We found D. radiodurans not only living in the cores of nuclear reactors, but surviving exposure to everything from toxic chemicals and corrosive acids to extreme heat above the boiling point of water, subzero temperatures in the Antarctic, and the vacuum of space.
We termed such microbes extremophiles – loving extreme environments – and have found them in many strange places. Three species of fungi were discovered inside the abandoned Chernobyl Nuclear Power Plant, where scientists found that they grew faster in the presence of radiation, that they actually “eat” the radiation using the pigment melanin that captures the radiant energy, similar to the way it absorbs UV radiation in human skin to help avoid sunburns.
But recently microbiologists, led by Dr. Michael Daly at the Uniformed Services University in Bethesda, have been using knowledge of these extremophiles to help produce vaccines faster, cheaper and safer.
We mainly think of radiation as doing damage to DNA and that protecting DNA is how cells protect themselves. But that idea is changing. It appears that cell death is more about protein damage, particularly the proteins that are enzymes, those molecules that carry out almost all cellular reactions. Daly refers to this as Death by Protein Damage. Extremophiles like D. radiodurans protect their DNA repair proteins, not the DNA itself, those enzymes that rebuild the DNA after it is damaged.
Radiation itself doesn’t do much damage in the cell or in our bodies. Just like oxygen in our bodies, a photon or subatomic particle usually rips an electron off of a hydrogen or carbon atom and that electron goes and rips off other electrons and so forth, causing a cascade of hundreds or even thousands of electrons, and creating large amounts of free radicals and oxidizing molecules that can cause damage across the cell.
Because we breath oxygen, oxygen usually causes much more damage than radiation in our cells. It’s why cells evolved these repair mechanisms billions of years ago when free oxygen first entered the atmosphere. It’s also why we have recently focused on ingesting foods with high levels of antioxidants.
But if radiation levels get really high, these repair mechanisms can be used to repair the same damage. D. radiodurans manufactures special antioxidant enzymes that incorporate the element manganese, to protect the cell’s repair proteins, not to protect the cell’s DNA or RNA.
Daly realized that this could be an ideal way to make vaccines. Using manganese antioxidants while developing the vaccine could protect the proteins needed for the vaccine – the stuff our immune system recognizes and makes antibodies to fight the infection – but not the DNA or RNA that makes the invading microbe infectious.
Traditional methods for vaccine production take a long time in trial and error to determine what proteins are needed to make the vaccine, and then use recombinant DNA to produce only those proteins.
But Daly’s method avoids this trial and error period by making an inactivated whole virus vaccine quickly by saving these antigen-producing proteins on the infecting microbes surface using the antioxidant while allowing the DNA and RNA inside to be destroyed by radiation.
Many infectious disease experts agree that Daly’s method could be uniquely suited for expediting vaccine production during pandemics, including Covid-19, as well as other scourges like malaria and HIV. Daly has already been successful in making vaccines for animal studies.