Bulk Fusion Studies of Sendai Virus and Application of Mass Action Kinetic Fusion Model

Abstract

Sendai virus is a negative-sense, single-stranded RNA, membrane-enveloped virus of the Paramyxoviridae family that causes respiratory disease in rodents. Because Sendai virus is non-pathogenic in humans, yet can infect human cells in cell culture, it has gained use as a virus vector candidate for gene therapy and vaccination. Previous bulk and cell culture studies indicate Sendai virus infects host cells via sialic-acid-mediated binding (SAMB) by the viral HN attachment protein. This binding then triggers the viral F protein to mediate membrane fusion. Here, we study single-particle Sendai virus binding to glass-supported lipid bilayers (SLBs) using a fluorescence microscopy-based microfluidic assay. Fluorescently labelled virions are observed under the microscope and bound virions are quantified using image processing. We investigate how lipid composition and ganglioside GD1a receptor density in the target membrane influences viral binding. Interestingly, we observe substantial non-sialic-acid-mediated binding (NSAMB) across a variety of conditions, much more than influenza virus strains which also bind the GD1a receptor. Results from monoclonal antibody interference experiments suggest that the viral HN attachment protein is involved in this NSAMB. We examine various hypotheses and experimental approaches to explain this recurring NSAMB, including the effects of electrostatics, hydrophobicity, and different sialic acid terminated glycolipid receptors, such as GD1a and GQ1b.