title: Class II enveloped viruses.
abstract: A number of viruses transport their genomic material from cell to cell enclosed within a lipid bilayer that is in turn encased within a symmetric protein shell. This review focuses in a group of RNA viruses that have this type of virions. This group includes several of important human pathogenic viruses, such as the hepatitis C virus, dengue virus, chikungunya virus, rubella virus and the bunyaviruses. The best studied are the flaviviruses and the alphaviruses, which have a β-sheet rich class II viral fusion protein used for entry into susceptible cells. We extend here the class II concept to encompass symmetric viruses in which the envelope proteins are derived from a precursor polyprotein containing two transmembrane glycoproteins arranged in tandem. The first glycoprotein acts as chaperone for the folding of the second one, which carries the membrane fusion function. Since the bunyaviruses, included here, are very similar to the class I arenaviruses in other respects, this analysis highlights the patchwork nature of the various viral functional modules acting at different stages of the virus cycle, which appear assembled from genes of different origins.
authors.affiliation: Institut Pasteur, Département de Virologie, Unité de Virologie Structurale, F-75724 Paris Cedex 15, France.
authors.forename: Marie-Christine
authors.initials: MC
authors.lastname: Vaney
authors.forename: Felix A
authors.initials: FA
authors.lastname: Rey
mesh_terms: D000818:Animals; D006801:Humans; D018832:Molecular Chaperones; D017510:Protein Folding; D012328:RNA Viruses / Q000737:chemistry / Q000235:genetics / Q000472:pathogenicity* / Q000648:ultrastructure*; D014759:Viral Envelope Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D014763:Viral Matrix Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D053586:Virus Internalization
chemical_list: D018832:Molecular Chaperones; D014759:Viral Envelope Proteins; D014763:Viral Matrix Proteins