invasion and response

Experts are still trying to decode how the novel coronavirus infiltrates the body and how the immune system can overreact—with deadly consequences. Here’s how an infection can begin: SARS-CoV-2, the virus that causes COVID-19, targets ACE-2 proteins that line the surface of many important human cells, including type II alveolar cells in the lungs.

BY Manuel Canales, alexander stegmaier, & taylor maggiacomo

Published October 14, 2020

BIOLOGY OF A THREAT

Thousands of times smaller than the width of a human hair, the coronavirus spreads mainly through respiratory particles in the air.

SARS-COV-2

Spike protein

Lipid

membrane

RNA

While most viral particles travel only a short distance, some may stay airborne for hours.

Infection occurs in the nasal passage; loss of smell or taste can be an early indicator.

lungs

In search of more ACE-2 receptors, viral particles can travel to the deepest part of the lungs, the alveoli.

alveolus

VIRAL INVASION

Responsible for the exchange of oxygen and carbon dioxide in the blood, the alveoli are ground zero for the virus’s attack on our cells.

Type II cell

alveolus

cavity

Type I cell

O2

CO2

invasion and response

Experts are still trying to decode how the novel coronavirus infiltrates the body and how the immune system can overreact—with deadly consequences. Here’s how an infection can begin: SARS-CoV-2, the virus that causes COVID-19, targets ACE-2 proteins that line the surface of many important human cells, including type II alveolar cells in the lungs.

BY MANUEL CANALES, alexander stegmaier,

& taylor maggiacomo

Published October 14, 2020

BIOLOGY OF A THREAT

Thousands of times smaller than the width of a

human hair, the coronavirus spreads mainly through

respiratory particles in the air.

SARS-CoV-2

Spike protein

Lipid

membrane

RNA

While most viral particles travel only a short distance, some may stay airborne for hours.

Infection occurs in the nasal passage; loss of smell or taste can be an early indicator.

lungs

In search of more ACE-2 receptors, viral particles can travel to the deepest part of the lungs, the alveoli.

alveolus

VIRAL INVASION

Responsible for the exchange of oxygen and carbon dioxide in the blood, the alveoli are ground zero for the virus’s attack on our cells.

Type II cell

Type I cell

alveolus

cavity

O2

CO2

4

As alveoli cavities fill with fluid and debris, exchange of oxygen and CO2 becomes impaired. In severe cases the immune system overreacts; excess inflammation can contribute to multi-organ failure and septic shock.

White blood cells

Protein-rich fluid

permeable capillary

SYSTEM DAMAGE

The virus doesn’t just attack the lungs–other organs including the heart, brain, kidney, and liver can also be affected. COVID-19 may cause long-term organ damage and dysfunction, and can lead to death.

Neurological damage manifested as confusion, delirium, and seizures have also been reported.

Lung damage can leave permanent scarring.

Blood clots can cause serious strokes, pulmonary embolisms, and heart attacks, and can restrict blood flow to the limbs.

manuel canales, TAYLOR MAGGIACOMO, AND EVE CONANT, NGM STAFF. research: alexander stegmaier; ART: manuel canales and ANTOINE COLLIGNON

SOURCES: HOWARD M. HELLER, HARVARD MEDICAL SCHOOL; DANIEL S. CHERTOW, NIH CLINICAL CENTER AND NIH NIAID

4

As alveoli cavities fill with fluid and debris, exchange of oxygen and CO2 becomes impaired. In severe cases the immune system overreacts; excess inflammation can contribute to multi-organ failure and septic shock.

permeable capillary

Rich Protein Fluid

White blood cells

SYSTEM DAMAGE

The virus doesn’t just attack the lungs–other organs including the heart, brain, kidney, and liver can also be affected. COVID-19 may cause long-term organ damage and dysfunction, and can lead to death.

Neurological damage manifested as confusion, delirium, and seizures have also been reported.

Lung damage can leave permanent scarring.

Blood clots can cause serious strokes, pulmonary embolisms, and heart attacks, and can restrict blood flow to the limbs.

manuel canales, TAYLOR MAGGIACOMO, AND EVE CONANT, NGM STAFF.

research: alexander stegmaier; ART: manuel canales and ANTOINE COLLIGNON

SOURCES: HOWARD M. HELLER, HARVARD MEDICAL SCHOOL; DANIEL S. CHERTOW, NIH CLINICAL CENTER AND NIH NIAID