BAR HARBOR—In February, MDI Biological Laboratory held an informative, virtual webinar about how mRNA is revolutionizing vaccines. The Science Café discussion, hosted by Director of Development Jeri Bowers, featured guest discussion leader Elisabeth Marnik, who received her doctorate from Tufts University.
Marnik began the presentation about mRNA with a general explanation of how the immune system works when fighting infections. “The goal of the vaccination is to cause your immune system to turn on so that you’re then protected from exposure to the real pathogen,” she said.
Marnik explained that the human immune system is composed of both memory cells and adaptive immune system memory cells that work together to defend the body against infection.
“You have a bunch of cells that are within the innate immune system and these cells are your first line of defense when a bacteria or virus penetrates the barrier and infects,” she said. When the innate immune system cells need backup, Marnik said they use the adaptive immune system.
According to Marnik, COVID mRNA vaccines, such as the two-dose Pfizer/BioNTech and Moderna vaccines, give cells instructions to make harmless pieces of what is called a spike protein, which is found on the surface of the virus that causes COVID-19. This unique spike protein is needed for the virus to enter cells.
“mRNA is different from DNA; mRNA cannot damage your DNA, it is very fragile and is constantly needing to be replaced by your cells to make new proteins,” she said.
According to Marnik, because mRNA is so fragile, scientists engineered a protective bubble, called a lipid envelope, to enclose it, which allows the mRNA to be used without being degraded. Ingredients such as salts, sugars and buffers are included in the vaccine to help stabilize the mRNA.
“The DNA has all this information to make these proteins with memory cell protection; the RNA takes the information from the DNA and lets it be converted into proteins.”
Marnik generalized the functions of DNA, mRNA and proteins in the immune system when invaded by a virus. “You have these innate immune cells, that survey their surroundings, and whenever something doesn’t belong—something that’s foreign—they eat the virus or bacteria, they break it down and then they have a mechanism that allows them to present the virus on the surface, and it lets the immune system know that your being invaded by a foreign pathogen,” she said.
“Scientists took just the region of the viral genome that makes the spike protein to make the mRNA vaccine.”
Once the cells make copies of the protein, they destroy the genetic material from the vaccine.
“The RNA cannot get into the nucleus, I know there is a lot of concern that the RNA vaccines could potentially damage individual’s DNA, but that’s not possible,” Marnik said. Essentially, to get into the nucleus, the vaccine would need specific access codes that allow molecules back into the nucleus, which the mRNA does not have.
Cells, however, do recognize RNA and will use it to make a spike protein. “Then all of the other immune cells will know it [RNA] doesn’t belong,” she said. Marnik said the vaccine will then mount an adaptive immune system response to clear whatever cells have the spike protein, which will expose and train the immune system to respond in the future to prevent infection.
Marnik said that the immune system responds to vaccines in a similar way, developing memory cells from the vaccine to prevent infection without having to go through the actual illness.
People given the vaccine can experience fatigue, headaches, joint pain, vomiting and fever. These are only symptoms of the body reacting to recognizing the infection. The vaccine’s second dose symptoms have been said to be much worse. “But that’s because you’re getting re-exposed to the spike protein again…when receiving the second dose, your immune system is going to act quicker and more strongly to the infection,” Marnik explained.
Despite the claims on the news reporting anaphylactic shock from the vaccine, Marnik assured that the risk of anaphylaxis is low.
She referenced studies that showed that just 21 of the 7.5 million people who got the Moderna vaccine reported anaphylactic shock, and the numbers were 50 out of 9.9 million for the Pfizer vaccine.
“Because these vaccines are new, we don’t know how long the protection will last,” said Marnik. Since it took less than a year to engineer, Marnik recognized that there may be some who are skeptical, but she advises everyone to get vaccinated.
“The more people we infect, the more the virus can mutate…Hopefully you can make a decision when your chance comes up to get the vaccine,” she said.