Detection of Epstein-Barr virus genome copies by polymerase chain reaction using dried blood spot samples

Epstein-Barr virus (EBV) is linked to a wide range of diseases, including infectious mononucleosis, hemophagocytic lymphohistiocytosis, and several malignancies. Quantitative EBV-DNA testing via polymerase chain reaction (PCR) is essential for diagnosis, but conventional testing using whole blood faces logistical challenges in resource-limited regions. Dried blood spot (DBS) samples offer a low-cost, stable alternative for EBV-DNA detection.

Paired whole blood and DBS samples were collected from seven patients at Shinshu University Hospital, Japan, who were undergoing EBV-DNA testing as part of routine care. DNA was extracted from both sample types and analyzed by quantitative PCR. The detection rate, DNA yield, and its correlation with EBV-DNA copy number were evaluated.

DNA was successfully extracted from all DBS samples stored for up to 40 days at room temperature. EBV-DNA was detected in all 21 whole blood samples and in 12 of 21 DBS samples. The mean EBV-DNA copy number was 3971 copies/μg DNA in whole blood and 2038 copies/μg DNA in DBS samples. When only samples with ≥1000 copies/μg DNA in whole blood were considered, the detection rate in DBS samples improved to 92.3 %. A strong correlation was observed between the two sample types (r = 0.74).

DBS sample-based PCR testing is a feasible and practical method for detecting clinically significant EBV-DNA levels. Its simplicity, stability, and affordability make it particularly useful for improving diagnostic access in resource-constrained regions, especially in Asia, where EBV-related diseases are more prevalent.