Ngaba i-coronavirus yadalwa elebhu? Usosayensi uyaphendula
Njengoko i-coronavirus entsha ebangela i-COVID-19 isasazeka kwihlabathi liphela, amatyala afikelela kuma-284.000 kwihlabathi liphela namhlanje (ngoMatshi 20), ulwazi olungelulo lusasazeka ngokukhawuleza.
Intsomi ethe gqolo kukuba le ntsholongwane, ebizwa ngokuba yi-SARS-CoV-2, yenziwe zizazinzulu kwaye yasinda kwilabhoratri e-Wuhan, e-China, apho kwaqala khona ukuqhambuka.
Uhlalutyo olutsha lwe-SARS-CoV-2 lunokuthi ekugqibeleni lubeke lo mbono wokugqibela. Iqela labaphandi lithelekisa igenome yale coronavirus entsha kwezinye iikoronavirus ezisixhenxe ezaziwa ngokusulela abantu: SARS, MERS, and SARS-CoV-2, ezinokubangela isifo esibi; kunye ne-HKU1, i-NL63, i-OC43 kunye ne-229E, ebangela ukuba kuphela iimpawu ezincinci, abaphandi babhala ngo-Matshi 17 kwiphephancwadi leNdalo yeNdalo.
"Uhlalutyo lwethu lubonisa ngokucacileyo ukuba i-SARS-CoV-2 ayisiyondawo yokwakhiwa kwelabhoratri okanye intsholongwane elawulwa ngokukodwa," babhala kwinqaku lejenali.
UKristian Andersen, unjingalwazi onxulumene ne-immunology kunye ne-microbiology kuPhando lweScripps, kunye noogxa bakhe bavavanya iplani yemfuza yeeproteni ze-spike eziphuma kumphezulu wentsholongwane. I-coronavirus isebenzisa ezi spikes ukubamba kwiindonga ezingaphandle zeeseli zomkhosi wayo kwaye ingene kwezo seli. Bajonge ngokuthe ngqo ukulandelelana kwemfuza ejongene neempawu ezimbini eziphambili zezi proteni ze-spike: i-grabber, ebizwa ngokuba yi-receptor-binding domain, ene-docks ene-host host; kunye nendawo ebizwa ngokuba yi-cleavage site evumela intsholongwane ukuba ivule kwaye ingene kwezo seli.
Olo hlalutyo lubonise ukuba indawo “ye-barbed” ye-spike iye yavela ukuze ijolise kwi-receptor engaphandle kweeseli zomntu ezibizwa ngokuba yi-ACE2, ebandakanyekayo ekulawuleni uxinzelelo lwegazi. Ilunge kakhulu ekubopheleleni kwiiseli zomntu kangangokuba abaphandi bathi iiproteni ze-spike zisisiphumo sokhetho lwendalo hayi ubunjineli bemfuza.
Nasi isizathu: I-SARS-CoV-2 inxulunyaniswe ngokusondeleyo nentsholongwane ebangela i-acute acute breathing syndrome (SARS), eyatshayela kwihlabathi lonke malunga neminyaka engama-20 eyadlulayo. Izazinzulu ziye zafunda ukuba i-SARS-CoV yahluke njani kwi-SARS-CoV-2 - kunye neenguqu ezininzi kwiileta eziphambili kwikhowudi yemfuza. Ukanti kulinganiso lwekhompyuter, utshintsho kwi-SARS-CoV-2 alubonakali lusebenza kakuhle ukunceda intsholongwane ibophelele kwiiseli zabantu. Ukuba izazinzulu ziye zayila ngabom le ntsholongwane, ngebengazange bakhethe iinguqulelo zemfuza ezithi imodeli yekhompyutha ayinakusebenza. Kodwa kuye kwavela ukuba indalo ikrelekrele kunezazinzulu, kwaye inoveli i-coronavirus yafumana indlela yokuguquka yayingcono-kwaye yahluke ngokupheleleyo - kunayo nayiphi na into eyayinokwenziwa ngusosayensi, uphando lufumene.
Esinye isikhonkwane kwithiyori "yokuphunyuka kwilebhu embi"? Ubume bemolekyuli buphelele bale ntsholongwane bohlukile kwiikoronavirus ezaziwayo kwaye endaweni yoko bufana ngokusondeleyo neentsholongwane ezifumaneka kumalulwane kunye neepangolin ebezifundwe kancinci kwaye engazange yaziwe ukuba yenza ukwenzakala ebantwini.
"Ukuba umntu ebezama ukwenza i-coronavirus entsha njenge-pathogen, ngeyakhiwe ukusuka kumqolo wentsholongwane eyaziwa ngokubangela isifo," ngokwengxelo evela kwiScripps.
Isuka phi le ntsholongwane? Iqela lophando leza neemeko ezimbini ezinokubakho zemvelaphi ye-SARS-CoV-2 ebantwini. Imeko enye ilandela amabali emvelaphi yezinye ii-coronavirus zamva nje ezonakalise abantu. Kuloo meko, sifumene intsholongwane ngokuthe ngqo kwisilwanyana - i-civets kwimeko ye-SARS kunye neenkamela kwimeko ye-Middle East yokuphefumla i-syndrome (MERS). Kwimeko ye-SARS-CoV-2, abaphandi bacebisa ukuba esi silwanyana yayililulwane, esasasaza intsholongwane kwesinye isilwanyana esiphakathi (mhlawumbi i-pangolin, ezinye izazinzulu ziye zatsho) ezithwele intsholongwane ebantwini.
Kuloo meko inokwenzeka, iimpawu zemfuzo ezenza ukuba i-coronavirus entsha isebenze kangaka ekosuleleni iiseli zomntu (amandla ayo e-pathogenic) ngebebekhona ngaphambi kokuba itsibele ebantwini.
Kwenye imeko, ezi mpawu ze-pathogenic ngezivelile kuphela emva kokuba intsholongwane ithe yatsiba ukusuka kwisilwanyana ukuya ebantwini. Ezinye ii-coronavirus ezisuka kwi-pangolins zine-“hook structure” (loo domeyini yokubopha isamkeli) efana naleyo ye-SARS-CoV-2. Ngale ndlela, i<em>pangolin yasasaza intsholongwane yayo ngokuthe ngqo okanye ngokungathanga ngqo kumntu okhoyo. Ke, xa sele ingaphakathi kwinginginya yabantu, intsholongwane yayinokuthi yavela ukuze ibe nenye into engabonakaliyo: indawo yokuqhekeka eyivumela ukuba ingene ngokulula kwiiseli zomntu. Nje ukuba obu buchule buphuhliswe, abaphandi bathi i-coronavirus iya kuba nako ngakumbi ukusasazeka phakathi kwabantu.
Zonke ezi nkcukacha zobuchwephesha zinokunceda izazinzulu ziqikelele ikamva lesi sifo. Ukuba intsholongwane ingene kwiiseli zomntu kwifomu ye-pathogenic, oku kwandisa amathuba okuqhambuka kwexesha elizayo. Intsholongwane isenokujikeleza kwizilwanyana kwaye inokutsibela ibuyele ebantwini, ilungele ukubangela uqhambuko. Kodwa amathuba okuqhambuka kwekamva asezantsi ukuba intsholongwane kufuneka iqale ingene eluntwini kwaye emva koko ivelise iipropathi ze-pathogenic, abaphandi bathi.