Ceudovitox: a novel pseudotyped-virus screening platform to identify cell entry factors for high consequence infections
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Development of scalable and highly adaptable platforms to characterise high consequence infections are essential for limiting the impact of future viruses with pandemic potential. As part of this, an understanding of the virus-host interactions is vital, with the cell entry mechanism being crucial for the development of therapeutics and vaccines. Current approaches in this field depend on assays with authentic (live) viruses that require high containment facilities. However, these are hindered by high costs, need for highly trained staff, slow processing times and limited scalability. Using pseudotyped viruses (PV) expressing the chikungunya (CHIKV) envelope protein as a proof-of-principle, we developed a novel screening platform, Ceudovitox , to identify cellular factors involved in viral entry. PVs were engineered to express the herpes simplex virus-1 thymidine kinase, which following addition of ganciclovir, can selectively kill infected cells. Then a heterogenous pool of knockout cells were produced using the CRISPR-Cas9 library. Infection of these cells with the “killer” PV system permitted positive selection of cells refractory to viral infection and, through next generation sequencing, identification of a number of factors involved in CHIKV entry. Matrix metalloproteinases were identified as novel entry factors and demonstrated that MMP-targeting drugs efficiently inhibit PV and authentic CHIKV infections. These results suggest this platform holds great promise as a pandemic-preparedness tool that increases the capacity and speed of screening for cell entry factors. It is also a safe platform able to dissect the gene network involved in virus entry. Ceudovitox will help identify new therapeutic targets, thereby aiding the development of treatments against future outbreaks or pandemic pathogens and making a significant contribution to the “100 days” mission.
Author Summary
The increased threat of the emergence of new viral pathogens with pandemic potential highlights the importance of developing scalable high-throughput screening platforms to quickly characterise new emergent viral pathogens. Improving understanding of virus-host interactions, including how viruses enter cells, can help fast development of new targeted therapeutics and reduce pandemic burdens. Current approaches rely on using ‘live’ viruses, which are highly infectious and must be manipulated in high containment facilities, which are slow and cumbersome. Our new screening platform, Ceudovitox , is a safer, faster and more scalable alternative. Through using pseudotyped viruses, which can only undergo one replication cycle, we are able to distinguish virus entry factors of high containment viruses within highly abundant low containment facilities, allowing us to quickly characterise potential entry factors of high containment viruses. Within this study, Ceudovitox was shown to recognise both known and novel entry factors of Chikungunya virus; a virus which causes chronic arthralgia and arthritis. Matrix metalloproteinases were amongst novel entry factors identified and were seen to reduce virus infection in both pseudotyped and authentic virus assays, demonstrating how Ceudovitox can correctly discover virus entry factors of ‘live’ high containment viruses. Ceudovitox’s utility as a screening platform for high containment viruses and new emerging pathogens, has the potential increase understanding and speed up the development of new therapeutics during pandemics, helping to reach the ‘100 Day Mission’ of pandemic preparedness.
