COVID-19 FYI #8
NOBODY, ANYBODY, ANTIBODY:
Well…that’s my feeble attempt at humor in this mind-numbing season of COVID-19 and also why the English language is such a mystery. (Say it out loud and you’ll see!) It is the reason I managed to flunk second grade in an unwillingness or inability to read. To this day, I can’t spell worth a darn.
And speaking of humor, today’s post involves humoral immunity, named for the substances founds in the humors (body fluids). Okay, let’s get serious (or serous if we continue with the puns).
A reader posted a great question the other day about ANTIBODIES. I’ll try not to get too bogged down in the science, but in the end, you’ll see why this is such an important topic—one that you’ll hear in the news over and over.
A brief and simplified biology lesson:
You’ve probably all had your white blood cell count measured at one time or another. These specialized cells of our immune system called leukocytes are our natural defense against infection and disease. Even as a bone doc, this aspect of medicine is vitally important in many processes around the musculoskeletal system, including fracture healing.
As the cells of the immune system, these leukocytes are typically divided into five primary types: neutrophils, eosinophils, basophils, monocytes, and lymphocytes. The lymphocytes are further divided into natural killer cells, T cells, and B cells, which circulate in the bloodstream with red blood cell and monitor for anything that shouldn’t be there.
The job of these T and B cells is to recognize foreign invaders called antigens (like bacteria and viruses). They respond in two separate ways: B cells produce antibodies that neutralized these invaders, and T cells produce cytokines. (I won’t talk about this here, but you may have heard the patients that get deathly ill with COVID-19 undergo a cytokine storm—the body’s overreaction to the illness.)
The antibodies that the B cell produce are glycoproteins known as immunoglobulins. (Remember our lesson on how proteins are made from the basic human code, DNA from COVID-19 FYI #1) https://www.authortimothybrowne.com/news/covid-19-fyi-1/
By now, all this biology may give you a headache, but we are almost there. These immunoglobulins come in five primary forms, IgA, IgD, IgE, IgG, and IgM. Each has differences in their function, but they all come as variations of a Y-shaped molecule. Each arm of the “Y” has a part that can bind with an antigen (the foreign invader, like a virus). Once the antibody is attached to the virus, it neutralizes it, and most often destroys it through another entire chain of events mediated by the white blood cells.
With the SARS-CoV-2 virus, our bodies produce the typical pattern of IgM and IgG. The IgM antibodies disappear at the end of week twelve, while the IgG antibody can last for a long time.
Once your body makes these specific antibodies to SARS-CoV-2, the lab can measure these in the blood (serology—the study of body serum). So instead of detecting the virus itself, it measures the body’s response to the virus. Thus, the race is on by many companies to develop, get FDA approval, and market these tests. Once they go on the market, people will know with reasonably high accuracy if they have been exposed and mounted an immune response to SARS-CoV-2.
This is a topic of great debate, and one that we want to know the answer to; if we’ve had COVID-19 once, can we get it again? Because this is another complicated topic, I will discuss it in the future. The answer is; the scientists hope that if you are infected once you are protected by those long-lived antibodies. But there are many factors, including if the virus mutates (why we get the common cold over and over again). No one is also sure how long this immunity will last—some are saying one to two years. So far, though, it looks like the virus mutates rather slowly- which is a good thing for immunity and vaccines.
You have heard in the news about recovered patients donating their blood (plasma) to help others. Because these recovered patients have already mounted a successful antibody response, it is hopeful (and promising) that by infusing this plasma into the sickest patients, it will help them fight the virus. This is a treatment called convalescent serum.
Designer Antibody Drugs
If you can design these antibodies against SARS-CoV-2 in the lab, mass-produce and concentrate them, you MIGHT be able to inject them into infected patients. Not just valuable to the patients, but they estimate this market in the tens of BILLIONS of dollars. It’s no wonder the big companies are jumping in:(
There are several vaccine strategies against the SARS-CoV-2 virus that are being investigated: live-attenuated virus and inactivated virus (has the make-up of the virus but doesn’t cause the disease), viral vectors, recombinant DNA and protein vaccines, among others.
1) It’s all about the antibodies!
2) The antibody test will be a game-changer.
3) A vaccine is twelve to eighteen months away.
Practical Tip of the Day:
I’m afraid I’ve presented you with way more science than humor. Find a humoral movie to watch…I’m serous:) My son pointed out that it’s just like a bone doctor to try to make things like this humerus!!!
Stay safe and healthy…With love, Timothy