How does the poliovirus particle evolve to be structurally stable?

• A. It is adapted to survive in acidic pH environments.
• B. It is resistant to ultraviolet light.
• C. It has multiple DNA repair mechanisms.
• D. It becomes larger in neutral pH.

Answer: (A)

Enteric viruses must survive the acidic environment of the stomach to reach the intestines and spread via the fecal-oral route. To accomplish this, the poliovirus particle is built to be acid-stable, meaning its capsid stays intact even under low pH. The non-enveloped icosahedral shell formed by its capsid proteins is tightly packed and resistant to proton-induced disruption, protecting the RNA genome during stomach passage and ensuring it remains infectious when it reaches its target cells in the gut.

This stability is not about UV resistance, which helps environmental survival in some contexts but isn’t the defining feature for enabling transmission through the acidic stomach. Poliovirus, being an RNA virus, lacks DNA repair mechanisms as a functional requirement. And increasing size in neutral pH wouldn’t confer a stability advantage or reflect how the virion maintains integrity. The acid-stable design directly supports successful transmission and infection, making it the best explanation.