Final answer:
Developing a vaccine against Neisseria gonorrhoeae is challenging due to the antigenic variability of the pili protein, enabling the bacterium to evade the host's immune system.
Step-by-step explanation:
Difficulties in Developing a Vaccine Against Neisseria gonorrhoeae
The issue of developing a vaccine against Neisseria gonorrhoeae, the bacterium responsible for the sexually transmitted infection gonorrhea, is complicated due to the pathogen's sophisticated antigenic variation mechanisms. One of the key difficulties lies in the antigenic variability of the pili protein. These type IV pili of N. gonorrhoeae are known for their ability to undergo structural changes to avoid immune detection by the host, which presents a significant challenge in creating an effective and long-lasting vaccine. In addition to these challenges, antibiotic resistance in N. gonorrhoeae is noted by the CDC as an urgent threat, making vaccine development an imperative but complex task.
Therefore, the answer to the student's question is option 1) Antigenic variability of the pili protein.