    Sentence E What kind of amino  acids are overrepresented — in  epitope regions?    Sentence 2: Early techniques relied  nainty om the observation that  hydrophilic amino acids are  overrepresented in epitope regions  hydrophobic ami acids,  however, more recent developments   on machine learning  niques using databases of  existing known epitopes, usually on  well-studied virus proteins, as a  training set.                        