURPOSE OF REVIEW

HIV-1 drug resistance (HIV DR) testing is routinely performed by genotyping plasma viruses using Sanger population sequencing. Next-generation sequencing (NGS) is increasingly replacing standardized Sanger sequencing. This opens up new opportunities, but also brings challenges.

RECENT FINDINGS

The number of NGS applications and protocols for HIV DR testing is increasing. All of them are noninferior to Sanger sequencing when comparing NGS-derived consensus sequences to Sanger sequencing-derived sequences. In addition, NGS enables high-throughput sequencing of near full-length HIV-1 genomes and detection of low-abundance drug-resistant HIV-1 variants, although their clinical implications need further investigation. Several groups have defined remaining challenges in implementing NGS protocols for HIV-1 resistance testing. Some of them are already being addressed. One of the most important needs is quality management and consequently, if possible, standardization.

SUMMARY

The use of NGS technologies on HIV DR testing will allow unprecedented insights into genomic structures of virus populations that may be of immediate relevance to both clinical and research areas such as personalized antiretroviral treatment. Efforts continue to tackle the remaining challenges in NGS-based HIV DR testing.