ANK1 and scrub typhus: [51] were found to react strongly with immune sera and could be utilized as target antigens for serodiagnosis. Considering our results, O. tsutsugamushi Ank proteins may not be an effective target for this purpose. Nevertheless, we detected active transcription of several ank genes in O. tsutsugamushi-infected cells and specific antibody responses in human scrub typhus patients, indicating that Ank proteins might be expressed in mammalian host cells after O. tsutsugamushi infection.