HOW COVID-19 VIRUSES HIGHJACK HOST CELL MACHINERY-MOLECULAR BIOLOGY-3

 DESTRUCTION OF HUMAN CELLS BY VIRUSES

Fig-1

The viral highjacking of the human cell machinery after invasion involves many complex processes carried on by a combination of a number of viral as well as host cell proteins.

The virus that attached to the outer surface of the host cell membrane surfs on it to find a way in. Once when it gets attached to a suitable receptor,

it enters the cell either by cell fusion, endocytosis, or direct injection methods.

In figure -1 above the fusion, the method is shown.

Usually, the COVID-19 virus enters the cell after when it gets attached to the ACE-2 receptor on the cell surface, by using its S2 spike protein cell fusion machinery. (Fig-1-1,2 and 3)

After entry, the viral envelope, and capsid disintegrate to release the viral genome in the cytoplasm of the host cell. The coronavirus genome contains a positive RNA encoded with its RNA dependent RNA Polymerase enzyme (RdRP).

The RdRP is activated as soon as the viral genome is freed in the host cell cytosol (cytoplasm)(Fig-1-4).

There are many RdRPs (RNA dependent RNA Polymerase enzyme) encoded in the viral RNA.

They transcribe the viral RNA template so rapidly with the formation of numerous mRNAs out of which some of them are erratic. The erratic mRNAs are either corrected or destroyed. (Fig-1-5 and 6)

Fig-1-7

The viral mRNA translation also occurs rapidly and simultaneously along with the transcription. Numerous numbers of mRNAs formed by transcriptions and are translated by highjacking the host cell tRNAs, amino acids, and the ribosomes available freely in the host cell cytosol as well as in the host cell endoplasmic reticulum. By the way, the host cell nucleus apparatus is totally inhibited. (Fig-1-7)

Fig-1-8 & 9

Numerous viral proteins are thus synthesized by using host cell machinery and the virions thus formed get their capsids and envelopes from the host cell cytoplasmic vacuoles and are assembled together to exit out. By the way, the host nucleus and nucleolus are totally disintegrated and destroyed. (Fig-1-8 & 9)

Fig-1-10

After the nucleus, the main hub of the cell has been dismembered the viral proteins easily disintegrate and break the cell wall and exit out to invade other healthy cells.

SUMMARY:-

Wherever ACE-2 receptors are highly concentrated in our body it is very convenient for the COVID-19 virus to infect there.

e.g- Lower Respiratory System, Cardiovascular System, Brain, and Central Nervous System, Liver, and Kidneys.