Final answer:
Interferons, not complement, are the signaling proteins released by virus-infected cells to warn neighboring cells and evoke an immune response. They inhibit viral replication and activate the immune system, with cytotoxic T cells and NK cells playing a critical role in destroying the infected cells.
Step-by-step explanation:
Infected cells do not secrete complement as a warning signal; instead, they release a group of proteins known as interferons. Interferons are a type of cytokine that infected cells release to notify nearby uninfected cells of the viral presence. These interferons prompt uninfected cells to produce substances that inhibit viral replication, stimulate apoptosis in already infected cells, and activate immune cells like macrophages and cytotoxic T cells, which are pivotal in the immune response to viral infections.
Viruses typically gain entry into cells by mimicking molecular structures, allowing them to bind to specific sites on a cell's surface. Once inside, they may prompt immune responses leading to antibody production. However, antibodies are ineffective against viruses within cells, and the rapid mutation of viruses can render antibodies less effective. This highlights the importance of cytotoxic T cells and Natural Killer (NK) cells, as they can recognize and destroy infected cells directly.