Which exterior structure helps some prokaryotes evade the host immune system?

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A protective polysaccharide capsule is the exterior structure that helps some prokaryotes evade the host immune system. This slimy layer acts as a shield that makes it harder for immune cells to recognize and engulf the bacteria. It reduces the binding of antibodies and complement, so phagocytes are less able to opsonize and digest the invader. In some cases, the capsule can also mimic host molecules, further dampening immune recognition and response.

The rigid cell wall provides structural support and helps resist osmotic stress but isn’t mainly about evading immune detection. The outer membrane of Gram-negative bacteria is a barrier that controls permeability, not primarily a stealth shield against immune cells. Pili or flagella are surface structures used for attachment and movement and are often targets of the immune response rather than shields. capsule.