Utzschneider et al. have recently shown that TPEX early in chronic LCMV (docile) infection could be identified by high expression of BTB and CNC homolog 2 (BACH2), a basic leucine zipper transcription factor that exerts an oppositional transcriptional program to BATF, and by higher levels of accessible chromatin bearing BACH2 binding sites than TEX. The gene discussed is BACH2; the disease is infection.