Mouse Fibroblast L۹۲۹ Cell Line as a Useful Tool for Replication and Adaptation of Infectious Bursal Disease Virus

Infectious bursal disease virus (IBDV) causes a highly contagious disease associated with immunosuppression in young chickens. Production of either egg-based or primary cell-based high-quality vaccines requires time-consuming and costly procedures. To determine a suitable cell line for IBDV replication, L۹۲۹ cell line was a candidate for the growth kinetics processing of the virus. The L۹۲۹ cells were proliferated in monolayer, and doubling time was calculated. Replication kinetics an IBDV isolate at the multiplicity of infection ۰.۱ PFU/cell were determined using virus titration. To adapt IBDV on L۹۲۹ cells, seven consecutive passages were performed. Virus titer and levels of apoptosis were quantitatively analyzed at each passage. The viral VP۲ gene was amplified and sequenced in three passages. An average doubling time of ۲۱ h was estimated for monolayers of L۹۲۹ cells. Although during early passages, virus growth did not produce a clear cytopathic effect (CPE), an increase in IBDV titers was observed. Serial passages led to the evidence of marked CPEs and an increase in the virus titer in the third passage. During the fourth to seventh passages, consistent CPEs characterized by the formation of granulated and round cells were evident within ۲۴ to ۴۸ hours post-inoculation. The titer of the virus was increased in the third passage onwards to peak in the fourth and constant at ۵.۹ TCID۵۰ until the end passage. The IBDV replication in connection with DNA fragmentation and FITC, revealed the characteristic picture of apoptosis in a time-dependent manner. We found that the IBDV could easily be adapted to L۹۲۹ cells, increasing virus yields by about two orders of magnitude. These results indicated that the cell line may be useful in the production of efficient virus particles.

کلیدواژه ها:

Adaptation ، Apoptosis ، Infectious bursal disease virus ، L۹۲۹ cell line