코로나바이러스의 종류와 모양

The two novel strains B814 and 229E were subsequently imaged by electron microscopy in 1967 by Scottish virologist June Almeida at St. Thomas Hospital in London. Almeida through electron microscopy was able to show that B814 and 229E were morphologically related by their distinctive club-like spikes. Not only were they related with each other, but they were morphologically related to infectious bronchitis virus (IBV). A research group at the National Institute of Health the same year was able to isolate another member of this new group of viruses using organ culture and named the virus strain OC43 (OC for organ culture). Like B814, 229E, and IBV, the novel cold virus OC43 had distinctive club-like spikes when observed with the electron microscope.

B814와 229E는 1967년 런던에 있는 토마스 병원의 스코틀랜드 바이러스학자 준 알메이다에 의해 전자현미경으로 촬영되었다. 전자현미경을 통하여 알메이다는 B814와 229E가 독특한 클럽과 같은 스파이크에 의해 형태학적으로 연관되어 있다는 것을 보여줄 수 있었다. 그들은 서로 연관되었을 뿐만 아니라, 형태학적으로 전염성 기관지염 바이러스(IBV)와 연관되어 있었다. 같은 해 국립보건원의 연구회는 장기 배양법을 사용하여 이 새로운 바이러스 그룹의 다른 구성원을 격리시킬 수 있었고, 바이러스 변종 OC43(장기 배양용 OC)이라고 명명했다. B814, 229E, IBV와 마찬가지로, 새로운 감기 바이러스 OC43은 전자현미경으로 관찰했을 때 독특한 클럽 같은 스파이크를 가지고 있었다.

 

 

The IBV-like novel cold viruses were soon shown to be also morphologically related to the mouse hepatitis virus. This new group of IBV-like viruses came to be known as coronaviruses after their distinctive morphological appearance. Human coronavirus 229E and human coronavirus OC43 continued to be studied in subsequent decades. The coronavirus strain B814 was lost. It is not known which present human coronavirus it was. Other human coronaviruses have since been identified, including SARS-CoV in 2003, HCoV NL63 in 2004, HCoV HKU1 in 2005, MERS-CoV in 2012, and SARS-CoV-2 in 2019.

There have also been a large number of animal coronaviruses identified since the 1960s.

IBV와 같은 새로운 감기 바이러스는 곧 쥐 간염 바이러스와도 형태학적으로 관련이 있는 것으로 나타났다. IBV와 유사한 이 새로운 바이러스의 그룹은 독특한 형태학적 외관 후에 코로나바이러스라고 알려지게 되었다. 인간 코로나바이러스 229E와 인간 코로나바이러스 OC43은 이후 수십 년 동안 계속 연구되었다. 코로나바이러스 변종 B814는 사라졌다. 그것이 지금의 어떤 인간 코로나바이러스였는지는 알려지지 않았다. 그 후 2003년 사스-CoV, 2004년 HCoV NL63, 2005년 HCoV HKU1, 2012년 메르스-CoV, 2019년 SARS-CoV-2 등 다른 인간 코로나바이러스가 확인되었다.

1960년대 이후 확인된 동물 코로나바이러스도 다수 발견되었다.

* 개·돼지·소·조류 등이 코로나바이러스에 감염되는데 SARS를 일으키는 SARS-CoV의 경우 사람에서 원숭이, 개, 고양이 등 다른 포유류에게도 전염될 수 있다.

* MERS를 일으키는 MERS-CoV의 경우, 사우디아라비아 내 단봉낙타 접촉에 의해 사람이 감염된 사례가 보고된 바 있다. 

 

■ Cross-sectional model of a coronavirus

Coronaviruses are large, roughly spherical, particles with bulbous surface projections. The average diameter of the virus particles is around 125 nm (.125 μm). The envelope of the virus in electron micrographs appears as a distinct pair of electron-dense shells (shells that are relatively opaque to the electron beam used to scan the virus particle).

코로나바이러스 단면 모형

코로나바이러스는 크고 대략 구면이며, 전구 표면 돌출부가 있는 입자들이다. 바이러스 입자의 평균 지름은 약 125nm(.125μm)이다. 전자 마이크로그래프에서 바이러스의 외피는 독특한 전자-감지 껍질 쌍(바이러스 입자를 스캔하는 데 사용되는 전자빔에 상대적으로 불투명한 껍질)으로 나타난다.

* 1μm= 0.001mm, 머리카락이 70μm(0.07mm)이고 미세먼지가 10μm(0.01mm) 이하, 초미세먼지가 2.5μm(0.025mm)이나까 코로나바이러스가 얼마나 작은지 짐작할 수 있다. 

 

The viral envelope consists of a lipid bilayer, in which the membrane (M), envelope (E) and spike (S) structural proteins are anchored. The ratio of E:S:M in the lipid bilayer is approximately 1:20:300. On average a coronavirus particle has 74 surface spikes. A subset of coronaviruses (specifically the members of betacoronavirus subgroup A) also have a shorter spike-like surface protein called hemagglutinin esterase (HE).

바이러스 외피는 지질 빌레이어로 구성되는데, 이 안에 막(M), 외피(E), 돌기(S) 구조 단백질이 붙어 있다. 지질 빌레이어 속의 E:S:M의 비율은 대략 1:20:300이다. 평균적으로 코로나바이러스 입자는 표면 스파이크를 74개 가지고 있다. 코로나바이러스(특히 베타코로나바이러스 부분군 A의 구성원)의 부분집합도 헤마글루틴 에스테라아제(HE)라고 하는 돌기 형태의 표면 단백질이 더 짧다.

 

The coronavirus surface spikes are homotrimers of the S protein, which is composed of an S1 and S2 subunit. The homotrimeric S protein is a class I fusion protein which mediates the receptor binding and membrane fusion between the virus and host cell. The S1 subunit forms the head of the spike and has the receptor binding domain (RBD). The S2 subunit forms the stem which anchors the spike in the viral envelope and on protease activation enables fusion. The E and M protein are important in forming the viral envelope and maintaining its structural shape.

코로나바이러스 표면 돌기는 S1과 S2 서브 유닛으로 구성된 S 단백질의 호모트리머다. 호모트리메릭 S단백질은 바이러스 및 숙주세포 사이의 수용체 결합과 막융합을 매개하는 I급 융합 단백질이다. S1 서브유닛은 돌기 머리를 형성하고 수용체 결합 영역(RBD)을 가지고 있다. S2 서브유닛은 바이러스성 외피의 돌기를 고정시키고 단백질 분해효소 활성화를 통해 융합을 가능하게 하는 스템을 형성한다. E와 M 단백질은 바이러스성 외피를 형성하고 구조적인 형태를 유지하는 데 중요하다.

 

 

Inside the envelope, there is the nucleocapsid, which is formed from multiple copies of the nucleocapsid (N) protein, which are bound to the positive-sense single-stranded RNA genome in a continuous beads-on-a-string type conformation. The lipid bilayer envelope, membrane proteins, and nucleocapsid protect the virus when it is outside the host cell. 

외피 안에는 뉴클레오캡시드가 있는데, 그것은 뉴클레오캡시드(N) 단백질의 여러 복사본으로 형성되어 있으며, 이는 염주알을 연속적으로 꿴 줄 모양의 구조로 양성 단일 가닥 RNA 게놈에 결합되어 있다. 지질빌라이어 외투, 막 단백질, 핵캡시드는 숙주세포 외부에 있을 때 바이러스를 보호한다. 

 

■ Schematic representation of the genome organization and functional domains of S protein for SARS-CoV and MERS-CoV

Coronaviruses contain a positive-sense, single-stranded RNA genome. The genome size for coronaviruses ranges from 26.4 to 31.7 kilobases. The genome size is one of the largest among RNA viruses. The genome has a 5′ methylated cap and a 3′ polyadenylated tail.

SARS-CoV 및 메르스-CoV용 S단백질의 게놈조직과 기능영역의 도식적 표현
코로나바이러스는 양성 단일 가닥 RNA 게놈을 포함하고 있다. 코로나바이러스의 게놈 크기는 26.4~31.7킬로바이트에 이른다. 게놈 크기는 RNA 바이러스 중 가장 큰 것 중 하나이다. 게놈은 5인치 메틸화 캡과 3인치 폴리아데닐화 꼬리를 가지고 있다.

The genome organization for a coronavirus is 5′-leader-UTR-replicase (ORF1ab)-spike (S)-envelope (E)-membrane (M)-nucleocapsid (N)-3′UTR-poly (A) tail. The open reading frames 1a and 1b, which occupy the first two-thirds of the genome, encode the replicase polyprotein (pp1ab). The replicase polyprotein self cleaves to form 16 nonstructural proteins (nsp1–nsp16).

The later reading frames encode the four major structural proteins: spike, envelope, membrane, and nucleocapsid. Interspersed between these reading frames are the reading frames for the accessory proteins. The number of accessory proteins and their function is unique depending on the specific coronavirus.

코로나바이러스 유전체 조직은 5 organization리더-UTR-replicase(ORF1ab)-spike(S)-envelope(E)-메브레인(M)-뉴클레오캡시드(N)-3utUTR-폴리(A) 꼬리다. 게놈의 처음 3분의 2를 차지하는 개방형 판독 프레임 1a와 1b는 복제효소 다단백질(pp1ab)을 인코딩한다. 복제효소 다단백질 자가 분해되어 16개의 비구조적 단백질(nsp1–nsp16)을 형성한다.
이후 판독 프레임은 스파이크, 외피, 막, 핵캡시드의 4대 구조 단백질을 암호화한다. 이 판독 프레임 사이에 있는 것은 부속 단백질의 판독 프레임이다. 부속 단백질의 수와 그 기능은 특정 코로나 바이러스에 따라 독특하다.

 

 

* 사진 및 내용 출처: 위기피디어, 네이버 백과