06-l病毒学virus巴斯德研究所.ppt

Virus assemblyPaul ZhouInstitut Pasteur of Shanghai General consideration Enveloped viruses – nucleus Enveloped viruses – cytosol Non-enveloped viruses – nucleus Non-enveloped viruses - cytosol Steps involve in viral assembly Viral protein and nucleotide synthesis Viral protein and nucleotide trafficking Encapsidate viral nucleotides to assemble viral core Envelopment of virus and retention of viral glycoproteins (for enveloped viruses) Viral release: budding and lysis of cells Virion maturation (proteolytic process) Intimate involvement of cellular machinery in viral assembly Cellular polymerase or a virus-encoded polymerase to viral genome replication Cell translational machinery for viral protein synthesis Cellular sorting machinery for viral components trafficking and releasing Cellular proteases, membranes, glycosylation machinery, kinases and chaperon proteins for protein maturation Protein localization in a mammalian cells Budding sites for different viruses Assembly within the cytoplasm by poliovirus Replicate exclusively in the cytoplasm Cytoplasmic localization of viral protein synthesis, of viral RNA replication, and viral particle assembly. Therefore, it is least trafficking within cells Cell free translation of naked poliovirus RNA, synthesis of virion RNA, and assembly of infectious poliovirus particles Release from apical surface of polarized human intestinal epithelial cells Assembly within the nucleus by Adenovirus and SV40 Viral proteins trafficking from the cytoplasm to the nucleus – NLS Assembly of empty protein shell (252 capsomes including 240 hexons and 12 pentons) then encapsidation of viral DNA or the encapsidation of viral DNA occurs along with assembly After the assembly in the nucleus, viral particle is released on lysis of the cells. Assembly of HSV In HSV after synthesis of the γ capsid proteins, VP5, VP26 and VP23 are initially assembled in the cytoplasm. They are localized into the nucleus by VP19C or pro-VP22a, where the fi