Role of giant grouper (Epinephelus lanceolatus) protein kinase R in antiviral responses and the regulation of eIF2α phosphorylation during nervous necrosis virus infection.

Giant grouper (Epinephelus lanceolatus) is an important aquaculture species in Taiwan. However, groupers in the fry stage are easily infected by the nerve necrosis virus (NNV), which has caused major problems in the grouper aquaculture industry in Taiwan. Interferon is an important molecule in the antiviral pathway, and protein kinase R (PKR), downstream of the transmission chain, plays an important role in disease resistance. To understand the NNV resistance system of PKR in giant groupers, we assessed how ggPKR gene expression was affected by NNV infection. Using in situ hybridization, we found that ggPKR was overexpressed in the brain and eyes upon NNV infection. A positive association between ggPKR and NNV was demonstrated by PKR inhibition in siRNA in vitro experiment, which resulted in higher levels of NNV infection in infected groupers; ggPKR phosphorylates eIF2α in response to NNV dsRNA, thereby inhibiting protein synthesis. Overall, this study contributes to a better understanding of the mechanism that underlie the role of ggPKR in antiviral infections and serves as the basis for future NNV defense strategies.