Antigenic variation

Not to be confused with Antigenic drift or Antigenic shift.

Antigenic variation or antigenic alteration refers to the mechanism by which an infectious agent such as a protozoan, bacterium or virus alters the proteins or carbohydrates on its surface and thus avoids a host immune response, making it one of the mechanisms of antigenic escape. It is related to phase variation. Antigenic variation not only enables the pathogen to avoid the immune response in its current host, but also allows re-infection of previously infected hosts. Immunity to re-infection is based on recognition of the antigens carried by the pathogen, which are "remembered" by the acquired immune response. If the pathogen's dominant antigen can be altered, the pathogen can then evade the host's acquired immune system. Antigenic variation can occur by altering a variety of surface molecules including proteins and carbohydrates. Antigenic variation can result from gene conversion,[1] site-specific DNA inversions,[2] hypermutation,[3] or recombination of sequence cassettes.[4] The result is that even a clonal population of pathogens expresses a heterogeneous phenotype.[5] Many of the proteins known to show antigenic or phase variation are related to virulence.[6]

  1. ^ Pays, Etienne; et al. (1983). "Gene conversion as a mechanism for antigenic variation in Trypanosomes". Cell. 34 (2): 371–381. doi:10.1016/0092-8674(83)90371-9. PMID 6616615. S2CID 688880.
  2. ^ Lysnyansky, I.; Ron, Y.; Yogev, D. (2001). "Juxtaposition of an Active Promoter to vsp Genes via Site-Specific DNA Inversions Generates Antigenic Variation in Mycoplasma bovis". Journal of Bacteriology. 183 (19): 5698–5708. doi:10.1128/JB.183.19.5698-5708.2001. PMC 95462. PMID 11544233.
  3. ^ Brunham, Robert C.; et al. (1993). "Bacterial Antigenic Variation, Host Immune Response, and Pathogen-Host Coevolution". Infection and Immunity. 61 (6): 2273–2276. doi:10.1128/IAI.61.6.2273-2276.1993. PMC 280844. PMID 8500868.
  4. ^ Zhang, Jing-Ren; et al. (1997). "Antigenic Variation in Lyme Disease Borreliae by Promiscuous Recombination of VMP-like Sequence Cassettes". Cell. 89 (2): 275–285. doi:10.1016/S0092-8674(00)80206-8. PMID 9108482.
  5. ^ Avery, S. V. (2006). "Microbial cell individuality and the underlying sources of heterogeneity". Nat Rev Microbiol. 4 (8): 577–87. doi:10.1038/nrmicro1460. PMID 16845428. S2CID 27337497.
  6. ^ van der Woude, Marjan W.; et al. (2004). "Phase and Antigenic Variation in Bacteria". American Society for Microbiology. 17 (3): 581–611. doi:10.1128/CMR.17.3.581-611.2004. PMC 452554. PMID 15258095.