Dried blood spots effectively detect HCV
An analysis of whole blood samples collected from dried blood spots was reliable in detecting and monitoring hepatitis C virus infection, according to recent findings.
“Dried blood spots are promising for the collection of venous or capillary blood specimens and their shipment … to a central laboratory well-equipped for classical virological diagnosis and monitoring,” Alexandre Soulier MD, from the National Reference Center for Viral Hepatitis B, C and Delta in France, and colleagues wrote. “Thus, the use of [dried blood spots (DBS)] has the potential to substantially simplify and decentralize hepatitis services in low- or middle-resource areas in order to expand screening and access to care.”
For the prospective study, the researchers evaluated blood samples from more than 500 patients between September 2012 and November 2013. The cohort included 170 HCV-negative patients (Group A); 26 patients with resolved infection (Group B); and 315 treatment-naive patients with chronic HCV who had detectable anti-HCV antibodies and quantifiably HCV RNA (Group C).
Whole blood samples extracted from DBS and serum samples were collected from each participant. The researchers used an enzyme immunoassay to determine total anti-HCV antibodies in the samples. All DBS were tested with two quantitative real-time PCR assays.
According to the researchers, after establishing a new signal-to-cutoff ratio threshold, enzyme immunoassay detection of anti-HCV antibodies from DBS was a reliable method. The mean signal-to-cutoff values were 0.1 ± 0.2 in group A; 10.5 ± 8.2 in group B; and 13.5 ± 7.1 in group C. No detectable RNA was found in whole blood from HCV-negative patients; specificity of DBS was therefore 100% (95% CI, 97.8%-100%). HCV RNA also was undetectable in patients with resolved infection from group B.
All patients with chronic HCV had quantifiable HCV RNA, and 314 had detectable HCV RNA using the two PCR assays.
In the majority of patients with active replication, HCV RNA was detected, but the RNA concentrations were significantly lower than in serum, suggesting that therapeutic decisions should be guided only by the presence or absence of HCV RNA or level changes. There was a lack of HCV core antigen sensitivity on DBS. Determination of HCV genotype was possible in the vast majority of blood samples taken on DBS.
In a related editorial, Mark Thursz, MD, of the division of digestive disease at Imperial College, London, and Karine Lacombe, MD, of the department of infectious diseases and tropical medicine at Saint-Antoine Hospital, Paris, wrote the collection of capillary samples from DBS may surmount obstacles of HCV care in low- or low -middle income countries.
“With limited reservations, DBS sample collection provides a solution to one of the practical barriers to HCV treatment access in low- or low-middle income countries,” they wrote. “Simplification of drug regimens and pangenotypic antiviral drugs should reduce the level of clinical expertise required to deploy therapy. Generic pricing agreements for HCV drugs are already being negotiated. Perhaps it is time for optimism around access to HCV treatment.” – by Jen Byrne
Disclosure: The study was supported by the National Agency for Research on AIDS and Viral Hepatitis, the French Ministry of Health and Janssen Pharmaceuticals. Soulier reports no relevant financial disclosures. Please see the full study and editorial for a list of all other authors’ relevant financial disclosures.