Parasites of the genus Trypanosoma evade immune responses through what defense mechanism?

• A. Complement activation
• B. Antigenic variation
• C. Phagocytosis
• D. Apoptosis

Answer: (B)

Verified step by step guidance

1. Understand the context: Trypanosoma is a genus of parasitic protozoa that can cause diseases such as sleeping sickness in humans. These parasites need to evade the host's immune system to survive and proliferate.
2. Identify the immune evasion strategies: Parasites have developed various mechanisms to avoid detection and destruction by the host's immune system. Common strategies include antigenic variation, complement activation inhibition, and avoiding phagocytosis.
3. Focus on antigenic variation: This is a process where the parasite changes its surface proteins to avoid recognition by the host's immune system. By frequently altering these proteins, the immune system struggles to mount an effective response.
4. Differentiate from other mechanisms: Complement activation is a part of the immune response that helps clear pathogens, not a mechanism used by parasites to evade the immune system. Phagocytosis is a process where cells engulf and digest pathogens, and apoptosis is programmed cell death, neither of which are evasion strategies used by Trypanosoma.
5. Conclude with the correct mechanism: The primary defense mechanism used by Trypanosoma to evade immune responses is antigenic variation, allowing it to persist in the host by continuously changing its surface antigens.