A brief article on viruses for my friends.
A mystery called Virus.
A virus is a small parasite that is incapable of reprodution by itself. It is on the cusp of living cells and nonIiving matter. It does not merit to be called a cell. It is just naked genetic material barely covered by a capsule. The virus therefore must necessarily piggyback (infect) a susceptible cell-(host) and hijack the host cell machinery to produce more viruses.
The most essential point to keep in mind is that the Virus inhabits and resides inside the host cell. This is why, there are no known drugs that directly kill the virus like anti biotics kill the bacteria, which remains outside the cell. Anti- viral drugs can at best arrest the multiplication of the virus.
The virus is actually just a particle. In singular form, it's referred to as a virion, and is made up of a nucleic acid and an outer shell of protein. A very elementary form of life. The simplest virus has just enough RNA or DNA to encode four proteins. The most complex can encode 100 – 200 proteins.
The Virus has mainly 3 protein products
1) special enzymes needed for viral replication
2) inhibitory factors that stop host-cell DNA, RNA, and protein synthesis
3) structural proteins used in the construction of new virions.
Infection typically causes attachement to host cell, penetration of the host cell, replication, and finally release of the newly produced round of viral particles and death of the host cell. The host cell is used to produce hundreds to thousands of new virions. Once this has been done, the infected host cells rupture.
There are mainly 2 types of viruses-
DNA and RNA. DNA viruses are double-stranded whereas RNA viruses are single-stranded.
Once the virus is injected into the host cell, it targets and enters the nucleus. The viral DNA thereafter integrates with the host cell's genome (The genetic code) . It then hijacks the host cell's enzymes to replicate the virus.
DNA viruses like the poxvirus are packaged with their own machinery so they can replicate in the host cytoplasm without the need to use host Nuclear DNA.
RNA viruses infect cells by injecting RNA into the cytoplasm of the host cells to transcribe and replicate viral proteins. RNA viruses also include a sub category of retroviruses which use a special enzyme- reverse transcriptase to create DNA from RNA templates. This new tailor made DNA can be incorporated into the host genome so that subsequent cell division by the cell produces cells with the viral DNA.
As a doctor, its really very fascinating to note, that the virus is such a primitive form of life. Just a strand of DNA or RNA. The ability of this primitive particle of Life to modify the DNA of the host cell is put to good use in Genetic Engineering. It is used as a vector to effect specific deletion or insertion of chromosomes.
What really intrigues is the intelligence, that even this single stand of protein sequence possesses. This tiny particle of RNA ( Corona virus is an RNA virus)is holding the human race to ransom, can destroy global economy, and really unleash a wave of destruction. This is akin to a nuclear Holocaust. Just that nuclear refers to this microscopic strand of proteins causing a nuclear explosion at the cellular level.
In some ways, I believe it is nature's way of asserting it's supremacy and bringing mankind's ego on its knees. Mankind will have to combat an enemy at the cellular level, an unprecedented war where there will be no winners. Only survivors.
Dr. Deepak Ranade
A mystery called Virus.
A virus is a small parasite that is incapable of reprodution by itself. It is on the cusp of living cells and nonIiving matter. It does not merit to be called a cell. It is just naked genetic material barely covered by a capsule. The virus therefore must necessarily piggyback (infect) a susceptible cell-(host) and hijack the host cell machinery to produce more viruses.
The most essential point to keep in mind is that the Virus inhabits and resides inside the host cell. This is why, there are no known drugs that directly kill the virus like anti biotics kill the bacteria, which remains outside the cell. Anti- viral drugs can at best arrest the multiplication of the virus.
The virus is actually just a particle. In singular form, it's referred to as a virion, and is made up of a nucleic acid and an outer shell of protein. A very elementary form of life. The simplest virus has just enough RNA or DNA to encode four proteins. The most complex can encode 100 – 200 proteins.
The Virus has mainly 3 protein products
1) special enzymes needed for viral replication
2) inhibitory factors that stop host-cell DNA, RNA, and protein synthesis
3) structural proteins used in the construction of new virions.
Infection typically causes attachement to host cell, penetration of the host cell, replication, and finally release of the newly produced round of viral particles and death of the host cell. The host cell is used to produce hundreds to thousands of new virions. Once this has been done, the infected host cells rupture.
There are mainly 2 types of viruses-
DNA and RNA. DNA viruses are double-stranded whereas RNA viruses are single-stranded.
Once the virus is injected into the host cell, it targets and enters the nucleus. The viral DNA thereafter integrates with the host cell's genome (The genetic code) . It then hijacks the host cell's enzymes to replicate the virus.
DNA viruses like the poxvirus are packaged with their own machinery so they can replicate in the host cytoplasm without the need to use host Nuclear DNA.
RNA viruses infect cells by injecting RNA into the cytoplasm of the host cells to transcribe and replicate viral proteins. RNA viruses also include a sub category of retroviruses which use a special enzyme- reverse transcriptase to create DNA from RNA templates. This new tailor made DNA can be incorporated into the host genome so that subsequent cell division by the cell produces cells with the viral DNA.
As a doctor, its really very fascinating to note, that the virus is such a primitive form of life. Just a strand of DNA or RNA. The ability of this primitive particle of Life to modify the DNA of the host cell is put to good use in Genetic Engineering. It is used as a vector to effect specific deletion or insertion of chromosomes.
What really intrigues is the intelligence, that even this single stand of protein sequence possesses. This tiny particle of RNA ( Corona virus is an RNA virus)is holding the human race to ransom, can destroy global economy, and really unleash a wave of destruction. This is akin to a nuclear Holocaust. Just that nuclear refers to this microscopic strand of proteins causing a nuclear explosion at the cellular level.
In some ways, I believe it is nature's way of asserting it's supremacy and bringing mankind's ego on its knees. Mankind will have to combat an enemy at the cellular level, an unprecedented war where there will be no winners. Only survivors.
Dr. Deepak Ranade
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