A 46-year-old man presents to the emergency department with sudden-onset fever, headache, and nuchal rigidity. His history is notable for a splenectomy following a motor vehicle accident 5 years ago. On examination, he is febrile to 39.5°C, photophobic, and has a positive Kernig sign. Lumbar puncture yields cloudy cerebrospinal fluid with a neutrophilic pleocytosis. Gram stain reveals gram-negative diplococci that are optochin-resistant. A quellung reaction is positive. Which of the following best explains how this organism’s capsule contributes to its virulence?