Detection of EBV in nasopharyngeal carcinoma by quantum dot fluorescent in situ hybridization

AimsNasopharyngeal carcinoma (NPC) is a common cancer in Southeast Asia and is frequently associated with Epstein–Barr virus (EBV) infection. The primary aim of this study was to improve the method of EBV detection by exploring quantum dots in FISH detection, and compare QD-based FISH with conventional ISH.Materials and methodsBiopsy specimens were retrospectively retrieved from 35 NPC patients as paraffin-embedded tissue blocks. QD-FISH was developed to detect the presence of EBV encoded small RNA (EBER) using biotin-labeled EBER oligonucleotide probe indirectly labeled with streptavidin-conjugated quantum dots. Conventional ISH was also performed using a commercial kit to assess concordance between the two methods.ResultsAll the 35 NPC cases were nonkeratinizing carcinoma (7 differentiated and 28 undifferentiated subtypes). EBER-positive signals were detected in 91.43% (32/35) and 80% (28/35) cases by QD-FISH and ISH, respectively. There was no significant difference in the number of EBER-positive cases by the two methods. A moderate concordance was found between QD-FISH and ISH for EBER status (κ = 0.55). Four EBER-negative cases by ISH showed EBER-positive signals when detected by QD-FISH.ConclusionsEBV is closely associated with NPC in Chinese patients. QD-FISH is a novel effective method for EBER detection, and has a moderate concordance with conventional ISH.

Research highlights
► This is the first report of EBER detection using QD-FISH in the NPC biopsy specimens.
► QD-FISH showed less morphological details in the tissue, but it can still localize EBER signals in the nuclei of NPC cells under ultraviolet and blue light excitation.
► QD-FISH is more effective and sensitive than ISH in EBER detection.