Cytomegalovirus US28 regulates cellular EphA2 to maintain viral latency

Abstract

Cytomegalovirus (CMV) reactivation from latency following immune dysregulation remains a serious risk for patients, often causing substantial morbidity and mortality. Here, we demonstrate the CMV-encoded G protein–coupled receptor, US28, in coordination with cellular Ephrin receptor A2, attenuates mitogen-activated protein kinase signaling, thereby limiting viral replication in latently infected primary monocytes. Furthermore, treatment of latently infected primary monocytes with dasatinib, a Food and Drug Association–approved kinase inhibitor used to treat a subset of leukemias, results in CMV reactivation. These ex vivo data correlate with our retrospective analyses of the Explorys electronic health record database, where we find dasatinib treatment is associated with a significant risk of CMV-associated disease (odds ratio 1.58, P = 0.0004). Collectively, our findings elucidate a signaling pathway that plays a central role in the balance between CMV latency and reactivation and identifies a common therapeutic cancer treatment that elevates the risk of CMV-associated disease.

Virion-associated US28 rapidly modulates Akt activity to suppress HCMV lytic replication in monocytes

“…US28 expression is essential for HCMV latency in CD34+ HPCs ( 12, 14, 15, 17 ), THP1 cells ( 10, 15, 35 ), Kasumi-3 cells ( 12, 14, 15 ), and monocytes ( 10, 36, 37 ). Accordingly, we found infection of CD14+ primary peripheral blood monocytes with an HCMV mutant lacking US28 (US28Δ) failed to establish a quiescent infection, leading to rapid IE1 protein expression at 24 through 48 hours post-infection (hpi) similar to WT infection in replication permissive fibroblasts ( Fig.…”

“…However, mechanisms by which HCMV promotes the establishment of a quiescent infection within monocytes remain unclear. US28 is essential for latency/quiescence in CD34+ HPCs ( 12, 14, 15, 17 ), THP1 cells ( 10, 15, 35 ), Kasumi-3 cells ( 12, 14, 15 ), and monocytes ( 10, 36, 37 ); thus, we sought to determine the mechanism through which US28 promotes the establishment of a quiescent infection within monocytes. Herein, we demonstrate that virion-associated US28 is necessary and sufficient to dampen EGFR signaling to limit Akt activity triggered by HCMV entry.…”

“…US28 also modulates multiple cellular pathways during lytic infection, including calcium signaling ( 20, 21 ), FAK/Src ( 29 ), PLC ( 20, 30 ), COX-2 ( 31 ), STAT3 ( 32 ), Akt, ERK1/2, eNOS ( 33 ), beta-catenin ( 34 ). Importantly, US28 is essential for viral latency/quiescence in cells of the myeloid lineage, including CD34+ HPCs ( 12, 14, 15, 17 ), THP1 cells ( 10, 15, 35 ), Kasumi-3 cells ( 12, 14, 15 ), and monocytes ( 10, 36, 37 ). During latency, US28-mediated signaling silences the major immediate-early promoter (MIEP) ( 10, 12, 14, 15 ), a key promoter in the latent-to-lytic switch that regulates the expression of immediate-early 1 (IE1) and immediate-early 2 (IE2) viral proteins, encoded by UL123 and UL122 , respectively.…”

Bacterial-Artificial-Chromosome-Based Genome Editing Methods and the Applications in Herpesvirus Research

“…The galK gene is a dual-selection cassette widely used in genome editing of herpesviruses [ 82 , 83 , 84 ]. The galK gene encodes galactokinase, which allows galK -deficient E. coli to grow on the medium with galactose as the sole carbon source during positive selection.…”

Therapeutic targeting of HCMV-encoded chemokine receptor US28: Progress and challenges

“…This effect is in part mediated by suppression of the mitogen-activated protein kinase (MAPK) and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) signaling pathways ( 25 ). Attenuation of MAPK signaling was recently shown to be the result of US28 interacting with the ephrin receptor A2 (EphA2) ( 30 ), whereas NF-κB signaling is subdued through rapid downregulation of interferon gamma inducible protein 16 (IFI16) by US28 ( 31 ). These functions underline an importance for HCMV immune evasion.…”