IFNG and infection: While other post-exposure prophylaxis studies have been done using replication-deficient and replication-competent VACV vaccine strains in order to protect against a lethal infection with VACV-WR or ECTV [23][24][49], our study is the first one that successfully uses a recombinant VACV expressing IFN-γ, v50ΔB13RMγ, for post-exposure protection.