2. Please compare the downstream reactions after a (A) ion channel-coupled (B) G protein-coupled neurotransmitter receptor binds to its ligand (10pts).

1. Covid-19 outbreak has caused not only severe impacts on people's livelihood, but also enormous social and economic disruptions. Please explain (A) the antiviral responses of innate immune system, and (B) the principles of antiviral actions of vaccine (10pts).