2024-03-29T11:53:08Zhttp://digital.csic.es/dspace-oai/requestoai:digital.csic.es:10261/2161462022-11-29T10:13:51Zcom_10261_79com_10261_1col_10261_332
00925njm 22002777a 4500
dc
Martínez-Vicente, Pablo
author
Farre, Doménec
author
Sánchez, Carolina
author
Alcamí, Antonio
author
Engel, Pablo
author
Angulo, Ana
author
2019-04-04
Throughout evolution, cytomegaloviruses (CMVs) have been capturing genes from their hosts, employing the derived proteins to evade host immune defenses. We have recently reported the presence of a number of CD48 homologs (vCD48s) encoded by different pathogenic viruses, including several CMVs. However, their properties and biological relevance remain as yet unexplored. CD48, a cosignaling molecule expressed on the surface of most hematopoietic cells, modulates the function of natural killer (NK) and other cytotoxic cells by binding to its natural ligand 2B4 (CD244). Here, we have characterized A43, the vCD48 exhibiting the highest amino acid sequence identity with host CD48. A43, which is encoded by owl monkey CMV, is a soluble molecule released from the cell after being proteolytically processed through its membrane proximal region. A43 is expressed with immediate-early kinetics, yielding a protein that is rapidly detected in the supernatant of infected cells. Remarkably, surface plasmon resonance assays revealed that this viral protein binds to host 2B4 with high affinity and slow dissociation rates. We demonstrate that soluble A43 is capable to abrogate host CD48:2B4 interactions. Moreover, A43 strongly binds to human 2B4 and prevents 2B4-mediated NK-cell adhesion to target cells, therefore reducing the formation of conjugates and the establishment of immunological synapses between human NK cells and CD48-expressing target cells. Furthermore, in the presence of this viral protein, 2B4-mediated cytotoxicity and IFN-γ production by NK cells are severely impaired. In summary, we propose that A43 may serve as a functional soluble CD48 decoy receptor by binding and masking 2B4, thereby impeding effective NK cell immune control during viral infections. Thus, our findings provide a novel example of the immune evasion strategies developed by viruses.
PLoS Pathogens 15 (2019)
http://hdl.handle.net/10261/216146
10.1371/journal.ppat.1007658
http://dx.doi.org/10.13039/501100003329
30947296
Subversion of natural killer cell responses by a cytomegalovirus-encoded soluble CD48 decoy receptor