Establishment and characterization of the Bactrocera dorsalis (Diptera: Tephritidae) embryonic cell line QAU-Bd-E-2

In this study, we successfully established a Bactrocera dorsalis (Diptera: Tephritidae) embryonic cell line, i.e., QAU-Bd-E-2, from the insect eggs. The cells have been stably passaged for more than 60 times in TNM-FH medium with 10% fetal bovine serum (FBS). QAU-Bd-E-2 cells are adherent cells. Most of the cells were round, spindle-shaped, and rod-shaped. Round cells accounted for 82.3%, with a diameter of 13.9 ± 2.6 µm; spindle-shaped cells accounted for 9.8%, with the size of 51.2 ± 11.2 µm × 10.3 ± 3.1 µm; the rod-shaped cells accounted for 7.9%, with the size of 35.2 ± 9.4 µm × 12.0 ± 2.5 µm. The mitochondrial cytochrome oxidase I subunit (CoI) gene from QAU-Bd-E-2 cells was amplified, and the 657 bp fragment had a 100% similarity with the CoI gene of B. dorsalis, suggesting that the cell line was derived from B. dorsalis. The chromosome number of QAU-Bd-E-2 cells was mostly 12, which is the same as the B. dorsalis chromosome number. The cell density of QAU-Bd-E-2 cells reached the maximum (3.4 × 10⁶ cells/mL) at 192 h, and the population doubling time was 31.9 h. Bactrocera dorsalis cripavirus (BdCV) could replicate in QAU-Bd-E-2 cells, suggesting that this cell line could be used for in-depth study of the relationship between virus and host.