Antigenic variation in the African trypanosome: molecular mechanisms and phenotypic complexity

@article{Morrison2009AntigenicVI,
  title={Antigenic variation in the African trypanosome: molecular mechanisms and phenotypic complexity},
  author={Liam J. Morrison and Lucio Marcello and Richard McCulloch},
  journal={Cellular Microbiology},
  year={2009},
  volume={11}
}
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… 
DNA Recombination Strategies During Antigenic Variation in the African Trypanosome.
TLDR
This chapter will discuss the implications of VSG diversity for immune evasion by antigenic variation, and consider how this expressed diversity can arise, drawing on a growing body of work that has begun to examine the proteins and sequences through which VSG switching is catalyzed.
Withstanding the Challenges of Host Immunity: Antigenic Variation and the Trypanosome Surface Coat
TLDR
The antigenic variation ‘diversity phenotype’ is thus a multifaceted one, enlisting and coordinating fundamental mechanisms of cell biology to bring about a process that unfolds across populations, thereby facilitating the success of the African trypanosomes.
Linking the antigen archive structure to pathogen fitness in African trypanosomes
TLDR
Inspired by the antigenic variation system of African trypanosomes, modelling approaches are applied to expanding understanding of the organization and expression of antigen repertoires, and links across these scales are explored.
Variant antigen diversity in Trypanosoma vivax is not driven by recombination
TLDR
It is shown that global VSG repertoire is broadly conserved across diverse T. vivax clinical strains, and indicates that either T.vivax has an alternate mechanism for immune evasion or else a distinct transmission strategy that reduces its reliance on long-term persistence.
Mosaic VSGs and the Scale of Trypanosoma brucei Antigenic Variation
TLDR
It is shown that individual growth peaks can contain at least 15 distinct variants, are estimated computationally to comprise many more, and that antigenically distinct ‘mosaic’ VSGs arise from segmental gene conversion between donor VSG genes or pseudogenes.
An investigation into the initiation of VSG switching in Trypanosoma brucei
TLDR
The initiation ofVSG switching is more complex than currently thought and requires careful further study and consideration of the relevance of using direct DSBs in this location to model VSG switching.
African trypanosomes: the genome and adaptations for immune evasion.
TLDR
The African trypanosome Trypanosoma brucei is a flagellated unicellular parasite transmitted by tsetse flies that causes African sleeping sickness in sub-Saharan Africa and has developed an extremely sophisticated strategy of antigenic variation of its VSG coat allowing it to evade host antibodies.
Does DNA replication direct locus-specific recombination during host immune evasion by antigenic variation in the African trypanosome?
TLDR
Three emerging models for VSG switching initiation are discussed and how these compare with processes for adaptive genome change found in other organisms are asked.
The within-host dynamics of African trypanosome infections
TLDR
African trypanosomes are single-celled protozoan parasites that are capable of long-term survival while living extracellularly in the bloodstream and tissues of mammalian hosts and there is considerable scope for a complex interplay between parasite immune evasion, transmission potential and host factors to govern the profile and outcome of infection.
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