Myoferlin is an essential component of late-stage vRNP trafficking vesicles for enveloped RNA viruses.

The Rab11a endosomal recycling pathway is exploited by important respiratory RNA viruses such as IAV and RSV, aiding viral egress from the apical surface of polarized epithelial cells. Late in infection, Rab11a-containing vesicles specifically transport viral ribonucleoprotein (vRNP) complexes towards the cell surface before packaging and budding. Rather than employing traditional Rab11a-positive recycling endosomes, virus-infected cells generate remodelled Rab11a-containing vesicles, as observed during IAV infection. Besides Rab11a, no other conserved host co-factors have been identified among these various vRNP trafficking vesicles. Here we discovered and confirmed myoferlin’s association with IAV vRNPs in the cytoplasm and colocalisation with Rab11a during late stages of infection. We also found that this role was conserved in late-stage vRNP trafficking of other viruses, including RSV and SeV. Myoferlin likely recruits the EHD family of proteins, which are involved in endosomal biogenesis, to these unique vRNP trafficking endosomes, highlighting myoferlin’s pivotal role in viral replication.