Antigenic drift

Antigenic drift

Antigenic driftcite journal
author=D. J. D. Earn, J. Dushoff, S. A. Levin
journal=Trends in Ecology and Evolution
title=Ecology and Evolution of the Flu
date=2002
volume=17
pages=334-340] [cite book
author=A. W. Hampson
chapter=Influenza virus antigens and antigenic drift
title=Influenza
editors= C. W. Potter
publisher=Elsevier Science B. V.
date=2002
pages=49-86] is the process of random accumulation of mutations in viral genes recognized by the immune system. Such accumulation may significantly change the antigens of the virus, and may help it evade the immune system. This process may lead to a loss of immunity, or in vaccine mismatch when one of the strains selected for the vaccine doesn't optimally match the circulating strains. Antigenic drift may also allow a virus to jump to a new host species.

In influenza viruses

In the influenza virus, the two relevant genes are the surface proteins, hemagglutinin and neuraminidase. The hemagglutinin is responsible for entry into host epithelial cells while the neuraminidase is involved in the process of new virions budding out of host cells. The host immune response to viral infection is largely determined by the immune system's recognition of these influenza antigens. Vaccine mismatch is a potentially serious problem. Antigenic Drift is continuous process of genetic change among flu strains.

As in all RNA viruses, mutations in influenza occur frequently because the virus' RNA polymerase has no proofreading mechanism, providing a strong source of mutations. Mutations in the surface proteins allow the virus to elude some host immunity, and the numbers and locations of these mutations that confer the greatest amount of immune escape has been an important topic of study for over a decade [cite journal
author=R. M. Bush, W. M. Fitch, C. A. Bender, N. J. Cox
journal=Molecular Biology and Evolution
title=Positive selection on the H3 hemagglutinin gene of human influenza virus
date=1999
volume=16
pages=1457-1465] [cite journal
author=W. M. Fitch, R. M. Bush, C. A. Bender, N. J. Cox
journal=Proceedings of the National Academy of Sciences USA
title=Long term trends in the evolution of H(3) HA1 human influenza type A
date=1997
volume=94
pages=7712-7718] [cite journal
author=D. J. Smith, A. S. Lapedes, J. C. de Jong, T. M. Bestebroer, G. F. Rimmelzwaan, A. D. M. E. Osterhaus, R. A. M. Fouchier
journal=Science
title=Mapping the antigenic and genetic evolution of influenza virus
date=2004
volume=305
pages=371-376] .

Antigenic drift has been responsible for heavier-than-normal flu seasons in the past, like the outbreak of influenza A Fujian (H3N2) in the 2003 - 2004 flu season. All influenza viruses experience some form of antigenic drift, but it is most pronounced in the influenza A virus.

Antigenic drift should not be confused with antigenic shift, which refers to a more abrupt change in the antigenes.As well, it is different from random genetic drift which is a very different but important process in population genetics.

ee also

*Antigenic shift

References

External links

* [http://www3.niaid.nih.gov/news/focuson/flu/illustrations/antigenic/antigenicdrift.htm An illustration of antigenic drift]
* [http://www.medterms.com/script/main/art.asp?articlekey=26116 A technical definition]


Wikimedia Foundation. 2010.

Игры ⚽ Поможем сделать НИР

Look at other dictionaries:

  • antigenic drift — antigenic drift. См. антигенный дрейф. (Источник: «Англо русский толковый словарь генетических терминов». Арефьев В.А., Лисовенко Л.А., Москва: Изд во ВНИРО, 1995 г.) …   Молекулярная биология и генетика. Толковый словарь.

  • antigenic drift — relatively minor changes in the antigenic structure of a virus strain, probably resulting from natural selection of virus variants circulating among an immune or partially immune population. Cf. antigenic shift, under shift …   Medical dictionary

  • antigenic drift — A small change in the antigenic character of an organism that allows it to avoid attack by the immune system …   Dictionary of microbiology

  • Antigenic shift — Not to be confused with antigenic drift or genetic drift. NIAID illustration of potential influenza antigenic shift Antigenic shift is the process by which two or more different strains of a virus, or strains of two or more different viruses …   Wikipedia

  • antigenic shift — a sudden, major change in the antigenicity of a virus, seen especially in influenza viruses, resulting from the recombination of the genomes of two virus strains; it is associated with pandemics because hosts do not have immunity to the new… …   Medical dictionary

  • antigenic variation — 1. a mechanism whereby microorganisms or parasites, such as trypanosomes, plasmodia, and Borrelia, are enabled to escape immune surveillance of a host by modifying or completely altering their surface antigens. 2. a phenomenon occurring in the… …   Medical dictionary

  • drift — 1. A gradual movement, as from an original position. 2. A gradual change in the value of a random variable over time as a result of various factors, some random and some systematic effects of trend, manipulation, etc. antigenic d. the …   Medical dictionary

  • Original antigenic sin — Original antigenic sin, also known as the Hoskins effect,[1] refers to the propensity of the body s immune system to preferentially utilize immunological memory based on a previous infection when a second slightly different version, of that… …   Wikipedia

  • Genetic drift — ] Especially in small populations, the statistical effect of sampling error ( during reproduction ) on certain alleles from the overall population may result in an allele ( and the biological traits that it confers ) becoming more common or rare… …   Wikipedia

  • антигенный дрейф — antigenic drift антигенный дрейф. Cовокупность постепенных, обычно незначительных изменений антигенных детерминант некоторых вирусов, обусловленных отбором антигенов оболочки вирусов; А.д. обусловлен мутациями и принципиально не отличется от… …   Молекулярная биология и генетика. Толковый словарь.

Share the article and excerpts

Direct link
… Do a right-click on the link above
and select “Copy Link”