{"id":879,"date":"2020-04-15T10:47:17","date_gmt":"2020-04-15T10:47:17","guid":{"rendered":"https:\/\/uni.hi.is\/apalsson\/?p=879"},"modified":"2020-04-15T10:47:17","modified_gmt":"2020-04-15T10:47:17","slug":"icelandic-hvort-er-liklegra-ad-veiran-sem-veldur-covid-19-verdi-haettulegri-eda-haettuminni-fyrir-menn-vegna-stokkbreytinga","status":"publish","type":"post","link":"https:\/\/uni.hi.is\/apalsson\/IS\/2020\/04\/15\/icelandic-hvort-er-liklegra-ad-veiran-sem-veldur-covid-19-verdi-haettulegri-eda-haettuminni-fyrir-menn-vegna-stokkbreytinga\/","title":{"rendered":"Hvort er l\u00edklegra a\u00f0 veiran sem veldur COVID-19 ver\u00f0i h\u00e6ttulegri e\u00f0a h\u00e6ttuminni fyrir menn vegna st\u00f6kkbreytinga?"},"content":{"rendered":"

Arnar P\u00e1lsson. \u201eHvort er l\u00edklegra a\u00f0 veiran sem veldur COVID-19 ver\u00f0i h\u00e6ttulegri e\u00f0a h\u00e6ttuminni fyrir menn vegna st\u00f6kkbreytinga?\u201c V\u00edsindavefurinn<\/i>, 1. apr\u00edl 2020. S\u00f3tt 15. apr\u00edl 2020. http:\/\/visindavefur.is\/svar.php?id=79103.<\/p>\n

Breytingar \u00e1 erf\u00f0aefni<\/a> lei\u00f0a sjaldan til st\u00f6kka \u00ed ger\u00f0 e\u00f0a h\u00e6fni l\u00edfvera<\/span>[1]<\/a><\/sup> og flestar st\u00f6kkbreytingar<\/a> sem finnst \u00ed stofnum eru hlutlausar.<\/span>[2]<\/a><\/sup> St\u00f6kkbreytingar sem skemma gen<\/a> og draga \u00far h\u00e6fni eru kalla\u00f0ar neikv\u00e6\u00f0ar en \u00fe\u00e6r sem auka h\u00e6fni l\u00edfveru \u00e1 einhvern h\u00e1tt eru kalla\u00f0ar j\u00e1kv\u00e6\u00f0ar. J\u00e1kv\u00e6\u00f0 breyting \u00e1 veiru<\/a> getur haft neikv\u00e6\u00f0 \u00e1hrif fyrir h\u00fdsil hennar. Hlutlausar breytingar eru \u00fe\u00e6r sem hafa engin \u00e1hrif \u00e1 h\u00e6fni. V\u00edsindamenn telja sl\u00edkar breytingar hins vegar mj\u00f6g gagnlegar \u00fev\u00ed \u00fe\u00e6r n\u00fdtast til a\u00f0 rekja s\u00f6gu stofna, tegunda og veira.<\/p>\n

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Litu\u00f0 rafeindasm\u00e1sj\u00e1rmynd af SARS-CoV-2-veirum.<\/p>\n<\/div>\n<\/div>\n

Ef svo \u00f3l\u00edklega vill til a\u00f0 \u00fer\u00f3unarlega j\u00e1kv\u00e6\u00f0 breyting ver\u00f0i \u00ed erf\u00f0aefni SARS-CoV-2 veirunnar sem veldur COVID-19<\/a>, \u00fe\u00e1 m\u00e1 spyrja hvort h\u00fan ver\u00f0i h\u00e6ttulegri vi\u00f0 \u00fea\u00f0? Umor\u00f0a m\u00e1 spurninguna og spyrja: Hversu algengt er a\u00f0 veiran sem veldur COVID-19 st\u00f6kkbreytist og geti vi\u00f0 \u00fea\u00f0 or\u00f0i\u00f0 meira smitandi e\u00f0a valdi\u00f0 alvarlegri sj\u00fakd\u00f3mum? Til \u00feess a\u00f0 svara \u00feessu \u00fearf a\u00f0 sko\u00f0a og skilja eftirfarandi:<\/p>\n

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  1. byggingu, l\u00edfsferil og erf\u00f0amengi veirunnar<\/li>\n
  2. l\u00edkurnar \u00e1 st\u00f6kkbreytingum RNA<\/a>-veira<\/li>\n
  3. hversu l\u00edklegt \u00fea\u00f0 er a\u00f0 breyting sem er veirunni \u00ed hag valdi h\u00e6ttulegri sj\u00fakd\u00f3mi<\/li>\n<\/ol>\n

    Um fyrsta atri\u00f0i\u00f0 er \u00fea\u00f0 a\u00f0 segja a\u00f0 veirur \u00feurfa \u00e1 lifandi h\u00fdsilfrumum a\u00f0 halda til a\u00f0 eftirmynda erf\u00f0aefni sitt og fj\u00f6lga s\u00e9r. COVID-19 er me\u00f0 ein\u00fe\u00e1tta 29.903 basapara RNA-streng.<\/span>[3]<\/a><\/sup> Erf\u00f0amengi veirunnar skr\u00e1ir fyrir nokkrum fj\u00f6lpr\u00f3t\u00ednum og minni pr\u00f3t\u00ednum. Eitt af \u00feessum pr\u00f3t\u00ednum er mj\u00f6g mikilv\u00e6gt en \u00fea\u00f0 er svokalla\u00f0 bindipr\u00f3t\u00edn (e. spike protein<\/span>[4]<\/a><\/sup>). \u00dea\u00f0 er \u00e1 ytra byr\u00f0i veirunnar og tengist vi\u00f0t\u00f6kum \u00e1 yfirbor\u00f0i h\u00fdsilfruma, nokkurn veginn eins og lykill gengur a\u00f0 skr\u00e1. Veiran n\u00fdtir s\u00e9r \u00feannig tengingu bindipr\u00f3t\u00edna vi\u00f0 tiltekna vi\u00f0taka til innr\u00e1sar \u00ed h\u00fdsilfrumuna. S\u00ed\u00f0an tekur veiran yfir kerfi frumunnar og fj\u00f6lfaldar b\u00e6\u00f0i erf\u00f0aefni sitt og nau\u00f0synleg pr\u00f3t\u00edn og myndar a\u00f0 endingu fj\u00f6lda n\u00fdrra veiruagna. \u00de\u00e6r geta svo \u00fdmist s\u00fdkt a\u00f0rar frumur sama einstaklings (\u00feegar s\u00fdkingin magnast inni \u00ed manni) e\u00f0a sloppi\u00f0 \u00fat \u00ed umhverfi\u00f0 og borist \u00ed a\u00f0ra einstaklinga.<\/p>\n

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    Einf\u00f6ld sk\u00fdringarmynd af veirunni SARS-CoV-2. Bindipr\u00f3t\u00ednin eru \u00e1 ytra byr\u00f0i veirunnar. \u00deau tengjast vi\u00f0t\u00f6kum h\u00fdsilfrumunnar og \u00feannig kemst veiran inn \u00ed hana.<\/p>\n<\/div>\n<\/div>\n

    Um atri\u00f0i tv\u00f6 er r\u00e9tt a\u00f0 hafa \u00ed huga a\u00f0 veirur, eins og l\u00edfverur almennt, m\u00f3tast af kr\u00f6ftum \u00fer\u00f3unar, svo sem st\u00f6kkbreytingum og n\u00e1tt\u00farulegu vali. St\u00f6kkbreytingar, sem r\u00e9ttara v\u00e6ri a\u00f0 kalla erf\u00f0afr\u00e1vik, eru n\u00e1tt\u00farulegt fyrirb\u00e6ri. St\u00f6kkbreytit\u00ed\u00f0ni veira er h\u00e1, s\u00e9rstaklega mi\u00f0a\u00f0 vi\u00f0 heilkj\u00f6rnunga og fl\u00f3knar l\u00edfverur.<\/span>[5]<\/a><\/sup> V\u00edsindamenn um allan heim hafa ra\u00f0greint erf\u00f0amengi COVID-19-veirunnar \u00far meira en 1.500 smitu\u00f0um einstaklingum \u00e1 innan vi\u00f0 tveimur m\u00e1nu\u00f0um. G\u00f6gnin eru a\u00f0gengileg \u00f6\u00f0rum v\u00edsindam\u00f6nnum \u00ed opnum gagnagrunnum.<\/span>[6]<\/a><\/sup> Me\u00f0 erf\u00f0amengjum og \u00e6ttartr\u00e9 veira \u00far smitu\u00f0um einstaklingum er h\u00e6gt a\u00f0 telja breytingarnar \u00ed hverri veirukynsl\u00f3\u00f0. \u00cd n\u00e1skyldu k\u00f3r\u00f3nuveirunni SARS-CoV-1 er til d\u00e6mis t\u00ed\u00f0ni breytinga \u00e1 hvert basapar \u00ed hverri kynsl\u00f3\u00f0 0,8 til 2,4 \u00d7 10-3<\/sup>. Vi\u00f0 hvert smit \u00feeirrar veiru ur\u00f0u a\u00f0 me\u00f0altali 16 breytingar \u00ed 30.000 basapara erf\u00f0amengi hennar. G\u00f6gn sameindal\u00edffr\u00e6\u00f0ingsins Peter Thielen vi\u00f0 John Hopkins-h\u00e1sk\u00f3lann \u00ed Baltimore og samstarfsmanna hans, s\u00fdna a\u00f0 st\u00f6kkbreytit\u00ed\u00f0ni COVID-19 er ef til vill \u00edvi\u00f0 l\u00e6gri. Vi\u00f0 smit fr\u00e1 k\u00ednverskum einstaklingum til bandar\u00edskra ur\u00f0u 4 til 10 breytingar \u00ed erf\u00f0amengi veirunnar.<\/span>[7]<\/a><\/sup> St\u00f6kkbreytit\u00ed\u00f0ni er m\u00e6ld sem fj\u00f6ldi st\u00f6kkbreytinga \u00e1 kynsl\u00f3\u00f0 og \u00fev\u00ed gefur auga lei\u00f0 a\u00f0 fj\u00f6ldi smita hefur \u00e1hrif. Me\u00f0 auknum fj\u00f6lda smita eykst h\u00e6ttan \u00e1 a\u00f0 j\u00e1kv\u00e6\u00f0 breyting ver\u00f0i \u00ed erf\u00f0aefni veirunnar. Ef a\u00f0eins 1000 manns smitast \u00fe\u00fd\u00f0ir \u00fea\u00f0 1000 m\u00f6guleika fyrir st\u00f6kkbreytingar me\u00f0 j\u00e1kv\u00e6\u00f0 \u00e1hrif \u00e1 h\u00e6fni veirunnar. Ef millj\u00f3n manns smitast aukast l\u00edkurnar \u00e1 breytingum sem eru veirunni \u00ed hag. R\u00e9tt er hins vegar a\u00f0 hafa \u00ed huga a\u00f0 l\u00edkurnar \u00e1 sl\u00edkum j\u00e1kv\u00e6\u00f0um breytingum eru fjarska litlar til a\u00f0 byrja me\u00f0. \u00de\u00e1 er komi\u00f0 a\u00f0 \u00feri\u00f0ja atri\u00f0inu. Ef svo illa vill til a\u00f0 j\u00e1kv\u00e6\u00f0 breyting ver\u00f0i \u00e1 veirunni, getum vi\u00f0 \u00fe\u00e1 sp\u00e1\u00f0 fyrir um \u00e1hrif hennar e\u00f0a hvort h\u00fan muni lei\u00f0a til \u00feess a\u00f0 veiran ver\u00f0i okkur h\u00e6ttulegri? Tv\u00e6r aflei\u00f0ingar v\u00e6ru alvarlegastar. \u00cd fyrsta lagi a\u00f0 veiran breytist og valdi alvarlegri sj\u00fakd\u00f3mi (til d\u00e6mis me\u00f0 h\u00e6rri d\u00e1nart\u00ed\u00f0ni) og \u00ed \u00f6\u00f0ru lagi a\u00f0 h\u00fan smitist betur manna \u00e1 milli. Mj\u00f6g \u00f3l\u00edklegt er a\u00f0 st\u00f6kkbreyting komi upp sem valdi hvoru tveggja, meira smiti og h\u00e6ttulegri einkennum. J\u00e1kv\u00e6\u00f0ar breytingar \u00e1 erf\u00f0aefni veiru geta auki\u00f0 h\u00e6fni \u00ed gegnum marga \u00f3l\u00edka \u00fe\u00e6tti l\u00edfsferils hennar. Til d\u00e6mis me\u00f0 \u00fev\u00ed a\u00f0 b\u00e6ta h\u00e6fileika hennar til a\u00f0 bindast frumum, til a\u00f0 s\u00fdkja fleiri ger\u00f0ir fruma, til a\u00f0 framlei\u00f0a fleiri agnir \u00e1\u00f0ur en einkenni koma fram hj\u00e1 h\u00fdsli (auka smitm\u00f6guleika), lifa lengur \u00ed umhverfinu e\u00f0a vi\u00f0 l\u00e6gra rakastig, valda til\u00ferifameiri hnerrak\u00f6stum (sem auka dreifingu), valda heiftarlegri s\u00fdkingu, sleppa undan \u00f3n\u00e6miskerfi h\u00fdsla og svo m\u00e6tti lengi telja. Mj\u00f6g erfitt er a\u00f0 sp\u00e1 fyrir um hva\u00f0a aflei\u00f0ingar breytingar sem \u00feessar (ef \u00fe\u00e6r ver\u00f0a) hj\u00e1 COVID-19 myndu \u00fe\u00fd\u00f0a fyrir menn.<\/p>\n

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    F\u00e1 d\u00e6mi eru \u00feekkt um a\u00f0 st\u00f6kkbreytingar e\u00f0a erf\u00f0afr\u00e1vik \u00ed veirum geri \u00fe\u00e6r h\u00e6ttulegri. St\u00f6kkbreytingar \u00e1 erf\u00f0aefni veiru sem lei\u00f0ir til br\u00e1\u00f0s andl\u00e1ts h\u00fdsils veldur til d\u00e6mis minni h\u00e6fni hennar samanbori\u00f0 vi\u00f0 \u00f3st\u00f6kkbreytta veiru.<\/p>\n<\/div>\n<\/div>\n

    F\u00e1 d\u00e6mi eru \u00feekkt um a\u00f0 veira st\u00f6kkbreytist yfir \u00ed verra og sv\u00e6snara form. Best skilgreinda d\u00e6mi\u00f0 er z\u00edkaveiran<\/a>. \u00cd henni var\u00f0 st\u00f6kkbreyting sem j\u00f3k s\u00e6kni veirunnar \u00ed taugavefi manna \u00feannig a\u00f0 h\u00fan olli meiri ska\u00f0a. Almennt er \u00fea\u00f0 veirum ekki \u00ed hag a\u00f0 drepa h\u00fdsla s\u00edna. St\u00f6kkbreyting \u00ed veiru sem lei\u00f0ir til br\u00e1\u00f0s andl\u00e1ts h\u00fdsils veldur minni h\u00e6fni hennar samanbori\u00f0 vi\u00f0 \u00f3st\u00f6kkbreytta veiru. \u00c1st\u00e6\u00f0an er einfaldlega s\u00fa a\u00f0 vi\u00f0 \u00fea\u00f0 \u00fea\u00f0 dregur \u00far s\u00fdkigetu veirunnar. \u00dev\u00ed er tali\u00f0 a\u00f0 eftir a\u00f0 veirur a\u00f0lagist a\u00f0 endingu h\u00fdslum s\u00ednum valdi \u00fe\u00e6r mildari s\u00fdkingum. Hinar fj\u00f3rar k\u00f3r\u00f3nuveirurnar<\/span>[8]<\/a><\/sup> sem s\u00fdkja menn valda til d\u00e6mis allar mildari sj\u00fakd\u00f3mi en COVID-19 og l\u00edklegt ver\u00f0ur a\u00f0 teljast a\u00f0 COVID-19 \u00fer\u00f3ist \u00ed svipa\u00f0a \u00e1tt og \u00fe\u00e6r. \u00c1 hinn b\u00f3ginn ver\u00f0a veirur a\u00f0 vi\u00f0halda s\u00fdkim\u00e6tti og tryggja dreifingu s\u00edna (me\u00f0 hnerrum, h\u00f3stum og nefrennsli), \u00feannig a\u00f0 \u00fea\u00f0 er veirum \u00ed hag a\u00f0 valda einkennum hj\u00e1 sj\u00faklingum sem tryggja dreifigetu veiranna. Veiran sem veldur COVID-19 \u00fer\u00f3ast \u00ed \u00fev\u00ed umhverfi sem h\u00fan b\u00fdr \u00ed. Umhverfi hennar er ma\u00f0urinn og samf\u00e9lag okkar \u00e1ri\u00f0 2020. Vi\u00f0br\u00f6g\u00f0 samf\u00e9laga vi\u00f0 veirunni eru hluti af \u00fev\u00ed umhverfi. Einn vinkill a\u00f0 auki, er s\u00e1 a\u00f0 \u00f3n\u00e6miskerfi okkar er lei\u00f0 til a\u00f0 verjast s\u00fdkingum og muna eftir \u00feeim. En s\u00fdklar geta einnig \u00fer\u00f3ast sem vi\u00f0brag\u00f0 vi\u00f0 auknu \u00f3n\u00e6mi me\u00f0al h\u00fdsla, eins og \u00feekkt er hj\u00e1 k\u00f3r\u00f3nuveiru sem nefnist OC43 (HCoV-OC43). H\u00fan veldur a\u00f0eins venjulegu kvefi. Samantekt<\/strong><\/p>\n