Viral-infected human cells often send out special proteins that serve as an early warning system to uninfected cells. in response, the uninfected cells develop antiviral proteins that protect them. the early warning proteins sent out by viral-infected cells are a) complement b) antigens c) antibodies d) antibiotics e) interferon

E) interferon

Explanation:

Interferons belong to the group of cytokines and are released by host cells when they are infected by virus. Neighboring cells are warned of the virus and they increase their defense mechanism. Interferons lead to activation of natural killer cells and macrophages and up regulate antigen presentation on cells. They are called interferons because they hinder the viral replication process.

They are found in animals. They produce symptoms like fever and muscle pain. When interferons are released they lead to activation of various signalling cascades which have different functions like decreasing protein synthesis in cells.