Ikamva le-Adenovirus esekwe kwi-COVID-19 yezitofu (ezifana ne-Oxford AstraZeneca) ekukhanyeni okufunyaniswe mva nje malunga nonobangela weziphumo ebezingalindelekanga ezinqabileyo zehlwili legazi

Iintsholongwane ezintathu ze-adenovirus ezisetyenziswa njengee-vectors ukuvelisa izitofu zokugonya ze-COVID-19, zibophelela kwi-platelet factor 4 (PF4), iprotein ebandakanyeka kwi-pathogenesis yokuphazamiseka kwe-clotting. 

Iigonyo ze -COVID-19 ezisekelwe kwi-Adenovirus ezifana ne-Oxford/AstraZeneca's ChAdOx1 zisebenzisa inguqulelo ebuthathaka neguqulwe ngokwemfuza ye-common cold virus adenovirus (i-DNA virus ) njengevector yokubonakalisa iproteni yentsholongwane ye-coronavirus entsha nCoV-2019 emzimbeni womntu. Iproteni yentsholongwane eveziweyo isebenza njenge-antigen yokuphuhlisa ukhuselo olusebenzayo. I-adenovirus esetyenzisiweyo ayisebenzi kakuhle oko kuthetha ukuba ayinakuphinda emzimbeni womntu kodwa njengevector inika ithuba lokuguqulela i-gene encoding Spike protein (S) ye- coronavirus entsha ^1. Ezinye iivector ezifana ne-human adenovirus type 26 (HAdV-D26; esetyenziselwa i-Janssen COVID vaccine), kunye ne-human adenovirus type 5 (HAdV-C5) nazo zisetyenzisiwe ukuvelisa iigonyo ezichasene ne-SARS-CoV-2.

Isitofu sokugonya se-Oxford/AstraZeneca COVID-19 (ChAdOx1 nCoV-2019) sifunyenwe sisebenza kulingo lwezonyango kwaye samkelwa ngabalawuli kumazwe aliqela (sifumene imvume yi-MHRA e-UK nge-30 kaDisemba 2020). Ngokungafaniyo nolunye ugonyo lwe-COVID-19 (ugonyo lwe-mRNA) olukhoyo ngelo xesha, oku kwakucingelwa ukuba kunenzuzo enxulumene nokugcinwa kunye nolungiselelo. Kungekudala yaba sesona sitofu sokugonya kumlo ochasene nobhubhane kwihlabathi liphela kwaye yenza igalelo elibalulekileyo ekukhuseleni abantu kwihlabathi liphela kwi-COVID-19.  

Nangona kunjalo, kukho unxibelelwano olunokwenzeka phakathi kwesitofu se-AstraZeneca se-COVID-19 kunye nokuqhekeka kwegazi okurhanelwayo xa kwaxelwa malunga namatyala angama-37 esiganeko esingaqhelekanga sokuqhekeka kwegazi (kwabantu abangaphezu kwezigidi ezili-17 abagonyiweyo) kwi-EU naseBritane. Ngenxa yesi siphumo esingalindelekanga, emva koko, i-Pfizer's okanye i-Moderna's mRNA ^Vaccines zacetyiswa ukuba zisetyenziswe kwabo bangaphantsi kweminyaka engama-30. Kodwa ukuba iingxaki zokuqhekeka kwegazi ezingaqhelekanga ezifana ne-thrombocytopenia syndrome (TTS), imeko efana ne-heparin-induced thrombocytopenia (HIT) ebonwa kubantu abanikwa isitofu se-AstraZeneca COVID-19 esisebenzisa i-ChAdOx1 (chimpanzee adenovirus Y25) zibangelwa yintoni kwaye indlela esisiseko ebandakanyekayo, ayicacanga.

Uphononongo lwakutshanje olupapashwe kwiScience Advances ngu-Alexander T. Baker et al. lubonisa ukuba ii-adenovirus ezintathu ezisetyenziswa njengeevektha ukuvelisa i-SARS-CoV-2 vaccines , zibopha kwi-platelet factor 4 (PF4), iproteni ebandakanyeka kwi-pathogenesis ye-HIT kunye ne-TTS.

Kusetyenziswa indlela eyaziwa ngokuba yi-SPR (Surface Plasmon Resonance), kwaboniswa ukuba i-PF4 ayibophani kuphela ngamalungiselelo e-vector acocekileyo ala ma-vector, kodwa ikwabopha namayeza okugonya aphuma kula ma-vector, anobuhlobo obufanayo. Olu nxibelelwano lubangelwa bubukho be-electropositive surface potential enamandla kwi-PF4 enceda ekubophaneni ne-electronegative potential iyonke kwi-adenoviral vectors. Kwimeko yokunikwa kwe-ChAdOx1 covid vaccine, i-vaccine efakwe kwimisipha inokuvuza egazini, nto leyo ekhokelela ekwakhiweni kwe-ChAdOx1/PF4 complex njengoko kuchaziwe apha ngasentla. Kwiimeko ezingaqhelekanga, umzimba uyayibona le complex njenge -virus yangaphandle kwaye ibangela ukwakheka kwee-antibodies ze-PF4. Ukukhululwa kwee-antibodies ze-PF4 kukhokelela ekuhlanganisweni kwe-PF4, ngaloo ndlela kwenze amahlwili egazi, kukhokelela kwiingxaki ezingaphezulu kwaye kwezinye iimeko, ukufa kwesigulana. Oku kude kube ngoku kubangele ukufa kwabantu abangama-73 kwi-doses eziphantse zibe zizigidi ezingama-50 ze-vaccine ye-AstraZeneca vaccine ezinikwe e-UK.

Isiphumo se-TTS esibonwayo sigqame kakhulu emva kwedosi yokuqala yesitofu sokugonya kunedosi yesibini, icebisa ukuba izilwa-buhlungu ezilwa ne-P4 zinokungahlali xesha lide. I-ChAdOx-1/PF4 complex ivinjwe ubukho be-heparin edlala indima ebalulekileyo kwi-HIT. I-Heparin ibophelela kwiikopi ezininzi zeprotheni ye-P4 kwaye yenze i-aggregates kunye ne-anti-P4 antibodies evuselela ukusebenza kweplatelet kwaye ekugqibeleni iholele kwi-blood clots.  

Ezi ziganeko zingaqhelekanga ezisongela ubomi zibonisa ukuba kukho imfuneko yokucwangcisa iintsholongwane ezithwala le ntsholongwane ngendlela enjalo, ukuze kuthintelwe naluphi na unxibelelwano neeproteni zeseli ezinokukhokelela kwi-SARs (Severe Adverse Reactions), ngaloo ndlela zikhokelela ekufeni kwesigulana. Ngaphezu koko, umntu unokujonga amanye amaqhinga okuyila amachiza asekelwe kwiiyunithi ezincinci zeproteni endaweni ye-DNA.

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Imithombo:  

1. Isitofu sokugonya se-Oxford/AstraZeneca COVID-19 (ChAdOx1 nCoV-2019) Sifunyaniswe sisebenza kwaye samkelwe. Inzululwazi yaseYurophu. Ipapashwe nge-30 kaDisemba 2020. Ifumaneka apha http://scientificeuropean.co.uk/covid-19/oxford-astrazeneca-covid-19-vaccine-chadox1-ncov-2019-found-effective-and-approved/ 

2. Soni R. 2021. Unxulumano olunokwenzeka phakathi kwe-AstraZeneca ye-COVID-19 yokugonya kunye namahlwili egazi: Ngaphantsi kweminyaka engama-30 iza kunikwa i-Pfizer's okanye iModerna's mRNA Vaccine. Inzululwazi yaseYurophu. Ipapashwe nge-7 kuTshazimpuzi 2021. Ifumaneka e http://scientificeuropean.co.uk/covid-19/possible-link-between-astrazenecas-covid-19-vaccine-and-blood-clots-under-30s-to-be-given-pfizers-or-modernas-mrna-vaccine/  

3. Baker AT, okqhubekayo 2021. I-ChAdOx1 isebenzisana ne-CAR kunye ne-PF4 kunye nemiphumo ye-thrombosis kunye ne-thrombocytopenia syndrome. Ukuqhubela phambili kwezeNzululwazi. Umqulu 7, ushicilelo 49. Ipapashwe nge-1 kaDec 2021. DOI: https//doi.org/10.1126/sciadv.abl8213 

 
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