atepeq/tico19 huggingface dataset:
Finally, same as the other HCoVs, SARS-CoV-2 can be detected in fecal samples.
Ekisembayo, nga bwe kiri ku buwuka bwa HCoVs obulala, SARS-CoV-2 kasobola okulabikira mu sampolo z’obubi.
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.
Eky’okuba ng’omuntu asobola okufuna SARS-CoV-2 ng’alidde obubi nga bwe kiri ku SARS-CoV mu mbeera ezimu kirina kumala kukakasibwa mu kunoonyereza okunaakolebwa gye bujja.
It is also of particularly great interest to see whether SARS-CoV-2 might exhibit seasonality as in the cases of community-acquired HCoVs.
Era kikulu nnyo okulaba oba nga SARS-CoV-2 ayinza okuba ng’aliko ekiseera kye yeegirisizaamu nga bwe kiri ku HCoVs.
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.
Newankubadde guli gutyo, ebikwata ku SARS-CoV-2 omuli okusiigibwa, obulwadde bw’aleeta n’okuba ng’asigala ng’akyasiigibwa ng’ayise mu bantu bujja kuba bwa mugaso ku ekinaava mu bulwadde bwa COVID-19 obuliwo kaakano.
All four community-acquired HCoVs causing mild symptoms have been well adapted to humans.
Obubonero bwonna obutali bwa maanyi obuleetebwa HCoVs abantu babugumidde bulungi.
From another perspective, it might also be true that humans have been well adapted to these four HCoVs.
Bwe kitunuulirwa mu ngeri endala, kiyinza era okubeera ekituufu nti abantu bagumidde bulungi obuwuka bwa HCoVs buno.
In other words, both could be the survivors of ancient HCoV pandemics.
Mu bigambo ebirala, buno bwombi buyinza okubeera nga bwe bukaawonawo ku bulwadde bwa HCoV obw’omutawaana obwaliwo edda.
HCoVs that cause severe diseases in humans and humans who developed severe HCoV diseases have been eliminated.
Obuwuka bwa HCoVs obuleeta obulwadde obw’omutawaana mu bantu n’abantu abaafuna obulwadde bwa HCoV obw’amaanyi baasaanawo.
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.
Kino okusobola okubaawo, HCoVs bulina okwekubisaamu mu bantu emirundi egimala okusobozesa omuwendo ogwekubisizzaamu okugumira ebijjawo ku muntu oba ku kintu kwe bubeera.
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.
Mu ngeri eyo, SARS-CoV-2 gye kakoma okulemerako era ne gye kakoma okukwata abantu abangi, n’omukisa gwako ogw’okumanyiira abantu gye gukoma okweyongera.
If it adapts well, its transmission in humans would be difficult to stop by quarantine or other infection control measures.
Bwe kamanyiira obulungi, okusaasaana kwako mu bantu kuba kuzibu okuyimiriza nga bakozesa omuggalo oba engeri endala ez’okuziyiza okusaasaana kw’obulwadde.
For many years, the four community-acquired CoVs circulate in human populations, triggering common cold in immunocompetent subjects.
Okumala emyaka egiwera, obuwuka bwa CoVs bwa mirundi ena obusaasaanidde mu bantu nga bubaleetera ssennyiga owa bulijjo mu bantu abalina obusibage obulungi.
These viruses do not need an animal reservoir.
Obuwuka obwo tebwetaaga kwekweka mu nsolo.
In contrast, highly pathogenic SARS-CoV and MERS-CoV have not adapted to humans well and their transmission within humans cannot be sustained.
Mu kugeraageranya, obuwuka bwa SARS-CoV ne MERS-CoV obuleeta ennyo endwadde tebunnamanyiira bantu bulungi era ensaasaana yaabwo mu bantu tesobola kubeezekawo.
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.
Buba bulina okubeerawo n’okuzaalukukira eyo gye bubeera era ne bunoonya omukisa okwekwata ku bantu abanafu oboolyawo nga buyitira ku muntu omu oba abangi abanafu mu mubiri ne babuwa amaanyi.
SARS-CoV-2 has features that are similar to both SARS-CoV/MERS-CoV and the four community-acquired HCoVs.
Akawuka ka SARS-CoV-2 kalina obubonero obufaanaganako ne SARS-CoV/MERS-CoV wamu n’obuwuka obuna obukwata abantu mu bitundu gye babeera obuyitibwa HCoVs.
It is highly transmissible like community-acquired HCoVs, at least for the time being.
Kasaasaana nnyo okufaananako n’obwo obukwata abantu obuyitibwa HCoVs, waakiri nga bwe kiri mu kimanyiddwa mu kiseera kino.
However, it is more pathogenic than community-acquired HCoVs and less pathogenic than SARS-CoV or MERS-CoV.
Wabula, kaleeta nnyo endwadde okusinga obwo obukwata abantu obuyitibwa HCoVs ate era tekaleeta nnyo ndwadde kwenkana na SARS-CoV oba 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.
Kikyalina okwetegerezebwa oba nga kanaamanyiira abantu mu bujjuvu era ne kasaasaanira mu bantu nga tekalina we keekutte oba okubeera ku nsolo ebeerako akawuka etasaasaanya.
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.
Nga tetunnaba kwogera ku nsolo ezaavaako akawuka ka HCoVs, kijja kutuyamba okwogera ku nnyinyonnyola y’ebigambo n’obubonero bw’ebigambo bino, enfuukafuuka, obutonde, obusaasaaniro, ekibeerako akawuka ekitasaasaanya n’ekibeerako akawuka ekisaasaanya HCoVs.
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.
Ensolo ekola ng’ekisaasaanya ekifuulafuula HCoV bwe kiba nga kirina enkula eyeefaanaanyiriza obujjajja nga kigabana endagabutonde ku mutendera gw’obutaffaali bw’omubiri.
The ancestral virus is usually well adapted and non-pathogenic in this host.
Akawuka akazaala katera okuba nga kaamanyiira era nga tekaleeta bulwadde ku kintu kwe kabeera.
Likewise, a reservoir host harbours HCoV continuously and for long term.
Mu ngeri y’emu, akawuka we keekwata wabeerawo HCoV ebbanga lyonna okumala ebbanga ggwanvu.
In both cases, the hosts are naturally infected and are the natural hosts of HCoV or its parental virus.
Mu mbeera zombi, ekibeerako akawuka kiba kirwadde era nga kye kitonde ekibeerako HCoV oba ekizadde ky’akawuka.
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.
Okwawukanako n’ekyo, akawuka ka HCoV bwe kateekebwa ku kibeerako akawuka ekitasaasaanya nga tekannaba oba nga mu kiseera kye kimu kateekeddwa mu bantu, kaba tekannamanyiira kintu ekyo kwe kabeera era katera okusaasaanya endwadde.
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.
Ekibeerako akawuka ekitasaasaanya kisobola okubeera ng’ensibuko y’obulwadde mu bantu era ne kizannya ekifo ky’ekibeerako akawuka ekisaasaanya nga kiganya akawuka okuzaalukana era ne kakwata abantu ate ne kasaasaanyiza ddala obulwadde mu bantu.
An HCoV can undergo a dead-end infection if it cannot sustain its transmission within the intermediate host.
HCoV tekasobola kusaasaana bwe kaba nga tekasobola kwebeezaawo ku ekyo ekibeerako akawuka ekitasaasaanya.
On the contrary, HCoVs can also adapt to the intermediate host and even establish long-term endemicity.
Mu ngeri endala, akawuka ka HCoVs kasobola okumanyiira ku kibeerako akawuka ekitasaasaanya era ne kabeera nga kye kalwaza okumala ekiseera ekinene.
In this case, the intermediate host becomes a natural reservoir host.
Mu ngeri eyo, ekibeerako akawuka ekitazaala kifuuka ekyekwatwako akawuka eky’obutonde.
Epidemiological data revealed retrospectively that the index case of SARS had a contact history with game animals.
Obubaka obukwata ku byendwadde buzze nga bulaga nti ensaasaana ya SARS yalina akakwate n’ensolo ez’omu nsiko.
Subsequent seroprevalence investigations indicated that animal traders had a higher prevalence of anti-SARS-CoV IgG compared with that of the general population.
Okunoonyereza okwakolebwa ku luzzizzi kwalaga nti abasuubuzi b’ebisolo baalina abasirikale abalwanyisa SARS-CoV IgG bangi mu mibiri bw’ogeraageranya n’abantu abalala.
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.
Amafumbe (Paguma larvata) n’embwa erabika ennyo mu Asia eyitibwa racoon zaasangibwa nga zirimu obuwuka obulinga SARS-CoV nga bufaananira ddala n’obwa SARS-CoV.
This was indirectly supported by the fact that no further SARS was reported after killing all civets in the markets.
Kino kyayongera okuwagirwa mu ngeri nti oluvannyuma lw’okutta ensolo ezo ezaali mu butale bwonna, akawuka ka SARS tekaddamu kulabikako.
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.
Wabula, n’amafumbe g’omu nsiko oba agabeera mu ddundiro nga tegannaba kugenda mu butale gaali tegalina kawuka ka SARS-CoV, nga kitegeeza nti akasolo ako kandiba nga kabeerako bubeezi kawuka naye nga tekasaasaanya naye nga si kye kintu eky’obutonde ekyekwatako akawuka ka SARS-CoV.
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.
Awo nno, olw’okuba nti ebitundu 80% eby’ensolo ez’enjawulo mu butale bw’e Guangzhou zirina abasirikale abalwanyisa SARS-CoV obusobozi bw’okuba nti obusolo obutono buyinza okuba nga nabwo bukola ng’ekibeerako akawuka ekisaasaanya SARS-CoV tetubosola kububuusa maaso.
All of these appear to be dead-end hosts of SARS-CoV.
Bino byonna bifaanana okuba nga bibeerako akawuka ka SARS-CoV naye nga tekasaasaana.
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.
N’ekyava mu ekyo, ekisolo ekitonde ekibeerako akawuka ka SARS-CoV kyalaga nga kyefaanaanyirizaako akawundo CoV, akayitibwa SARS Rhinolophus bat CoV HKU3 (SARSr-Rh-BatCoV HKU3), akabeera mu buwundo bw’e China obuyitibwa horseshoe bats.
These bats are positive for anti-SARS-CoV antibodies and genome sequence of SARSr-Rh-BatCoV HKU3.
Obuwundo buno bulina abasirikale abalwanyisa SARS-CoV n’obutaffaali obuli mu kika kya BatCoV HKU3.
This and other bat CoVs share 88-92% nucleotide sequence homology with SARS-CoV.
Kano n’obuwuka bwa CoV obulala obw’obuwundo bugabana ebitundu 88-92% by’endagabutonde ne SARS-CoV.
These studies have laid the foundation for the new concept that bats host emerging human pathogens.
Okunoonyereza kuno kwateekawo omusingi ogw’entegeera empya nti obuwundo bubeeramu endwadde empya ezikwata abantu.
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.
Obuwuka obulala bungi obwefaananyirizaako ne SARS CoVs (SL-CoVs) nabwo buzuuliddwa mu buwundo naye nga tewali n’akamu okuggyako akayitibwa WIV1 akasobola okwawulibwa ng’akawuka akalamu.
Human angiotensin converting enzyme 2 (ACE2) is known to be the receptor of SARS-CoV.
Ekirungo ky’omu mubiri ekiyitibwa angiotensin converting enzyme 2 (ACE2) kimanyiddwa ng’ekisembeza SARS-CoV.
WIV1 derived from fecal sample of bats was demonstrated to use bat, civet and human ACE2 as receptor for cell entry.
WIV1 kaava mu sampolo z’obubi bw’obuwundo era kaalagibwa ng’akakozesa akawundo, effumbe ne ACE2 mu bantu ng’ekisembeza obutaffaali okuyingirirwa akawuka.
Intriguingly, sera of convalescent SARS patients were capable of neutralizing WIV1.
Ekisanyusa, oluzzizzi lw’akawuka ka SARS mu balwadde abagenda bawona lwali lusobola okusaabulula WIV1.
Thus far, WIV1 represents the most closely related ancestor of SARS-CoV in bats, sharing 95% nucleotide sequence homology.
Ne gye buli eno, WIV1 kakiikirira oluganda olusinga okuba okumpi ne SARS-CoV mu buwundo, obugabana ebitundu 95% eby’endabutonde.
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.
Ng’oggyeeko endagabutonde efaanana ennyo wakati w’obuwuka buno bwombi, kikkirizibwa wonna nti WIV1 si ke kawuka ka SAR-CoV akazaala obulala akali okumpi ate n’obuwundo si ke kali okumpi ku byekwatako akawuka ka SARS-CoV.
Phylogenetic analysis clusters MERS-CoV to the same group as bat CoV-HKU4 and bat CoV-HKU5.
Enneekenneenya y’enfuukafuuka y’obuwuka eteeka MERS-CoV mu kibinja kye kimu ne CoV-HKU4 wamu ne CoV-HKU5.
Bat CoV-HKU4 and MERS-CoV utilize the same host receptor, dipeptidyl peptidase 4 (DPP4), for virus entry.
Akawundo CoV-HKU4 ne MERS-CoV bukozesa ekibeerako akawuka kye kimu, dipeptidyl peptidase 4 (DPP4), okuyingiza akawuka.
RNA-dependent RNA polymerase sequences of MERS-CoV are phylogenetically closer to counterparts in bat beta-CoVs identified from Europe and Africa.
Endagabutonde (RNA) ya MERS-CoV yeefaananyiriza n’eyo erabikira mu buwundo beta-CoVs obwalabibwa e Bulaaya ne mu Afrika.
Up to now, no live MERS-CoV can be found in wild bats.
Ne gye buli eno, tewali kawuka ka MERS-CoV kalamu kasobola kusangibwa mu buwundo.
MERS-CoV and its closest relative bat CoV-HKU25 share only 87% nucleotide sequence homology.
MERS-CoV n’abooluganda lwe akawundo CoV-HKU25 bigabana ebitundu 87% byokka eby’endagabutonde.
Thus, bats might not be the immediate reservoir host of MERS-CoV.
Awo nno, obuwundo buyinza okuba nga si bwe bwekwatako akawuka ka-MERS-CoV amangu.
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 ludda olulala okunoonyereza okukoleddwa mu mawanga agagwa mu kitundu kya Middle East kulaze nti eŋŋamiya ziraga nti zirina MERS-CoV-mu basirikale abalwanyisa endwadde mu mubiri, era nga bwe kiri mu ŋŋamiya eziri mu mawanga ga Afrika ezaava mu mawanga ga Middle East.
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.
Obuwuka obulamu bu-MERS-CoV obufaanagana n’akawuka akasangibwa mu bantu obwayawulwa nga buva mu lunyira lw’eŋŋamiya, ne kyongera okulaga nti eŋŋamiya ze zikola ng’ekyekwatwako akawuuka ka-MERS-CoV.
It is also noteworthy that generally mild symptoms but massive virus shedding were observed in camels experimentally infected with MERS-CoV.
Kikulu nnyo nti obubonero obutonotono naye nga bweyolekeramu obuwuka buyitirivu bwalabibwa mu ŋŋamiya ezaalina 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.
Genderera, eŋŋamiya endwadde ziba n’obuwuka si miyitiro gy’omukka gyokka, ate ng’era gwe muyitiro omukulu ogw’akawuka mu buwundo.
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.
Wabula, ebibuuzo bikyaliwo kubanga abalwadde ba MERS abakakasiddwa tebalina be bakwatagana nabo mabega na ŋŋamiya ng’obubonero obuliwo tebunnalabika, obwandiba nga bukwanyizibwa na muntu-ku-muntu oba emiyitiro gy’okusaasaanya egitamanyiddwa omuli ebika by’ebisolo ebitamanyiddwa ebirimu MERS-CoV.
SARS-CoV-2 shares 96.2% nucleotide homology with a bat CoV RaTG13 isolated from Rhinolophus affinis bats.
SARS-CoV-2 egabana ebitundu by’endagabutonde 96.2% n’akawundo CoV RaTG13 akaayawulwa okuva mu buwundo buyitibwa Rhinolophus affinis bats.
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.
Era nga bwe kiri ku SARS-CoV ne MERS-CoV, enjawulo wakati wa SARS-CoV-2 ne RaTG13 ya maanyi nnyo mu ngeri nti kizibu okulengera oluganda oluli wakati w’obuwuka obwo.
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.
Kwe kugamba, obuwundo buyinza okuba nga si bwe bwekwatibwako amangu okubeerako akawuka ne busaasaanya SARS-CoV-2 okuggyako nga eyo gye bujja waliwo obuwundo bu-CoVs obubufaanana obuzuuliddwa.
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.
Mu ngeri y’okuteebereza, ekisolo ekibeerako akawuka ekitasaasaanya SARS-CoV-2 kirina okuba nga kimu ku bika ebyo ebibeera mu nsiko nga bitundibwa era ne bittibwa mu katale ka Huanan Seafood Wholesale Market, nga mu kusooka obulwadde bwa COVID-19 obwasooka kwe bwakwanyizibwa nga kirabika, waliwo okusaasaanyizibwa kw’obulwadde okuva ku nsolo-okudda-ku-muntu.
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.
Okunoonyereza okuwerako okukoleddwa emabegako awo nga kwesigamiziddwa ku ntereeza y’endagabutonde kulaze nti ekibinja ky’ensolo eziri mu katyabaga eziyitibwa pangolins (Manis javanica) zandiba nga nazo zirimu obuzadde obwekwanya ku beta-CoVs obufaananako ne SARS-CoV-2.
These novel pangolin CoV genomes share 85-92% nucleotide sequence homology with SARS-CoV-2.
Obusolo buno bu-Pangolin obutalabwangako obulimu endagabutonde ya CoV bugabana ebitundu 85-92% ne SARS-CoV-2.
However, they are equally closely related to RaTG13 with about 90% identity at the level of nucleotide sequence.
Wabula, bufaanaganira ddala ne RaTG13 n’ebitundu nga 90% ku ddaala ly’entereeza y’endagabutonde.
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.
Zeegabanyizzaamu ennyiriri 2 entonotono ez’obuwuka obulinga SARS-CoV-2 mu neeyoleka y’endabutonde ng’emu ku yo egabana obukole ne (RBD) SARS-CoV-2, ng’ebitundu 97.4% eby’ekirungo ky’endagabutonde bifaanagana.
In stark contrast, the RBDs of SARS-CoV-2 and RaTG13 are more divergent, albeit a higher degree of sequence homology genome-wide.
Mu ngeraageranya ey’enjawulo, obukole bwa RBDs obwa SARS-CoV-2 ne RaTG13 bweyawudde nnyo naye nga bweyawulidde mu busiŋŋanyi bwa ntereeza ya ndagabutonde.
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.
Okunoonyereza okwasooka ku pangolin ezaali endwadde nakwo kwalaga okukengebwa kw’obuwuka obwali mu sampolo z’amawuggwe obulina oluganda ne 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.
Okunoonyereza kuno kwakozesa obukodyo obw’enjawulo omuli n’obwokukyusiriza okufuna entereeza y’endagabutonde erimu ebitundu 86.3% eby’enfaanana y’akawuka.
We cannot exclude the possibility that pangolin is one of the intermediate animal hosts of SARS-CoV-2.
Tetusobola kuggyawo busobosi bwa kuba nti pangolin ke kamu ku busolo obubeerako akawuka obutasaasaanya 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.
Mu kiseera kino, tewali bubaka bukakasa buvo bwa SARS-CoV-2 owa pangolin olw’entereeza eyawukana wakati wa SARS-CoV-2 ne SARS-CoV-2 beta-CoVs owa pangolin .
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.
Mu ngeri y’emu, ebbanga wakati wa SARS-CoV-2 ne RaTG13 limpiko okusinga ku eryo eriri wakati wa SARS-CoV-2 ne SARS-CoV-2-related beta-CoVs owa pangolin .
The evolutionary pathway of SARS-CoV-2 in bats, pangolins and other mammals remains to be established.
Enfuukafuuka y’omuyitiro gwa SARS-CoV-2 mu buwundo, pangolin n’ensolo endala eziringa abantu tennaba kutegeerekeka.
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.
Weewaawo entereeza mu ndagabutonde ezuuliddwa wakati wa RBDs ne SARS-CoV-2 ne pangolin, obuwuka obwekwanya ku SARS-CoV-2 beta-CoVs, SARS-CoV-2 ne RaTG13 bugabana endagabutone eyaawamu.
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.
Kisuubirwa nti obufaanane obw’amaanyi wakati wa RBDs mu buwuka obwekwanya ku pangolin SARS-CoV-2 beta-CoVs ne SARS-CoV-2 bufugibwa enfuukafuuka eyeeyawudde.
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.
Ekiteeso ekirala ekyawukana ku ekyo kiwagira engattagatta wakati w’obuwuka bwa pangolin SARS-CoV-2 beta-CoV ne RaTG13 mu kika ky’ensolo ez’omu nsiko.
As a driving force in evolution, recombination is widespread among beta-CoVs.
Ng’amaanyi agasindiikiriza mu kufuukafuuka, okugattagatta kuli nnyo mu beta-CoVs.
The jury is still out on the immediate zoonotic origin of SARS-CoV-2.
Okusalawo tekunnatuukiibwako ku nsolo esibukako 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.
Ng’oggyeeko obuwuka obuleeta ennyo endwadde obwa HCoVs, ensibuko ya HCoV-229E, HCoV-OC43, HCoV-NL63 ne HCoV-HKU1 ey’omu nsolo nayo enoonyerezeddwako.
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.
Obuvo obukwata ku kunoonyereza ku nfuukafuuka y’ebitonde bulaga nti HCoV-NL63 ne HCoV-229E bwandiba nga bwava mu CoVs mu buwundo, ate nga muzadde w’akawuka ka HCoV-OC43 ne HCoV-HKU1 azuuliddwa mu mmese.
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.
Kitegeezeddwa nti CoV ey’akawundo eyitibwa ARCoV.2 (Appalachian Ridge CoV) kaakengebwa mu Amerika ey’obukiikakkono (North American) nga ka langi ssatu era nga kaalaga nti kalina oluganda olw’okumpi ne 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.
Mu ngeri endala, HCoV-229E yakwanyizibwa n’endagabutonde n’akawundo CoV, akayitibwa Hipposideros/GhanaKwam/19/2008, akaalangibwa e Ghana, ate nga n’eŋŋamiya nazo ziteeberezebwa okubeera ekibeerako akawuka ekitasaasaanya.
For clarity, the current knowledge on animal origins of known HCoVs is summarized in Figure ​1 and Table 2.
Olw’okutangaazamukko, amagezi agaliwo ku nsibuko y’ensolo ku HCoVs obumanyiddwa gafunziddwa mu Kifaananyi​ 1 n’Omweso 2.
Phylogenetic analysis has provided evidence for interspecies transmission events of HCoVs in the history.
Obwekenneenyi bw’enfuukafuuka buleese obubaka obulaga nti HCoVS busaasaana mu bika by’ensolo eby’enjuwulo nga bwe kiri mu byafaayo.
When HCoV-OC43 crossed species to infect humans from domestic livestock around 1890, a pandemic of respiratory infection was recorded.
HCoV-OC43 bwe kaabuka okuva mu kika ekimu ne kadda mu bantu okuva mu bisolo ebirundibwa ewaka eyo mu 1890, ekirwadde ekikwata omuyungo gw’okussa kyazuulibwa.
The interspecies transmission history of HCoV-229E is less clear.
Ebyafaayo by’okusaasaana kw’ebika eby’enjawulo ebya HCoV-229E tebitangaala bulungi.
Bat alpha-CoVs closely related to HCoV-229E have been found.
Obuwuka obuyitibwa bat alpha-CoVs obulina oluganda olw’amaanyi ne HCoV-229E buzuuliddwa.
Between them there is an alpaca alpha-CoV.
Wakati waabyo waliwo ekiyitibwa alpaca alpha-CoV.
Several lines of evidence support the transmission of virus from bats to humans directly.
Obubaka obw’enjawulo buwerako obuwagira okusaasaana kw’akawuka okuva mu buwundo okudda mu bantu obutereevu.
First, humans but not alpacas might have contact with bats in a shared ecological niche.
Okusooka, abantu naye nga si nsolo eyitibwa alpacas birina enkwatagana n’obuwundo mu kugabana ebifo mwe bibeera.
Instead, humans have close contact with alpacas.
Wabula, abantu balina enkwatagana ey’okumpi ne alpacas.
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.
Ekyokubiri, akawuka ka HCoV-229E-related bat alpha-CoVs kalimu enjawulo ate tekalwaza buwundo so ng’ate alpaca alpha-CoV kaaleeta ekirwadde mu muyungiro gw’okussa mu nsolo endwadde.
Finally, alpaca alpha-CoV has not been found in feral animals.
Ekisembayo, alpaca alpha-CoV tekazuuliddwa mu nsolo ezaava ewaka ne zidda mu nsiko.
Thus, the possibility cannot be excluded that alpacas obtain the HCoV-229E-related alpha-CoV from humans.
Awo nno, obusobozi tebuyinza kuggyibwawo nti alpacas zijja HCoV-229E-related alpha-CoV okuva mu bantu.
In fact, bats are the direct source of human pathogenic viruses including rabies virus, Ebola virus, Nipah virus and Hendra virus.
Mu butuufu, obuwundo y’ensibuko y’obuwuka obusaasaanya endwadde mu bantu omwo nga mwe muli n’akawuka rabies virus, Ebola virus, Nipah virus ne Hendra virus.
It is therefore not too surprising that bats might transmit HCoV-229E to humans directly.
Awo nno tekyewuunyisa nnyo nti obuwundo busobola okusaasaanya HCoV-229E obutereevu mu bantu.
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 ngeri endala, weewaawo bat alpha-CoVs bukola nga ensibuko y’endagabutonde eya HCoV-229E, alpacas n’eŋŋamiya (dromedary camels) ziyinza okukola ng’ekibeerako akawuka ekitasaasaanya ekitambuza obuwuka mu bantu nga bwe kiri ddala ku 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 kakola ng’ekyokulabirako ekirungi ddala eky’ensaasaanya okuva mu kika ekimu okudda mu kirala okuva mu buwundo okudda ku ŋŋamiya (dromedary camels) ate n’okuva mu ŋŋamiya (dromedary camels) okudda mu bantu.
The evolutionary origin of MERS-CoV from bats is known at its initial identification and has also been strengthened by subsequent findings.
Ensibuko y’okufuukafuuka kwa MERS-CoV okuva ku buwundo emanyibwa okuva ku ntandikwa eyasooka era okumanyibwa okwo ne kunywezebwa mu bizze nga bizuulibwa.
It is obvious that bats provide a rich pool of virus species for interspecies exchange of genetic fragments and interspecies transmission.
Kyoleka lwatu nti obuwundo bulina ebika by’obuwuka bingi ddala ebitambula mu bika eby’enjawulo ebyeyawulayawula mu bika eby’enjawulo ate ne busaasaana mu bika eby’enjawulo.
Longevity, densely packed colonies, close social interaction and strong ability to fly are all favourable conditions for bats to be an ideal 'virus spreader'.
Obuwangaazi, ebibinja by’obuwundo obungi, okukwatagana ennyo wamu n’obusobozi bw’okubuuka ennyo byonna bisobozesa obuwundo okubeera ‘ekisaasaanya akawuka’.
On the other hand, MERS-CoV has been introduced to dromedary camels for decades.
Ku ludda olulala, MERS-CoV kateekeddwa mu ŋŋamiya (dromedary camels) okumala ebbanga eriwera.
It is well adapted to these camels that have turned from an intermediate host to a stable and natural reservoir host.
Kabeera bulungi mu ŋŋamiya ezo ezaafuuka okuva ku kibeerako akawuka ekitasaasaanya okudda ku kitonde ekyekwatako akawuka.
MERS-CoV causes very mild disease and maintains a relatively low mutation rate in these animals.
MERS-CoV kaleeta obulwadde obutonotono era kazaalukuka kitono nga kali mu nsolo ezo.
Its sporadic transmission to humans is an accident and humans remain a dead-end host of MERS-CoV as its transmission cannot be sustained.
Okusaasaanya kwakwo okw’ebbalirirwe mu bantu kwa ngeri ya kabenje era abantu basigala nga beekwatako akawuka MERS-CoV ako naye ne katasaasaana kubanga okusaasaana kwako tekubeezekawo.
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.
Mu kugeraageranya omulimu gw’eŋŋamiya mu kusaasaanya MERS-CoV, omulimu gwa pangolins, bwe guba nga weeguli, mu kusaasaanya SARS-CoV-2 gwa njawulo.
Particularly, pangolin beta-CoVs are highly pathogenic in pangolins.
Okusinga ennyo, obuwuka bu-pangolin beta-CoVs buleeta nnyo endwadde mu pangolins.
They might be a dead-end host for SARS-CoV-2-related beta-CoVs, similar to civets in the case of SARS-CoV.
Buyinza okuba ekibeerako akawuka ekitasaasaanya SARS-CoV-2-related beta-CoVs, nga bwe kiri ku ffumbe ku 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.
Obusobozi bwa maanyi obw’okusaasaanya SARS-CoV-2 mu bika eby’enjawulo okuva ku nsolo okudda mu bantu obulina okukakasibwa oba okusazibwamu mu kunoonyereza okujja eyo mu maaso.
First, bats could be the reservoir host of a SARS-CoV-2-related virus almost identical to SARS-CoV-2.
Okusooka, obuwundo buyinza okuba ekyekwatwako ky’obuwuka obwekwanya ku SARS-CoV-2 nga kumpi bufaanagana ne SARS-CoV-2.
Humans might share the ecological niche with bats through butchering or coal mining.
Abantu bayinza okufaananya engeri gye bibeerawo mu ndya ne mu kusima.
Second, pangolins could be one of intermediate amplifying host to which a SARS-CoV-2-related virus had been newly introduced.
Ekyokubiri, pangolin zisobola okubeera ekibeerako akawuka ekisaasaanya obuwuka obwekwanya ku SARS-CoV-2 kwe bwakateekebwa.
Humans contract the virus through butchering and consumption of game meat.
Abantu bakwatibwa akawuka nga kayitira mu kutta n’okulya ennyama enjigge.
It is possible that many mammals including domestic animals are susceptible to SARS-CoV-2.
Kisoboka nti ensolo eziringa omuntu omwo nga mwe muli n’ezirundibwa ewaka zisobola okukwatibwa SARS-CoV-2.
A survey of domestic and wild animals for antibodies is warranted.
Okunoonyereza ku nsolo z’awaka n’ez’omu nsiko okuzuula abasirikale b’omubiri abazirimu kwetaagisa.
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.
Ekyokusatu, nga bwe kyogeddwako waggulu, okugattagatta endagabutonde n’okumanyiira kwa SARS-CoV-2 kuyinza okuba nga kwagwawo mu kika ekyokusatu ekikwatagana n’obuwundo ne pangolin.
The search for the animal origins of SARS-CoV-2 is still on.
Okunoonyereza ku nsibuko ya SARS-CoV-2 mu nsolo kukyagenda mu maaso.
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.
Ng’oggyeeko ebika by’ensolo ebyekwatwako obuwuka, ensonga enkulu ssatu ku ludda lw’obuwuka nazo nkulu mu kubeezaawo CoVs okusala ebiziyiza okubuuka okudda mu bika ebirala.
First of all, their relatively high mutation rates in RNA replication.
Ekisookera ddala, okuzaalukana kwabwo okulabika nga kuli waggulu ddala mu kuzaalukana kw’endagabutonde (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.
Mu kugeraageranya obuwuka obulala obukozesa endagabutonde (single-stranded RNA viruses), omuwendo gw’obuzaalukanyi bw’obuwuka guteeberezebwa okubeera wakati “w’omusaamusaamu” ne “ogwa waggulu” nga guliko omuwendo omukkati oguli wakati wa ~10-4 buli mwaka buli kifo 2, okusinziira ku mutendera gwa CoV ogw’okumanyiira n’ekyekwatako akawuka ekibadde tekimanyiddwa.
CoVs have a proof-reading exoribonuclease, deletion of which results in exceedingly high mutability and attenuation or even inviability.
Obuwuka bwa CoVs bumanyi okutebuka ekirungo ki exoribonuclease, era nga bwe kisangulwa kivaamu okufuukafuuka okw’amaanyi n’okukendeera oba oluusi n’obutasoboka.
Interestingly, the nucleotide analogue Remdesivir is known to suppress CoV replication through inhibition of this exoribonuclease and the RNA-dependent RNA polymerase.
Ekyewuunyisa, ekirungo nucleotide analogue Remdesivir kimanyiddwa ng’ekinyigiriza okuzaalukana kwa CoV nga kiyitira mu kuziyiza exoribonuclease n’endagabutonde (RNA) eyeesigamye ku RNA polymerase.
Remdesivir is one of most promising anti-SARS-CoV-2 agents to be tested in clinical trials.
Remdesivir kye kimu ku birungo ebirwanyisa SARS-CoV-2 ebigezesebwa mu kugezesa kw’ekisawo.
Nevertheless, mutation rates of CoVs are about a million times higher than those of their hosts.
Ebyo ng’obiggyeeko, ekigero ky’okufuukafuuka ekya CoVs kiri awo nga mu mirundi kakadde nga kiri waggulu w’ekyo eky’ekyekwatibwako akawuka.
In addition, mutation rate is often high when CoVs are not well adapted to the host.
Mu ngeri y’emu, ekigero ky’okufuukafuuka kitera okuba waggulu bu CoV bwe buba nga tebumanyidde kintu kwe bwekutte.
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.
Bw’ogeraageranya ne SARS-CoV akalina ekigero ky’okufuukafuuka ekya waggulu, ekigero ky’okufuukafuuka ekya SARS-CoV-2 kirabika nga kiri wansi, era ng’ekyo kiraga nti kati kagenze kamanyiirira ddala abantu.
Presumably, it has already been adapted to another host close to humans.
Kyandiba nga kaamala dda okumanyiira ekintu ekirala ekifaananako n’abantu.
In addition to SARS-CoV-2, this also applies to MERS-CoV, which is well adapted to dromedary camels.
Ng’oggyeeko SARS-CoV-2, kino kikola ne ku MERS-CoV, akaamanyiira edda eŋŋamiya.
Theoretically, it is unlikely that genetic drift would render vaccines and antivirals against SARS-CoV-2 ineffective quickly.
Mu kulowooza, kirabika nga enkyukakyuka mu ndagabutonde eyinza okuleetera eddagala erigema n’erirwanyisa obuwuka bwa SARS-CoV-2 obutakola mu bwangu.
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.
Ekyokubiri, ekirungo kya RNA genome ekinene mu CoVs kinyigiriza enfuula ya genome olw’enfuukafuuka n’engattagatta, olwo ne kyongera omukisa gw’ebika ebyenjawulo okubeerana mu nkula yaabyo, ekintu ekirungi mu kusibuka kw’akawuka ka CoV akatamanyiddwa embeera bw’eba ng’eganya.
This is supported by the copious unique open reading frames and protein functions encoded towards the 3′ end of the genome.
Kino kiwagirwa enkola ya copious unique open reading frames n’omugaso gwa puloteyini ebeera mu 3′ end eya genome.
Third, CoVs randomly and frequently switch templates during RNA replication through a unique “copy-choice” mechanism.
Ekyokusatu, CoVs butera ate mu ngeri ya kulabira awo okukyusa obutiba mu kiseera ky’okuzaalukana nga buyita mu nkola eya “koppa-kyolonzeeko”.
In a host that serves as the mixing vessel, strand switching occurs frequently during CoV RNA transcription.
Mu kibeerako akawuka ekikola ng’ekikompe ekitabula, enkyukakyuka ebaawo nnyo mu kiseera kya CoV RNA transcription.
Highly homologous full-length and subgenomic RNAs could recombine to generate new CoVs.
Endagabutonde (RNAs) ezifaanagana ennyo wamu ne subgenomic RNAs zisobola okwegattagatta okufunamu bu CoV obulala.
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.
Obubaka bw’enfuukafuuka y’obuwuka ey’okwegattagatta okw’obutonde erabiddwa mu HCoV-HKU1 ne mu HCoV-OC43, wamu ne CoV ow’ensolo gamba nga bat SL-CoV ne batCoV-HKU9.
Virus-host interaction in relation to transmission
Enkolagana y’akawuka n’ekibeerako akawuka mu nsaasaana y’obulwadde
Besides three viral factors stated above, viral interaction with host receptor is another key factor influential on interspecies transmission.
Ng’oggyeeko ensonga z’akawuka essatu ezoogeddwako waggulu, enkolagana y’akawuka n’ekibeerako akawuka nayo nsonga nkulu ekola mu nsaasaanya y’obulwadde mu bika eby’enjawulo.
Herein, recombination of SARS-CoV is taken as a typical example, which also showed evidence of positive selection during interspecies transmission events.
Mu kiwandiiko kino, okwegattagatta kwa SARS-CoV kutwalibwa ng’ekyokulabirako ekimanyiddwa ekyalaba n’obubaka mu kiseera ky’okusaasaanya obulwadde ekiyitibwa positive selection.
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.
Okusinziira ku kwekenneenya wakati w’ebyawuliddwa okwekalirizibwa eby’abantu n’eby’effumbe SARS-CoVs, SARS-CoV kalowoozebwa okufuna amangu okumanyiira ebibeerako obuwuka, naddala mu kufuukafuuka ku RDB mu S protein.
Generally, the RBD in the S protein of a CoV interacts with the cellular receptor and is intensely selected by the host antibody response.
Okutwaliza awamu, RBD mu S protein eya CoV ekolagana n’ekifuna obutaffaali era nga kirondebwa nnyo abasirikale b’omubiri mu kibeerako obuwuka.
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.
Mu SARS-CoV, RBD eri mu amino acid owa 318 okutuuka ku 510 ku S1 fragment, eyeekwata ku ACE2 mu bantu wamu n’ebyo ebifuna obuwuka okuyingirirako.
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 eya SARS-CoV esobola okukenga ebifuna obuwuka ACE2 mu nsolo ez’enjawulo, omuli akawundo, effumbe, emmese n’embwa (raccoon dog), ekkiriza okusaasaana kw’akawuka mu bika eby’enjawulo.
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.
Mu butuufu, ebisigalira bya amino acid 6 byalabibwa nga bya njawulo okuva ku ebyo ebyawulibwa mu bantu n’effumbe mu RBD ate nga 4 ku byo bisangibwa mu nfaanana y’ebifuna obuwuka olw’okukolagana n’ekifuna obuwuka ACE2.
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 ow’effumbe alimu okufuukafuuka kwa K479N ne S487T RBD we, ekiyinza okwongeza enkwatagana y’enkolagana ya spike protein ne ACE2 ey’ekifuna akwuka mu bantu.
In other words, these two amino acid substitutions might be critical to viral adaption to humans.
Kwe kugamba, ebika bya amino acid ebibiri ebisikira ebirala biyinza okuba nga bya maanyi nnyo mu kumanyiira kw’akawuka mu bantu.
It is noteworthy that SARS-CoV-2 shares the same cellular receptor with SARS-CoV.
Kikulu okumanya nti SARS-CoV-2 kagabana ekifuna obulwadde eky’obutaffaali obufaanagana ne 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.
Enjawulo ey’ebitundu 30% wakati wa SARS-CoV-2 ne SARS-CoV mu kigero ekya S1 ekya S protein kitegeeza nti y’enyweza oluganda eya S protein ne ACE2 mu bantu eyinza okuba nga yakyuka.
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 butuufu, okunoonyereza kwa cryo-EM kulaga 10- ku-20 kulimu oluganda lwa maanyi mu kunyweza kuno okusinga ACE2 mu bantu ne SARS-CoV S protein.
It will also be of interest to determine whether any other coreceptor might be required for SARS-CoV-2 transmission.
Kijja kuba kirungi era okulaba oba nga ekintu ekirala ekifuna obuwuka kiyinza okwetaagisa mu kusaasaanya SARS-CoV-2.
Intriguingly, HCoV-NL63 also binds to ACE2 but with a different part of S.
Mu ngeri eyeewuunyisa, HCoV-NL63 nakyo kinyweza ACE2 naye nga kikozesa akatundu ka S akalala.
There exist many other HCoV receptors, such as aminopeptidase N for HCoV-229E, and 9-O-acetylated sialic acid for HCoV-OC43.
Waliwo n’ebifuna HCoV ebirala bingi, gamba nga aminopeptidase N ku HCoV-229E, ne 9-O-acetylated sialic acid ku HCoV-OC43.
They might also account for successful adaptation of these CoVs in humans after interspecies transmission from their animal hosts.
Busobola era okunnyonnyola okumanyiira obulungi okw’obuwuka bwa CoV mu bantu oluvannyuma lw’okusaasaanira mu bika ebyenjawulo nga buva ku nsolo kwe bubeera.
In addition to cellular receptors, the outcome of interspecies transmission of HCoVs is also governed by other host dependency and restriction factors.
Ng’oggyeeko ebifuna obuwuka eby’obutaffaali, ekiva mu HCoV okusaanasaanira mu bika eby’enjawulo kifugibwa ensonga endala ezeesigama ku kibeerako obuwuka n’ebikugira.
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.
Enjawulo mu host proteins wakati w’abantu n’ebitonde ebisaasaanya HCoVs gamba ng’obuwundo, eŋŋamiya n’emmese ( rodents) biyinza okukola ng’omuziziko mu kusaasaanya obulwadde mu bika eby’enjawulo.
HCoVs have to usurp host dependency factors and subvert host restriction factors for a successful interspecies transmission.
HCoVs bunaayiza ekibeerako obuwuka era ne kyewala ebikugira by’ekibeerako obuwuka olw’okusaasaanya obulungi obulwadde mu bika eby’enjawulo.
In this regard, molecular determinants in this important area of virus-host interaction remain to be identified and characterized.
Mu ngeri eyo, ebisalawo ku molecule mu kitundu kino ekikulu eky’akawuka-ekibeerako obuwuka kikyetaaga okulengerwa n’okunnyonnyola.
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.
Okusunsula mu genome okw’awamu okutaliimu kyekubiira (genome-wide screening) okw’ekibeerako obuwuka n’ebikugira bya SARS-CoV-2 omuli okukozesa tekinologiya ow’ekika ekya waggulu kiyinza okuvaamu ebibala.
Emergence of novel HCoVs: back to ground zero
Okubalukawo kwa HCoVs abadde tamanyiddwa: okuddayo ku ntandikwa
The diversity of bat CoVs provides ample opportunities for the emergence of novel HCoVs.
Enjawulo mu CoVs ow’obuwundo aleetawo emikisa gya maanyi mu kubalukawo kwa HCoVs obubadde tebumanyiddwa.
In this sense, bat CoVs serve as the gene pool of HCoVs.
Mu ngeri eno, CoV ow’obuwundo bukolanga ng’ensibuko ya giini eza HCoVs.
In addition, rapid mutation and genetic recombination also drive HCoV evolution and serve as two important steps in this process.
Okwongereza ku ekyo, okufuukafuuka okw’amangu n’okwegattagatta kwa giini nabyo bifuga enkula ya HCoV era bikola ng’emitendera ebiri emikulu mu nkwajja eno.
For example, the acquisition or loss of novel protein-coding genes has the potential to drastically modify viral phenotypes.
Okugeza, okufuna oba okufiirwa entereeza ya giini za protein (protein-coding genes) okubadde kutamanyiddwa kulimu obusobozi bw’okukyusiza ddala enfaanana y’obuwuka.
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.
Mu SARS-CoV accessory proteins, ORF8 zirowoozebwa okubeera enkulu mu kumanyiira abantu, ng’obuwuka bwa SARS-CoV obwekwanya ku buwundo bwayawulibwa naye ate ne busangibwa nga bulina divergent ORF8 proteins.
A 29-nucleotide deletion characteristic of SARS-CoVs has been found in strains isolated at the beginning of the human epidemic.
Akabonero ka 29-nucleotide deletion aka SARS-CoVs kasangiddwa mu bwawuzi obwayawulibwa ku ntandikwa ya nawookeera w’ekirwadde kino mu bantu.
This deletion splits ORF8 into ORF8a and ORF8b and is thought to be an adaptive mutation that promotes the switch of hosts.
Okusangula kuno kwawulamu ORF8 mu ORF8a ne ORF8b era nga kirowoozebwa okubeera enfuukafuuka y’okumanyiira etumbula okukyusakyusa ekibeerako obuwuka.
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.
Ng’oggyeeko ekyo, SARS-CoV kalina ebyafaayo by’obusobozi bw’okwegattagatta mu nnyiriri za alpha- ne gamma-CoVs, omwalabibwa omuwendo gw’okwegattagatta mu nkula omutono mu RNA-dependent RNA polymerase.
Recombination locations were also identified in the nsp9, most of nsp10, and parts of nsp14.
Ebifo ebimu eby’okwegattagatta byalengerwa mu nsp9, ebisinga mu nsp10, n’ebitundu 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 ngeri y’emu, kiragiddwa nti nawookeera w’ekirwadde kya MERS-CoV yalimu okwegattagatta wakati w’ennyiriri ez’enjawulo, okwaliwo mu ŋŋamiya mu Saudi Arabia.
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.
Ng’oggyeeko SARS-CoV ne MERS-CoV, emirundi gy’okwegattagatta era girabiddwa mu HCoVs obulala, HCoVs mwe bwegattira ne CoVs ez’ensolo mu giini zaazo eziyitibwa non-structural genes.
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.
Kisaana era okulabula nti okulondoba okukolebwa abantu kusobola okuleetawo enkyukakyuka ezitalabiddwa mu viral genomes, ng’okusinga ennyo kiva ku kuwewula ku buwuka ku kunyigirizibwa kw’okulondoba, gamba ng’okwo okuva ku busibage bw’ekibeerako obuwuka.
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.
Ekyokulabirako ky’okukosebwa kuno kwe kufiirwa okw’amaanyi okwa ORF4 mu HCoV-229E prototype strain, nga kiva ku kusangula kwa nucleotide kwa mirundi ebiri.
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.
Weewaawo nga ORF4 atafuusefuuse asobola okulabibwa mu buwuka bw’obuwundo ne mu ŋŋamiya obwekwanya ku HCoV-229E, alpaca alpha-CoV kooleka okusonsekebwa kwa nucleotide, okuva ku frameshift.
Last but not least, the evolution of novel HCoVs is also driven by the selection pressure in their reservoir hosts.
Ekisembayo naye nga si kye kisemberayo ddala, okukula kwa HCoVs akabadde tekamanyiddwa era kufugibwa okusindiikirizibwa kw’okulonda mu kibeerako obuwuka.
Asymptomatic or only mild symptoms were detected when bats were infected with CoVs, indicating the mutual adaptation between CoVs and bats.
Obutalaga bubonero oba obubonero obutono bwalabibwa ng’obuwundo bulwadde CoVs, nga kiraga okumanyiira okw’awamu wakati wa CoVs n’obuwundo.
It appeared that bats are well adapted to CoVs anatomically and physiologically.
Kyalabika nti obuwundo bwamanyidde bulungi CoVs mu nkula yaabwo (anatomically) ate ne mu mbeera z’obulamu obwa bulijjo.
For example, defects in the activation of pro-inflammatory response in bats efficiently reduce the pathology triggered by CoVs.
Okugeza, obunafu mu kuzimba okujjawo mu buwundo bukendeeza embeera etali ya bulijjo ereetebwa CoVs.