688. Pseudotyping FIV-Based Lentiviral Vectors with Baculovirus GP64 Confers Apical Entry into Airway Epithelia

Abstract

Top of pageAbstract The use of gene transfer to treat or prevent cystic fibrosis lung disease has been limited in part by the inability of vectors to efficiently transduce airway epithelia from the apical surface. Using a feline immunodeficiency virus (FIV)-based lentiviral vector system, we recently observed that the envelope glycoprotein GP64 from baculovirus Autographa californica nucleopolyhedrovirus (AcMNPV) confers apical entry into polarized primary cultures of human airway epithelia. High titer FIV-vector (>10e9 TU/ml) was achieved by pseudotyping with baculovirus GP64 (GP64-FIV) and these titers meet or exceed those obtained with the VSV-G envelope. We tested fusion (F) proteins from four other baculoviruses for their ability to pseudotype FIV, and obtained very low titers (less than or equal to 10e2). Interestingly, AcMNPV GP64 shares sequence identity with influenza D envelope GPs such as Thogotovirus. Pseudotyping FIV with Thogoto GP resulted in titers of ~10e6 TU/ml and also conferred apical entry into polarized human airway epithelial cell cultures. These data lend support to the notion of horizontal transfer of GPs during the evolution of AcMNPV and Influenza D viruses. The receptor for GP64 is currently unknown; however, we investigated the entry of GP64-FIV into epithelia. Pretreating A549 cells with the ionophores monensin or NH4Cl significantly decreased the transduction by GP64-FIV as measured by beta-Galactosidase expression. These data suggest that similar to VSV-G, GP64-FIV transduction requires a low pH endosome pathway. These findings identify a pseudotyped, integrating viral vector with the capacity to infect from the apical surface for the convenient delivery of transgenes to airway epithelia.