Infection with L. monocytogenes produces an antibody response, but this response is not very protective. Explain why this is so. Also, make an educated guess as to why adults exhibit only mild...

Infection with L. monocytogenes produces an antibody response, but this response is not very protective. Explain why this is so. Also, make an educated guess as to why adults exhibit only mild symptoms whereas intrauterine infections or infections of immunocompromised people can be serious.