非包膜病毒如何侵入细胞 - Stephen Harrison P3
本视频由科普中国和生物医学大讲堂出品
Stephen Harrison (Harvard) Part 3: Non-enveloped virus entry
Harrison begins his talk by asking why most non-enveloped viruses and some enveloped viruses are symmetrical in shape. He proceeds to show us lovely images of the structures obtained by x-ray crystallography of numerous viral coat proteins. Deciphering these structures allowed scientists to understand that viral coat proteins form multimers, such as dimers and pentamers, which in turn interact with a scaffold that ensures that the coat proteins are correctly placed. This arrangement results in symmetrically shaped viruses.
In Part 1, Harrison also explains that enveloped viruses infect cells by inducing the fusion of the viral and host cell membranes. He delves deeper into the molecular mechanism of membrane fusion driven by the hemagglutinin or HA protein of the influenza virus in Part 2 of his talk.
Non-enveloped viruses, on the other hand, must enter cells by a mechanism other than membrane fusion. This is the focus of Part 3. Using rotavirus as a model, Harrison and his colleagues have used a combination of Xray crystallography and electron cryomicroscopy to decipher how the spike protein on the viral surface changes its conformation and perforates the cell membrane allowing the virus to enter the cell.
病毒包膜的内吞和渗透作用 - Ari Helenius P2
本视频由科普中国和生物医学大讲堂出品
Ari Helenius (ETH Zurich) Part 2: Endocytosis and Penetration
In the second lecture, the next steps in viral infection are described. Endocytosis of plasma membrane bound viruses can occur via a number of mechanisms including caveolar, clathrin, non-clathrin, or lipid raft mediated pathways. The internalized virus is enclosed in an endosome that may undergo increasing acidification resulting in acid mediated fusion between the viral envelope and the vesicle membrane. Following membrane penetration, the virus, once again, makes use of cellular machinery such as microtubules and their motors, to transfer its genome to the nucleus. Helenius describes experiments from his lab and others that have deciphered these complex processes.