Decoding India’s First-of-its-Kind DNA Vaccine

 Decoding India’s First-of-its-Kind DNA Vaccine

Since the outbreak of COVID-19, we have witnessed two waves of this pandemic that have caused havoc. While our brave frontline workers continue to endlessly help people infected with the virus, our scientists and medical professionals are looking for the best possible ways to prevent this virus from causing further harm. These experts studied different vaccines and tried and tested them in labs before moving forward with clinical trials in humans. Initially, it seemed like a distant dream, but now they are not only being able to produce mass vaccines in a brief period but also developing different types and versions. And one such latest variant is the ZyCoV-D, the world’s first DNA vaccine produced by India.

Structure of SARS CoV-2 or Covid-19

Viruses come in different shapes and size essentially they are packages of DNA or RNA inside a protein cell. Talking about the SARS CoV-2, the outermost layer is the viral envelope. This layer is usually made up of
fats or lipids and proteins get embedded into them.

Soaps actually break this fat that is why washing
our hands with soap renders these viruses ineffective.

Now embedded in that fatty layer there are three different layers of proteins but what I am interested in is the Spike protein which actually helps that virus to bind to a healthy human cell. Now strip that layer another protein layer called the Capsid is present. Stripe that we find the Nucleic protein or the N-Protein onto which the RNA or the genetic material is bound.

Covid-19’s mechanism of getting into an organism’s body
Once this virus enters the body, it lands on top of a live host cell. The real damage begins once the outer spike actually latches on to the receptors on the surface of the cell in our respiratory track. This binding triggers the cell to think that the virus is one of its own and let the virus fuse with itself.

Method of making copies of Covid-19
 At the time the virus entered the body, the viral envelop merges with the membrane of the cell allowing the virus to inject the RNA inside. Now the viral RNA hijacks the cellular machinery. The cells instead of making body proteins start making these viral proteins. The RNA also replicates. At this stage, the live human cell has created all the raw materials which are required to construct a new virus. The result is a human cell filled with copies of the virus.

FUN FACT!
One cell can actually make millions of copies of that virus before all the viruses burst out of that particular cell leaving it dead.

How do vaccines work?

The immune system
These viruses go on to infect other cells. This causes havoc and this is where our immune system comes to our rescue. The immune system has a whole army of microscopic assassins that prevent these viruses from turning our body into a virus manufacturing unit factory. Now the immune system responds in two ways to protect us. One is the innate or non-specific immunity and another is the adaptive or specific immunity.
Innate Immunity
As the name suggests, this kind of immunity is there from birth and is non-specific which means that it responds to all kinds of pathogens in the same way. Its ultimate job is to kill the pathogen. The need here is to actually get into action very very quickly. In fact, as soon as the pathogens are detected. We can think about this type of immunity as more bran and less brain. The cells of the innate immunity go berserk as soon as they know that there are pathogens around. They are like the mad assassins trying to start killing anything and everything around them including their own body cells. Well, this kind of madness cannot go on for long. It will harm us more than doing good. In fact, some mechanisms keep this under control. This type of immunity is not connected to “How do vaccines work.”

 Adaptive or Acquired immunity

This type of immune cells are not present at birth. They develop more slowly and require the body to learn the wiley ways of the pathogen before it can defeat it. This is more brain than bran.

It identifies specific pathogens and destroys them. This is the first step in any good defense strategy to be able to tell friend from foe and in the case of our immune system that means being able to identify our own body cells from pathogens. This is done by identifying certain specific molecules such as proteins or glycolipids on the pathogen. These specific identifier molecules are called by a special name called “Antigen”. In the case of the corona virus, the spike protein is what gives away its identity. As soon as the antigen is discovered the adaptive immunity or the adaptive immune system actually gets all riled up.

     

 Take a look at the pictures    

To see the adaptive immune system in action, first, stop “Lymph Node”.

Lymph Node
This is where the intelligent part of our immune system resides introducing the “B-Lymphocyte” which is the spy of our adaptive immune system. Its job is to spot and mark the intruders that need to be neutralized. For this job, the “B-Lymphocyte” is equipped with a lot of different shapes of protein receptors called “Antibodies” on its cell surface.

FUN FACT!
A fully matured “B-Lymphocyte” displays at least 10,000 different antibodies on its surface. Different is the cool thing about them. Every lymphocyte has its own set of antibodies ready to identify and bind to a particular antigen like a key and lock, very very specific. So talking of all the lymphocytes put together, it’s like having 2 billion keys on our immune system’s key chain each of which can actually open one door or bind only to one antigen.

As soon as the match happens all hell breaks lose. The “B-Lymphocytes” sends out distress signals alerting the cells of the identity and location of the antigen. Post this, a cascade of events occur. A full-blown attack is launched on the pathogens. The pathogens neutralized and the body saved. This match-making process is actually a race against time. Till the match-making happens the innate immune system or the innate immune cells keep fighting mindlessly but are not in a position to completely neutralize all the pathogens. Even now the pathogens are continuously replicating in the body and wreaking havoc. So faster the matchmaking process better it is for the body. Sometimes this matchmaking process happens within a “Few hours” a “Few days” or it “may not happen at all” in which case the pathogen is victorious. 

In a good case scenario when it does find a match, along with alerting other immune cells and going in for a full kill some of the “B-Lymphocytes” become a long-lasting memory cell. Memory cells register the shape of the antibody that matched with the antigen. So in case, the same antigen and thereby the same pathogen is encountered again the response is quicker and our body can eliminate the pathogen quickly.

Vaccines

A vaccine is a biological preparation that provides active acquired immunity to a particular infectious disease. Vaccines contain tiny inactive parts of a particular antigen that help trigger an immune response within the body. For instance, when we get a vaccine for smallpox, our body remembers the smallpox antigens and how it harms the body. So in the future, if the smallpox virus ever tries to enter our body, the immune system can easily identify it and produce suitable antibodies to fight against it. Just like how the smallpox vaccine helps prevent the smallpox virus from entering our body, COVID-19 vaccines also work similarly. While there are many vaccines around the world for the COVID-19 virus, one of its latest types is a DNA-based vaccine.

Objective of vaccines

The objective of vaccines is to expose the body to these antigens before the actual pathogens get entry into the body different kinds of vaccines to expose the pathogen in different ways to the body. It could be either be in a weekend or a dead state sometimes just the antigen part of the pathogen is exposed to the body and a new technique called “mRNA” vaccines can also be designed or developed for this but all of these have the same result that is triggering the “B-Lymphocytes” response without actually causing the disease. When we take the jab the “B-Lymphocytes” get into action finds the match creates the memory cells that are required so that just in case of exposure to the actual pathogen our body can go kill the pathogen full-on ninja style. 

                

                Take a look at the  pictures    

             Take a look at the pictures    

                Take a look at the pictures    

What is a DNA-based vaccine?

DNA and RNA are some of the basic building blocks of life. They are molecules that carry that genetic information that is passed on from parents to molecules. Once administered, just like any other vaccine, a DNA-based vaccine also teaches our body’s immune system to fight the real virus. They insert a genetically engineered blueprint of viral genes into the DNA molecules called “Plasmid”. Once inside, it gives direct instruction to our body to build viral proteins, which the immune system recognizes as foreign and triggers an immune response that protects us from the disease. The latest ZyCoV-D is also a DNA-based vaccine for the COVID-19 virus that recently got approval from the Drug Controller General of India (DCGI) to be tested on humans.

How does  ZyCoV-D work?

ZyCov-D is the world’s first-ever DNA-based vaccine against the SARS-CoV-2 virus. It is developed and manufactured by Zydus Cadila, an Ahmedabad-based pharmaceutical company. According to the World Health Organisation, this ‘radical fresh approach’ offers several advantages over traditional vaccines, including improved vaccine stability, the absence of any infectious agent, and the relative ease of large-scale manufacture.

How is ZyCoV-D different from the other COVID-19 vaccines?
Unlike other intramuscular vaccines available around the world, ZyCov-D is very different in terms of mode of administration and the number of doses:

1.      ZyCoV-D is a genetic or nucleic acid vaccine. It is a three-dose vaccine that needs to be administered on day 1, day 28, and day 56.

2.     Unlike other vaccines, ZyCov-D is a needle-free Covid-19 jab. It uses the ‘Jet Injector’ method, a technique where the needle piercing the skin is replaced by a pressure jet injecting the liquid directly through the upper layer of the skin and into the underlying tissues. This method is a great help for those who show hesitancy because of a fear of needles. Further, the absence of needles can also lead to a significant reduction in side effects like pain at the injection site, swelling, rash, and arm soreness.

3.     As per the interim analysis from Phase 3 clinical trials, in over 28,000 volunteers, Zydus Cadila’s COVID vaccine has shown an efficacy rate of 66.6 percent for symptomatic Reverse Transcription Polymerase Chain Reaction (RT-PCR) positive cases.         
                                                                             

4.     Moreover, ZyCoV-D is the first vaccine candidate found to be eligible for use for children above the age of 12.