SIMPLY EXPLAINED: What is mRNA, what does it do, what is its role in a Covid-19 vaccine? How can we be sure that a mRNA-based Covid-19 vaccine is safe?

 (Source: Moderna, 

https://www.modernatx.com/mrna-technology/science-and-fundamentals-mrna-technology)

What does mRNA do? mRNA produces instructions to make proteins that may treat or prevent disease

mRNA medicines aren’t small molecules, like traditional pharmaceuticals. And they aren’t traditional biologics (recombinant proteins and monoclonal antibodies) – which were the genesis of the biotech industry. Instead, mRNA medicines are sets of instructions. And these instructions direct cells in the body to make proteins to prevent or fight disease.

It’s actually basic human biology. 

DNA (deoxyribonucleic acid) is a double-stranded molecule that stores the genetic instructions your body’s cells need to make proteins. Proteins, on the other hand, are the ‘workhorses’ of the body. Nearly every function in the human body – both normal and disease-related – is carried out by one or many proteins.

mRNA is just as critical as DNA.

Without mRNA, your genetic code would never get used by your body. Proteins would never get made. And your body wouldn’t – actually couldn’t – perform its functions. Messenger ribonucleuc acid, or mRNA for short, plays a vital role in human biology, specifically in a process known as protein synthesis. mRNA is a single-stranded molecule that carries genetic code from DNA in a cell’s nucleus to ribosomes, the cell’s protein-making machinery.

mRNA’s role in protein synthesis

 

• Through a process known as transcription, an RNA copy of a DNA sequence for creating a given protein is made.
• This copy – mRNA – travels from the nucleus of the cell to the part of the cell known as the cytoplasm, which houses ribosomes. Ribosomes are complex machinery in the cells that are responsible for making proteins.
• Then, through another process known as translation, ribosomes ‘read’ the mRNA, and follow the instructions, creating the protein step by step. 
• The cell then expresses the protein and it, in turn, carries out its designated function in the cell or the body. 

Using mRNA to develop a new category of medicines.

At Moderna, we are leveraging the fundamental role that mRNA plays in protein synthesis. We have developed proprietary technologies and methods to create mRNA sequences that cells recognize as if they were produced in the body. We focus on diseases where enabling targeted cells to produce – or turn ‘on’ – one or more given proteins will enable the body to fight or prevent a given disease.

• We start with our desired sequence for a protein.
• We design and synthesize the corresponding mRNA sequence – the code that will create that protein.
• Before synthesis, we also engineer that mRNA sequence to optimize the mRNA’s physical properties, as well as those of the encoded protein.
• We deliver the mRNA sequence to the cells responsible for making that protein via one of several modalities. Reaching different types of cells requires different delivery methods.
• And, once the mRNA – the instructions – are in the cell … human biology takes over. Ribosomes read the code and build the protein, and the cells express the protein in the body.

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(Source: CDC Centers for disease control and prevention

https://www.cdc.gov/coronavirus/2019-ncov/vaccines/different-vaccines/mrna.html)

Vaccines Are New, But Not Unknown

Researchers have been studying and working with mRNA vaccines for decades. Interest has grown in these vaccines because they can be developed in a laboratory using readily available materials. This means the process can be standardized and scaled up, making vaccine development faster than traditional methods of making vaccines.

mRNA vaccines have been studied before for flu, Zika, rabies, and cytomegalovirus (CMV). As soon as the necessary information about the virus that causes COVID-19 was available, scientists began designing the mRNA instructions for cells to build the unique spike protein into an mRNA vaccine.

Future mRNA vaccine technology may allow for one vaccine to provide protection for multiple diseases, thus decreasing the number of shots needed for protection against common vaccine-preventable diseases.

Beyond vaccines, cancer research has used mRNA to trigger the immune system to target specific cancer cells.

A Closer Look at How COVID-19 mRNA Vaccines Work

COVID-19 mRNA vaccines give instructions for our cells to make a harmless piece of what is called the “spike protein.” The spike protein is found on the surface of the virus that causes COVID-19.

COVID-19 mRNA vaccines are given in the upper arm muscle. Once the instructions (mRNA) are inside the immune cells, the cells use them to make the protein piece. After the protein piece is made, the cell breaks down the instructions and gets rid of them.

Next, the cell displays the protein piece on its surface. Our immune systems recognize that the protein doesn’t belong there and begin building an immune response and making antibodies, like what happens in natural infection against COVID-19.

At the end of the process, our bodies have learned how to protect against future infection. The benefit of mRNA vaccines, like all vaccines, is those vaccinated gain this protection without ever having to risk the serious consequences of getting sick with COVID-19.

COVID-19 mRNA Vaccines cannot give someone COVID-19.

• mRNA vaccines do not use the live virus that causes COVID-19.

They do not affect or interact with our DNA in any way.

• mRNA never enters the nucleus of the cell, which is where our DNA (genetic material) is kept.
• The cell breaks down and gets rid of the mRNA soon after it is finished using the instructions.