Final answer:
Interferons are proteins produced by virus-infected cells that help resist viral replication and stimulate the immune system, including activation of immune cells and increasing MHC I expression.
Step-by-step explanation:
Virus-infected cells produce interferons which will induce resistance to viral replication, increase MHC I expression, activate dendritic cells, macrophages as well as NK cells.
When a cell is infected by a virus, it responds by producing a group of proteins known as interferons. These proteins serve as crucial components of the innate immune response. Interferons have several roles in immune regulation and antiviral defense. Firstly, they stimulate the infected cells and those nearby to produce proteins that inhibit viral replication. This provides a first line of defense by limiting the spread of the virus. Secondly, interferons enhance the expression of Major Histocompatibility Complex (MHC) class I molecules, which are essential for presenting viral antigens to T cells. This action facilitates the adaptive immune response against the virus. Additionally, interferons activate various immune cells - dendritic cells, macrophages, and Natural Killer (NK) cells. Dendritic cells are vital for antigen presentation; macrophages engulf and digest pathogens; and NK cells are involved in the destruction of infected or tumor cells. Together, these actions help to control and eliminate viral infections.