Vaccines: Antibodies + Antigens

Valmik Rao
5 min readApr 9, 2020

Not a day goes by where I don’t hear about a new breakthrough in the COVID-19 vaccine trials. But it’s commonly overseen because not everybody knows how a vaccine works and how we would use it to prevent more people from getting infected.

Vaccines are multifaceted, there’s a huge process when it comes to creating one, an even bigger one when it comes to validating its safety and efficacy. The more we know, the more we can play our part in creating awareness.

It’d be naive to think that I can cover everything in this article, but here’s what you’ll know after reading this article:

  • What are Vaccines
  • Antibodies + Antigens
  • Synthetic processes for Antibodies (Hyperdoma + Phage image)

What are Vaccines?

Vaccines are considered the pinnacle of preventative medicine, first discovered by Edward Jenner in 1796 when his vaccine gave a kid with cowpox immunity to further infection.

It’s going to be hard to go through the rest of this article, without understanding what vaccines are, so let’s break that down first 👇

Vaccines are substances that trigger an immune response in the body using different causative agents, synthetic replacements, and components of a virus.

Wait why would inject the virus in the patient’s body, isn’t the opposite of what you want? Stay with me here.

All these viral components are weakened versions of the real virus, but still strong enough to induce an immune response. The immune system develops the proper antibodies to kill those components without causing any symptoms in the body. Once the immune system develops the proper antibodies for killing that virus, then the body develops a faster and more prepared response for the real thing, therefore developing immunity.

^Knowing everything above is necessary because now we’re going to go deep into antibodies and how they play an integral part in defending the body from viruses.

Antibodies and Antigens

Antibodies and antigens are the substances that the immune system creates to defend the body from viruses. Antibodies are y shaped blood proteins, that specifically bind to certain antigens, which are infectious agents that are found in viruses (we’ll focus on this later on). But throughout this section, we’re going to break down where they come from, their structure, and how they work:


Antibodies are produced naturally in the body by B Lymphocytes or B Cells, these cells are created in the bone marrow and then migrate to different lymphoid tissue as part of the adaptive immune response. Lymphoid tissue is located at points in the body that are more susceptible to viral infection, for example a popular example of lymph node placement would be in the neck because viral infections in the throats are very common.

So how do they know to create the right antibodies?

B cells attach to the antigens through the beta-cell receptor on the surface of the antigen. Once they attach to the antigen, the B cell starts to proliferate and create either plasma cells or memory B cells. All B cells that derive from the attached B cell carry the same B cell receptor(BCR), which allows them to target specific antigens by using the surface indicators.


Antibodies are y-shaped proteins with two main body parts, a variable region, and a constant region. The variable regions contain the two chains: Light and Heavy. Light chains are characterized in the picture as the shorter chain that is colored red, while the heavy chains are blue and longer. On the left, we can see the antigen on the antibody binding site touching both the L chain and the H chain.

Due to the fact that the antigen-binding site isn’t located in the constant region, it doesn’t change as frequently, thus the name “constant”. The main function of the constant region is to determine the mechanism used to destroy the antigen.


There are four three main functions:

  • Antibodies are secreted into the blood and mucosa, where they bind to and activate foreign substances such as pathogens and toxins (neutralization)
  • Antibodies activate the complement system to destroy bacterial cells by lysis (punching holes in the cell wall)
  • Antibodies facilitate phagocytosis of foreign substances by phagocytic cells (opsonization)

These are the three bodily processes that antibodies are involved in, especially when it comes to activating different cycles that are performed to destroy foreign cells. But here’s more detail on a function that makes antibodies successful against antigens:


Each antibody recognizes one antigen, while each beta cell produces one type of antibody to which competes with the millions of harmful factors that the virus produces.

An advantage that the body does have would be the tens to millions of different beta cells are produced in the body so that every antigen is recognized (antibody diversity). In addition, after infection the number of B cells that are produced increases proportionately (immunological memory).

Synthetic Processes

Throughout this entire article, I’ve been talking about how the body can generate antibodies in a natural way but did you know that we can also generate the required antibodies in a lab?

Here are the two main ways that we use right now to generate antibodies 👇


It’s a process that allows researchers to produce monoclonal antibodies, that then allow researchers to perform in vivo experiments and diagnostics.

Hybridoma requires antibody-producing b cells and an immortal myeloma cell.

The steps are as follows:

  1. Injecting the host with the antigen
  2. Extracting different spleen cells
  3. Fusing spleen cells with the myeloma cells (hybridomas)
  4. Harvesting antigen-specific cells, and replicating

The main value proposition of this method is that we now know that testing in vivo will work because the spleen cells that are originally from the host carry the same genetic data as for every other cell in the host.

Phage Imaging

Here’s another process of how we can achieve monoclonal antibodies by using phage antibodies and their receptors.

The steps of this process are as follows:

  1. Find a phage antibody library
  2. Use the pathogen to find a suitable receptor in the library
  3. Then take the genes from the antibody phage, and create cellular factories (often bacteria cells) to mass-produce the needed antibody drug.

The main value proposition of this method is that we often don’t need to repeat steps because phage antibody libraries already exist, all we need is to isolate the pathogen for which the antibodies are needed for.

Reaching the end of the breakdown, here’s what I told you today:

  • Vaccines are actually versions of the pathogen that we are trying to get rid of, and we use these versions to trigger an immune response in the body, which will help generate the needed antibodies.
  • Antibodies are produced by B cells that are found in lymphatic tissues, originally from the bone marrow. They help fight off antigens in the body.
  • Hybridoma and Phage Imaging are processes that allow researchers to create monoclonal antibodies, which in turn helps create a drug for vaccination purposes.

Leave some claps if you enjoyed my little breakdown. Don’t hesitate to reach out



Valmik Rao

Just a 16-year-old trying to solve the world’s biggest problems…