Interferon-induced transmembrane protein 3 blocks fusion of sensitive but not resistant viruses by partitioning into virus-carrying endosomes

Suddala, Krishna C.; Lee, Christine C.; Meraner, Paul; Marin, Mariana; Markosyan, Ruben M.; Desai, Tanay M.; Cohen, Fredric S.; Brass, Abraham L.; Melikyan, Gregory B.

To further test whether the presence of IFITM3 is necessary and sufficient to restrict IAV fusion, we generated control IAV particles that incorporated IFITM3 through co-expression in virus-producing cells. These pseudoviruses contained BlaM-Vpr to assess their fusion-competence. IFITM3 incorporation into virions and its possible effects on HIV-1 maturation or the influenza HA incorporation into pseudoviruses were verified by Western blotting ( Fig 8A) . IFITM3 was present in pseudoviruses prepared in producer cells expressing IFITM3 but not in the Vector control. Furthermore, the amount of p24 protein and influenza HA were the same in the two preparations (Fig 8A) , indicating that IFITM3 incorporation does not perturb the expression or proteolytic processing of HA.