Final answer:
Interferons are proteins released by virus-infected cells to warn adjacent noninfected cells, prompting them to produce compounds that inhibit viral replication and activate immune cells for a better defense against the invasion.
Step-by-step explanation:
The proteins produced by virus-infected cells as a warning to noninfected cells in the area are known as interferons. These early induced proteins have a crucial role in the immune response. When a cell is infected with a virus, it releases interferons to signal the infection to neighboring cells. Upon receiving this signal, the noninfected cells begin to produce compounds that interfere with viral replication. Interferons not only prompt the production of antiviral proteins but also activate macrophages and other immune cells, thereby enhancing the body's overall defense mechanism against viruses. This protective effect extends to nearby cells, which, although the initial infected cell may be sacrificed, have a better chance of fighting off the viral infection due to the early warning.