MicrobiologyBytes

During travel between hosts, the genome of a virus is well protected by the capsid and/or envelope. After binding specifically to target cells, the virus particles enter cells by hijacking cell trafficking pathways and then deliver the viral genome into the appropriate compartment of the cell where it directs the production of progeny virus particles. How nonenveloped viruses, such as poliovirus, enter target cells is not well understood. Jim Hogle and his colleagues produced fully infectious poliovirus with both genome and capsid specifically labeled by fluorescent dyes, then used real-time fluorescent microscopy to follow single virus particles during infection to define how they enter cells and to determine when and where in the cell the genome gets released. They show that poliovirus enters live cells in a process that requires energy, an intact actin cytoskeleton, and cell signaling pathways, but does not depend on the well-known markers of endocytic pathways. Surprisingly, genome release by PV is highly efficient and rapid, and thus does not limit the overall infectivity or the infection rate. The results define a pathway in which PV binds to receptors on the cell surface and enters the cell by a clathrin-, caveolin-, flotillin-, and microtubule-independent, but tyrosine kinase- and actin-dependent, endocytic mechanism. Immediately after the internalization of the virus particle, genome release takes place from vesicles or tightly sealed membrane invaginations located within 100-200 nm of the plasma membrane. These results settle a long-lasting debate of whether PV directly breaks the plasma membrane barrier or relies on endocytosis to deliver its genome into the cell. These experiments offer new insights into the early steps of poliovirus infection, and describe methods that can be used for a wide variety of other viruses.

Imaging Poliovirus Entry in Live Cells. PLoS Biol. 2007 5 (7): e183

This entry was posted on Wednesday, August 15th, 2007 at 7:44 am and is filed under Biology, Health, Microbiology, Science, Virology. You can follow any responses to this entry through the RSS 2.0 feed. Both comments and pings are currently closed.