atepeq/tico19 huggingface dataset:
On one hand, SARS-CoV-2 infection exhibits features that are more commonly seen during infection with community-acquired HCoVs, including the presentation of non-specific, mild or even no symptoms.
Ku rundi ruhande, indwara ya SARS-CoV-2 igaragaza ibimenyetso usanga bikunze kugaragara cyane mu gihe cy’ubwandu bwa HCoVs zifata ubwoko bitewe n’aho buba, twavuga nko kugira ibimenyetso bitihariye, byoroheje cyangwa se no kutabigira.
On the other hand, a small subset of severe cases of COVID-19 can also be seen as in the case of SARS-CoV infection, although the ratio is a bit lower.
Na none, umubare muto cyane w’abantu baremba barwaye COVID-19 na wo ushobora kuboneka igihe cy’indwara ya SARS-CoV, nubwo igipimo kiri hasi ho gato.
Third, the transmission of SARS-CoV-2 also shows interesting patterns characteristic of both community-acquired HCoVs and SARS-CoV.
Icya gatatu, ikwirakwizwa rya SARS-CoV-2 na ryo ryerekana imisusire ikwiye kwitabwaho iranga HCoVs zifata ubwoko bitewe n’aho buba na SARS-CoV.
On one hand, the transmissibility of SARS-CoV-2 is at least as high as that of community-acquired HCoVs.
Ku ruhande rumwa, usanga uburyo SARS-CoV-2 ikwirakwira usanga nibura buri hejuru kimwe n’ubwa HCoVs zifata ubwoko bitewe n’aho buba.
On the other hand, it remains to be verified whether the transmissibility of SARS-CoV-2 decreases after passages in humans as in the cases of SARS-CoV and MERS-CoV.
Ku rundi ruhande, haracyakenewe kugenzurwa niba uburyo SARS-CoV-2 ikwirakwira bugabanyuka nyuma yo kwinjira mu bantu nk’uko bigenda kuri SARS-CoV na MERS-CoV.
Finally, same as the other HCoVs, SARS-CoV-2 can be detected in fecal samples.
Icya nyuma, kimwe no ku zindi HCoVs, SARS-CoV-2 ishobora gutahurwa mu bizamini by’umusarane.
Whether fecal-oral transmission of SARS-CoV-2 plays an important role as in the case of SARS-CoV at least under some circumstance remains to be clarified by future studies.
Ubushakashatsi butaha bukwiye kugaragaza niba ikwirakwizwa rya SARS-CoV-2 mu musarane no mu matembabuzi yo mu kanwa rigira uruhare rukomeye nk’uko bigenda kuri SARS-CoV nibura ahantu hamwe na hamwe.
It is also of particularly great interest to see whether SARS-CoV-2 might exhibit seasonality as in the cases of community-acquired HCoVs.
Na none ni ngombwa kureba by’umwihariko niba SARS-CoV-2 ishobora kugaragara mu bihe bitandukanye nk’uko bigenda kuri HCoVs zifata ubwoko bitewe n’aho buba.
Nevertheless, the features of SARS-CoV-2 including its transmissibility, pathogenicity and sustainable spreading after passages in humans will be influential on the ultimate fate of the ongoing outbreak of COVID-19.
Nyamara, ibiranga SARS-CoV-2 birimo uburyo ikwirakwira, ubushobozi bwo gutera indwara no gukwirakwira birambye nyuma yo kujya mu bantu bizagira uruhare mu iherezo ry’icyorezo gikomeje cya COVID-19.
All four community-acquired HCoVs causing mild symptoms have been well adapted to humans.
HCoVs zifata ubwoko bitewe n’aho buba zose uko ari enye zigira ibimenyetso byoroheje zabashije kumenyera abantu neza.
From another perspective, it might also be true that humans have been well adapted to these four HCoVs.
Ku rundi ruhande, byanashoboka ko mu by’ukuri ari n’abantu bashoboye kumenyera izi HCoVs enye.
In other words, both could be the survivors of ancient HCoV pandemics.
Mu yandi magambo, byombi bishobora kuba byararokotse ibyorezo bya HCoV byabayeho kera.
HCoVs that cause severe diseases in humans and humans who developed severe HCoV diseases have been eliminated.
HCoVs zitera abantu indwara zikaze n’abantu barwara indwara zikaze ziterwa na HCoV barapfuye.
For this to happen, HCoVs have to replicate in humans to sufficient extent to allow the accumulation of adaptive mutations that counteract host restriction factors.
Kugira ngo bibeho, koronavirusi zifata umuntu (HCoV) zivamo utundi duce duhagije mu gutuma zibona uko zihinduka zikangiza poroteyine y’umubiri irwanya virusi iyibuza kwiyongera.
In this sense, the longer the SARS-CoV-2 outbreak persists and the more people that it infects, the greater chance that it will fully adapt to humans.
Bityo, uko icyorezo cya SARS-CoV-2 kimara igihe kikananduza abantu benshi, hari ibyago byinshi ko kizamenyera neza umubiri w’umuntu.
If it adapts well, its transmission in humans would be difficult to stop by quarantine or other infection control measures.
Nikimenyera neza, kwandura mu bantu biziyongera kubihagarika hakoreshejwe akato cyangwa izindi ngamba bizagorana.
For many years, the four community-acquired CoVs circulate in human populations, triggering common cold in immunocompetent subjects.
Mu myaka myinshi, ubwoko bune bwa virusi za CoV zandurira hanze y’ibitaro zigenda mu bantu, zigatera inkorora abantu basanzwe bafite ubudahangarwa bw’umubiri.
These viruses do not need an animal reservoir.
Izo virusi ntizikenera kuba ziri mu nyamaswa.
In contrast, highly pathogenic SARS-CoV and MERS-CoV have not adapted to humans well and their transmission within humans cannot be sustained.
Ku rundi ruhande, virusi za SARS-CoV na MERS-CoV zitera indwara cyane ntizigeze zimenyera umubiri w’umuntu neza, bituma kwandura mu bantu bitamara igihe kirekire.
They need to maintain and propagate in their zoonotic reservoirs and seek the chance to spillover to susceptible human targets, possibly via one or more intermediate and amplifying hosts.
Zikenera kuguma kwiyongerera mu nyamaswa zibamo virusi zinategereje uko zagera ku bantu badafite ubudahangarwa bw’umubiri bukomeye, zinyuze mu nyamaswa imwe cyangwa nyinshi zikuriramo n’izo zororokeramo cyane.
SARS-CoV-2 has features that are similar to both SARS-CoV/MERS-CoV and the four community-acquired HCoVs.
SARS-CoV-2 ifite imiterere imeze nk’iya SARS-CoV/MERS-CoV na virusi ya HCoV enye zandurira hanze y’ibitaro.
It is highly transmissible like community-acquired HCoVs, at least for the time being.
Irandura cyane kimwe nka virusi za HCoV zandurira hanze y’ibitaro, byibuze kugeza ubu.
However, it is more pathogenic than community-acquired HCoVs and less pathogenic than SARS-CoV or MERS-CoV.
Ariko, itera indwara kurusha virusi za HCoV zandurira hanze y’ibitaro ntinanatere indwara cyane nka SARS-CoV cyangwa MERS-CoV.
It remains to be seen whether it will adapt fully to humans and circulate within humans without a reservoir or intermediate animal host.
Haracyategerejwe kureba niba izamenyera neza abantu no kugenda mu bantu nta nyamaswa ivuyemo.
Before discussing the animal origins of HCoVs, it will serve us well to discuss the definitions and characteristics of evolutionary, natural, reservoir, intermediate and amplifying hosts of HCoVs.
Mbere yo kuvuga ku nyamaswa zakomotseho virusi ya HCoV, byaba byiza tuganiriye ku bisobanuro n’ibiranga inyamaswa virusi za HCoV zihindukiramo, zibana na zo mu buryo karemano, zigira indiri, zikuriramo n’izo zororokeramo cyane.
An animal serves as the evolutionary host of an HCoV if it harbours a closely related ancestor sharing high homology at the level of nucleotide sequence.
Inyamaswa ni yo ituma virusi ya HCoV ikura iyo ifitanye isano ya hafi n’iyo ikomokaho bisangiye byinshi ku rwego rw’imiterere y’isanomuzi.
The ancestral virus is usually well adapted and non-pathogenic in this host.
Ubusanzwe virusi y’inyamaswa ikomokaho iba yaramenyereye kandi ntitere indwara iyi nyamaswa irimo.
Likewise, a reservoir host harbours HCoV continuously and for long term.
Bityo inyamaswa yagizwe indiri ikomeza kuba indiri ya virusi ya HCoV kandi bikamara igihe kirekire.
In both cases, the hosts are naturally infected and are the natural hosts of HCoV or its parental virus.
Kuri izo mpamvu zombi, inyamaswa zirimo virusi ziba zaranduye mu buryo karemo zirimo virusi ya HCoV cyangwa virusi iyibyara.
In contrast, if the HCoV is newly introduced to an intermediate host right before or around its introduction to humans, it is not well adapted to the new host and is often pathogenic.
Ku rundi ruhande, iyo HCoV ije ari nshya mu nyamaswa ikuriramo mbere gato cyangwa hafi yo kuba yakwanduza abantu, ntimenyera neza aho igiye kandi akenshi itera indwara.
This intermediate host can serve as the zoonotic source of human infection and play the role of an amplifying host by allowing the virus to replicate transiently and then transmitting it to humans to amplify the scale of human infection.
Iyo nyamaswa ikuriramo ishobora kuba ari yo yakwanduza abantu ikanaba inyamaswa yororoheramo cyane ituma virusi yiyongera vuba maze ikayanduza abantu mu kongera igipimo cy’ubwandu bwa muntu.
An HCoV can undergo a dead-end infection if it cannot sustain its transmission within the intermediate host.
Virusi ya HCoV ishobora kutagira uwo yanduza igihe itabashije guhinduka iri mu nyamaswa ikuriramo.
On the contrary, HCoVs can also adapt to the intermediate host and even establish long-term endemicity.
Ku rundi ruhande, HCoVs ishobora kumenyera inyamaswa ikuriramo maze ikayigumamo igihe kirekire.
In this case, the intermediate host becomes a natural reservoir host.
Iyo bimeze bityo, inyamaswa ikuriramo ihinduka inyamaswa yagizwe indiri mu buryo karemano.
Epidemiological data revealed retrospectively that the index case of SARS had a contact history with game animals.
Amakuru y’ibyorezo yagaragaje ko uwagaragaweho bwa mbere na virusi ya SARS yayanduriye mu mukino wo guhiga inyamaswa.
Subsequent seroprevalence investigations indicated that animal traders had a higher prevalence of anti-SARS-CoV IgG compared with that of the general population.
Ibipimo by’amaraso byakurikiyeho byagaragaje ko abacuruzi b’inyamaswa bari bihariye ubudahangarwa bw’umubiri burwanya SARS-CoV IgG ugereranyije n’abaturage basanzwe.
Masked palm civets (Paguma larvata) and a racoon dog in live animal markets were first identified to carry SARS-CoV-like viruses that are almost identical to SARS-CoV.
Impimbi n’imbwa yo mu bwoko bw’impimbi mu masoko abagirwamo inyamaswa bwa mbere zagaragaye ko zifite virusi zimeze nka SARS-CoV isa cyane nka SARS-CoV.
This was indirectly supported by the fact that no further SARS was reported after killing all civets in the markets.
Ibi byemejwe mu buryo butaziguye ni uko SARS yakomeje kuvugwa nyuma yo kwica ipimbi zose ziri mu masoko.
However, it has been reported that masked palm civets from the wild or farms without exposure to the live animal markets were largely negative for SARS-CoV, suggesting that masked palm civets might only serve as the intermediate amplifying host but not the natural reservoir of SARS-CoV.
Ariko, byavuzwe ko impimbi zo mu mashyamba cyangwa mu nzuri zitigeze zihura n’inyamaswa zo mu masoko abagirwamo inyamaswa zapimwe bagasanga zidafite SARS-CoV, bivuze ko impimbi na zo zishobora kuba inyamaswa SARS-CoV ikuriramo ikanororokeramo cyane ariko idashobora kubana na zo mu buryo karemano.
Notably, since 80% of the different animals in the markets in Guangzhou have anti-SARS-CoV antibodies, the possibilities that multiple species of small mammals might also serve as intermediate amplifying hosts of SARS-CoV cannot be excluded.
By’umwihariko, mu gihe 80% by’inyamaswa zitandukanye mu masoko yo muri Guangzhou zifite abasirikare barwanya SARS-CoV, ntawahakana ko ubwoko bwinshi bw’inyamabere nto SARS-CoV ishobora gukuriramo no kororokeramo cyane.
All of these appear to be dead-end hosts of SARS-CoV.
Izo zose bigaragara ko zidashobora kwanduza SARS-CoV.
Subsequent search for the natural animal host of SARS-CoV unveiled a closely related bat CoV, termed SARS-related Rhinolophus bat CoV HKU3 (SARSr-Rh-BatCoV HKU3), which exists in Chinese horseshoe bats.
Ubushakashatsi bwakurikiyeho bukorerwa inyamaswa zirimo virusi itarakura ya SARS-CoV bwagaragaje ko virusi ya CoV isa cyane na CoV yo mu ducurama, yiswe SARS yo mu ducurama CoV HKU3 (SARSr-Rh-BatCoV HKU3), iba mu ducurama two mu Bushinwa.
These bats are positive for anti-SARS-CoV antibodies and genome sequence of SARSr-Rh-BatCoV HKU3.
Utwo ducurama dufite abasirikare barwanya SARS-CoV n’imiterere ya jenome ya SARSr-Rh-BatCoV HKU3.
This and other bat CoVs share 88-92% nucleotide sequence homology with SARS-CoV.
Izi n’izindi CoV zo mu ducurama bisangiye 88-92% by’imiterere y’isanomuzi cya SARS-CoV.
These studies have laid the foundation for the new concept that bats host emerging human pathogens.
Ubwo bushakashatsi bwashimangiye igitekerezo gishya ko uducurama turimo virusi itarakura dutera abantu indwara.
Several SARS-like CoVs (SL-CoVs) have also been identified from bats, but none except for one designated WIV1 can be isolated as live virus.
SARS nyinshi zimeze nka CoV (SL-CoVs) zagaragaye mu ducurama, ariko nta n’imwe uretse iyitwa WIV1 ifatwa nka virusi yatera indwara.
Human angiotensin converting enzyme 2 (ACE2) is known to be the receptor of SARS-CoV.
Umusemburo wa anjiyotensini ihindura anzime uba mu muntu (ACE2) izwiho kwakira SARS-CoV.
WIV1 derived from fecal sample of bats was demonstrated to use bat, civet and human ACE2 as receptor for cell entry.
WIV1 yakuwe mu bipimo by’umusarani w’uducurama ikoresha ACE2 y’agacurama, impimbi n’abantu mu kwinjira mu mubiri.
Intriguingly, sera of convalescent SARS patients were capable of neutralizing WIV1.
Igitangaje ni uko serumu y’abarwayi bakira SARS yashoboye guca intege virusi ya WIV1.
Thus far, WIV1 represents the most closely related ancestor of SARS-CoV in bats, sharing 95% nucleotide sequence homology.
Kugeza ubu, WIV1 igaragaza ko ikomoka cyane kuri SARS-CoV yo mu ducurama, bikaba bisangiye 95% mu gusa ku isanomuzi.
Albeit the high homology between these two viruses, it is generally believed that WIV1 is not the immediate parental virus of SARS-CoV and bats are not the immediate reservoir host of SARS-CoV.
N’ubwo izo virusi ebyiri zifitanye isano ya hafi, muri rusange hatekerezwa ko WIV1 atari yo ibyara virusi ya SARS-CoV kandi uducurama si two ndiri virusi ya SARS-CoV ikuriramo.
Phylogenetic analysis clusters MERS-CoV to the same group as bat CoV-HKU4 and bat CoV-HKU5.
Isesengura ry’imihindagurikire ya virusi rishyira MERS-CoV mu itsinda rimwe virusi za CoV-HKU4 na CoV-HKU5 zo mu ducurama.
Bat CoV-HKU4 and MERS-CoV utilize the same host receptor, dipeptidyl peptidase 4 (DPP4), for virus entry.
CoV-HKU4 yo mu ducurama na MERS-CoV zakirwa na poroteyine ya DPP4 imwe, ikoreshwa na virusi mu kwinjira mu mubiri.
RNA-dependent RNA polymerase sequences of MERS-CoV are phylogenetically closer to counterparts in bat beta-CoVs identified from Europe and Africa.
Poroteyine y’imiterere ya polimerase ya RNA yo mu MERS-CoV isa cyane na virusi ngenzi yayo ifata uducurama ya beta-CoV yabonetse mu Burayi n’Afurika.
Up to now, no live MERS-CoV can be found in wild bats.
Kugeza ubu, nta virusi nzima ya MERS-CoV wabona mu ducurama two mu ishyamba.
MERS-CoV and its closest relative bat CoV-HKU25 share only 87% nucleotide sequence homology.
MERS-CoV n’indi virusi bisa cyane yo mu ducurama ya CoV-HKU25 bihuje gusa 87% ku isanomuzi.
Thus, bats might not be the immediate reservoir host of MERS-CoV.
Bityo, uducurama dushobora kuba atari two ndiri virusi ya MERS-CoV ikuriraho.
On the other hand, studies in Middle East have shown that dromedary camels are seropositive for MERS-CoV-specific neutralizing antibodies, same as camels of Middle East origin in multiple African countries.
Ku rundi ruhande, ubushakashatsi bwakorewe mu Burasirazuba bwo hagati bwagaragaje ko ingamiya zifitemo abasirikare baca intege by’umwihariko virusi ya MERS-CoV, kimwe nk’ingamiya zikomoka mu Burasirazuba bwo hagati zo mu bihugu byinshi by’Afurika.
Live MERS-CoV identical to the virus found in humans was isolated from the nasal swabs of dromedary camels, further indicating that camels serve as the bona fide reservoir host of MERS-CoV.
Virusi nzima ya MERS-CoV isa nka virusi igaragara mu bantu yakuwe mu bipimo byo mu mazuru by’ingamiya, bigaragaraza kurushaho ko ingamiya ari indiri nyayo ya virusi ya MERS-CoV.
It is also noteworthy that generally mild symptoms but massive virus shedding were observed in camels experimentally infected with MERS-CoV.
Biranakwiye kuvuga muri rusange ari ibimenyetso byoroheje ariko bigaragaza ko virusi yakuze ikanava ku bwinshi byagaragaye mu ngamiya zakoreweho ubushakashatsi zikanduzwa virusi ya MERS-CoV.
Notably, infected camels shed viruses not only through respiratory route but also through fecal-oral route, which is also the main route for virus shedding from bats.
By’umwihariko, ingamiya zanduye virusi zayirekuye bitanyuze gusa mu nzira z’ubuhumekero ahubwo binanyuze mu musarani, bikaba ari na yo nzira y’ibanze virusi zanduramo zivuye mu ducurama.
However, questions still remain since many confirmed cases of MERS have no contact history with camels prior to symptom onset, plausibly ascribed to human-to-human transmission or unknown transmission routes involving unrecognized animal species that harbour MERS-CoV.
Ariko, hari ibibazo bikibazwa kuko abenshi bemejwe ko banduye virusi ya MERS batigeze bahura n’ingamiya mbere yo gutangira kugaragaza ibimenyetso, byakwitwa ko abantu banduje abandi cyangwa bitazwi aho banduriye bikaba bishoboka ko amoko y’inyamaswa atazwi afite virusi ya MERS-CoV.
SARS-CoV-2 shares 96.2% nucleotide homology with a bat CoV RaTG13 isolated from Rhinolophus affinis bats.
SARS-CoV-2 ifite 96,2% by’igice cy’isanomuzi na CoV RaTG13 yo mu gacurama yakuwe mu bwoko bw’uducurama.
As in the cases of SARS-CoV and MERS-CoV, the sequence divergence between SARS-CoV-2 and RaTG13 is too great to assign parental relationship.
Ku byerekeye virusi za SARS-CoV na MERS-CoV, imiterere itandukanye hagati ya SARS-CoV-2 na RaTG13 ni minini cyane ku buryo ntawavuga ko zikomoka hamwe.
That is to say, bats might not be the immediate reservoir host(s) of SARS-CoV-2 unless almost identical bat CoVs are found in future.
Uducurama dushobora kuba atari two ndiri virusi ya SARS-CoV-2 ikuriramo keretse mu minsi iri imbere hagaragaye isa na CoV ikurira mu ducurama.
Presumably, the intermediate animal hosts of SARS-CoV-2 should be among the wildlife species sold and killed at the Huanan Seafood Wholesale Market, with which many of the initial cases of COVID-19 were associated, indicative of a probable animal-to-human transmission event.
Birashoboka ko inyamaswa zikuriramo SARS-CoV-2 ziba ari zo mu mashyamba zigurishwa zikabagirwa mu Isoko rya Huanan Seafood Wholesale, aho abenshi mu banduye bwa mbere COVID-19 baturutse, bikaba ari ikimenyetso kigaragaza ko bishoboka ko inyamaswa zanduje abantu.
Several recent studies based on metagenomic sequencing have suggested that a group of endangered small mammals known as pangolins (Manis javanica) could also harbour ancestral beta-CoVs related to SARS-CoV-2.
Ubushakashatsi bwinshi buherutse gukorwa bushingiye ku miterere ya metajenome, bwavuze ko itsinda ry’inyamabare nto ziri mu kaga zizwi nk’igisamujyonjyo na zo zishobora kuba zikomokaho virusi ya beta-CoV ifitanye isano na SARS-CoV-2.
These novel pangolin CoV genomes share 85-92% nucleotide sequence homology with SARS-CoV-2.
Izo jenome za CoV nshya z’igisamujyonjyo zifite 85-92% by’isanomuzi rya virusi ya SARS-CoV-2.
However, they are equally closely related to RaTG13 with about 90% identity at the level of nucleotide sequence.
Ariko, zifitanye isano ingana na RaTG13 bikaba bisa kuri 90% ku rwego rw’isanomuzi.
They cluster into two sub-lineages of SARS-CoV-2-like viruses in the phylogenetic tree, one of which share a more similar receptor binding domain (RBD) with SARS-CoV-2, with 97.4% amino acid sequence identity.
Ziri mu matsinda abiri mato bisa ya virusi zisa nka SARS-CoV-2 mu mihindagurikire ya virusi, imwe muri yo ifite poroteyine ituma ifata ku ngirabuzimafatizo (RBD) isa nk’iya SARS-CoV-2 kuri 97,4% by’ibiranga imiterere ya aside amino.
In stark contrast, the RBDs of SARS-CoV-2 and RaTG13 are more divergent, albeit a higher degree of sequence homology genome-wide.
Ku buryo butandukanye cyane, RBD za SARS-CoV-2 na RaTG13 ziratandukanye cyane, nubwo zisa ku rugero rwo hejuru mu byerekeye isano rya jenome.
An earlier study on diseased pangolins also reported the detection of viral contigs from lung samples, which turn out to be similarly related to SARS-CoV-2.
Ubushakashatsi bwakozwe mbere ku ndwara zifata igisamujyonjyo byanavuze ko hatahuwe uduce tw’isanomuzi twa virusi two mu bipimo byo mu bihaha, bikaba bifitanye isano risa na SARS-CoV-2.
This study adopted different assembly methods and manual curation to generate a partial genome sequence comprising about 86.3% of the full-length viral genome.
Ubu bushakashatsi bwakoresheje uburyo butandukanye bwo guhuza no gutoranya hatangwa imwe mu miterere ya jenome igizwe na 86,3% bya jenome yose ya virusi.
We cannot exclude the possibility that pangolin is one of the intermediate animal hosts of SARS-CoV-2.
Twitareka kuvuga ko bishoboka ko igisamujyonjyo ari kimwe mu nyamaswa zikuriramo virusi y a SARS-CoV-2.
However, currently there is no evidence in support of a direct pangolin origin of SARS-CoV-2 due to the sequence divergence between SARS-CoV-2 and pangolin SARS-CoV-2-related beta-CoVs.
Ariko, ubu nta bimenyetso byemeza ko virusi ya SARS-CoV-2 ikomoka bitaziguye ku gisamujyonjyo kuko imiterere itandukanye hagati ya SARS-CoV-2 na SARS-CoV-2 ijyanye na beta-CoV ifata igisamujyonjyo.
In addition, the distance between SARS-CoV-2 and RaTG13 is even shorter than that between SARS-CoV-2 and pangolin SARS-CoV-2-related beta-CoVs.
Kandi, intera iri hagati ya SARS-CoV-2 na RaTG13 ni ngufi y’iri hagati ya SARS-CoV-2 na SARS-CoV-2 ijyanye na beta-CoV ifata igisamujyonjyo.
The evolutionary pathway of SARS-CoV-2 in bats, pangolins and other mammals remains to be established.
Inzira y’ihinduka rya SARS-CoV-2 mu ducurama, ibisamujyonjyo n’izindi nyamaswa igomba gusobanurwa.
Whereas the highest sequence homology has been found in the RBDs between SARS-CoV-2 and pangolin, SARS-CoV-2-related beta-CoVs, SARS-CoV-2 and RaTG13 share the highest genome-wide sequence homology.
Mu gihe imiterere y'isano ikomeye yagaragaye muri RBD hagati ya SARS-CoV-2 n’igisamujyonjyo, SARS-CoV-2 ijyanye na beta-CoVs, SARS-CoV-2 na RaTG13 bisangiye imiterere y’isano rya jenome ikomeye.
It is highly speculative that the high degree of similarity between the RBDs of pangolin SARS-CoV-2-related beta-CoVs and SARS-CoV-2 is driven by selectivity-mediated convergent evolution.
Biravugwa cyane ko urugero rwo hejuru rwo gusa hagati ya RBD ya virusi ya SARS-CoV-2 ijyanye na beta-CoV ifata igisamujyonjyo na SARS-CoV-2 iterwa n’ihinduka rigendera ku gutoranya.
A counter-proposal is in favour of a recombination between a pangolin SARS-CoV-2-related beta-CoV and RaTG13 in the third wild animal species.
Undi mushinga urifuza guhinduranya ingirangingofatizo hagati ya SARS-CoV-2 ijyanye na beta-CoV ifata igisamujyonjyo na RaTG13 igaterwa mu moko ya gatatu y’inyamaswa zo mu ishyamba.
As a driving force in evolution, recombination is widespread among beta-CoVs.
Ku byerekeye igitera ihinduka, guhinduranya ingirangingofatizo birakorwa cyane muri za beta-CoV.
The jury is still out on the immediate zoonotic origin of SARS-CoV-2.
Inteko iracyasesengura ku nyamaswa ikuriramo virusi ya SARS-CoV-2.
Besides the highly pathogenic HCoVs, the zoonotic origin of HCoV-229E, HCoV-OC43, HCoV-NL63 and HCoV-HKU1 have also been studied.
Usibye HCoV zitera indwara cyane, ikomoka rya HCoV-229E, HCoV-OC43, HCoV-NL63 na HCoV-HKU1 ku nyamaswa na ryo ryakozweho ubushakashatsi.
Phylogenetic evidence indicated that both HCoV-NL63 and HCoV-229E might have originated from bat CoVs, while the parental viruses of HCoV-OC43 and HCoV-HKU1 have been found in rodents.
Ibimenyetso by’imihindagurikire ya virusi byagaragaje ko HCoV-NL63 na HCoV-229E zishobora kuba zarakomotse kuri CoV yo mu gacurama, mu gihe virusi zibyara HCoV-OC43 na HCoV-HKU1 zasanzwe mu ngugunnyi.
It has been reported that a bat CoV termed ARCoV.2 (Appalachian Ridge CoV) detected in North American tricolored bat displayed close relationship with HCoV-NL63.
Byavuzwe ko CoV yo mu gacurama yiswe ARCoV.2 (CoV yo mu misozi ya Appalachia) yatahuwe mu gacurama k’amabara atatu ko muri Amerika ya ruguru yagaragaje isano ya hafi na HCoV-NL63.
On the other hand, HCoV-229E was genetically related to another bat CoV, termed Hipposideros/GhanaKwam/19/2008, which was detected in Ghana, while camelids have also been suspected as its intermediate host.
Ku rundi ruhande, HCoV-229E yari ifite isano ishingiye kuri jene n’indi CoV yo mu gacurama, yiswe Hipposideros/GhanaKwam/19/2008, yatahuwe muri Gana, mu gihe ubwoko bw’ingamiya bwaketsweho kuba bukuriramo iyo virusi.
For clarity, the current knowledge on animal origins of known HCoVs is summarized in Figure ​1 and Table 2.
Mu kubisobanura neza, ubumenyi buhari ku nyamaswa bizwi ko yazanye virusi ya HCoVs yavuzwe muri make mu gishushanyo cya​1 n’imbonerahamwe ya 2.
Phylogenetic analysis has provided evidence for interspecies transmission events of HCoVs in the history.
Isesengura ry’imihindagurikire ya virusi ryatanze ibimenyetso ko mu mateka habayeo kwanduzanya hagati y’amoko kwa HCoV.
When HCoV-OC43 crossed species to infect humans from domestic livestock around 1890, a pandemic of respiratory infection was recorded.
Igihe HCoV-OC43 yavuye mu moko amwe akanduza abantu biturutse ku matungo yororerwa mu ngo ahagana mu 1890, hagaragaye icyorezo cy’indwara yo mu buhumekero.
The interspecies transmission history of HCoV-229E is less clear.
Amateka yo kwanduzanya hagati y’amoko kwa virusi ya HCoV-229E ntagaragara neza.
Bat alpha-CoVs closely related to HCoV-229E have been found.
alpha-CoV yo mu gacurama isa na HCoV-229E yaragaragaye.
Between them there is an alpaca alpha-CoV.
Hagati yazo harimo alpha-CoV ifata arupaga.
Several lines of evidence support the transmission of virus from bats to humans directly.
Ibimenyetso byinshi bishyigikira ko kwandura kwa virusi iturutse mu ducurama igahita ijya mu bantu.
First, humans but not alpacas might have contact with bats in a shared ecological niche.
Icya mbere, abantu atari za arupaga, bahurira n’uducurama henshi mu buturo basangiye.
Instead, humans have close contact with alpacas.
Ariko, abantu ni bo bakunda guhura cyane na za arupaga.
Second, HCoV-229E-related bat alpha-CoVs are diverse and non-pathogenic in bats, whereas alpaca alpha-CoV caused an outbreak of respiratory disease in infected animals.
Icya kabiri, HCoV-229E ijyanye na alpha-CoV yo mugacurama ntizisa kandi ntizanduza uducurama, aho alpha-CoV yo muri arupaga yatewe n’icyorezo cyo mu buhumekero mu nyamaswa.
Finally, alpaca alpha-CoV has not been found in feral animals.
Hanyuma, alpha-CoV yo muri arupaga yasanzwe mu nyagasozi.
Thus, the possibility cannot be excluded that alpacas obtain the HCoV-229E-related alpha-CoV from humans.
Bityo, ntawashidikanya ko za arupaga zandujwe HCoV-229E ijyanye na alpha-CoV n’abantu.
In fact, bats are the direct source of human pathogenic viruses including rabies virus, Ebola virus, Nipah virus and Hendra virus.
Muri make, uducurama ni two twanduza abantu virusi itera ibisazi, virusi itera ebola, virusi ya Nipah na virusi ya Hendra.
It is therefore not too surprising that bats might transmit HCoV-229E to humans directly.
Bityo, ntibitangaje cyane kubona uducurama dushobora guhita twanduza abantu virusi ya HCoV-229E.
Alternatively, whereas bat alpha-CoVs serve as the gene pool of HCoV-229E, alpacas and dromedary camels might serve as intermediate hosts that transmit viruses to humans, exactly as in the case of MERS-CoV.
Mu buryo bunyuranye n’ubwo, aho alpha-CoVs ari itsinda rya jene rya HCoV-229E, za arupaga n’ingamiya zishobora kuba zakuriramo virusi zikananduza virusi abantu, bimeze neza nko kuri virusi ya MERS-CoV.
MERS-CoV serves as an excellent example of interspecies transmission from bats to dromedary camels and from dromedary camels to humans.
MERS-CoV ni urugero rwiza rwo kwanduzanya virusi hagati y’amoko uhereye ku ducurama ukagera ku ngamiya ukanahera ku ngamiya ukageza ku bantu.
The evolutionary origin of MERS-CoV from bats is known at its initial identification and has also been strengthened by subsequent findings.
Imihindagurikire y’inkomoko ya MERS-CoV yo mu ducurama izwi mu gihe yamenyekanye bwa mbere kandi byanashimangiwe n’ibyavuye mu bushakashatsi byakurikiyeho.
It is obvious that bats provide a rich pool of virus species for interspecies exchange of genetic fragments and interspecies transmission.
Biragaragara ko uducurama ari itsinda rikomeye rya virusi zo mu nyamaswa mu ihererekanya ry’uduce twa jene no kwanduzanya hagati y’inyamaswa.
Longevity, densely packed colonies, close social interaction and strong ability to fly are all favourable conditions for bats to be an ideal 'virus spreader'.
Kuramba, gutura ahantu hamwe, kubana bya hafi n’ubushobozi bukomeye bwo kuguruka ni byo bintu bituma uducurama tuba inyamaswa zikomeye mu 'gukwirakwiza virusi'.
On the other hand, MERS-CoV has been introduced to dromedary camels for decades.
Ku rundi ruhande, hashize imyaka myinshi virusi ya MERS-CoV yinjiye mu ngamiya.
It is well adapted to these camels that have turned from an intermediate host to a stable and natural reservoir host.
Yamenyereye neza izo ngamiya zaretse kuba inyamaswa ikuriramo zikaba inyamaswa zigirwa indiri ya virusi zibamo zitekanye no mu buryo karemano.
MERS-CoV causes very mild disease and maintains a relatively low mutation rate in these animals.
Virusi ya MERS-CoV itera indwara idakomeye kandi ikomeza kugenda ihinduka gahoro muri izo nyamaswa.
Its sporadic transmission to humans is an accident and humans remain a dead-end host of MERS-CoV as its transmission cannot be sustained.
Kwandura ikagera mu bantu ni impanuka kandi abantu ntibanduza virusi ya MERS-CoV kuko ikwirakwira ryayo ridakomeye.
In contrast to the role of camels in the transmission of MERS-CoV, the role of pangolins, if there is any, in the transmission of SARS-CoV-2 is different.
Ku bitandukanye n’uruhare rw’ingamiya mu kwanduza MERS-CoV, uruhare rw’ibisamujyonjyo niba ruhari, mu kwanduza virusi ya SARS-CoV-2 ruratandukanye.
Particularly, pangolin beta-CoVs are highly pathogenic in pangolins.
By’umwihariko, beta-CoV yo mu bisamujyonjyo itera indwara cyane mu bisamujyonjyo.
They might be a dead-end host for SARS-CoV-2-related beta-CoVs, similar to civets in the case of SARS-CoV.
Zishobora kuba zirimo virusi ya SARS-CoV-2 ijyanye na beta-CoV ariko zitayanduza bisa nko ku mpimbi kuri SARS-CoV.
Several possibilities for interspecies transmission of SARS-CoV-2 from animals to humans have to be ruled in or ruled out in future studies.
Birashoboka cyane ko inyamaswa zanduzanya SARS-CoV-2, inyamaswa na zo zikanduza abantu byakwemezwa cyangwa ntibyemezwe mu bushakashatsi bw’ahazaza.
First, bats could be the reservoir host of a SARS-CoV-2-related virus almost identical to SARS-CoV-2.
Icya mbere, uducurama dushobora kuba ari ndiri ya virusi ifitanye isano na SARS-CoV-2 ijya gusa na virusi ya SARS-CoV-2.
Humans might share the ecological niche with bats through butchering or coal mining.
Abantu bashobora gusangira ubuturo n’uducurama binyuze mu kutubaga no gucukura amakara.
Second, pangolins could be one of intermediate amplifying host to which a SARS-CoV-2-related virus had been newly introduced.
Icya kabiri, ibisamujyonjyo bishobora kuba ari zimwe mu nyamaswa virusi zikuriramo zikanororokeramo cyane zifashwe vuba na virusi zifitanye isano na SARS-CoV-2.
Humans contract the virus through butchering and consumption of game meat.
Abantu bandura virusi biturutse mu kubaga no kurya inyama z’inyamaswa z’ishyamba.
It is possible that many mammals including domestic animals are susceptible to SARS-CoV-2.
Birashoboka ko inyamabere nyinshi harimo n’amatungo yo mu rugo zikekwaho kuba zifite virusi ya SARS-CoV-2.
A survey of domestic and wild animals for antibodies is warranted.
Ubushakashatsi ku matungo yo mu rugo n’inyamaswa zo mu ishyamba bwasanze zifite abasirikare barwanya virusi.
Third, as mentioned above, recombination and adaptation of SARS-CoV-2 might have occurred in a third species that has contact with both bats and pangolins.
Icya gatatu, ku byavuzwe ku guhinduranya ingirangingofatizo no kumenyera kwa SARS-CoV-2 bishobora kuba byarabayeho mu bwoko bwa gatatu bw’inyamaswa zahuye n’uducurama n’ingamiya.
The search for the animal origins of SARS-CoV-2 is still on.
Gushakisha inyamaswa itera SARS-CoV-2 birakomeje.
Apart from different types of the animal hosts, three major factors on the viral side are also important in facilitating CoVs to cross species barriers.
Usibye amoko atandukanye y’inyamaswa zikuriramo virusi, ibintu bitatu ku ruhande rwa virusi na byo ni ingenzi mu korohereza CoV kujya mu yandi moko y’inyamaswa.
First of all, their relatively high mutation rates in RNA replication.
Mbere na mbere, ni igipimo cyo guhinduka kinini cyane mu kwikoramo utundi duce twa RNA.
In comparison to other single-stranded RNA viruses, the estimated mutation rates of CoVs could be regarded as “moderate” to “high” with an average substitution rate being ~10-4 substitution per year per site 2, depending on the phase of CoV adaptation to novel hosts.
Zigereranyijwe n’izindi virusi za jene imwe ya RNA, guhinduka kwa CoV kuri mu “rugero” cyangwa “hejuru” n’impuzandengo yo guhindura jene ni ~10-4 ku mwaka kuri buri jene 2, bitewe n’icyiciro cy’imenyera rya CoV mu nyamaswa nshya yagiyemo.
CoVs have a proof-reading exoribonuclease, deletion of which results in exceedingly high mutability and attenuation or even inviability.
CoV ifite anzime ihindura RNA, igasiba ibice byayo bituma ihinduka cyane igacika intege cyangwa ntibe yanabaho.
Interestingly, the nucleotide analogue Remdesivir is known to suppress CoV replication through inhibition of this exoribonuclease and the RNA-dependent RNA polymerase.
Igitangaje ni uko ku gice cy’isanomuzi, umuti wa Remdesivir uzwiho guhagarika kwikoramo utundi duce kwa CoV hifashishijwe anzime ibuza poroteyine ya polimerase ya RNA gukora.
Remdesivir is one of most promising anti-SARS-CoV-2 agents to be tested in clinical trials.
Remdesivir ni umwe mu muti utanga icyizere ku kurwanya SARS-CoV-2 wasuzumwe n’abaganga.
Nevertheless, mutation rates of CoVs are about a million times higher than those of their hosts.
Nyamara, guhinduka kwa CoV ni hafi miliyoni kurusha inyamaswa izo virusi zikuriramo.
In addition, mutation rate is often high when CoVs are not well adapted to the host.
Kandi, guhinduka akenshi biba biri hejuru iyo CoV zitamenyereye neza inyamaswa zikuriramo.
Compared to SARS-CoV with a high mutation rate, the mutation rate of SARS-CoV-2 is apparently lower, suggestive of a higher level of adaptation to humans.
Mu kugereranya SARS-CoV ihinduka cyane, guhinduka kwa SARS-CoV-2 kuri hasi bigaragara, bikaba ari byo bituma imenyera cyane abantu.
Presumably, it has already been adapted to another host close to humans.
Bivugwa ko yari yaramaze kumenyera indi nyamaswa hafi cyane y’abantu.
In addition to SARS-CoV-2, this also applies to MERS-CoV, which is well adapted to dromedary camels.
Usibye SARS-CoV-2, ibi binareba MERS-CoV, yamenyereye neza kuba mu ngamiya.
Theoretically, it is unlikely that genetic drift would render vaccines and antivirals against SARS-CoV-2 ineffective quickly.
Bityo, ntibyashoboka ko guhinduka kwa jene byatuma inkingino n’imiti igabanya ubukana bwa SARS-CoV-2 byacika intege vuba.
Second, the large RNA genome in CoVs exerts extra plasticity in genome modification for mutations and recombination, thereby increasing the probability for interspecies co-evolution, which is advantageous for the emergence of novel CoVs when the conditions become appropriate.
Icya kabiri, jenome nini ya RNA iri muri CoVs ikoresha ubundi buryo bwo guhindura imiterere muri jenome igahinduka ikanahinduranya ingirangingofatizo; bityo, ikongera amahirwe yo guhindukana n’inyamaswa ibamo, bikaba ari inyungu mu mikurire ya virusi nshya za CoV igihe bikwiye.
This is supported by the copious unique open reading frames and protein functions encoded towards the 3′ end of the genome.
Ibi bishimangirwa n’imiterere ya RNA ivamo poroteyine n’imikorere yayo isobetse y’umusozo wa 3 wa jenome.
Third, CoVs randomly and frequently switch templates during RNA replication through a unique “copy-choice” mechanism.
Icya gatatu, CoV irahinduka kandi kenshi ikavamo utundi duce twa RNA binyuze mu buryo bwo “guhindura jenome ikenewe”.
In a host that serves as the mixing vessel, strand switching occurs frequently during CoV RNA transcription.
Mu nyamaswa ikurimo, guhinduka kwa jenome bibaho kenshi igihe RNA ya CoV iri kujya ku ngirangingofatizo.
Highly homologous full-length and subgenomic RNAs could recombine to generate new CoVs.
RNA zisa cyane kandi zifite jenome zungirije zishobora guhindura ingirangingofatizo zigatanga CoV nshya.
Phylogenetic evidence of natural recombination has been found in both HCoV-HKU1 and HCoV-OC43, as well as animal CoVs such as bat SL-CoV and batCoV-HKU9.
Imihindagurikire karemano ya virusi yasanzwe muri HCoV-HKU1 na HCoV-OC43, ndetse na CoV zifata inyamaswa nka SL-CoV na batCoV-HKU9 ziba mu ducurama.
Virus-host interaction in relation to transmission
Imibanire ya virusi n’inyamaswa ibamo mu byo kwanduzanya
Besides three viral factors stated above, viral interaction with host receptor is another key factor influential on interspecies transmission.
Usibye virusi eshatu zavuzwe haruguru, imibanire ya virusi n’inyamaswa ikuriramo ni ikindi kintu gituma habaho kwanduzanya hagati y’ubwoko bunyuranye.
Herein, recombination of SARS-CoV is taken as a typical example, which also showed evidence of positive selection during interspecies transmission events.
Bityo, guhinduka kwa SARS-CoV bifatwa nk’urugero rufatika, byanagaragaje guhitamo neza igice cy’umubiri virusi ijyamo mu kwanduzanya hagati y’inyamaswa.
Based on the comparative analysis between isolates of human and civet SARS-CoVs, SARS-CoV is thought to undergo rapid adaptation in different hosts, particularly with mutations at the RBD of the S protein.
Hashingiwe ku isesengura rigereranya hagati ya SARS-COV ifata abantu n’impimbi, hatekerezwa ko SARS-CoV imenyera vuba imibiri itandukanye ibamo, by’umwihariko ihinduka rya RBD rya poroteyine ya S.
Generally, the RBD in the S protein of a CoV interacts with the cellular receptor and is intensely selected by the host antibody response.
Muri rusange, RBD yo muri poroteyine ya S ya virusi ya CoV ibana n’ingirangingofatizo iyakira kandi itoranywa bitewe n’uko irwanywa n’abasirikare b’umubiri yinjiyemo.
In SARS-CoV, the RBD is in the 318th to 510th amino acids on the S1 fragment, which binds to the human ACE2 as well as its coreceptors for viral entry.
Muri SARS-CoV, RBD iri ku mwanya wa 318 kugeza ku wa 510 muri aside amino zo ku gice cya S1, bigatuma ifata kuri ACE2 y’umuntu ndetse akaba ari na ho virusi ishingira yinjira mu mubiri.
The RBD of SARS-CoV is capable of recognizing the ACE2 receptors of various animals, including bat, civet, mouse and raccoon dog, allowing interspecies transmission of the virus.
RBD ya SARS-CoV ishobora kumenya ACE2 zakira virusi z’inyamaswa zitandukanye, harimo agacurama, impimbi, imbeba, ubwoko bw’impimbi, bituma inyamaswa zanduzanya virusi.
In fact, only 6 amino acid residues were observed to be different from human and civet viral isolates in the RBD and 4 of them locate in the receptor-binding motif for interaction with the ACE2 receptor.
Muri make, ibisigazwa bya aside amino 6 gusa ni byo byasuzumwe hasangwa bitandukanye n’iby’abantu n’impimbi bifite virusi muri RBD kandi 4 muri byo bifite igice kibihuza na ACE2 yakira virusi.
Civet SARS-CoV has K479N and S487T mutations in its RBD, which might increase the affinity of the interaction of spike protein with human ACE2 receptor.
SARS-CoV yo mu mpimbi ifite imihindukire ya K479N na S487T muri RBD yayo, bishobora kongera isano ry’imibanire na poroteyine ya S hamwe na ACE2 y’umuntu yakira virusi.
In other words, these two amino acid substitutions might be critical to viral adaption to humans.
Mu yandi magambo, guhindura izo aside amino ebyiri bishobora kuba ari ingenzi mu gutuma virusi imenyera umubiri w’umuntu.
It is noteworthy that SARS-CoV-2 shares the same cellular receptor with SARS-CoV.
Birashishikaje kumenya ko SARS-CoV-2 yakirwa n’ingirangingofatizo imwe nk’iyakira SARS-CoV.
A 30% difference between SARS-CoV-2 and SARS-CoV in the S1 unit of the S protein implicates that the binding affinity of its S protein with human ACE2 might have altered.
Kuri 30% by’itandukaniro hagati ya SARS-CoV-2 na SARS-CoV mu gice cya S1 cya poroteyine ya S bigaragaza isano iyo poroteyine ya S ifitanye na ACE2 yo mu bantu ishobora kuba yarahinduwe.
Indeed, a cryo-EM study indicates a 10- to 20-fold higher affinity of this binding than that between human ACE2 and SARS-CoV S protein.
Mu by’ukuri, ubushakashatsi kuri cryo-EM bugaragaza ubwikube 10 - 20 bw’isano rikomeye ryo kwihuza kwa ACE2 yo mu bantu na poroteyine ya S yo muri SARS-CoV.
It will also be of interest to determine whether any other coreceptor might be required for SARS-CoV-2 transmission.
Biranashishikaje kwemeza niba hari indi ngirangingofatizo yakira virusi yifashishwa mu kwanduza SARS-CoV-2.
Intriguingly, HCoV-NL63 also binds to ACE2 but with a different part of S.
Igitangaje ni uko HCoV-NL63 na yo yihuza na ACE2 ariko ku gice gitandukanye cya poroteyine ya S.
There exist many other HCoV receptors, such as aminopeptidase N for HCoV-229E, and 9-O-acetylated sialic acid for HCoV-OC43.
Hari izindi ngirangingo zakira HCoV, nka aminopepitidaze N ya HCoV-229E, na aside siyalike ifite asetili 9-O ya HCoV-OC43.
They might also account for successful adaptation of these CoVs in humans after interspecies transmission from their animal hosts.
Bishobora gusobanura ukuntu virusi za CoV zimenyera umubiri w’umuntu azandujwe n’inyamaswa zakuriyemo.
In addition to cellular receptors, the outcome of interspecies transmission of HCoVs is also governed by other host dependency and restriction factors.
Usibye ingirangingofatizo zakira virusi, kuba inyamaswa zanduzanya virusi ya HCoV binagengwa n’aho zikurira na poroteyine irwanya virusi.
The divergence of these host proteins between humans and natural reservoir hosts of HCoVs such as bats, dromedary camels and rodents might constitute a barrier to interspecies transmission.
Itandukaniro ry’izo poroteyine z’aho virusi zikurira hagati y’abantu n’inyamaswa zagizwe indiri karemana ya virusi za HCoV nk’uducurama, ingamiya n’ingugunnyi bishobora gukumira kwanduzanya virusi hagati y’ubwoko bunyuranye.
HCoVs have to usurp host dependency factors and subvert host restriction factors for a successful interspecies transmission.
HCoV zihinduramo ingirangingo z’aho ziri maze zikangiza poroteyine irwanya virusi kugira ngo zibashe kwanduza izindi nyamaswa.
In this regard, molecular determinants in this important area of virus-host interaction remain to be identified and characterized.
Bityo, ibice bya molekire muri iyi mibanire ikomeye ya virusi n’inyamaswa ikuriramo bikwiye gukomeza kugaragazwa no gusobanurwa.
An unbiased genome-wide screening of host dependency and restriction factors for SARS-CoV-2 using the state-of-the-art technology of CRISPR might be fruitful.
Isuzuma rya jenome ndakemwa ry’aho virusi ikurira na poroteyine irwanya virusi ya SARS-CoV-2 hakoreshejwe ikoranabuhanga rigezweho rya CRISPR bishobora gutanga umusaruro.
Emergence of novel HCoVs: back to ground zero
Kwigaragaza kwa virusi nshya ya HCoV: Inkomoko yayo
The diversity of bat CoVs provides ample opportunities for the emergence of novel HCoVs.
Amoko menshi ya CoV yo mu ducurama atanga amahirwe akomeye yo kwigaragaza kwa virusi nshya ya HCoV.
In this sense, bat CoVs serve as the gene pool of HCoVs.
Bityo, CoV yo mu ducurama ni yo ivamo jene za HCoV.
In addition, rapid mutation and genetic recombination also drive HCoV evolution and serve as two important steps in this process.
Kandi guhinduka vuba no guhinduranya jene bituma HCoV ihindagurika bikaba ari intambwe ebyiri zikomeye muri iki gikorwa.
For example, the acquisition or loss of novel protein-coding genes has the potential to drastically modify viral phenotypes.
Urugero: Kubona cyangwa gutakaza jene zikora poroteyine bifite ubushobozi bwo guhindura cyane agace ka virusi.
Among SARS-CoV accessory proteins, ORF8 has been thought to be important in adaptation to humans, as SARS-CoV-related bat viruses were isolated but found to encode divergent ORF8 proteins.
Muri poroteyine ngereka za SARS-CoV, bitekerezwa ko ORF8 ari ingenzi mu kumenyera umubiri w’umuntu, naho virusi zo mu ducurama zifitanye isano na SARS-CoV zashyizwe ukwazo bigaragara ko zikora poroteyine itandukanye ya ORF8.
A 29-nucleotide deletion characteristic of SARS-CoVs has been found in strains isolated at the beginning of the human epidemic.
Isanomuzi ya 29 isiba SARS-CoV yagaragaye muri jene mu ntangiriro z’icyorezo cyibasiye abantu.
This deletion splits ORF8 into ORF8a and ORF8b and is thought to be an adaptive mutation that promotes the switch of hosts.
Iri siba rigabanya ORF8 mo ORF8a na ORF8b kandi bitekerezwa ko ishobora kumenyera ihinduka rituma ihinduranya inyamaswa.
Besides, SARS-CoV has a possible recombination history with lineages of alpha- and gamma-CoVs, where a large number of smaller recombinant regions were identified in the RNA-dependent RNA polymerase.
Kandi SARS-CoV izwiho guhindura ingirangingofatizo z’amoko ya virusi za alpha na gamma-CoV, aho umubare munini w’ingirangingofatizo zahinduwe zasazwe muri poroteyine ya polimerase ya RNA.
Recombination locations were also identified in the nsp9, most of nsp10, and parts of nsp14.
Ahahinduwe ingirangingofatizo hanagaragaye muri nsp9, inyinshi muri nsp10, n’ibice bya nsp14.
Likewise, it has been shown that the epidemic MERS-CoV experienced recombination events between different lineages, which occurred in dromedary camels in Saudi Arabia.
Mu buryo bumwe binagaragara ko icyorezo cya MERS-CoV cyahinduye ingirangingofatizo hagati y’amoko abiri ya virusi atandukanye bikaba byarabaye mu ngamiya zo muri Arabiya Sawudite.
Besides SARS-CoV and MERS-CoV, recombination events have also been observed in other HCoVs, in which the HCoVs recombine with other animal CoVs in their non-structural genes.
Usibye SARS-CoV na MERS-CoV, ibikorwa byo guhindura ingirangingofatizo byanagaragaye mu zindi HCoV, aho HCoV ihindura ingirangingofatizo za CoV z’indi nyamaswa muri jene zihariye zayo.
It should also be cautioned that artificial selection can contribute to unintended changes in viral genomes, most likely resulting from relieving viruses from selection pressures exerted, such as by the host immune system.
Birakwiye kumenya ko guhitamo bitari karemano byagira uruhare mu mpinduka zitagamijwe muri jenome za virusi, bika byatuma virusi zisohoka muri icyo gice cyatoranyijwe, nk’urugero abasirikare b’umubiri w’inyamaswa virusi ibamo.
An example of these effects is the loss of a full-length ORF4 in the HCoV-229E prototype strain, owing to a two-nucleotide deletion.
Urugero rw’iyo mikorere ni kutagira jene isanzwe ya ORF4 muri HCoV-229E bigatuma isanomuzi nyabubiri isibwa.
While intact ORF4 could be observed in bat and camel viruses related to HCoV-229E, the alpaca alpha-CoV displays a single nucleotide insertion, resulting in a frameshift.
Mu gihe ORF4 ikomeye yasanzwe muri virusi zo mu gacurama na lama zifitanye isano na HCoV-229E, alpha-CoV yo muri arupaga igaragaza kwinjirwamo n’isanomuzi imwe, bituma ihinduka.
Last but not least, the evolution of novel HCoVs is also driven by the selection pressure in their reservoir hosts.
Icya nyuma, imihindagurikire ya virusi nshya za HCoV inaterwa n’ibibazo byo kutaramba kw’inyamaswa zigira indiri.
Asymptomatic or only mild symptoms were detected when bats were infected with CoVs, indicating the mutual adaptation between CoVs and bats.
Kutagaragaza ibimenyetso cyangwa ibimenyetso byoroheje gusa byatahuwe ubwo uducurama twanduzwagwa CoV, bikagaraza kumenyerana hagati ya CoV n’uducurama.
It appeared that bats are well adapted to CoVs anatomically and physiologically.
Biragaragara ko uducurama tumenyerana neza na CoV mu rwego rw’imiterere y’umubiri.
For example, defects in the activation of pro-inflammatory response in bats efficiently reduce the pathology triggered by CoVs.
Urugero: Kudakora neza kwa molekire zirwanya indwara mu ducurama bigabanya neza indwara ziterwa na virusi ya CoV.
Besides, the natural killer cell activity in bats is suppressed due to upregulation of inhibitory natural killer cell receptor NKG2/CD94 and low expression level of major histocompatibility complex class I molecules.
Kandi ingirangingofatizo zica virusi mu buryo karemano mu ducurama zaretse gukora bitewe no kongeramo ingirangingofatizo zakira virusi za NKG2/CD94 no kutagaragara cyane kwa molekire igenga imikoranire ya tisi yo mu bwoko bwa I.