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#C1209N 3CLPro L50F + E166V Expression Kit


Express 3CLpro with the L50F + E166V mutation in mammalian cells including HEK293, A549, and many more. Use alongside other 3CLpro mutant proteases and our 3CLglow biosensor assays to test 3CLpro inhibitor efficacy against a panel of mutations in the protease.



3CLpro (Mpro) L50F + E166V mutation Expression Kit

In a recombinant SARS-COV-2 assay conducted in huh7-ACE2 cells, the E166V mutation alone displayed a 100-fold IC50 resistance to nirmatrelvir, although it led to reduced fitness (Iketani et al. 2023). However, when combined with the mutation L50F, virus replication was restored, resulting in a 53-fold increase in IC50 to nirmatrelvir (Iketani et al. 2023). The L50F, E166V mutation has been detected in patients and reported to the GISAID database (Shu and McCauley 2017; Iketani et al. 2023). Pfizer also reported a 34 to 175-fold increase in EC50 to nirmatrelvir using a biochemical assay (Pfizer Laboratories 2022).

  • Identify protease inhibitors that maintain efficacy against the L50F + E166V mutation
  • Easy co-expression with our 3CLglow and 3CLglowUp sensors
  • Cost effective screening with minimal safety requirements (BSL-1)

Materials in the Kit:

• 3CLpro L50F + E166V in BacMam
• Sodium Butyrate, 500 mM in H2O


Iketani, S., Mohri, H., Culbertson, B., Hong, S. J., Duan, Y., Luck, M. I., Annavajhala, M. K., Guo, Y., Sheng, Z., Uhlemann, A.-C., Goff, S. P., Sabo, Y., Yang, H., Chavez, A., & Ho, D. D. (2023). Multiple pathways for SARS-COV-2 resistance to Nirmatrelvir. Nature613(7944), 558–564.


Shu, Y., & McCauley, J. (2017). GISAID: Global initiative on sharing all influenza data – from vision to reality. Eurosurveillance22(13).

Additional information


We strive for prompt delivery of each order, so we ship by FedEx 2-day service in lightweight, sturdy, and reusable/biodegradable packaging with an insulated cooler and moisture-resistant refrigerant gel packs. Shipping days are Mon-Wed so product does not sit in transit over the weekend. Web store ships to US & Canada only, contact sales for other locations.

Protocol for Use


Kit Volume

5mL, 30mL

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