title: Antigenic variation in the African trypanosome: molecular mechanisms and phenotypic complexity.
abstract: Antigenic variation is an immune evasion strategy that has evolved in viral, bacterial and protistan pathogens. In the African trypanosome this involves stochastic switches in the composition of a variant surface glycoprotein (VSG) coat, using a massive archive of silent VSG genes to change the identity of the single VSG expressed at a time. VSG switching is driven primarily by recombination reactions that move silent VSGs into specialized expression sites, though transcription-based switching can also occur. Here we discuss what is being revealed about the machinery that underlies these switching mechanisms, including what parallels can be drawn with other pathogens. In addition, we discuss how such switching reactions act in a hierarchy and contribute to pathogen survival in the face of immune attack, including the establishment and maintenance of chronic infections, leading to host-host transmission.
authors.affiliation: University of Glasgow, Wellcome Centre for Molecular Parasitology and Division of Infection and Immunity, Glasgow Biomedical Research Centre, 120 University Place, Glasgow, G12 8TA, UK.
authors.forename: Liam J
authors.initials: LJ
authors.lastname: Morrison
authors.forename: Lucio
authors.initials: L
authors.lastname: Marcello
authors.forename: Richard
authors.initials: R
authors.lastname: McCulloch
mesh_terms: D000818:Animals; D000940:Antigenic Variation; D005785:Gene Conversion; D017125:Genes, Protozoan; D006801:Humans; D008562:Membrane Glycoproteins / Q000235:genetics / Q000276:immunology; D010641:Phenotype; D014345:Trypanosoma / Q000235:genetics / Q000276:immunology; D014353:Trypanosomiasis, African / Q000276:immunology / Q000469:parasitology* / Q000635:transmission
chemical_list: D008562:Membrane Glycoproteins