{"id":5437,"date":"2020-04-18T02:23:11","date_gmt":"2020-04-17T23:23:11","guid":{"rendered":"http:\/\/blog.ulubat.org\/?p=5437"},"modified":"2021-02-11T20:26:37","modified_gmt":"2021-02-11T17:26:37","slug":"sars-cov-2-yapisal-fonksiyonel-ozellikleri-ve-yapilan-son-incelemeler","status":"publish","type":"post","link":"https:\/\/blog.ulubat.org\/index.php\/genel\/sars-cov-2-yapisal-fonksiyonel-ozellikleri-ve-yapilan-son-incelemeler\/","title":{"rendered":"SARS-CoV-2 Yap\u0131sal-Fonksiyonel \u00d6zellikleri ve Yap\u0131lan Son \u0130ncelemeler"},"content":{"rendered":"\n
\"\"
(COVID-19. G\u00f6rsel Kayna\u011f\u0131: Fotomay\/Shutterstock<\/a>)<\/figcaption><\/figure>\n\n\n\n

Genel Bak\u0131\u015f ve Son \u00c7al\u0131\u015fmalar<\/strong><\/p>\n\n\n\n

\u00c7in\u2019in Wuhan kentinden\nyay\u0131lan COVID-19 RNA vir\u00fcs\u00fcn\u00fcn d\u00fcnyada yaratt\u0131\u011f\u0131 etki g\u00fcn ge\u00e7tik\u00e7e artmaktad\u0131r.\nTotalde 2 milyon 100 bin ki\u015fide tespit edilmi\u015f olup 140 bin \u00f6l\u00fcm mevcuttur.\n\u0130yile\u015fenlerin say\u0131s\u0131 yakla\u015f\u0131k 530 bin olsa da bu iyile\u015fenler hastal\u0131\u011fa tekrar\nyakalanabilmektedir. T\u00fcm d\u00fcnyaya yay\u0131ld\u0131\u011f\u0131 i\u00e7in hakk\u0131nda ara\u015ft\u0131rma yap\u0131l\u0131p\nbilgi toplanmas\u0131 kolay olmu\u015ftur. Bu vir\u00fcsle ayn\u0131 cinste olan SARS-CoV ise\nCOVID-19 kadar yay\u0131l\u0131m g\u00f6stermese de aralar\u0131ndaki ili\u015fki sebebiyle \u00e7ok benzer\n\u00f6zellikler ta\u015f\u0131maktad\u0131rlar. 2003\u2019te genel anlamda Uzak Do\u011fu \u00fclkelerinde g\u00f6r\u00fclen\nSARS-CoV-1, bug\u00fcnk\u00fc COVID-19\u2019u a\u00e7\u0131\u011fa \u00e7\u0131kard\u0131\u011f\u0131 i\u00e7in yeni koronavir\u00fcs\u00fcn di\u011fer\nad\u0131 SARS-CoV-2 olmu\u015ftur. 55 \u00fclkede tespit edilen SARS-CoV\u2019dan filogenetik\nbilgiler yeterli \u00f6l\u00e7\u00fcde al\u0131nabilirse COVID-19\u2019un kayna\u011f\u0131, evrimi ve yay\u0131l\u0131m\u0131\nhakk\u0131nda daha fazla bilgi edinilebilir. Bunun i\u00e7in bulunan her SARS-CoV-1\n\u00fczerinde dizileme (sekanslama) uygulanmaktad\u0131r. Bu  y\u00f6ntemle mutasyona u\u011fram\u0131\u015f koronavir\u00fcsler de\ntespit edilmektedir. Ayr\u0131ca sekans analizleri sonucu elde edilen verilerin, d\u00fcnyadaki\nhangi \u00e7al\u0131\u015fmada olursa olsun, GenBank ve GISAID gibi platformlarda payla\u015f\u0131lmas\u0131\ngereklidir. <\/p>\n\n\n\n

\u015eu ana kadar SARS-CoV ve\nCOVID-19 aras\u0131nda bir\u00e7ok benzerlik bulunmu\u015ftur. Bunlar aras\u0131nda s\u0131ca\u011fa\ndayan\u0131ks\u0131z protein zarf\u0131, RNA genetik materyali, ikisinin de zat\u00fcreye sebep\nolmas\u0131 ve yarasadan gelmeleri yer al\u0131r. RNA vir\u00fcsleri DNA vir\u00fcslerine g\u00f6re, tek\nzincirli olduklar\u0131 i\u00e7in daha \u00e7ok mutasyona u\u011framaktad\u0131r. Ayda yakla\u015f\u0131k 2 kere\nmutasyona u\u011framaktad\u0131r. Fakat 29 bin baz i\u00e7erisinde yakla\u015f\u0131k birka\u00e7 on\ntanesinde mutasyon ger\u00e7ekle\u015fmektedir. Ayr\u0131ca bir ki\u015finin COVID-19\u2019la enfekte\nolup olmad\u0131\u011f\u0131n\u0131 anlamak i\u00e7in SARS-CoV-1 geneti\u011finden yararlan\u0131lmaktad\u0131r. \u00d6rne\u011fin\nbaz\u0131 ki\u015filer SARS-CoV-2 ile enfekteyse, bu demektir ki bu ki\u015filer k\u0131sa zaman\n\u00f6nce b\u00fcy\u00fck ihtimalle bu vir\u00fcs\u00fcn genetik anlamda \u00e7ok benzer oldu\u011fu vir\u00fcs\u00fcn\nlokalize oldu\u011fu b\u00f6lgede ayn\u0131 ortamda bulunmu\u015f ya da bu b\u00f6lgede ya\u015fayan enfekte\nbir birey onlara bula\u015ft\u0131rm\u0131\u015ft\u0131r. Yani biri Alman biri Hollandal\u0131 iki birey \u0130ran\u2019da\nkar\u015f\u0131la\u015fm\u0131\u015fsa, bu ki\u015filerin ikisinin de \u0130ran\u2019da ayn\u0131 anda bulundu\u011fu ortaya\n\u00e7\u0131kar\u0131labilmektedir. Ayn\u0131 \u015fekilde \u0130ranl\u0131 bir vatanda\u015f\u0131n yurt d\u0131\u015f\u0131na \u00e7\u0131k\u0131p\nonlar\u0131 enfekte etmesi de m\u00fcmk\u00fcnd\u00fcr. Bu gibi ayr\u0131nt\u0131lar i\u00e7in SARS-CoV-1 \u00f6nem\nta\u015f\u0131r. Epideminin ABD\u2019de nas\u0131l yay\u0131ld\u0131\u011f\u0131 bu \u015fekilde ortaya \u00e7\u0131kabilmektedir\nancak Washington\u2019da Ocak 2020\u2019den beri SARS-CoV-2, g\u00f6zlem aparatlar\u0131nda kolay ay\u0131rt\nedilememektedir. <\/p>\n\n\n\n

SARS-CoV-2, ABD\u2019de ilk\n\u00f6nce New York\u2019ta tespit edilmi\u015f olup belirtilen y\u00f6ntemler do\u011frultusunda bu\nvir\u00fcs\u00fcn buraya Avrupa\u2019dan geldi\u011fi g\u00f6r\u00fclm\u00fc\u015ft\u00fcr ve buradan k\u0131taya yay\u0131lm\u0131\u015ft\u0131r. \u0130ngilizlerin\nkat\u0131ld\u0131\u011f\u0131 bir \u00e7al\u0131\u015fmada bu vir\u00fcs\u00fcn d\u0131\u015far\u0131da de\u011fil, insan v\u00fccudunda evrim\nge\u00e7irdi\u011fi \u00f6ne s\u00fcr\u00fclm\u00fc\u015ft\u00fcr. Stanford \u00dcniversitesi\u2019ndeki bir \u00e7al\u0131\u015fmada da bu mutasyonlar\u0131n\nvir\u00fcs\u00fcn yay\u0131l\u0131m\u0131 hakk\u0131nda bilgi ta\u015f\u0131yabilece\u011fi \u00f6ne s\u00fcr\u00fclm\u00fc\u015ft\u00fcr. <\/p>\n\n\n\n

Yeni koronavir\u00fcslerin ilk\nkez tam genomu ortaya \u00e7\u0131kar\u0131l\u0131rken illumina, nanopore ve sanger sekanslama\ny\u00f6ntemleri uygulanm\u0131\u015ft\u0131r. Bu \u015fekilde COVID-19\u2019lar\u0131n \u00fc\u00e7 tane su\u015fu\nbelirlenmi\u015ftir. Bunlar\u0131n ve betakoronavir\u00fcslerin (SARS\/MERS\/COVID-19) SARS\nbenzeri Bat-SL-CoVZC45 ile yak\u0131ndan ili\u015fkili oldu\u011fu bulunmu\u015ftur. Bu vir\u00fcs yarasada\nbulunmaktad\u0131r. COVID-19\u2019dan sorumlu bu vir\u00fcs betakoronavir\u00fcs i\u00e7inde sarbekovir\u00fcs\naltcinsine aittir. <\/p>\n\n\n\n

Endemik salg\u0131na sebep olan koronavir\u00fcsler bulunmaktad\u0131r. Bunlar \u00a0HCoV-229E, HCoV-NL63, HCoV-HKU1 ve HCoV-OC43\u2019t\u00fcr. \u0130lk ikisi alfakoronavir\u00fcs ve di\u011fer ikisi betakoronavir\u00fcst\u00fcr. Bunlar\u0131n hi\u00e7birine kar\u015f\u0131 a\u015f\u0131 ve terapi geli\u015ftirilememi\u015ftir. <\/p>\n\n\n\n

\"\"
(Koronavir\u00fcs. G\u00f6rsel Kayna\u011f\u0131: Andrii Vodolazhskyi\/Shutterstock<\/a>, ID: 1643947495)<\/figcaption><\/figure>\n\n\n\n

SARS-CoV-2 Fonksiyonel ve Yap\u0131sal \u00d6zellikleri<\/strong><\/p>\n\n\n\n

SARS-CoV-2 alt solunum\nyollar\u0131n\u0131 etkilemektedir ve buradaki ACE2 resept\u00f6rlerine ba\u011flanmaktad\u0131r. Yani vir\u00fcs\nanjiyotensin metabolizmas\u0131n\u0131n analo\u011fudur. Anjiyotensinin i\u00e7inde bulundu\u011fu\nreaksiyonlar zinciri, aldosteronla birlikte v\u00fccut s\u0131v\u0131 hacmini d\u00fczenler. V\u00fccut\nsusuz kald\u0131\u011f\u0131nda suyun d\u0131\u015far\u0131 at\u0131lmas\u0131n\u0131 \u00f6nler. Dolay\u0131s\u0131yla SARS-CoV-2 fazla su\nat\u0131m\u0131na sebep olur. Bu y\u00fczden COVID-19 enfekte bireylerin normalden \u00e7ok daha\nfazla su i\u00e7mesi gerekir. Bu ayn\u0131 zamanda vir\u00fcs\u00fcn v\u00fccuttan at\u0131m\u0131n\u0131\nkolayla\u015ft\u0131r\u0131r. Bu vir\u00fcs ve SARS-CoV-1 benzer bir afiniteyle ACE2 resept\u00f6rlerine\nba\u011flan\u0131r. Fakat SARS koronavir\u00fcs\u00fcn\u00fcn poliklonal antikorlar\u0131 COVID-19\u2019un h\u00fccrelere\ngirmesini engeller. Bu durumda iki vir\u00fcs\u00fcn de v\u00fccudunda bulundu\u011fu birinin SARS-CoV-1\nenfekte olmas\u0131 beklenir. SARS-CoV-2\u2019nin kendi transmembran diken (S) glikoproteinleri\niki farkl\u0131 konformasyonda bulunur. Bunlar pref\u00fczyon ve f\u00fczyon konformasyondur,\nvir\u00fcs y\u00fczeyinden \u00e7\u0131k\u0131nt\u0131 yapan ve homotrimer olu\u015fturan glikoproteinlerin\nba\u011flanmadan \u00f6nceki ve sonraki durumlar\u0131n\u0131 ifade ederler. Bu glikoproteinlerin alt\nbirimleri  S1 ve S2\u2019dir. S1 konak h\u00fccre\nresept\u00f6r\u00fcne ba\u011flanmay\u0131 sa\u011flarken S2 de konak h\u00fccre ve viral membranlar\u0131n\nbirle\u015fmesini sa\u011flar. Distal S1 alt birimi, membrana ba\u011fl\u0131 S2\u2019yi stabilize eder.\nFakat b\u00fct\u00fcn koronavir\u00fcslerde S alt birimi, konak h\u00fccrenin proteazlar\u0131\ntaraf\u0131ndan S2\u2019 b\u00f6lgesinden b\u00f6l\u00fcnmeye u\u011frar. Ancak bu vir\u00fcs\u00fcn h\u00fccreyle geri\nd\u00f6n\u00fc\u015f\u00fcms\u00fcz bir konformasyon de\u011fi\u015fimiyle birle\u015fimine sebep olur. <\/p>\n\n\n\n

Her koronavir\u00fcs h\u00fccrelere\nS1 alt biriminin farkl\u0131 b\u00f6lgelerinden ba\u011flan\u0131r. \u00d6rne\u011fin OC43 ve HKU1 endemik\nkoronavir\u00fcsleri h\u00fccrenin 5-N-asetil-9-sialosidlerine S^A b\u00f6lgesinden ba\u011flan\u0131r. MERS-CoV\u2019un\nS b\u00f6lgesi ise asetil i\u00e7ermeyen sialosidlere ba\u011flan\u0131r, bu da S^B b\u00f6lgesinin\ndipeptidil peptidaz 4 giri\u015f resept\u00f6r\u00fcne ba\u011flanmas\u0131n\u0131 sa\u011flar.  SARS-CoV, h\u00fccrenin i\u00e7ine girebilmek i\u00e7in S^B\nb\u00f6lgeleriyle anjiyotensin d\u00f6n\u00fc\u015ft\u00fcr\u00fcc\u00fc enzim 2 ile etkile\u015fime girer. Ayr\u0131ca bu S\nb\u00f6lgeleri a\u015f\u0131 ve terapilerde n\u00f6tralizasyon antikorlar\u0131 i\u00e7in hedef noktas\u0131d\u0131r. Uygun\nkonformasyonu ve konak h\u00fccre proteazlar\u0131n\u0131n etkile\u015fime girmesini ayarlamak i\u00e7in\nS proteini N-ba\u011fl\u0131 glikanlarla donanm\u0131\u015ft\u0131r. SARS-CoV ve MERS-CoV ile enfekte\nbir B haf\u0131za h\u00fccresinden n\u00f6tralizasyon Abs\u2019leri (n\u00f6tralizasyon antikorlar\u0131)\nsalg\u0131lan\u0131r. Bu da S^B b\u00f6lgesinin ba\u011flanmas\u0131nda kompetitif inhibisyon i\u00e7in bilgi\nal\u0131nmas\u0131n\u0131 sa\u011flar. <\/p>\n\n\n\n

De\u011ferlendirme <\/strong><\/p>\n\n\n\n

COVID-19 hakk\u0131nda her\nge\u00e7en g\u00fcn yeni \u00e7al\u0131\u015fmalar yap\u0131lmakta ve yeni bilgiler toplanmaktad\u0131r. Bilim\ninsanlar\u0131n\u0131n vir\u00fcsle ilgili bu yeni bilgileri almas\u0131 ve kullanmas\u0131, vir\u00fcs\u00fc\nyenebilmek i\u00e7in \u00e7ok \u00f6nemlidir. Son \u00e7al\u0131\u015fmalarda g\u00f6r\u00fclm\u00fc\u015ft\u00fcr ki, hen\u00fcz a\u015f\u0131\ngeli\u015ftirilmemi\u015f olsa da, vir\u00fcs\u00fcn yay\u0131l\u0131m\u0131n\u0131 engellemek m\u00fcmk\u00fcnd\u00fcr ancak \u00f6nlemlerin\nhepsi al\u0131n\u0131rsa bu s\u00f6z konusudur. Aksi taktirde iyile\u015fenler tekrar hasta olabilmektedir.\nBilim insanlar\u0131 SARS-CoV-2 hakk\u0131nda ileride daha \u00e7ok i\u015fe yarar bilgi toplamay\u0131 umuyorlar.\n<\/p>\n\n\n\n

Referanslar<\/strong><\/p>\n\n\n\n

  1. Walls, Alexandra\nC. . \u201cStructure, Function, and Antigenicity of the SARS-CoV-2 Spike\nGlycoprotein\u201d. Cell <\/em>181:2 (2020):\n281-292. ScienceDirect. 17.04.2020. <\/li>
  2. Anderson, Andrea. \u201cSARS-CoV-2\nGenomes Let Researchers Retrace Viral Spread, Mitigation Effects\u201d. GenomeWeb. Web.\n13.04.2020. 16.04.2020. <\/li>
  3. \u201cCOVID-19\nDashboard by the Center for Systems Science and Engineering (CSSE) at Johns\nHopkins University (JHU)\u201d. 16.04.2020. https:\/\/gisanddata.maps.arcgis.com\/apps\/opsdashboard\/index.html#\/bda7594740fd40299423467b48e9ecf6<\/a><\/li>
  4. Sade, Gizem. \u201cG\u00fcney\nKore’de \u0130yile\u015fen 91 Covid-19 Hastas\u0131n\u0131n Test Sonucu Yeniden Pozitif \u00c7\u0131kt\u0131\u201d. Euronews.\nhttps:\/\/tr.euronews.com\/2020\/04\/10\/guney-kore-de-iyilesen-91-covid-19-hastas-n-n-test-sonucu-yeniden-pozitif-c-kt<\/a>,\n10.04.2020. 17.04.2020. <\/li>
  5. \u201cCOVID-19 (SARS-Cov-2\nEnfeksiyonu) Rehberi\u201d. T.C. Sa\u011fl\u0131k Bakanl\u0131\u011f\u0131 Halk Sa\u011fl\u0131\u011f\u0131 Genel M\u00fcd\u00fcrl\u00fc\u011f\u00fc. 5-7.\n25.03.2020. 17.04.2020. <\/li><\/ol>\n\n\n\n

    G\u00f6rsel Kaynaklar\u0131<\/strong><\/p>\n\n\n\n

    1. Fotomay\/Shutterstock<\/a><\/li>
    2. Andrii Vodolazhskyi\/Shutterstock<\/a>, ID: 1643947495<\/li><\/ol>\n","protected":false},"excerpt":{"rendered":"

      Genel Bak\u0131\u015f ve Son \u00c7al\u0131\u015fmalar \u00c7in\u2019in Wuhan kentinden yay\u0131lan COVID-19 RNA vir\u00fcs\u00fcn\u00fcn d\u00fcnyada yaratt\u0131\u011f\u0131 etki g\u00fcn ge\u00e7tik\u00e7e artmaktad\u0131r. Totalde 2<\/p>\n","protected":false},"author":267,"featured_media":5439,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":[],"categories":[1],"tags":[693,691,696,694,695,692],"acf":[],"views":674,"_links":{"self":[{"href":"https:\/\/blog.ulubat.org\/index.php\/wp-json\/wp\/v2\/posts\/5437"}],"collection":[{"href":"https:\/\/blog.ulubat.org\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/blog.ulubat.org\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/blog.ulubat.org\/index.php\/wp-json\/wp\/v2\/users\/267"}],"replies":[{"embeddable":true,"href":"https:\/\/blog.ulubat.org\/index.php\/wp-json\/wp\/v2\/comments?post=5437"}],"version-history":[{"count":9,"href":"https:\/\/blog.ulubat.org\/index.php\/wp-json\/wp\/v2\/posts\/5437\/revisions"}],"predecessor-version":[{"id":9841,"href":"https:\/\/blog.ulubat.org\/index.php\/wp-json\/wp\/v2\/posts\/5437\/revisions\/9841"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/blog.ulubat.org\/index.php\/wp-json\/wp\/v2\/media\/5439"}],"wp:attachment":[{"href":"https:\/\/blog.ulubat.org\/index.php\/wp-json\/wp\/v2\/media?parent=5437"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/blog.ulubat.org\/index.php\/wp-json\/wp\/v2\/categories?post=5437"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/blog.ulubat.org\/index.php\/wp-json\/wp\/v2\/tags?post=5437"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}