Vaccination misinformation. How’s a layperson supposed to distinguish between the conflicting voices? Parent’s heads could spin right off, with one party saying vaccination could lead to autism and another claiming not getting a shot could lead to death! What’s the deal?
As the saying goes, information is power. So, allow a scientist to unravel the tangled web. This week, I’ll discuss how the immune system fights viruses; next, I will write about how vaccines work.
The War
The interaction between a virus and our immune system is analogous to a war: on one side are the viral particles and, on the other, our white blood cells. However, the freaky thing about viruses is that they only come alive inside our cells. There, they hijack the cell’s internal machinery to make more viruses.
Our white blood cells fight this by trying to capture the virus before it enters our cells. They also help blow up virus-infected cells so the virus dies. Seriously! Sometimes, the white blood cell generals get overwhelmed and panic, which can cause worse symptoms than the infection itself.
Note that, in a war, he with the most soldiers often wins. Wearing a mask reduces the number of viral particles that can reach you. If fewer viruses invade you, your immune system has a better chance of assembling the soldiers, artillery, and bombs, being ready to go before the virus takes over the body. And the white blood cell generals are less likely to panic.
The Lock and Key
The second analogy that may be helpful is a lock and a key. Our cells communicate in a way that viruses use to their advantage. Locks and keys. Really! A cell knows it should act when a chemical key touches a cellular lock. To get into our cells, viruses act like locksmiths. They use a key that works on a particular cell type’s lock. This results in the cell unwittingly opening the door and taking the virus in, and that’s the end of that cell. Truly nefarious!
The Immune System
When we’re infected, our immune system “learns” what every part of the invading virus and its “key” look like. Antibodies stick to those micro-parts and participate in ongoing battles and short-term clean-up.
But about three months after the battle has been won, there are no more antibodies. None. Otherwise, our blood would be a slurry—we are exposed to and protected from so much every day! Moreover, the army appears to have gone to sleep.
The Enemy Returns
Imagine that the virus now sneaks in past the walls and hijacks a couple of cells, telling them to make more virus. The hapless cells do as they’re told, but not before putting a help flag on their surface. The sentry immune cells see it and send a signal to other white blood cells.
Enter the memory cells, which were educated about each part of the key during the initial infection. The white cells wake up the memory cells, which jump into action. Within 5-7 days, the cells that act as antibody factories are up and running. Each cell pumps out thousands of antibodies per second until the factory cell dies of exhaustion in about three days.
The antibodies stick to the invader, virus-infected cells are blown up, eaten, and viruses are mopped up out of the tissues. The immune system wins again!
What If?
But what if the immune system has never seen a deadly virus before? Can it fight it off in time? Maybe. That’s when the army needs to be trained in advance. How? That’s the subject for next time.