Natural Killer Cell Evasion Is Essential for Infection by Rhesus Cytomegalovirus

Sturgill, Elizabeth R.; Malouli, Daniel; Hansen, Scott G.; Burwitz, Benjamin J.; Seo, Seongkyung; Schneider, Christine L.; Womack, Jennie; Verweij, Marieke C.; Ventura, Abigail B.; Bhusari, Amruta; Jeffries, Krystal; Legasse, Alfred W.; Axthelm, Michael K.; Hudson, Amy W.; Sacha, Jonah B.; Picker, Louis J.; Früh, Klaus

doi:10.1371/journal.ppat.1005868

Cited by 37 publications

(37 citation statements)

References 56 publications

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“…Lastly, we sought to gain insight into whether the effects of UL148 on the ER and on CD58 surface expression might be conserved by assaying HCMV UL148 against its homologs from other primate CMVs. Rh159, the rhesus CMV homolog, shares 25% amino acid identity with HCMV UL148 and has been shown to retain NKG2D receptor activating ligands of the MIC- and ULBP families (7). Furthermore, Rh159 fails to activate the UPR and does not appear to remodel ER membranes (23, 24).…”

Section: Resultsmentioning

confidence: 99%

“…Taken together, our findings highlight the various functionally divergent roles among three different UL148 homologs in CMVs endemic to humans, rhesus macaques, and chimpanzees. While all three proteins act as ER-resident immunevasins, the rhesus CMV homolog lacks the potential to trigger the UPR (29, 30), and apparently functions to evade NK cells by preventing MIC- and ULBP family NKG2D ligands from reaching the cell surface (7). Chimpanzee and human CMV UL148 target CD58 instead of NKG2D ligands [(13), FIG 3 )], but only HCMV UL148 is capable of remodeling the ER ( FIG 6 ), a property that appears to depend on the capacity of UL148 to activate the integrated stress response downstream of UPR activation (30).…”

Section: Discussionmentioning

confidence: 99%

“…CMVs have evolved a number of functions that dampen antiviral responses that would otherwise produce sterilizing immunity. Rodent and primate cytomegalovirus (CMV) species, such as mouse cytomegalovirus (MCMV) and human cytomegalovirus (HCMV), express a large number of proteins and microRNAs that interfere with antigen presentation and prevent activation of cytotoxic T cells and NK cells [reviewed in (3–6)], (7). In HCMV, several viral gene products involved in immune evasion, such as UL141 (8, 9), UL142 (10–12), and UL148 (13), are encoded within a region of the genome termed the ‘UL b’ ,’ which undergoes extensive rearrangements and deletions during extensive serial passage in cultured cells (14–16).…”

Section: Introductionmentioning

confidence: 99%

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ER reorganization and intracellular retention of CD58 are functionally independent properties of the human cytomegalovirus ER resident glycoprotein UL148

Nguyen

Zhang

et al. 2019

Preprint

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The human cytomegalovirus (HCMV) endoplasmic reticulum (ER)-resident glycoprotein UL148 is posited to play roles in immune evasion and regulation of viral cell tropism. UL148 prevents cell surface presentation of the immune cell costimulatory ligand CD58 while promoting maturation and virion incorporation of glycoprotein O, a receptor binding subunit for an envelope glycoprotein complex involved in entry. Meanwhile, UL148 activates the unfolded protein response (UPR) and causes large-scale reorganization of the ER. In an effort to determine whether the seemingly disparate effects of UL148 are related or discrete, we generated charged-cluster-to-alanine (CCTA) mutants of six charged clusters within the UL148 ectodomain, and compared them against wildtype UL148, in the context of recombinant viruses and in ectopic expression, assaying for effects on ER remodeling and CD58 surface presentation. Two mutants, targeting charged clusters spanning residues 79-83 (CC3) and 133-136 (CC4), respectively, retained the potential to impede CD58 presentation, and did so to an extent comparable to wildtype. Of the six mutants, only CC3 retained the capacity to reorganize the ER, showing a partial phenotype. Wildtype UL148 accumulates in a detergent-insoluble form during infection. However, all six CCTA mutants were fully soluble, which may imply a relationship between insolubility and organelle remodeling. Additionally, we found that the chimpanzee cytomegalovirus UL148 homolog suppresses CD58 presentation but fails to reorganize the ER, while the homolog from rhesus cytomegalovirus shows neither activity. Collectively, our findings illustrate varying degrees of functional divergence between homologous primate cytomegalovirus immunevasins and suggest that ER reorganization is unique to HCMV UL148.IMPORTANCEIn myriad examples, viral gene products cause striking effects on cells, such as activation of stress responses. It can be challenging to decipher how such effects contribute to the biological roles of the proteins. The HCMV glycoprotein UL148 retains CD58 within the ER, thereby preventing it from reaching the cell surface where it functions to stimulate cell-mediated antiviral responses. Intriguingly, UL148 also triggers the formation of large, ER-derived membranous structures, and activates the UPR, a set of signaling pathways involved in adaptation to ER stress. We demonstrate that the potential of UL148 to reorganize the ER and to retain CD58 are separable by mutagenesis and possibly, by evolution, since chimpanzee cytomegalovirus UL148 retains CD58 but does not remodel the ER. Our findings imply that ER reorganization contributes to other roles of UL148, such as modulation of alternative viral glycoprotein complexes that govern the virus’ ability to infect different cell types.

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Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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ER reorganization and intracellular retention of CD58 are functionally independent properties of the human cytomegalovirus ER resident glycoprotein UL148

Nguyen

Zhang

et al. 2019

Preprint

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“…Intriguingly, UL148 causes markedly reduced N-glycosylation of CD58 (20), which is exactly the opposite of its effect on gO (16, 19). Rh159, which shares significant sequence homology with UL148 and is involved in retention of a distinct set of costimulatory molecules(18), does not appear to activate the UPR (Figs. 1-3).…”

Section: Discussionmentioning

confidence: 99%

The human cytomegalovirus ER resident glycoprotein UL148 activates the unfolded protein response

Siddiquey

Nguyen

Domma

et al. 2018

Preprint

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17Eukaryotic cells are equipped with three sensors that respond to the accumulation of 18 misfolded proteins within the lumen of the endoplasmic reticulum (ER) by activating the 19 unfolded protein response (UPR), which functions to resolve proteotoxic stresses 20 involving the secretory pathway. Here, we identify UL148, a viral ER resident 21 glycoprotein from human cytomegalovirus (HCMV) as an inducer of the UPR. Metabolic 22labeling results indicate that global mRNA translation is markedly decreased when 23 UL148 expression is induced in uninfected cells. Further, we find evidence suggesting 24 that ectopic expression of UL148 is sufficient to activate at least two UPR sensors: the 25 inositol requiring enzyme-1 (IRE1), as indicated by splicing of Xbp1 mRNA, and the 26 PKR-like ER kinase (PERK), as indicated by phosphorylation of eIF2 and 27 accumulation of ATF4 protein. During WT HCMV infection, Xbp-1 splicing, eIF2 28 phosphorylation and ATF4 accumulation neatly accompanied the onset of UL148 29 expression. However, the appearance of these UPR indicators was either markedly 30 delayed or absent during UL148-null infections. siRNA depletion of PERK dampened 31 the extent of eIF2 phosphorylation and ATF4 induction observed during WT infection, 32 further implicating PERK as opposed to other eIF2 kinases. Finally, UL148-null 33 infections showed statistically significant 2-to 4-fold decreases in the levels of 34 transcripts canonically regulated by PERK/ATF4 and by the ATF6 pathway, when 35 compared to WT virus infection. Taken together, our results argue that UL148 is 36 sufficient to activate the UPR when expressed ectopically and that UL148 is an 37 important cause of UPR activation in the context of the HCMV infected cell. 38 39 3 IMPORTANCE. 40

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“…Immune evasion mechanisms that contribute to infection persistence have been found to be similar between rhesus monkeys and humans. Specifically, induction of the cellular interleukin-10 signaling pathway and avoidance of natural killer cell activation, via preventing NKG2D ligand surface expression, contributes to RhCMV and HCMV viral persistence [32–35]. …”

Section: Rhcmv Acquisition and Persistencementioning

confidence: 99%

Rhesus monkeys for a nonhuman primate model of cytomegalovirus infections

Itell

Kaur

Deere

et al. 2017

Current Opinion in Virology

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Human cytomegalovirus (HCMV) is the leading opportunistic viral infection in solid organ transplant patients and is the most common congenitally transmitted pathogen worldwide. Despite the significant burden of disease HCMV causes in immunosuppressed patients and infected newborns, there are no licensed preventative vaccines or effective immunotherapeutic treatments for HCMV, largely due to our incomplete understanding of the immune correlates of protection against HCMV infection and disease. Though CMV species-specificity imposes an additional challenge in defining a suitable animal model for HCMV, nonhuman primate (NHP) CMVs are the most genetically related to HCMV. In this review, we discuss the advantages and applicability of rhesus monkey models for studying HCMV infections and pathogenesis and ultimately informing vaccine development.

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Natural Killer Cell Evasion Is Essential for Infection by Rhesus Cytomegalovirus

Cited by 37 publications

References 56 publications

ER reorganization and intracellular retention of CD58 are functionally independent properties of the human cytomegalovirus ER resident glycoprotein UL148

ER reorganization and intracellular retention of CD58 are functionally independent properties of the human cytomegalovirus ER resident glycoprotein UL148

The human cytomegalovirus ER resident glycoprotein UL148 activates the unfolded protein response

Rhesus monkeys for a nonhuman primate model of cytomegalovirus infections

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