TIM-1 serves as a receptor for Ebola virus in vivo, enhancing viremia and pathogenesis

Abstract

Background T cell immunoglobulin mucin domain-1 (TIM-1) is a phosphatidylserine (PS) receptor, mediating filovirus entry into cells through interactions with PS on virions. TIM-1 expression has been implicated in Ebola virus (EBOV) pathogenesis; however, it remains unclear whether this is due to TIM-1 serving as a filovirus receptor in vivo or, as others have suggested, TIM-1 induces a cytokine storm elicited by T cell/virion interactions. Here, we use a BSL2 model virus that expresses EBOV glycoprotein to demonstrate the importance of TIM-1 as a virus receptor late during in vivo infection. Methodology/Principal findings Infectious, GFP-expressing recombinant vesicular stomatitis virus encoding either full length EBOV glycoprotein (EBOV GP/rVSV) or mucin domain deleted EBOV glycoprotein (EBOV GPΔO/rVSV) was used to assess the role of TIM-1 during in vivo infection. GFP-expressing rVSV encoding its native glycoprotein G (G/rVSV) served as a control. TIM-1-sufficient or TIM-1-deficient BALB/c interferon α/β receptor -/- mice were challenged with these viruses. While G/rVSV caused profound morbidity and mortality in both mouse strains, TIM-1-deficient mice had significantly better survival than TIM-1-expressing mice following EBOV GP/rVSV or EBOV GPΔO/rVSV challenge. EBOV GP/rVSV or EBOV GPΔO/rVSV in spleen of infected animals was high and unaffected by expression of TIM-1. However, infectious virus in serum, liver, kidney and adrenal gland was reduced late in infection in the TIM-1-deficient mice, suggesting that virus entry via this receptor contributes to virus load. Consistent with higher virus loads, proinflammatory chemokines trended higher in organs from infected TIM-1-sufficient mice compared to the TIM-1-deficient mice, but proinflammatory cytokines were more modestly affected. To assess the role of T cells in EBOV GP/rVSV pathogenesis, T cells were depleted in TIM-1-sufficient and -deficient mice and the mice were challenged with virus. Depletion of T cells did not alter the pathogenic consequences of virus infection. Conclusions Our studies provide evidence that at late times during EBOV GP/rVSV infection, TIM-1 increased virus load and associated mortality, consistent with an important role of this receptor in virus entry. This work suggests that inhibitors which block TIM-1/virus interaction may serve as effective antivirals, reducing virus load at late times during EBOV infection.

Frontline Science: CD40 signaling restricts RNA virus replication in Mϕs, leading to rapid innate immune control of acute virus infection

“…In these studies, we also extensively utilized a BSL‐2 model virus of EBOV, recombinant vesicular stomatitis virus encoding EBOV glycoprotein and GFP in place of the native G glycoprotein (rVSV/EBOV GP). Our laboratory has previously found that rVSV/EBOV GP recapitulates many aspects of EBOV infection both in vitro and in vivo, including virus tropism and responsiveness to proinflammatory and anti‐inflammatory cytokines during Mϕ infection 40‐42 . Use of this chimeric virus allowed us to perform studies in a more cost‐effective manner, while maintaining the tropism of EBOV GP.…”

“…Our laboratory has previously found that rVSV/EBOV GP recapitulates many aspects of EBOV infection both in vitro and in vivo, including virus tropism and responsiveness to proinflammatory and anti-inflammatory cytokines during M infection. [40][41][42] Use of this chimeric virus allowed us to perform studies in a more cost-effective manner, while maintaining the tropism of EBOV GP.…”

Chikungunya and Zika Viruses: Co-Circulation and the Interplay between Viral Proteins and Host Factors

“…The overexpression of TIM-1 in restricted cell lines significantly enhances EBOV infection, while, in contrast, TIM-1-silenced cells markedly decrease the viral infection of even highly permissive cells [ 221 , 222 ]. In keeping with in vitro results, in vivo experiments with TIM-1-sufficient or -deficient BALB/c mice showed that TIM-1 increases viral load and the associated mortality [ 223 ]. These results imply that TIM-1 is essential for, at least, viral entry and pathogenesis.…”

Ebola virus requires phosphatidylserine scrambling activity for efficient budding and optimal infectivity

“…Although previous paradigms suggest that all viral GPs orchestrate enveloped viral attachment to host cells in a lock-and-key-like manner, evidence now suggests that less-specific mechanisms of virion attachment can be utilized to facilitate internalization. Attachment factors such as lectins and PS receptors effectively bind and internalize viral particles without specific GP interaction (12,20,21,23,24). In order to interact with cellular PS receptors, viral particles must contain PS in the outer leaflet of their envelopes.…”

“…Several studies have confirmed the importance of PS receptor-mediated EBOV entry in cultured cells (17,18,(20)(21)(22)(23). Futhermore, groups examining EBOV pathogenesis in TIM -/mice found TIM1 to be critical for viral loads in the liver, kidneys, spleen, and lymph nodes, and serum cytokine induction, which are both characteristic of human EBOV infection (24,25).…”