A group of researchers have isolated a new bacterium, W, from the lymph nodes of several patients who returned from a camping trip and presented in the emergency room with high fever, rash, and...

A group of researchers have isolated a new bacterium, W, from the lymph nodes of several patients who returned from a camping trip and presented in the emergency room with high fever, rash, and swollen lymph nodes. The bacterium produces a unique surface protein (called OmpW) and an unusual polysaccharide capsule (called WPS) that the researchers can see on the surfaces of the bacteria in electron micrographs from fresh isolates (bacteria just obtained from the patients). However, after culturing the bacteria in vitro on agar plates, they find that most of the bacteria still have OmpW but no longer have WPS on their surfaces. The researchers also find that bacterium W binds to and invades phagocytic cells and inhibits their function.

A. The researchers propose that OmpW and WPS might make excellent targets for development of a vaccine against bacterium W. What led the researchers to propose this?

B. The researchers find that a vaccine made of WPS alone does not evoke long-lasting immune responses. How does it elicit an immune response? What strategy could the researchers use to generate long-lasting immunity to bacterium W using WPS as part of the vaccine?