After reading an article, I saw expressions like "cross-immunoreactivity among epitopes", "cross-immunoreactivity among variants of virus", "immunological reactions among pairs of peptides" and so on.
I wish to verify my following understandings:
An epitope is also called antigenic determinant, and it is part of the antigen that is recognized by the antibody. An epitope, then, is a part of a virus variant. Peptides are short chains of amino acids. Thus, we can talk about the immunological reactions among peptide-pairs, because the virus variant itself is a protein, which is composed of peptides? Did I understand it correctly?
Moreover, I saw a sentence like "this antibody is against a few variants while reacting with all tested peptides", so I guess reacting here includes against? Reacting may include other situations, right?