Expression and strain variation of the novel “small open reading frame” (smorf) multigene family in Babesia bovis

► The smorf gene family is the second largest in Babesia bovis. ► Smorf genes have a large hypervariable insertion in 20 of the 44 genes. ► The smorf gene repertoire varies between strains, with both conserved and unique genes in each strain. ► Multiple smorf genes are transcribed and expressed in merozoites.