Peptides released from reovirus outer capsid form membrane pores that recruit virus particles

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 mu 1. Here, we demonstrate that mu 1 fragments released from reovirus particles are sufficient for pore formation. Both myristoylated N-terminal fragment mu 1N and C-terminal fragment phi are released from particles. Both also associate with RBC membranes and contribute to pore formation in the absence of particles, but mu 1N has the primary and sufficient role. Particles with a mutant form of mu 1, unable to release mu 1N 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 mu 1N. 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.