Tecovirimat

Successful viral replication leads to the formation of a number of infectious virion forms. Mature viruses are infectious but remain intracellularly until cell lysis. On the other hand, enveloped virion form is created when mature viruses wrap with late endosomal membranes. The formation of a wrapping complex for enveloped virions is mediated by the orthopoxvirus P37 protein. These egress-competent enveloped virions are released in a nonlytic fashion from the cell and play an essential role in cell-to-cell and long-range dissemination of the virus in the host.

The P37 protein is encoded by a highly conserved gene in all members of the orthopoxvirus genus. P37 interacts with the Rab9 GTPase and TIP47, which are components of late endosome-derived transport vesicles. Interaction of P37 and Rab9 GTPase and TIP47 leads to the formation of the virus-specific wrapping complex for enveloped virions. Tecovirimat is an inhibitor of P37: it blocks the interaction of P37 with Rab9 and TIP47, preventing the formation of the wrapping complex.