Kuchulukitsa kwa ma virus m'maselo a wolandirayo
Mavairasi ndi tizilombo toyambitsa matenda tating'onoting'ono tomwe sitingathe kukhala ndi moyo ndikuberekana tokha. Mosiyana ndi mabakiteriya kapena bowa, omwe ali ndi machitidwe awoawo a kagayidwe kachakudya, mavairasi amadalira pafupifupi maselo a anthu kuti apange zigawo zatsopano. Chifukwa chake, njira yoberekera mavairasi—njira yomwe mavairasi amakopera majini awo ndikusonkhanitsa tinthu tatsopano ta mavairasi—nthawi zonse imachitika mkati mwa selo la anthu. Kumvetsetsa magawo a kuberekana kwa mavairasi ndikofunikira kwambiri mu sayansi ya zamoyo, zamankhwala, ndi thanzi la anthu, chifukwa njira zambiri zopewera ndi kuchiza zimapangidwa kuti ziletse gawo limodzi lofunika kwambiri la nthawi ino.
Kapangidwe koyambira ka mavairasi ndi kudalira kwawo pa wolandirayo
Kawirikawiri, mavairasi amapangidwa ndi zinthu za majini (nucleic acid), zomwe zingakhale DNA kapena RNA, zotetezedwa ndi puloteni yotchedwa capsid. Mavairasi ena ali ndi gawo lina, lomwe limachokera ku nembanemba ya selo la host, yokhala ndi mapuloteni apamwamba kuti amamatire ku maselo omwe akufuna. Mavairasi alibe ma ribosome, mitochondria, kapena ma enzymes athunthu a kagayidwe kachakudya. Chifukwa chake, kuti abereke, mavairasi ayenera "kulanda" makina a maselo a host, kuphatikizapo ma enzyme obwerezabwereza, machitidwe omasulira zolemba, ndi magwero a mphamvu ndi zinthu zopangira.
Ngakhale mavairasi amasiyana kwambiri, nthawi yoberekera kwawo imatha kumveka kudzera m'magawo angapo ofunikira: kuyamwa (kulumikizana), kulowa (kulowa), kumasula (kutulutsa zinthu za majini), kubwerezabwereza ndi kupanga mapuloteni, kusonkhana, ndi kutulutsidwa. Kusiyana kumadalira mtundu wa majini a kachilombo (DNA/RNA, yokhala ndi chingwe chimodzi/yokhala ndi chingwe ziwiri) komanso kupezeka kapena kusakhalapo kwa envelopu.
1. Kulowetsedwa kwa kachilombo: kumamatira kachilomboka ku selo ya wolandirayo
Gawo loyamba pakubwerezabwereza ndi kulowetsedwa kwa ma virus, njira yomwe kachilomboka kamazindikira ndikumangirira pamwamba pa selo lolandira. Kulumikizana kumeneku sikwachisawawa; ma virus ali ndi mapuloteni apadera (monga kukwera kwa ma virus ena ozungulira) omwe amamangirira ku ma receptor enaake pa nembanemba ya selo. Ma receptor awa akhoza kukhala mapuloteni, ma glycoprotein, kapena zigawo zina pamwamba pa selo.
Kulumikizana kwa kachilombo ndi cholandirira matenda kumatsimikizira kutsika kwa kachilomboka, kutanthauza kuti, mitundu ya maselo kapena minofu yomwe ingayambitse matendawa. Mwachitsanzo, mavairasi ena amatha kukhudza maselo a m'mapapo chifukwa ma receptors ofunikira amapezeka ambiri mu minofuyo. Ichi ndi chimodzi mwa zifukwa zomwe kachilombo kamatha kuukira ziwalo zinazake ndikuyambitsa zizindikiro zinazake.
2. Kulowa: kulowa kwa kachilombo mu selo
Pambuyo polumikizana, kachilomboka kayenera kulowa mu selo. Njira zolowera zimasiyana malinga ndi mtundu wa kachilomboka:
1. Kusakanikirana kwa Membrane: mu ma virus omwe ali ndi ma virus, ma virus amatha kusakanikirana ndi membrane ya cell ya host, kotero kuti nucleocapsid imalowa mu cytoplasm.
2. Endocytosis: maselo "amameza" mavairasi popanga ma vesicles (endosomes). Mavairasi ambiri amagwiritsa ntchito njira iyi, yonse yophimbidwa komanso yosaphimbidwa.
3. Kulowetsa majini: komwe kumachitika kawirikawiri mu mabakiteriya (mavairasi omwe amapatsira mabakiteriya). Kachiromboka kamamatirira pakhoma la maselo a bakiteriya kenako n’kulowetsa nucleic acid yake mu selo.
Gawo lolowera m'thupi nthawi zambiri limakhala cholinga cha kupanga mankhwala, chifukwa ngati kachilomboka kalephera kulowa, nthawi yodwalayo singapitirire.
3. Kutsegula chivundikiro: kutulutsidwa kwa zinthu za majini a kachilombo
Kalowa mkati mwa selo (kaya mu cytoplasm kapena mu endosome), kachilomboka kamatuluka, komwe ndi kutulutsidwa kwa capsid yake, zomwe zimapangitsa kuti majini ake azitha kupangidwanso. Mu ma virus ena, kusintha kwa pH mkati mwa endosome kumayambitsa kusintha kwa mawonekedwe a mapuloteni a capsid, zomwe zimapangitsa kuti majini a kachilomboka atulutsidwe. Mu ma virus ena, ma enzyme a maselo a host kapena ma enzyme a kachilomboka amathandizira kuchotsa capsid.
Kutsegula chivundikiro ndi gawo lofunika kwambiri: ngati genome sinatulutsidwe bwino, kuberekana sikungachitike. Kuphatikiza apo, panthawiyi, chitetezo cha selo chikhoza kuyamba kuzindikira kupezeka kwa kachilomboka, mwachitsanzo kudzera mu masensa akunja a RNA/DNA omwe amayambitsa chitetezo chamthupi.
4. Kuchulukitsa majini ndi kupanga mapuloteni a mavairasi
Gawo lotsatira ndi tanthauzo la kubwerezabwereza: kachilomboka kamagwiritsa ntchito selo lolandirayo kuti libwereze majini ake ndikupanga mapuloteni a mavairasi. Kachitidwe kake kamakhudzidwa kwambiri ndi mtundu wa majini a mavairasi.
a. Mavairasi a DNA
Mavairasi ambiri a DNA amalowa mu mtima mwa selo la host pogwiritsa ntchito ma enzymes obwerezabwereza a DNA a selo ndi makina olembera. DNA ya kachilombo imasinthidwa kukhala mRNA ndi RNA polymerase ya host, yomwe kenako imasinthidwa kukhala mapuloteni a kachilombo ndi ribosomes. Mavairasi ena akuluakulu a DNA amakhala ndi ma enzyme awoawo, zomwe zimapangitsa kuti azidzidalira okha, koma amafunikirabe zinthu zamaselo.
b. Ma virus a RNA
Ma RNA virus nthawi zambiri amaberekana mu cytoplasm chifukwa maselo a anthu alibe ma enzyme omwe amatha kuberekana ndi RNA kuchokera ku RNA. Chifukwa chake, ma RNA virus nthawi zambiri amanyamula kapena kuyika enzyme ya RNA-dependent RNA polymerase (RdRp). Enzyme iyi imapanga makope a RNA ya kachilombo ndikupanga mRNA kuti ipange mapuloteni.
Ma RNA virus akhoza kukhala:
– RNA yokhala ndi strand imodzi (+): genome yake imatha kugwira ntchito mwachindunji ngati mRNA ndipo imasinthidwa nthawi yomweyo.
– Kuzindikira koipa (-) RNA yokhala ndi chingwe chimodzi: choyamba iyenera kukopedwa kukhala RNA yomveka bwino kuti imasuliridwe.
– RNA yokhala ndi zingwe ziwiri (dsRNA): imafuna enzyme yapadera kuti ipange mRNA.
c. kachilombo ka Retrovirus
Ma retrovirus ali ndi genome ya RNA koma amagwiritsa ntchito enzyme reverse transcriptase kuti asinthe RNA kukhala DNA. Kenako DNA iyi imaphatikizidwa mu genome ya selo la host mothandizidwa ndi enzyme integrase. Akaphatikizidwa, majini a mavairasi amatha kukhala "odekha" kapena ogwira ntchito, ndikupanga ma mRNA atsopano ndi majini a mavairasi. Njira yolumikizira iyi imapangitsa kuti matenda a retrovirus akhale ovuta kuwathetsa kwathunthu.
Kuwonjezera pa kubwerezabwereza kwa majini, maselo a anthu omwe ali m'thupi amakakamizidwanso kupanga mapuloteni omangira thupi (capsid, mapuloteni ozungulira) ndi mapuloteni osamangira thupi (ma enzyme obwerezabwereza, ma protease, ndi zinthu zowongolera). Ma virus ambiri amapanga mapuloteni mu mawonekedwe a ma polyprotein aatali, omwe kenako amagawidwa m'magawo ogwira ntchito ndi ma virus protease.
5. Kusonkhanitsa ndi kukhwima
Genome ndi mapuloteni akamaliza, kachilomboka kamalowa mu gawo lokonzekera. Mapuloteni a Capsid amasonkhana m'mapangidwe enaake (monga icosahedral kapena helical) pamene akuyika genome ya kachilomboka. Njirayi imatha kuchitika mu cytoplasm kapena nucleus, kutengera kachilomboka.
Mavairasi ena amafunika nthawi yokhwima kuti ayambe kupatsirana matenda. Kukhwima kungaphatikizepo kugawanika kwa mapuloteni ndi ma protease, kusintha kwa kapangidwe ka capsid, kapena kuwonjezera zina zowonjezera. Popanda kukhwima, tinthu ta kachilomboka tingawoneke ngati tili tomwe tili tomwe koma sitingathe kupatsira maselo ena.
6. Kutulutsidwa kwa mavairasi atsopano kuchokera ku maselo a anthu
Gawo lomaliza ndi kutulutsidwa kwa ma virion (tinthu tating'onoting'ono ta kachilombo) kuchokera mu selo kuti tilowe m'maselo ena. Njira zake ndi izi:
1. Kuphulika kwa maselo: selo limaphulika ndi kufa, kutulutsa ma virion ambiri nthawi imodzi. Limapezeka kwambiri m'mavairasi osatsekedwa komanso m'matenda ena oopsa omwe amawononga minofu.
2. Kuphuka: Mavairasi ozungulira amatuluka mwa kutenga gawo la nembanemba ya selo lokhalamo ngati chivundikiro. Njira imeneyi siimapha selo nthawi yomweyo, koma ingasokoneze ntchito ya selo ndi kuyambitsa kutupa.
3. Exocytosis: mavairasi ena amagwiritsa ntchito njira yotulutsira madzi m'selo kuti atuluke kudzera m'ma vesicles.
Kuzungulira kumeneku kumatha kukhala kofulumira (maola mpaka masiku) kapena pang'onopang'ono ndipo kumatha kutsagana ndi gawo lobisika, kutengera mawonekedwe a kachilomboka komanso momwe kachilombo kamene kakuchiyankhira.
Zotsatira za kufalikira kwa mavairasi pa maselo ndi thupi
Kuchulukana kwa mavairasi kungayambitse kuwonongeka kwa maselo m'njira zingapo: mwa kuchepetsa mphamvu za maselo, kuwononga ma nembanemba ndi ma organelle, kuyambitsa kufa kwa maselo mwadongosolo (apoptosis), kapena kuyambitsa kupsinjika kwa chitetezo cha mthupi. Pa mulingo wa minofu, kuwonongeka ndi kutupa kumabweretsa zizindikiro za matenda.
Kumbali ina, chitetezo cha mthupi chimayesetsa kuletsa kuchulukitsa kwa ma interferon, maselo opha tizilombo toyambitsa matenda, ma antibodies, ndi maselo a T omwe ali ndi poizoni. Komabe, mavairasi ali ndi njira zosiyanasiyana zopewera, monga kuletsa ma interferon kufalikira, kusintha mofulumira, kapena kubisala mu gawo lobisika.
Kubwerezabwereza ngati chandamale cha chithandizo ndi kupewa
Mankhwala ambiri oletsa mavairasi amapangidwira magawo enaake, mwachitsanzo:
- imaletsa kulowa kwa mavairasi,
- imaletsa ma enzyme obwerezabwereza (RdRp, reverse transcriptase),
- imaletsa ma protease kuti aletse kukhwima,
- imaletsa kutulutsidwa kwa ma virus.
Katemera amagwira ntchito makamaka poyambitsa chitetezo chamthupi kuti chizindikire kachilomboka mwachangu chisanabwerezedwe mosalamulirika. Ndi ma antibodies oletsa komanso kuyankha kwamphamvu kwa maselo a T, kachilomboka kamatha kupewedwa kuti kasamamatire, kulowa, kapena kufalikira kwambiri.
Kutseka
Kuchulukitsa mavairasi m'maselo a anthu ndi njira yosamala kwambiri, yochitika m'magawo ambiri, kuyambira pa kugwirizana mpaka kutulutsidwa kwa mavairasi atsopano. Ngakhale kuti mavairasi amawoneka "osavuta," luso lawo logwiritsa ntchito ma cell system limawapangitsa kukhala othandiza kwambiri pakufalitsa ndikuyambitsa matenda. Kumvetsetsa njira zochulukitsa izi sikuti ndikofunika kwambiri pamaphunziro okha komanso ndikofunikira kwambiri pakupanga mankhwala oletsa mavairasi, katemera, ndi njira zowongolera kufalikira kwa matenda. Mwa kuyang'ana kwambiri mfundo zofunika kwambiri pa moyo wa mavairasi, anthu amatha kuchepetsa mphamvu ya matenda ndikuwonjezera kulimba mtima pa thanzi la anthu.
