Splicing-dependent restriction of the HBZ gene by Tax underlies biphasic HTLV-1 infection

HTLV-1 is an oncovirus that encodes a transactivator Tax and a latent oncogene HBZ. While HTLV-1 early or infectious replication depends on Tax, latent HTLV-1 persists or propagates as a chromatin-integrated provirus driven primarily by HBZ. The biphasic replication pattern of HTLV-1 dictated by Tax and HBZ represents a result of viral host adaptation, but how HTLV-1 coordinates Tax and HBZ expression to facilitate early and late infection remains elusive.