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

Nasopharyngeal 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.

Biopsy 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.

All 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.

EBV 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.