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

The efficiency with which viruses utilize PS receptors also appears to be dependent on the cellular background. For example, we show that overexpression of hTIM1 had a lesser effect on viral entry in 3T3 compared to 293T cells (Fig. 1) . This difference may be due to cell-specific expression of various endogenous PS receptors. Consistent with this explanation, 3T3 cells express Axl [60, 61] , while 293T cells do not [11, 35] . In addition, WNV VLPs, which do not efficiently utilize Axl (Fig. 7A) , were the only VLP/ pseudovirus showing strong TIM1-mediated entry enhancement in 3T3 cells (Fig. 1D ). This example emphasizes that results obtained with specific cell lines need to be generalized with caution.