Not an expert, but I've read that the antigen presenting cells break down the antigen into short peptides too (8-20 amino acids) when creating antibodies. One

Not an expert, but I've read that the antigen presenting cells break down the antigen into short peptides too (8-20 amino acids) when creating antibodies. One might however still ask if the body is better at selecting exactly which portions are cut and chosen than however these were selected. Also, if the antigen is small from the start, that might have implications too (like being ignored).