Human herpesvirus 6 (HHV6) is an opportunistic pathogen whose infection or reactivation is associated with diseases such as roseola, central nervous system disorders and organ transplant anomalies. Following its entry into the host cell, the virus utilizes the cellular machinery in order to transcribe its genes and insure the replicative cycle progression. HHV-6 can also latently persist in its host. Immediate-early proteins are rapidly expressed upon cell infection. In particular, IE1 and IE2 proteins play an important role in the establishment of infection. IE1 inhibits interferon-b transcription and may participate in the PML nuclear body aggregation induced by the viral infection. IE2 is a strong transactivator of multiple cell and viral promoters, and contributes to the initiation of the replicative cycle. In this review we have synthesized the current body of knowledge pertaining to the immediate early phase of HHV6 infection, including the role of immediate-early proteins in the replicative cycle and during latency, as well as that of the promoter who regulates their expression.
Keywords: Human herpesvirus 6; IE1; IE2; immediate-early proteins.