WordNet

vary or move from a fixed point or course; "stock prices are drifting higher"
a force that moves something along (同)impetus, impulsion
a process of linguistic change over a period of time
the gradual departure from an intended course due to external influences (as a ship or plane)
a horizontal (or nearly horizontal) passageway in a mine; "they dug a drift parallel with the vein" (同)heading, gallery
the pervading meaning or tenor; "caught the general drift of the conversation" (同)purport
a general tendency to change (as of opinion); "not openly liberal but that is the trend of the book"; "a broad movement of the electorate to the right" (同)trend, movement
a large mass of material that is heaped up by the wind or by water currents
be piled up in banks or heaps by the force of wind or a current; "snow drifting several feet high"; "sand drifting like snow"
be subject to fluctuation; "The stock market drifted upward"
cause to be carried by a current; "drift the boats downstream"
drive slowly and far afield for grazing; "drift the cattle herds westwards"
move in an unhurried fashion; "The unknown young man drifted among the invited guests"
any substance (as a toxin or enzyme) that stimulates an immune response in the body (especially the production of antibodies)
of or relating to antigens
aimless wandering from place to place

PrepTutorEJDIC

〈U〉『漂流』,流されること / 〈U〉(海流・風などの)流れ,流れの方向(速度) / 〈C〉(雪・砂などの)吹きだまり,漂流物《+『of』+『名』》 / 〈U〉〈C〉大勢,風潮,傾向 / 〈U〉《時にa~》主意,主旨 / (水・風に)『流される』,漂う,漂流する / あてもなくさまよう / 〈雪・砂などが〉吹き積もる,吹きだまりになる / 〈砂・雪など〉‘を'吹き寄せる;〈場所〉‘を'吹きだまりにする
抗原(生物の体内にはいって免疫体を作る物質)

Wikipedia preview

出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2015/12/01 12:44:17」(JST)

wiki en

Antigenic drift is a mechanism for variation in viruses that involves the accumulation of mutations within the genes that code for antibody-binding sites. This results in a new strain of virus particles which cannot be inhibited as effectively by the antibodies that were originally targeted against previous strains, making it easier for the virus to spread throughout a partially immune population. Antigenic drift occurs in both influenza A and influenza B viruses.

The immune system recognizes viruses when antigens on the surfaces of virus particles bind to immune receptors that are specific for these antigens. This is similar to a lock recognizing a key. After an infection, the body produces many more of these virus-specific immune receptors, which prevent re-infection by this particular strain of the virus and produce acquired immunity. Similarly, a vaccine against a virus works by teaching the immune system to recognize the antigens exhibited by this virus. However, viral genomes are constantly mutating, producing new forms of these antigens. If one of these new forms of an antigen is sufficiently different from the old antigen, it will no longer bind to the receptors and viruses with these new antigens can evade immunity to the original strain of the virus. When such a change occurs, people who have had the illness in the past are nevertheless not immune to the new strain and thus the vaccines against the original virus will be less effective against the illness^{[clarification needed]}. Two processes drive the antigens to change: antigenic drift^[1]^[2] and antigenic shift, antigenic drift being the more common. The rate of antigenic drift is dependent on two characteristics: the duration of the epidemic, and the strength of host immunity. A longer epidemic allows for selection pressure to continue over an extended period of time and stronger host immune responses increase selection pressure for development of novel antigens.^[3]

In influenza viruses

In the influenza virus, the two relevant antigens are the surface proteins, hemagglutinin and neuraminidase.^[4] The hemagglutinin is responsible for binding and entry into host epithelial cells while the neuraminidase is involved in the process of new virions budding out of host cells.^[5] Sites recognized on the hemagglutinin and neuraminidase proteins by host immune systems are under constant selective pressure. Antigenic drift allows for evasion of these host immune systems by small mutations in the hemagglutinin and neuraminidase genes that make the protein unrecognizable to pre-existing host immunity.^[6] Antigenic drift is this continuous process of genetic and antigenic change among flu strains.^[7]

In human populations, immune (vaccinated) individuals exert selective pressure for single point mutations in the hemagglutinin gene that increase receptor binding avidity, while naive individuals exert selective pressure for single point mutations that decrease receptor binding avidity.^[6] These dynamic selection pressures facilitate the observed rapid evolution in the hemagglutinin gene. Specifically, 18 specific codons in the HA1 domain of the hemagglutinin gene have been identified as undergoing positive selection to change their encoded amino acid.^[8] To meet the challenge of antigenic drift, vaccines that confer broad protection against heterovariant strains are needed against seasonal, epidemic and pandemic influenza.^[9]

As in all RNA viruses, mutations in influenza occur frequently because the virus' RNA polymerase has no proofreading mechanism, resulting in an error rate between 6997100000000000000♠1×10⁻³ and 6997800000000000000♠8×10⁻³ substitutions per site per year during viral genome replication.^[7] 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.^[10]^[11]^[12]

Antigenic drift has been responsible for heavier-than-normal flu seasons in the past, like the outbreak of influenza H3N2 variant A/Fujian/411/2002 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 reassortment of the virus' gene segments. As well, it is different from random genetic drift, which is an important mechanism in population genetics.

Notes

^ D. J. D. Earn, J. Dushoff, S. A. Levin (2002). "Ecology and Evolution of the Flu". Trends in Ecology and Evolution 17 (7): 334–340. doi:10.1016/S0169-5347(02)02502-8.
^ A. W. Hampson (2002). "Influenza virus antigens and antigenic drift". In C. W. Potter. Influenza. Elsevier Science B. V. pp. 49–86. ISBN 0-444-82461-8.
^ Boni, T; S. Cobey; P. Beerli; M. Pascual (2006). "Epidemic dynamics and antigenic evolution in a single season of influenza A". Proceedings of the Royal Society B 273 (1592): 1307–1316. doi:10.1098/rspb.2006.3466. PMC 1560306. PMID 16777717.
^ Bouvier NM, Palese P (Sep 2008). "The biology of influenza viruses". Vaccine 26 (Suppl 4): D49–53. doi:10.1016/j.vaccine.2008.07.039. PMC 3074182. PMID 19230160.
^ Nelson, M. I.; Holmes, E. C. (March 2007). "The evolution of pandemic influenza". Nature Reviews Genetics 8 (3): 196–205. doi:10.1038/nrg2053. PMID 17262054. Retrieved 13 November 2011.
^ ^a ^b Hensley, S. E.; Das, S. R.; Bailey, A. L.; Schmidt, L. M.; Hickman, H. D.; Jayaraman, A.; Viswanathan, K.; Raman, R.; Sasisekharan, R.; Bennink, J. R.; Yewdell, J. W. (30 October 2009). "Hemagglutinin receptor binding avidity drives influenza A virus antigenic drift". Science 326 (5953): 734–736. doi:10.1126/science.1178258. PMC 2784927. PMID 19900932. Retrieved 13 November 2011.
^ ^a ^b Taubenberger, Jeffery K.; Kash, John C. (17 June 2010). "Influenza virus evolution, host adaptation and pandemic formation". Cell Host & Microbe 7 (6): 440–451. doi:10.1016/j.chom.2010.05.009. Retrieved 13 November 2011.
^ Bush, R. M.; K. Subbarao; N. J. Cox; W. M. Fitch (3 December 1999). "Predicting the evolution of human influenza A". Science 286 (5446): 1921–1925. doi:10.1126/science.286.5446.1921. PMID 10583948. Retrieved 13 November 2011.
^ Carrat F, Flahault A (September 2007). "Influenza vaccine: the challenge of antigenic drift". Vaccine 25 (39–40): 6852–62. doi:10.1016/j.vaccine.2007.07.027. PMID 17719149.
^ R. M. Bush, W. M. Fitch, C. A. Bender, N. J. Cox (1999). "Positive selection on the H3 hemagglutinin gene of human influenza virus". Molecular Biology and Evolution 16 (11): 1457–1465. doi:10.1093/oxfordjournals.molbev.a026057. PMID 10555276.
^ W. M. Fitch, R. M. Bush, C. A. Bender, N. J. Cox (1997). "Long term trends in the evolution of H(3) HA1 human influenza type A". Proceedings of the National Academy of Sciences of the United States of America 94 (15): 7712–7718. doi:10.1073/pnas.94.15.7712. PMC 33681. PMID 9223253.
^ 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 (2004). "Mapping the antigenic and genetic evolution of influenza virus". Science 305 (5682): 371–376. doi:10.1126/science.1097211. PMID 15218094.

External links

An illustration of antigenic drift
A technical definition

UpToDate Contents

全文を閲覧するには購読必要です。 To read the full text you will need to subscribe.

1. インフルエンザの疫学 epidemiology of influenza
2. 鳥インフルエンザの疫学、伝播、および病因 epidemiology transmission and pathogenesis of avian influenza
3. 免疫グロブリンの機能および臨床応用 function and clinical applications of immunoglobulins
4. 成人における季節性インフルエンザワクチン seasonal influenza vaccination in adults
5. ヒトメタニューモウイルス感染 human metapneumovirus infections

English Journal

ANTIGENIC DRIFT IN H5N1 AVIAN INFLUENZA IN POULTRY IS DRIVEN BY MUTATIONS IN MAJOR ANTIGENIC SITES OF THE HEMAGGLUTININ MOLECULE ANALOGOUS TO HUMAN INFLUENZA.

Cattoli G, Milani A, Temperton N, Zecchin B, Buratin A, Molesti E, Aly MM, Arafa A, Capua I.SourceOIE/FAO Reference Laboratory for avian influenza and Newcastle Disease, Istituto Zooprofilattico Sperimentale delle Venezie, 35020 Legnaro (PD), Italy.
Journal of virology.J Virol.2011 Jul 6. [Epub ahead of print]
H5N1 Highly Pathogenic Avian Influenza virus has been endemic in poultry in Egypt since 2008, notwithstanding the implementation of mass vaccination and culling of infected birds. Extensive circulation of the virus has resulted in a progressive genetic evolution and an antigenic drift. In poultry, t
PMID 21734057

Japanese Journal

ノロウイルスのゲノム解析と流行発生のしくみ

本村和嗣,横山勝,岡智一郎,片山和彦,野田衛,田中智之,佐藤裕徳
感染症学雑誌 : 日本伝染病学会機関誌 : the journal of the Japanese Association for Infectious Diseases 86(5), 563-568, 2012-09-20
NAID 10031144078

第84回日本感染症学会総会座長推薦論文ノロウイルスのゲノム解析と流行発生のしくみ

本村和嗣,横山勝,岡智一郎 [他]
感染症学雑誌 = The journal of Japanese the Association for Infectious Diseases 86(5), 563-568, 2012-09
NAID 40019436605

Related Pictures

★リンクテーブル★

リンク元	「抗原ドリフト」
関連記事	「drift」「antigenic」

「抗原ドリフト」

　　[★]

英: antigenic drift
関: 抗原変異

「drift」

　　[★]

n.
vi.

漂流する、吹き流される。(風または水に)運ばれて積もる、不吉モル、吹き溜まりになる、漂積する
受動的に(あてどなく、ゆっくり)移動する。(予定のコースから)それる、逸脱する、知らぬ間に(ずるずると)陥る。流浪/放浪する

As the start to drift back together, ventricular contraction forces them shut, from whatever position the are at, as soon as the ventricular pressure exceeds that in the atrium.(PHD.33)

穴をあける、広げる

vt.

漂流させる、(気流が)吹き流す。吹き寄せる。(野・道などを)吹き寄せでおおう。(水の作用が)堆積させる。

「antigenic」

　　[★]

adj.

抗原性の、抗原の

関: Ag、antigen、antigenically、antigenicity

[antigenicdrift-1] D. J. D. Earn, J. Dushoff, S. A. Levin (2002). "Ecology and Evolution of the Flu". Trends in Ecology and Evolution 17 (7): 334–340. doi:10.1016/S0169-5347(02)02502-8.

[2] A. W. Hampson (2002). "Influenza virus antigens and antigenic drift". In C. W. Potter. Influenza. Elsevier Science B. V. pp. 49–86. ISBN 0-444-82461-8.

[3] Boni, T; S. Cobey; P. Beerli; M. Pascual (2006). "Epidemic dynamics and antigenic evolution in a single season of influenza A". Proceedings of the Royal Society B 273 (1592): 1307–1316. doi:10.1098/rspb.2006.3466. PMC 1560306. PMID 16777717.

[4] Bouvier NM, Palese P (Sep 2008). "The biology of influenza viruses". Vaccine 26 (Suppl 4): D49–53. doi:10.1016/j.vaccine.2008.07.039. PMC 3074182. PMID 19230160.

[5] Nelson, M. I.; Holmes, E. C. (March 2007). "The evolution of pandemic influenza". Nature Reviews Genetics 8 (3): 196–205. doi:10.1038/nrg2053. PMID 17262054. Retrieved 13 November 2011.

[Hensley_2009_734.E2.80.93736-6] Hensley, S. E.; Das, S. R.; Bailey, A. L.; Schmidt, L. M.; Hickman, H. D.; Jayaraman, A.; Viswanathan, K.; Raman, R.; Sasisekharan, R.; Bennink, J. R.; Yewdell, J. W. (30 October 2009). "Hemagglutinin receptor binding avidity drives influenza A virus antigenic drift". Science 326 (5953): 734–736. doi:10.1126/science.1178258. PMC 2784927. PMID 19900932. Retrieved 13 November 2011.

[Taubenberger_2010_440.E2.80.93451-7] Taubenberger, Jeffery K.; Kash, John C. (17 June 2010). "Influenza virus evolution, host adaptation and pandemic formation". Cell Host & Microbe 7 (6): 440–451. doi:10.1016/j.chom.2010.05.009. Retrieved 13 November 2011.

[8] Bush, R. M.; K. Subbarao; N. J. Cox; W. M. Fitch (3 December 1999). "Predicting the evolution of human influenza A". Science 286 (5446): 1921–1925. doi:10.1126/science.286.5446.1921. PMID 10583948. Retrieved 13 November 2011.

[9] Carrat F, Flahault A (September 2007). "Influenza vaccine: the challenge of antigenic drift". Vaccine 25 (39–40): 6852–62. doi:10.1016/j.vaccine.2007.07.027. PMID 17719149.

[10] R. M. Bush, W. M. Fitch, C. A. Bender, N. J. Cox (1999). "Positive selection on the H3 hemagglutinin gene of human influenza virus". Molecular Biology and Evolution 16 (11): 1457–1465. doi:10.1093/oxfordjournals.molbev.a026057. PMID 10555276.

[11] W. M. Fitch, R. M. Bush, C. A. Bender, N. J. Cox (1997). "Long term trends in the evolution of H(3) HA1 human influenza type A". Proceedings of the National Academy of Sciences of the United States of America 94 (15): 7712–7718. doi:10.1073/pnas.94.15.7712. PMC 33681. PMID 9223253.

[12] 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 (2004). "Mapping the antigenic and genetic evolution of influenza virus". Science 305 (5682): 371–376. doi:10.1126/science.1097211. PMID 15218094.

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antigenic drift