During the begi看家nning of this year, a novel coron好務avirus disease — terme歌司d Covid-19 by the WHO — was ident媽上ified as being responsible for道不 a sudden increase in ca和裡ses of pneumonia in hospitalized pat家黑ients. We have seen this ra麗水pidly escalate int睡車o a global crisis with this new coron務白avirus named severe acute respi們還ratory syndrome coronavirus 2 or SA區日RS-CoV-2. As of Feb錢喝ruary 25, 2020, a total of 81,銀工109 laboratory-confirmed cases ha車有d been documented globall美吧y (1). A recent paper in the New Engl他個and Medical Journal describes how S學影ARS-CoV-2 was initially identified a慢這nd characterized (2). &藍請nbsp;
Coronaviruses are positiv林樹e-sense single-s子就tranded RNA viruses ((+)ssRNA viru能輛s), meaning the vir他兒al RNA genome can se林廠rve as messenger RNA (mRNA) and ca開下n be directly translated into pro高草tein in the host cell. Other examples o窗校f (+)ssRNA viruses include hepatitis視靜 C virus, West Nile virus, dengue virus得視, rhinoviruses that cause the commo對說n cold as well as SARS 話習(Severe acute respirator地月y syndrome) and MERS (Middle East 很秒respiratory syndrome) (3醫呢-5). While SARS-CoV and MERS-CoV can ca場亮use fatality, the other 4 known coron光錢aviruses — 229E, O低就C43, NL64 and HKU1 — ty女開pically manifest a些間s a common cold (6). However, given the放冷 prevalence of coron樹能aviruses and their ability 道都to undergo genetic recombination 什喝combined with ever從長 increasing human-animal i快高nteraction, zoonosis is likely t道如o occur from tim月音e to time as we have witnessed and are畫不 witnessing now.
A link between seafood and animal whole我來sale markets in Wuhan火人, China, alerted the Chinese Center答船 for Disease Contr高作ol and Prevention (China C這花DC) to a potential 上計outbreak, and they rapidly implemented 場理an investigation to identify the sour動多ce. Following isolation o體外f virus from supernatants of lung sam河女ples and infection of 劇明cultured human airway epithelial ce到來lls as well as per影著missive Vero E6 and Huh-7 cell li銀厭nes, cytopathic effects wer拍愛e observed. RT-PCR confirmed the區書 presence of viral nucle錯和ic acid in the super化作natant. Electron 有森micrography (EM) of negative-stain對山ed virus revealed 得信spherical particles varyin電雪g in diameter (60 to 140 nm近訊) with distinctiv志外e spikes. This and the presenc外多e of virus particles engu身如lfed in cytoplasmic membranes, is c花弟onsistent with the morphology of the C輛房oronaviridae family, which inclu知村des coronavirus.
Respiratory tract samples from p哥小atients, analysed by PC聽匠R, tested negative for 22 kno務報wn pathogens in了對cluding members of t工新he coronavirus family弟你. In order to identify the pat頻新hogen, a combination of Illumina很愛 and nanopore sequencing together with影門 5’ and 3’ RACE (rap水事id amplification of cDNA ends) wa放我s employed usin城生g RNA from lung samples as a template計爸 for cloning and contig assembly. Multi機老ple-sequence alignment an術飛d phylogenetic analysis revealed an 85%們員 identity to the genome from line算場age B of the genus be票腦tacoronavirus (β-CoV);做長 namely a bat SARS-l去雪ike CoV (bat-SL-Co生大VZC45, MG772933.1). Additional通光 confirmation that the pathog笑短en was an RNA-virus was obtained by數謝 RT-PCR targeting a the Rd舊好Rp sequence common to β-CoV. 玩上However, while the 車來genome contained typical 你子β-CoV sequences including明什 5’UTR, replicase complex, (orf1ab火城), S gene, E gene, M g化玩ene, N gene and 3′ UTR, several uni對說dentified open reading frames we費照re evident. The 人睡virus was named SARS-吃報CoV-2 and confirmed as a novel β-C購分oV belonging to the sarbecovirus 很河subgenus of Coronaviridae famil子呢y.
In summary, through the use of s但得everal molecular bio購商logy techniques and unbiased DNA se木刀quencing, the above describ看村es the initial sampling and sub風錢sequent identification of the novel b女睡etacoronavirus — S慢通ARS-CoV-2. While th慢志e outcome of Covid-19 is curre河理ntly unclear, a不相 rapid approach as taken here 機哥to identify the patho音去gen is essential when responding t老跳o new infectious disease outbre樂放aks and ultimately impr器市oves our chances of preventing a pan影坐demic and developing a兒通n effective vaccine.
VectorBuilder is carefully following慢生 the Covid-19 situation. To date, we了中 are pleased to say that we have no歌嗎t experiecned any major delays i低船n production and h森家ope for a speed有店y end to this u你車nfortunate crisis.
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