Antibody Neutralization & Viral Replication

Instructor: Bridgett Payseur

Bridgett has a PhD in microbiology and immunology and teaches college biology.

How can a single antibody stop a virus from copying itself repeatedly and taking over? Read on to learn how antibodies neutralize viruses and stop them from replicating.

What is an Antibody?

You've probably heard the word 'antibody' before. It might have been mentioned on the news, on social media, or in your biology class. Antibodies are touted for their ability to stop infections. But what is an antibody, and how does it work?

An antibody is a protein made by the immune system to help fight infections. Antibodies recognize antigens, which are pieces of a foreign germ. They can do this in numerous ways.

They can help target the antigen to be removed by other parts of the immune system, basically painting a giant 'EAT ME' sign on say, an invading bacterium. It could also cause all the germs to clump together, so they can be found and removed more easily.

Antibodies can bind to antigens and neutralize them

Another way that antibodies can work is by neutralizing the threat, preventing the bad guy from doing its bad guy stuff.

How Does an Antibody Neutralize a Virus?

Remember that a virus, in essence, is genetic material in some kind of package. The genetic material can be either DNA or RNA, and either of those can be single or double stranded. The packaging can simply be proteins, or it can include an envelope, which is made from cellular membrane.

A virus is genetic material in a protein package, sometimes encased in a membrane envelope

Unlike bacteria, viruses are not able to replicate on their own. They need a host cell to do the work for them. A virus will enter a host cell, use that cell's machinery to make copies of itself, then leave to go infect more host cells.

Virus neutralization is pretty straightforward for an antibody. The main goal is to block the virus from grabbing onto the host cell. If the virus can't grab the host cell, it can't get in and get copies made.

Example of Antibody Neutralizing a Virus

Let's look at how antibody neutralization works with the help of Vira the Influenza Virus. Inez, like her fellow influenza viruses, loves to infect cells in the respiratory tract. She uses a protein called hemagglutinin to grab onto the respiratory cells. After she's grabbed on, she can go inside the cell, where she begins her infection process.

Annie Antibody, however, wants to protect the respiratory cells from Vira. Annie is able to grab onto Vira's hemagglutinin as well as the respiratory cells. But surprise! Annie isn't a respiratory cell! Vira is unable to let go of Annie. They're stuck together. Vira is no longer able to infect cells. She has been neutralized.

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