SARS-CoV2 has a protein called the S or Spike-Protein, it is a homo-trimer protein that binds, with high affinity, to the membrane protein Angiotensin-converting enzyme 2 (ACE2), which is richly deposited in epithelial cells of the respiratory system. Upon binding to ACE2, the SARS-CoV2 is able to infect the cells expressing that receptor by fusing with the cell membrane, initiating the lytic cycle, and subsequently depositing the ~30kbp RNA payload that begins replication/exponential biosynthesis & assembly, and ultimately lysis of the cell with mostly identical copies, attaching to more ACE2+ expressing cells. Eventually the damage becomes so severe that inflammation in the lungs allows aqueous secretions that obstruct gas exchange and create an environment that facilitates the flourishing of log-phase bacterial pneumonia growth; this secondary bacterial infection is ultimately the direct cause of death or elicits the deadly immunological cytokine storm.

Because its a Respiratory Virus. mostly effected on Respiratory tract as well as Lungs.

Think about route of transmission, its an aerosol or via contact and enters via the nose, mouth eyes etc It can colonise the respiratory tract and lungs quite easily especially with the flow of air bringing it down compared to say the stomach so its a prime location for a lot of virus's

necause it is a repiratory disease virus

Hi muhammad,

I completely agree with Stephen Reynolds. Route of transmission can be the reason since scientists are still learning about this new virus. I think the journey of the virus, infection cycle, and time period in the body organs can be the reason for priority in where it will multiply after entry of the virus.

The new coronavirus can infect the upper or lower part of your respiratory tract. It travels down your airways. The lining can become irritated and inflamed. In some cases, the infection can reach all the way down into your alveoli.

The link below is the reference https://www.webmd.com/lung/what-does-covid-do-to-your-lungs#1-2

SARS-CoV2 has a protein called the S or Spike-Protein, it is a homo-trimer protein that binds, with high affinity, to the membrane protein Angiotensin-converting enzyme 2 (ACE2), which is richly deposited in epithelial cells of the respiratory system. Upon binding to ACE2, the SARS-CoV2 is able to infect the cells expressing that receptor by fusing with the cell membrane, initiating the lytic cycle, and subsequently depositing the ~30kbp RNA payload that begins replication/exponential biosynthesis & assembly, and ultimately lysis of the cell with mostly identical copies, attaching to more ACE2+ expressing cells. Eventually the damage becomes so severe that inflammation in the lungs allows aqueous secretions that obstruct gas exchange and create an environment that facilitates the flourishing of log-phase bacterial pneumonia growth; this secondary bacterial infection is ultimately the direct cause of death or elicits the deadly immunological cytokine storm.

I think also the strain or genotype of the virus would play a role on which is the target organ to infect.

Although ACE2 receptors on epithelial cells are expressed in significant quantities in the organs enumerated, SARS CoV2 responsible for COVID 19 has high affinity for ACE2 receptors on human respiratory epithelial cells. This explains why it is referred to as severe acute respiratory syndrome. Also, differentiation of epithelial cells vary from one organ to the other in the human body based on their function and this could also influence viral proliferation rate.

It is transmitted via nose, mouth eyes and ultimately enters the lungs with the flow of air. It, therefore, effects the lungs the most. If it reaches the stomach it will be destroyed due to the acidic environment in the stomach.

the chances of its effecting other vital organs like kidneys and heart, of course, cannot be ruled out.

This virus creates respiratory problems and it transmits through nose, mouth, eyes and finally it enters into the lungs.

As other RG colleagues have mentioned, SARS-CoV-2 is a respiratory RNA virus that mainly enters the body through the respiratory tract by docking with the ACE2 receptors located on the pneumocytes. Lung has the most abundant ACE2 receptors compared to other organs of the human body.

This is why social distancing (keeping a distance of at least 2 meters), masking, cleaning hands, avoid touching mouth or nose, and covering the cough or sneeze, have been the paramount preventive measures.

I agree with Muhammad Haddad and have faced the same enigma. Please note that it is the angiotensin converting enzyme 2 (hACE2) which acts as the receptor of SARS-CoV-2 and not angiotensin 2 receptor. As seen in the chart attached, the tissue expression of hACE2 is by no means concentrated in lung tissues. Therefore, it is a valid question to ask why SARS-CoV-2 has special affinity to pneumocytes. Is it only the route of transmission that plays a key role? What if the virus is injected into the systemic circulation?

Please avoid speculation and provide evidence. Thank you.