CD8A and viral infectious disease: For example, CD8+TRM cells located in lung tissues rapidly secrete protective molecules such as IFN-γ and IL-2 after confronting with RSV, SARS-CoV-1, and SARS-CoV-2.151,530 In mice model with virus infection, brain-CD8+TRM cells provide immune defense against the reinfection of mouse polyomavirus,531,532 and tissue-resident ILC1s can make an early robust immune response against mouse cytomegalovirus in the liver.484 Generally, most TRICs contribute to protective immunity in response to various virus infections.