CD2v Interacts with Adaptor Protein AP-1 during African Swine Fever Infection

Abstract

African swine fever virus (ASFV) CD2v protein is believed to be involved in virulence enhancement, viral hemadsorption, and pathogenesis, although the molecular mechanisms of the function of this viral protein are still not fully understood. Here we describe that CD2v localized around viral factories during ASFV infection, suggesting a role in the generation and/or dynamics of these viral structures and hence in disturbing cellular traffic. We show that CD2v targeted the regulatory trans-Golgi network (TGN) protein complex AP-1, a key element in cellular traffic. This interaction was disrupted by brefeldin A even though the location of CD2v around the viral factory remained unchanged. CD2v-AP-1 binding was independent of CD2v glycosylation and occurred on the carboxy-terminal part of CD2v, where a canonical di-Leu motif previously reported to mediate AP-1 binding in eukaryotic cells, was identified. This motif was shown to be functionally interchangeable with the di-Leu motif present in HIV-Nef protein in an AP-1 binding assay. However, we demonstrated that it was not involved either in CD2v cellular distribution or in CD2v-AP-1 binding. Taken together, these findings shed light on CD2v function during ASFV infection by identifying AP-1 as a cellular factor targeted by CD2v and hence elucidate the cellular pathways used by the virus to enhance infectivity.

Deletion of CD2-Like (CD2v) and C-Type Lectin-Like (EP153R) Genes from African Swine Fever Virus Georgia-∆9GL Abrogates Its Effectiveness as an Experimental Vaccine

“…In addition, the presence of CD2v produced decreased lymphoproliferative responses in swine peripheral blood mononuclear cells to specific white cell mitogens [ 18 ], although the immunomodulatory role of the protein remains to be shown. The interaction of CD2v with host protein AP-1 has been described [ 30 ] and believed to modulate vesicle transport, although the importance of that interaction during the processes of virus replication or virulence are currently unknown. Regarding EP153R, it has an inhibitory effect on the caspase-3 activation and the apoptosis induced both in ASFV-infected cells and in cell lines transfected, either stably or transiently, with the EP153R gene and is treated with different pro-apoptotic stimuli [ 31 ].…”

A Proteomic Atlas of the African Swine Fever Virus Particle

“…Of the 26 virus-encoded proteins with predicted transmembrane domains (5), 15 were detected in the virus proteome, which represents 22% (15 of 68) of the total virus-packaged proteins. Whereas some have been studied with some detail (p17 [pD117L], pE183L, p12 [pO61R], p22 [pKP177L], pE248R, pE199L, pEP152R, pEP402R) (30,31,(40)(41)(42)(43)(44)(45)(46)(47), about half of them remain uncharacterized. This includes proteins pCP123L, pI177L, pE146L, pC257L, and pB117L, which contain a single putative transmembrane segment, and proteins pB169L and pEP84R with two membrane domains.…”

“…Protein pEP402R has been shown to be responsible for the adhesion of erythrocytes to infected cells and for the binding of ASFV particles to erythrocytes. Intriguingly, it has been localized to the Golgi network around the virus factories but not at the cell surface (47,50). To ascertain the subviral localization of membrane proteins p22 and pEP402R, we performed immunogold labeling on cryosections of ASFV-infected cells.…”

Approaches and Perspectives for Development of African Swine Fever Virus Vaccines

“…These molecules may also include intracellular host proteins. For example, cellular proteins involved in virus release from endosomes to the cytoplasm or transport within the cytoplasm may be important [ 101 , 102 ]. The CD2v/EP402Rp interaction with the cellular adaptor AP-1 may be involved in movement of the viral particle, and thus have consequences for virulence and immune escape [ 101 ].…”