Evading innate immunity during human cytomegalovirus latency

NIH RePORTER · NIH · R01 · $355,828 · view on reporter.nih.gov ↗

Abstract

Innate immunity senses intracellular pathogens and induces the expression of cellular genes with antiviral functions. Most if not all viruses encode proteins that inhibit innate immunity during productive, lytic infections, but the role of innate immunity during viral latency is underappreciated and understudied. Latency permits human cytomegalovirus (HCMV) to colonize its hosts for their lifetime by avoiding immune detection and clearance. During latency, the levels of lytic (productive) phase HCMV proteins such as IE1 (Immediate Early 1) are kept extremely low (or completely absent) because the promoter that drives its expression, the Major Immediate Early Promoter (MIEP) is transcriptionally silenced by heterochromatin. IE1 is a transcription factor that promotes progression through the viral lytic phase and is a target of cytotoxic T cells. Therefore, keeping IE1 protein levels low or absent protects latently infected cells from immune surveillance and restricts reactivation events until the proper stimulus is sensed. We published that the viral UL138 protein silences IE1 transcription during latency by inhibiting the recruitment of lysine- specific demethylases (KDMs) to the MIEP that otherwise remove repressive epigenetic histone methylations to activate transcription. Our preliminary data indicates this occurs, in part, through a suppression of cellular innate immune pathways. Here we propose to determine how UL138-mediated evasion of cellular innate immunity contributes to the establishment and maintenance of HCMV latency, with a particular focus on viral epigenetics and the transcriptional silencing of IE1.

Key facts

NIH application ID
10137186
Project number
5R01AI139180-04
Recipient
UNIVERSITY OF WISCONSIN-MADISON
Principal Investigator
ROBERT F KALEJTA
Activity code
R01
Funding institute
NIH
Fiscal year
2021
Award amount
$355,828
Award type
5
Project period
2018-05-02 → 2023-04-30