摘要：

Ebola viruses, and other members of the family filoviridae, are enveloped, negative sense, RNA viruses that can cause hemorrhagic fever. Currently, there are no antivirals or approved vaccines available that target or protect from Ebola virus infection. However, recently, T-cell immunoglobulin and mucin domain-1 (TIM-1) has been identified as an epithelial-cell receptor for filoviruses and could be a potential target for antivirals. However, little is known about how TIM-1 enhances virus entry and the role of TIM-1 during in vivo infection. In order to determine the key residues of TM-1 involved in interaction with virus, we generated a panel of point-mutations in the immunoglobulin-like variable (IgV) domain of TIM-1. We determined that several residues within the IgV domain that are involved in binding of phosphatidylserine (PtdSer) are also critical for Ebola virus entry. Further, we found that TIM-1 interacts with Ebola virus through binding of PtdSer on the viral envelope. PtdSer liposomes, but not phosphatidylcholine liposomes, competed with TIM-1 for EBOV pseudovirion binding and transduction. In addition, annexin V (AnxV) substituted for the TIM-1 IgV domain, supporting a PtdSer-dependent mechanism. Our findings suggest that TIM-1-dependent uptake of EBOV occurs by apoptotic mimicry. We also determined that TIM-1 expression can enhance infection of a wide range of enveloped viruses, including alphaviruses and a baculovirus. As further evidence of the critical role of enveloped virion associated PtdSer in TIM-1-mediated uptake, TIM-1 enhanced internalization of pseudovirions and virus-like particles (VLPs) lacking a glycoprotein, providing evidence that TIM-1 and PtdSer-binding receptors can mediate virus uptake independent of a glycoprotein. These results provide evidence for a broad role of TIM-1 as a PtdSer-binding receptor that mediates enveloped virus uptake. The PtdSer-binding activity of the IgV domain is essential for both virus binding and internalization by TIM-1. However, another member of the TIM family, TIM-3, whose IgV domain also binds PtdSer, does not effectively enhance virus entry. These data indicate that other domains of TIM proteins are functionally important. We investigated the domains of the TIM family members that play a role in the enhancement of enveloped virus entry, thereby defining the features necessary for a functional PVEER. Using a variety of chimeras and deletion mutants, we found that in addition to a functional PtdSer binding domain PVEERs require a stalk domain of sufficient length, containing sequences that promote an extended structure. Neither the cytoplasmic nor the transmembrane domain of TIM-1 is essential for enhancing virus

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