National Institutes of Health, USA
"Petr Chlanda completed Ph.D. in virology at the University of Heidelberg where he studied vaccinia virus assembly. He subsequently conducted post-doctoral research on influenza virus budding at European Molecular Biology Laboratory in Heidelberg. Currently he is a post-doctoral fellow at NIH where he uses electron microscopy techniques to study influenza virus driven membrane fusion"
"Influenza A virus is a major human pathogen, assembling enveloped virus particles that are heterogeneous in shape. The contribution of main components of the influenza virus haemaglutinin (HA), neuramindase (NA), and matrix protein 1 (M1) to virus assembly, release and virion morphology remain unclear. They can all, under certain conditions, mediate release of membrane-enveloped particles, while none of them appear to be essential for particle release. Here we have produced membraneenveloped particles by plasmid-based expression of all combinations of HA (H3), NA (N2) and M1, and have monitored particle release, particle morphology, and plasma membrane morphology using biochemical methods, electron microscopy, electron tomography and cryo-electron tomography. HA or NA expression leads to changes of the plasma membrane curvature which appear as membrane-enveloped particles. Although these pleomorphic membrane-enveloped particles are connected to the plasma membrane without an obvious constriction they are capable of release. In contrast, when either HA or NA is expressed together with M1, well defined filamentous protrusions are formed, which constrict at their base forming a budding neck to release filamentous virus-like particles (VLPs) from the cell surface. The VLPs are released in the absence of M2, and most efficiently when NA is expressed. NA localizes in a membrane-curvature dependent manner to the tips of VLPs. Together our data indicate that one of the glycoproteins together with M1 represents the minimal requirement to assemble and release filamentous VLPs. These results suggest NA and M1 as key players in virus assembly."