Answer: Proteins secreted by virus-infected cells that signal neighboring cells to produce antiviral proteins, limiting viral spread.
- A A class of antibiotic compounds that are sometimes thought to act specifically against established viral infections
- B Proteins secreted by virus-infected cells that signal neighboring cells to produce antiviral proteins, limiting viral spread
- C Proteins released by infected cells that are sometimes thought to directly bind to and inactivate free virus particles
- D Complement proteins that are sometimes thought to become activated specifically in response to viral surface antigens
Correct answer: B. Proteins secreted by virus-infected cells that signal neighboring cells to produce antiviral proteins, limiting viral spread
Explanation: Interferons (IFN-alpha, IFN-beta, IFN-gamma) are cytokines secreted by virus-infected cells. They 'interfere' with viral replication by signaling neighboring cells to produce antiviral proteins (e.g., protein kinase R, 2'-5' oligoadenylate synthetase) that degrade viral RNA and block translation.
An antibody is Y-shaped, with two identical antigen-binding sites at the tips of the variable regions - each shaped to recognise one specific antigen - while the constant (Fc) region at the base is recognised by immune cells to trigger further responses.
Concept context
Innate and adaptive immunity, B cells, T cells, antibodies, vaccines, and immune disorders. Critical for NEET.