Preliminary investigations on the role of Drp-1 dependent mitochondrial fission in attenuating RLR downstream signaling during nervous necrosis virus infection.

Member of the dynamin family of large GTPases, dynamin-related protein 1 (Drp1) dependent mitochondrial fission is an intricate process regulating both cellular and organ dynamics. Present study shows that NNV perturbs mitochondrial dynamics by promoting Drp-1 dependent mitochondrial fission, which attenuates MAVS mediated downstream signaling. NNV infected SISS cells revealed induction in Drp1 expression and subsequent translocation into mitochondria. The level of MAVS expression was up-regulated over a period of 24 hpi and declined with the progression of NNV infection at 48 and 72 hpi confirmed by western blot and mRNA transcript analysis. Drp-1 displayed its association with fragmented mitochondria and the transcript abundance was significant post infection along with Mff. Expression levels of IRF-3 IFN-1 and Mx followed a similar pattern with abundant expression at 48 hpi and diminished expression during the further period. Importantly, silencing of Drp1 caused significant elevation in the RLR downstream molecules and reduction in viral RNA expression. These results suggest that NNV-induced mitochondrial fission serve to attenuate host RLR signaling. This provides an illustration of host-pathogen interaction in which the virus evades innate immunity by enhancing mitochondrial fission and perturbs MAVS, and the downstream molecules.