Abstract
Nonenveloped animal viruses must disrupt or perforate a cell membrane during entry. Recent work with reovirus has shown formation of size-selective pores in RBC membranes in concert with structural changes in capsid protein μ1. Here, we demonstrate that μ1 fragments released from reovirus particles are sufficient for pore formation. Both myristoylated N-terminal fragment μ1N and C-terminal fragment φ are released from particles. Both also associate with RBC membranes and contribute to pore formation in the absence of particles, but μ1N has the primary and sufficient role. Particles with a mutant form of μ1, unable to release μ1N or form pores, lack the ability to associate with membranes. They are, however, recruited by pores preformed with peptides released from wild-type particles or with synthetic μ1N. The results provide evidence that docking to membrane pores by virus particles may be a next step in membrane penetration after pore formation by released peptides.