page_title: Alphavirus
section_title: Genome
hierarchical_section_title: Alphavirus / Genome
caption_attribution_description: English: Cartoon representation of the molecular structure of protein registered with 1rer code. Deutsch: Grafik des Molekularstruktur von jenem Protein, das mit 1rer code registriert ist. Plattdüütsch: Grafik, de de Molekularstruktur von dat Protein wiest, dat mit’n Kood 1rer registreert is.
context_page_description: Alphavirus is a genus of RNA viruses, the sole genus in the Togaviridae family. Alphaviruses belong to group IV of the Baltimore classification of viruses, with a positive-sense, single-stranded RNA genome. There are 31 alphaviruses, which infect various vertebrates such as humans, rodents, fish, birds, and larger mammals such as horses, as well as invertebrates. Transmission between species and individuals occurs mainly via mosquitoes, making the alphaviruses a member of the collection of arboviruses – or arthropod-borne viruses. Alphavirus particles are enveloped, have a 70 nm diameter, tend to be spherical, and have a 40 nm isometric nucleocapsid.
context_section_description: The alphaviruses are small, spherical, enveloped viruses with a genome of a single strand of positive-sense RNA. The total genome length ranges between 11,000 and 12,000 nucleotides, and has a 5’ cap and a 3’ poly-A tail. The four non-structural protein genes are encoded in the 5′ two-thirds of the genome, while the three structural proteins are translated from a subgenomic mRNA colinear with the 3′ one-third of the genome.
  There are two open reading frames (ORFs) in the genome, nonstructural and structural. The first is non-structural and encodes proteins (nsP1–nsP4) necessary for transcription and replication of viral RNA. The second encodes three structural proteins: the core nucleocapsid protein C, and the envelope proteins P62 and E1, which associate as a heterodimer. The viral membrane-anchored surface glycoproteins are responsible for receptor recognition and entry into target cells through membrane fusion.
caption: Crystal structure of the homotrimer of fusion glycoprotein E1 from Semliki Forest virus
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