Video Transcript
What do virally infected cells release to inhibit the replication of the virus in
neighboring cells?
The immune system is a network of cells and proteins that defend us against
infection. It can be divided into innate, or nonspecific, immunity, and adaptive, or specific,
immunity. This question is asking us about features of the innate immune system, so let’s
describe that in some detail.
Innate immunity is the first line of defence while the adaptive immune response
develops. It is rapid and includes barriers like our skin that can prevent pathogens from
entering and causing infection. Innate immunity is nonspecific, meaning it fights all pathogens in the same way. If pathogens do enter our body, for instance, through a cut on the skin, then
specialized cells called phagocytes can work to eliminate them from the body.
But these phagocytes don’t just appear out of nowhere; they need to be recruited to
the site of injury. This is possible because specialized immune cells, called mast cells, can sense when
there is tissue damage and release proteins called cytokines. These cytokines act as alarm signals for other immune cells, like phagocytes, who
then migrate to the site of injury. And if there are any pathogens present, like bacteria for example, then these can be
engulfed, or phagocytosed, by the phagocytes.
Now that we’ve introduced what a cytokine is, let’s look at an example of one that
works to stop viral infections.
When one of our cells becomes infected with a virus, the cell produces a cytokine
called interferon that it secretes into its environment. Interferon can bind to receptors on nearby cells, which then causes the cell to
express different genes to produce antiviral proteins that are involved in
inhibiting the replication of the virus. This way, interferon can help protect cells from infection with a virus.
Going back to our question, virally infected cells can release interferon to inhibit
the replication of virus in neighboring cells.
