Question

Describe the structure of the COVID-19 virus

Answer 1

Coronavirus belongs to a large family of viruses that are known to cause two major outbreaks in the past; MERS and SARS.COVID 19 is an example of SARS that has created pandemic and are thought to be transmitted in humans via it's two hosts Bats and Pangolins.COVID 19 refers to Corona virus infectious disease 2019.

Coronavirus is spherical in shape and derives it's name due to the presence of spike like structures on it's outer surface;corona is the latin term for crown.There are four main structural proteins namely Spike,Membrane,Envelope and Nucleocapsid protein.All of these are encided within the 3'end of the viral genome.

SPIKE PROTEIN The S protein is around 150kDa and mediates it's attachment to the host receptor.It has receptor binding domain ANGIOTENSIN CONVERTING ENZYME RECEPTOR 2 which is responsible for the virus's binding to heart,kidney lungs and intestines.Spike proteins on cleavege with protease shows two functional subunits.

1) S1- mediates binding to host cells.

2) S2- Forms Stalk of the spike and mediates fusion of the stalk with viral cellular membrane.

MEMBRANE PROTEINS The M protein is around 30kDa and has three transmembrane domain.It the central organiser of the viral assembly and it's responsible for giving the virus it's shape.

ENVELOPE PROTEIN It is the smallest protein with of weight of around 8-12 kDa.Within the cell it is commonly present in intracellular trafficking mainly in Endoplasmic reticulum and Golgi body.The E protein has ion channel activity.Viral envelope is derived from host cell membrane and is made up of fatty acids.Underneath this envelope is the capsid.

NUCLEOCAPSID PROTEIN The N protein is the only protein present in nucleocapsid.It is a multifunctional protein and has two domains N terminal domain and C terminal domain.The N protein mainly participates in overtaking host immune machinery and creating new virus particle.