Q.Assertion (A) : Virus-infected cells produce interferons. Reason (R) : Interferons can cause inflammation of virus-infected cells. (A) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of the Assertion (A). (B) Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of the Assertion (A). (C) Assertion (A) is true, but Reason (R) is false. (D) Assertion (A) is false, but Reason (R) is true.

The key idea here is the function of interferons in the innate immune response against viral infections.

1. Assertion (A) Analysis: Virus-infected cells, upon detecting viral components, produce interferons (a type of cytokine). These interferons are crucial for initiating an antiviral state in neighboring cells and modulating the immune response. Thus, Assertion (A) is true.
2. Reason (R) Analysis: Interferons primarily act by signaling to uninfected cells to produce antiviral proteins, thereby making them resistant to viral infection. They also activate natural killer (NK) cells and macrophages. Interferons do not directly cause inflammation of virus-infected cells. Inflammation is a broader immune response involving various mediators, and while interferons can …

Concept and Intuition

Our bodies have a sophisticated defense system against pathogens like viruses. When a cell gets infected by a virus, it's not a passive victim; it actively tries to alert its neighbors and the broader immune system. One crucial way it does this is by producing signaling molecules called interferons.

Interferons are a type of cytokine (cell-signaling protein) that play a vital role in the innate immune response, particularly against viral infections. Their primary function is to "interfere" with viral replication. They achieve this mainly by:

1. Signaling to uninfected cells: Interferons bind to receptors on nearby healthy cells, prompting them to produce antiviral proteins. These proteins can then block viral replication if those cells become infected. This is like putting up a protective shield around healthy cells.
2. Activating immune cells: Interferons also activate various immune cells, such as Natural Killer (NK) cells and macrophages, which are crucial for destroying virus-infected cells and clearing the infection.
3. Modulating immune responses: They can also influence the adaptive immune system.

Inflammation, on the other hand, is a complex biological response of vascular tissues to harmful stimuli, such as pathogens, damaged cells, or irritants. It's characterized by redness, swelling, heat, pain, and loss of function. While interferons are part of the broader immune response that can contribute to inflammation by activating immune cells, their direct action is not to cause inflammation of the virus-infected cells themselves. Instead, they focus on protecting uninfected cells and orchestrating the elimination of infected ones.

Step-by-Step Evaluation

1. Evaluate Assertion (A): "Virus-infected cells produce interferons."

   • When a virus infects a cell, the cell recognizes viral components (like viral RNA or DNA). This recognition triggers a signaling pathway within the infected cell, leading to the production and secretion of interferons (specifically Type I interferons, such as IFN-alpha and IFN-beta). These interferons are then released into the extracellular space.
   • This statement accurately describes a fundamental aspect of the innate antiviral immune response.
   • Therefore, Assertion (A) is true.

2. Evaluate Reason (R): "Interferons can cause inflammation of virus-infected cells."

   • As discussed, the primary role of interferons is to induce an antiviral state in neighboring uninfected cells and to activate other immune cells to clear the infection. They do not directly cause inflammation of the virus-infected cells. …