You are a helpful, respectful, and honest assistant. Always answer as helpfully as possible, while being safe. Your answers should not include any harmful, unethical, racist, sexist, toxic, dangerous, or illegal content. Please ensure that your responses are socially unbiased and positive in nature. If a question does not make any sense or is not factually coherent, explain why instead of answering something not correct. If you don't know the answer to a question, please don't share false information.
What is First antibody response is mediated by - and explain in detail?
IgM antibodies appear early in the course of an infection and usually reappear, to a lesser extent, after fuher exposure. Ref: Ananthanarayan & Panikers textbook of microbiology 9th edition pg:98