PPIA and viral infectious disease: They constantly switch between offense and defense in their interactions with the host, as exemplified by their hijacking of miRNA and CypA mentioned earlier [56]: miRNA can fine-tune antiviral genes to help the host inhibit viral infection, while it may also be hijacked by the virus to shut down the interferon pathway; in contrast, CypA, which normally aids in immune activation, can be exploited by the virus to encapsulate itself and evade immune recognition.