This family consists of a number of exported protein precursor (EppA and BapA) sequences which seem to be specific to Borrelia burgdorferi (Lyme disease spirochete). bapA gene sequences are quite stable but the encoded proteins do not provoke a strong immune response in most individuals. Conversely, EppA proteins are much more antigenic but are more variable in sequence. It is thought that BapA and EppA play important roles during the Borrelia burgdorferi infectious cycle [1].

1: Immunological and genetic characterization of Borrelia burgdorferi BapA and EppA proteins. Miller JC, Stevenson B; Microbiology 2003;149:1113-1125. PMID:12724373