Strengthening Our Defenses
News about SARS CoV-2, the virus that causes a flu-like respiratory illness, is encouraging us to keep our “social distance” from each other; to limit travel, work from home, and to only venture out if necessary. The overabundance of caution is due to this strain of the coronavirus being a “novel” virus in humans – meaning there is no vaccine or cure and experts cannot predict with certainty how contagious it is or how the disease progresses once a person is infected.
Health professionals speculate that the virus probably originated in a bat population in eastern China and mutated to infect a human host, quickly spreading around the globe. But how does this happen and why is the coronavirus any different from the flu?
A virus is a microscopic organism, about 1/100th the size of a bacteria, found practically anywhere that plants, animals, and humans live. Scientists predict that there are millions of undiscovered viruses and that they’ve existed for about 1.5 billion years.
Though each one has unique characteristics, a virus is basically a protein shell containing genetic material, usually segments of RNA. Scientists have classified them as “infectious pathogens” because they’re unable to metabolize proteins or reproduce themselves without a host organism.
We mostly encounter viruses when we breathe them in or by coming into contact with the bodily fluids of an infected person. A virus enters the lungs or the bloodstream and immediately searches for a cell to invade. The outer shell of the virus contains protein “spikes” or antigens, that connect to receptors on the host cell’s membrane. Most viruses are harmless to humans because they’re only able to infiltrate a cell if it is able to connect with a host cell’s receptor like a lock and key. This is how scientists believe the COVID-19 virus was able to “jump” from animals to humans; a mutation of the protein spikes occurred, making an animal virus suddenly able to connect with human cells.
Once a virus connects, it either injects its genetic material into the host cell’s cytoplasm or enters it whole through the cell membrane. The virus then disassembles and takes over the cell’s protein-building structures, causing it to read it’s genetic code instead of the host cell’s. The virus is then able to create the building blocks needed to duplicate itself, while interrupting the healthy functioning of the host cell.
Fever, coughing, and fatigue means our immune system is fighting an infection, and these symptoms usually worsen for a short period of time and then subside when our body has cleared the virus. Antibodies produced by white blood cells are a crucial part of the immune response. These small protein segments take on the shape of the antigens on the outer shell of the virus, locking onto them and making it impossible for the virus to connect with a host cell. Often, antibodies stay in the bloodstream for years to defend against reinfection.
If our white blood cells cannot keep pace by producing antibodies at a faster rate than the virus is reproducing itself, our immune system becomes overwhelmed. This could result in critical tissue and organ damage.
Health experts are working closely with local and national governments to quickly adapt and advise the public about strategies for coping with this emerging pandemic. Dr. Tom Frieden, in a March 20 article on CNN.com, provides a glimpse of the global realities of this “novel” virus and the challenge of working together to protect our society while staying a safe distance away from each other.