TIM-family Proteins Promote Infection of Multiple Enveloped Viruses through Virion-associated Phosphatidylserine

Jemielity, Stephanie; Wang, Jinyize J.; Chan, Ying Kai; Ahmed, Asim A.; Li, Wenhui; Monahan, Sheena; Bu, Xia; Farzan, Michael; Freeman, Gordon J.; Umetsu, Dale T.; DeKruyff, Rosemarie H.; Choe, Hyeryun

EBOV and MARV entry was recently shown to critically depend on NPC1, a cholesterol-transporting protein located in the endo/lysosomal compartment [15] [16] [17] . To test whether hTIM1 usage by EBOV and MARV is dependent on NPC1, we used NPC1-null CHO cells (NPC1 2/2 ), as well as NPC1-null CHO cells engineered to overexpress mouse NPC1 (NPC1 2/2 mNPC1), which supports EBVO entry [36] . As expected based on our earlier results (Fig. 1) , EBOV pseudovirus entry, and to a lesser extent MARV entry, in NPC1 2/2 mNPC1 cells was increased in the presence of hTIM1 (right panels of Figs. 8A, B) . In contrast, the previously reported non-permissiveness of NPC1 2/2 cells to EBOV and MARV [15] was not circumvented by hTIM1 overexpression (left panels of Figs. 8A, B) . These data indicate that hTIM1 expression cannot overcome NPC1 dependence, confirm the role of NPC1 as a filovirus entry factor and suggest that hTIM1 itself may best be regarded as an attachment factor.