Genome-scale CRISPR screen identifies TMEM41B as a multi-function host factor required for coronavirus replication

Abstract

Emerging coronaviruses (CoVs) pose a severe threat to human and animal health worldwide. To identify host factors required for CoV infection, we used α-CoV transmissible gastroenteritis virus (TGEV) as a model for genome-scale CRISPR knockout (KO) screening. Transmembrane protein 41B (TMEM41B) was found to be a bona fide host factor involved in infection by CoV and three additional virus families. We found that TMEM41B is critical for the internalization and early-stage replication of TGEV. Notably, our results also showed that cells lacking TMEM41B are unable to form the double-membrane vesicles necessary for TGEV replication, indicating that TMEM41B contributes to the formation of CoV replication organelles. Lastly, our data from a mouse infection model showed that the KO of this factor can strongly inhibit viral infection and delay the progression of a CoV disease. Our study revealed that targeting TMEM41B is a highly promising approach for the development of broad-spectrum anti-viral therapeutics.

Molecular Mechanism of Porcine Epidemic Diarrhea Virus Cell Tropism

“…Receptor interaction plays a key role in coronaviruses' cell, tissue, and host tropism. Unfortunately, even though porcine aminopeptidase N (pAPN), transmembrane protein 41B (TMEM41B), transmembrane serine protease (TMPRSS2), a trypsin-like serine protease (MSPL), and transferrin receptor I can effectively facilitate PEDV invasion of cells ( 22 , 44 , 45 ) and sialic acid-binding activity of the PEDV S1 subunit facilitates cell entry ( 46 ), the functional receptors of PEDV are still unclear. Isolated exchange of S1 and S2 of adaptive strains did not make PEDV adapt to cells ( Fig.…”

Scrambled or flipped: 5 facts about how cellular phosphatidylserine localization can mediate viral replication

“…Recent evidence suggests that PtdSer scramblases are important for (+)RNA virus replication, likely due to their impact on RC formation (Fig 2C). Independent genome-wide screens for viral host factors identified ER scramblase TMEM41B as an essential component in flavivirus and coronavirus replication [47][48][49][50][51]. Cells deficient in TMEM41B failed to form flavivirus RC, while other viruses that do not replicate in ER RCs were unaffected [50].…”

“…Cells deficient in TMEM41B failed to form flavivirus RC, while other viruses that do not replicate in ER RCs were unaffected [50]. Eliminating TMEM41B in mice also significantly delayed murine coronavirus disease progression in vivo [51]. ER scramblase VMP1, which shares a number of functional and structural similarities with TMEM41B [52], also appeared in 2 of these viral host factor screens [47,50].…”

“…ER scramblase VMP1, which shares a number of functional and structural similarities with TMEM41B [52], also appeared in 2 of these viral host factor screens [47,50]. Cells lacking VMP1 were significantly resistant to flavivirus infection [50] and somewhat resistant to coronavirus infection [47,51]; however, indepth mechanistic studies on how VMP1 interferes with virus replication were not performed. Likely, the loss of trans-bilayer phospholipid movement in the ER, combined with altered lipid mobilization and cholesterol distribution observed in TMEM41B and VMP1 knockout cells [9,49,50], prevents ER membrane rearrangements that enable robust genome replication of (+)RNA viruses that replicate in this compartment.…”

“…Targeting scramblases and flippases to limit viral replication in a host may not be viable; these enzymes and the processes they mediate are highly conserved in eukaryotes and are often essential. While many groups cited in this review established viable scramblase and flippase knockout cell lines, defects in several of these proteins have been linked to diseases or disorders in mammals [8,51,[57][58][59][60][61][62][63][64]. In the quest for new and broadly inhibiting antivirals, some have opted to target PtdSer enriched on viral envelopes rather than interfere with essential PtdSer scramblases.…”