As mentioned above, Tecovirimat was chosen here to target MPXV because it is a FDA-aproved inhibitor for vaccinia targeting F13L, active in vaccinia at low nanoMolar concentrations and which also inhibits MPXV infections . Thus, Tecovirimat and several analogues have been recommended to inhibit MPXV with an estimated EC50 of ~150 nM . Tecovirimat is an small molecule containing a complex-ring structure, inhibiting poxviral membrane wrapping and replication of most poxviruses including vaccinia, MPXV, variola, smallpox, cowpox, camel, and others .. With respect to its mechanism of inhibition, it was demonstrated that Tecovirimat changes the intracellular membrane colocalizations of vaccinia F13L (from membrane to cytoplasm) and B5R (disaggregation from Golgi to vesicles) and reduces the immunoprecipitation of F13L-B5R complexes . However, despite its reported inhibitory activities, F13L-Tecovirimat complexes, nor F13L-B5R(B6R) structures have been crystallographically solved yet.