CORONOVIRUS-COVID-19
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| Fig-1 The COVID-19 |
The Coronavirus now named by the WHO as COVID-19 belongs to the main family Coronaviridae.
The gene of the Coronavirus is composed of Ribonucleic Acid(RNA) moiety
Usually, viruses have a head and a tail with crown-like spikes resembling a spider at the base plate of the tail(See the structure in the Side Bar)
But coronaviruses are rounded in shape and the spikes are fixed on them like ornaments on a crown hence the name corona. (See Fig-1)
Coronaviruses of type 229E and OC43 are very mild in nature to cause common cold and cough symptoms which may last for a week to 15 days and disappear. They also help the host to strengthen their immune system by stimulating the body to produce more antibodies without much harm. Regular use of citrus fruits and vitamin C can cure these viruses.
The typical coronavirus now called COVID-19 is believed to be originated from the Horse Shoe bats in the Wuhan seafood market at the central Hubei province of China.
In the year 2002, an epidemic was spotted in China with severe respiratory depressions. It was named as SARS-CoV. (SARS-Severe and Acute Respiratory Syndrome). This virus also has the structure of the Coronaviridae Family
An infection was spotted in Saudi Arabia in 2012 known as Camel Fever which claimed around 800 lives. It was named MERS-CoV. The structure of the MERS-CoV virus is also very similar to the SARS-CoV and the novel 2019-NCoV(now named COVID-19).
But coronaviruses are rounded in shape and the spikes are fixed on them like ornaments on a crown hence the name corona. (See Fig-1)
Coronaviruses of type 229E and OC43 are very mild in nature to cause common cold and cough symptoms which may last for a week to 15 days and disappear. They also help the host to strengthen their immune system by stimulating the body to produce more antibodies without much harm. Regular use of citrus fruits and vitamin C can cure these viruses.
The typical coronavirus now called COVID-19 is believed to be originated from the Horse Shoe bats in the Wuhan seafood market at the central Hubei province of China.
In the year 2002, an epidemic was spotted in China with severe respiratory depressions. It was named as SARS-CoV. (SARS-Severe and Acute Respiratory Syndrome). This virus also has the structure of the Coronaviridae Family
An infection was spotted in Saudi Arabia in 2012 known as Camel Fever which claimed around 800 lives. It was named MERS-CoV. The structure of the MERS-CoV virus is also very similar to the SARS-CoV and the novel 2019-NCoV(now named COVID-19).
Now China has officially given a name to the syndrome produced by the virus 2019-nCoV (and now COVID-19) as Novel Corona Virus Pneumonia (NCVP).
The NCVP infection has the epicenter in the city of Wuhan, the capital of the central Chinese province of Hubei.
The virus started its first infection in December 31,2019 in Wuhan, in China. A patient who was working as a seller in the market came to the hospital with a fever.
Once he experienced breathing difficulties, he was admitted to the hospital and subjected to various diagnostic procedures.
The morphology of these viruses is different from other viruses. They have a circular global body with spikes attached to their surface (See Fig-1). They look like a crown and hence the name Coronaviridae.
TYPES OF CORONAVIRIDAE
The coronavirus family (Coronaviridae) can be classified as follows(See the above Fig.2)
Viruses are generally either RNA or DNA in type.DNA viruses are more comforted inside the host cell as they can utilize the host genome for their replication. But RNA virus has no other choice unless to produce its own mRNA to replicate as the host cell mRNA cannot transcript the viral RNA to replicate. All Coronaviridae have belonged to RNA viruses.
1. Alphacoronovirus:
In this class, there are three subtypes as
a)Humancoronovirus or HCoV-NL63.:-Which contains several strains and some of them(HCoV-229E) cause common cold symptoms only.
b)Porcine Transmissible Gastroenteritis Coronavirus (TGEV/PEDV). These viruses infect mostly pigs and cause them severe GI distress and diarrhea.
c)Porcine Respiratory Corona(PRCV)which also affects pigs and spread to others.
2. Betacoronavirus:-
In this class there 4 strains have been discovered:-
a)SARS CoV-In 2002 in Guangdong province of southern China Severe Acute Respiratory Symptoms attacked human beings with serious symptoms. It was found out that civets and cats are the culprits for this outbreak. It claimed around 800 lives. But now medicines and vaccines are available for these infections.
b)MERS CoV/HKU4-CoV:-In 2012 Saudi Arabia got respiratory viral infections claimed around 700 lives. They discovered the virus is spread from infected camels. They named it MERS CoV.
HKU4 CoV: Very similar to MERS Co V with little difference in receptor binding. Both use the Dipeptidyl peptidase (DPP4) receptor on the human cell for entry but MERS binds with greater affinity than HKU4 Co V. Both viruses can affect bat cells without but to affect the human cell HKU4 virus needs a mediator whereas the MERS CoV does not need any mediator. The mediators are usually a protease (An enzyme that can dissolve the cell protein)
Both viruses are later discovered that they originated from bats.
HKU4 virus causes lesser casualties than MERS CoV because of their functional difference in receptor affinities as described above.
c)Mouse Hepatitis Corona -(MH CoV) This is also similar to the MERS CoV that originated from the mouse. Bovine Corona-B CoV/Human Corona-OC43
Bovine Coronaviruses cause infections mainly in cattle. It causes diarrhea and dysentery mostly in calves.
OC43 coronavirus is causing the common cold in human beings.
3-Gammacoronaviruses:-In this class there is one virus known as Avian Infectious Bronchitis Virus AIBV.
This virus is infecting mostly chickens and causing respiratory distress, damages to the gut, kidney, and reproductive system in chickens. This causes heavy losses in the poultry industry as mostly egg-producing chickens are very easily infected by this virus.
4.Porcine DeltacoronavirusPDCoV
These viruses were first spotted in the Henan province of China in 2017 in two swine farms and affected different ages of pigs with diarrhea. Later they transmitted to the poultry farm.
Many coronaviruses that cause common cold to pneumonia are mostly targeting the respiratory system. They have differences in receptor affinity.
There are two common receptors are on the respiratory tract epithelium. The upper respiratory tract (nose) epithelium is concentrated with a group of receptors called acetylneuraminic acid or sialic acid receptors. The lower portion of the respiratory tract(below the throat up to the lungs) is concentrated with angiotensin-converting enzyme-2(ACE-2) receptors. The novel Wuhan Virus or COVID-19 has a stronger affinity towards these receptors (ACE-2) than any other virus in the corona family (See Fig 3)Moreover they have a very little affinity towards sialic acid receptors in the upper respiratory system. Hence they are very likely to precipitate serious consequences like pneumonia rather than to produce a mild common cold and cough.
Angiotensin-Converting Enzymes are of two types such as ACE, and ACE-2. They are polypeptides that contain many amino acids in their molecular structure.
In the blood (cardio-vascular) system ACE increases the blood pressure by converting the inactive Angiotensin-1 to the active Angiotensin-2.
But the ACE-2 works oppositely and decreases blood pressure.
In the respiratory system (RS) the function of ACE is unknown and the function of ACE-2 is well described as receptors.
When the COVID virus (Now the WHO has removed the old names 2019n-CoV and Wuhan Virus, and we can conveniently call it by the official name COVID-19)) comes in contact with the respiratory tract it is attracted by the ACE-2 receptors in the lower side of the track and the upper side is not much affected as it contains sialic acid receptors only.
As the virus is received by the receptor the virus attaches any one of its S-1 spikes (small ornaments like projections on the viral body surface) with the receptor. (See Fig-4)
Once it is attached to the receptor the virus induces many steps by step actions to get into the cell cytoplasm. One of the steps in lowering the pH of the cell surface, in order to rupture or soften the cell to form a protective vesicle around it and dip lower to begin the process of endocytosis.
Endocytosis is a process by which a cell can pick up nutrients from the blood plasma. In the same manner, the virus tricks the cell into consideration as a nutrient in order to get the cell entry.
Viruses are medically considered nonliving parasites as they do not have a cell, and cytoplasm to perform metabolism. They need a host cell to perform all the living processes. Otherwise, they are only lifeless carriers of their own genome.
The entered virus gets comfort in the cytoplasm and also protects itself into a vesicle to prevent damages from many cell defensive mechanisms. The virus attacks the nucleus and kills it and makes the entire host cell for its own metabolism. Virus mRNA spreads and helps the virus to multiply by its own transcriptions and protein translations. The multiplied individual viruses get out of the dead host cell by a process known as exocytosis to invade other healthy cells.
SYMPTOMS:-
Once he experienced breathing difficulties, he was admitted to the hospital and subjected to various diagnostic procedures.
The morphology of these viruses is different from other viruses. They have a circular global body with spikes attached to their surface (See Fig-1). They look like a crown and hence the name Coronaviridae.
TYPES OF CORONAVIRIDAE
 |
| Fig-2 |
Viruses are generally either RNA or DNA in type.DNA viruses are more comforted inside the host cell as they can utilize the host genome for their replication. But RNA virus has no other choice unless to produce its own mRNA to replicate as the host cell mRNA cannot transcript the viral RNA to replicate. All Coronaviridae have belonged to RNA viruses.
1. Alphacoronovirus:
In this class, there are three subtypes as
a)Humancoronovirus or HCoV-NL63.:-Which contains several strains and some of them(HCoV-229E) cause common cold symptoms only.
b)Porcine Transmissible Gastroenteritis Coronavirus (TGEV/PEDV). These viruses infect mostly pigs and cause them severe GI distress and diarrhea.
c)Porcine Respiratory Corona(PRCV)which also affects pigs and spread to others.
2. Betacoronavirus:-
In this class there 4 strains have been discovered:-
a)SARS CoV-In 2002 in Guangdong province of southern China Severe Acute Respiratory Symptoms attacked human beings with serious symptoms. It was found out that civets and cats are the culprits for this outbreak. It claimed around 800 lives. But now medicines and vaccines are available for these infections.
b)MERS CoV/HKU4-CoV:-In 2012 Saudi Arabia got respiratory viral infections claimed around 700 lives. They discovered the virus is spread from infected camels. They named it MERS CoV.
HKU4 CoV: Very similar to MERS Co V with little difference in receptor binding. Both use the Dipeptidyl peptidase (DPP4) receptor on the human cell for entry but MERS binds with greater affinity than HKU4 Co V. Both viruses can affect bat cells without but to affect the human cell HKU4 virus needs a mediator whereas the MERS CoV does not need any mediator. The mediators are usually a protease (An enzyme that can dissolve the cell protein)
Both viruses are later discovered that they originated from bats.
HKU4 virus causes lesser casualties than MERS CoV because of their functional difference in receptor affinities as described above.
c)Mouse Hepatitis Corona -(MH CoV) This is also similar to the MERS CoV that originated from the mouse. Bovine Corona-B CoV/Human Corona-OC43
Bovine Coronaviruses cause infections mainly in cattle. It causes diarrhea and dysentery mostly in calves.
OC43 coronavirus is causing the common cold in human beings.
3-Gammacoronaviruses:-In this class there is one virus known as Avian Infectious Bronchitis Virus AIBV.
This virus is infecting mostly chickens and causing respiratory distress, damages to the gut, kidney, and reproductive system in chickens. This causes heavy losses in the poultry industry as mostly egg-producing chickens are very easily infected by this virus.
4.Porcine DeltacoronavirusPDCoV
These viruses were first spotted in the Henan province of China in 2017 in two swine farms and affected different ages of pigs with diarrhea. Later they transmitted to the poultry farm.
HOW COVID-19 ATTACKS HUMAN CELLS
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| Fig-3 |
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| Fig-4 |
There are two common receptors are on the respiratory tract epithelium. The upper respiratory tract (nose) epithelium is concentrated with a group of receptors called acetylneuraminic acid or sialic acid receptors. The lower portion of the respiratory tract(below the throat up to the lungs) is concentrated with angiotensin-converting enzyme-2(ACE-2) receptors. The novel Wuhan Virus or COVID-19 has a stronger affinity towards these receptors (ACE-2) than any other virus in the corona family (See Fig 3)Moreover they have a very little affinity towards sialic acid receptors in the upper respiratory system. Hence they are very likely to precipitate serious consequences like pneumonia rather than to produce a mild common cold and cough.
Angiotensin-Converting Enzymes are of two types such as ACE, and ACE-2. They are polypeptides that contain many amino acids in their molecular structure.
In the blood (cardio-vascular) system ACE increases the blood pressure by converting the inactive Angiotensin-1 to the active Angiotensin-2.
But the ACE-2 works oppositely and decreases blood pressure.
In the respiratory system (RS) the function of ACE is unknown and the function of ACE-2 is well described as receptors.
When the COVID virus (Now the WHO has removed the old names 2019n-CoV and Wuhan Virus, and we can conveniently call it by the official name COVID-19)) comes in contact with the respiratory tract it is attracted by the ACE-2 receptors in the lower side of the track and the upper side is not much affected as it contains sialic acid receptors only.
As the virus is received by the receptor the virus attaches any one of its S-1 spikes (small ornaments like projections on the viral body surface) with the receptor. (See Fig-4)
Once it is attached to the receptor the virus induces many steps by step actions to get into the cell cytoplasm. One of the steps in lowering the pH of the cell surface, in order to rupture or soften the cell to form a protective vesicle around it and dip lower to begin the process of endocytosis.
Endocytosis is a process by which a cell can pick up nutrients from the blood plasma. In the same manner, the virus tricks the cell into consideration as a nutrient in order to get the cell entry.
Viruses are medically considered nonliving parasites as they do not have a cell, and cytoplasm to perform metabolism. They need a host cell to perform all the living processes. Otherwise, they are only lifeless carriers of their own genome.
The entered virus gets comfort in the cytoplasm and also protects itself into a vesicle to prevent damages from many cell defensive mechanisms. The virus attacks the nucleus and kills it and makes the entire host cell for its own metabolism. Virus mRNA spreads and helps the virus to multiply by its own transcriptions and protein translations. The multiplied individual viruses get out of the dead host cell by a process known as exocytosis to invade other healthy cells.
SYMPTOMS:-
The symptoms are almost similar to the infection of pneumococcal pneumonia.
1. Fever
2. Sneezing
3. Severe cough
4. Thick mucus
5. Mucus with blood
6. Breathing difficulties.Short breath lead to Respiratory Depression (RI)
7. Death.
PRECAUTIONS
Once the virus infects human beings then becomes virulent in spreading from human to human.
Through coughing and sneezing the virus can spread in the air.
Avoid crowds
Wear thick face masks
Frequently wash hands with soaps and detergents
Dry them with sanitizers.
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