The major antibody in the second exposure is IgG and in the first exposure it is IgM. IgG and IgM would be produced by Plasma Cells, which are effector B-Cells activated by Cytokines.
If you want to see which antibodies (not just antibody types) are produced by the B-Cell, I would suggest transforming a GFP gene into a Naive B cell and using a Restriction ...
There are too many questions embeded here to cover in a single answer. I'll summarize and answer what I interpret to be the "central" question.
How do animals A) locate, B) isolate, and C) contain/eliminate bacterial endotoxins?
LPS in the blood stream is rapidly bound by LPS-binding protein (LBP) and localized to the liver for detoxification and ...
"I think, though am not at all sure, that pathogens need to invade cells to be dangerous."
True in the case of viruses and some bacteria.
Hiding within the cells of the host is the intracellular pathogenesis.
But other "tricks" are possible. Four examples:
surface proteins that "catch" antibodies
fast mutation of ...
The following review has extensive answers to the complex of this question. They also include MERS and SARS-Cov-1 in their discussion, as there is good data on them.
Huang et al., A systematic review of antibody mediated immunity to coronaviruses: antibody kinetics, correlates of protection, and association of antibody responses with severity of disease
It's an interesting question.
More interestingly there are a number of articles and a lot of studies are going on to prove that by manipulating oral microbiota, Caries or Periodontal diseases can be prevented.
At this I want to point out as the OP has asked about the body's way of 'taming' the flora, I will share the references of the studies in which the ...