Responding to quickly evolving and developing pathogens and/or sudden outbreaks is limited by current vaccine technologies and production methods. This was clearly seen in the Ebola outbreak of 2014 that killed more than 10,000 people where an Ebola vaccine was not and is still not readily available for human administration.
Engineers from the Massachusetts Institute of Technology (MIT) may have solved this conundrum by developing a new type of modifiable, rapid-response, fully synthetic vaccine that seems to work against Ebola, H1N1 influenza, and Toxoplasma gondii (a common parasite relative to malaria) in mice.
The Science Behind this Breakthrough Vaccine
MIT postdocs from the Whitehead Institute for Biomedical Research and the David H. Koch Institute for Integrative Cancer Research have found a way to use and package genetic material, known as messenger RNA (mRNA), to combat disease. Jasdave Chahal, PhD, and Omar Khan, PhD, have utilized a customized nanomaterial that is large enough to carry mRNA molecules, but small enough to inject directly into muscle tissue, similar to how traditional vaccines are injected. These vaccines can code for any viral, parasitic, or bacterial protein. The molecule containing the mRNA is delivered into cells, where it can be translated into proteins that can incite an immune response from the host.
Traditional vaccines are made up of several types: dead inactivated microorganisms, live non-virulent or attenuated bacteria/viruses, and viral fragments or bacterial subunits. These organisms are grown in culture, purified and then either killed or attenuated. The dead or attenuated organisms are used in a vaccine that induces an immune response producing antibodies against that specific disease. There are, however, several drawbacks to this method of vaccination. For example, development of vaccines against organisms not grown in culture proves unlikely. Also, non-virulent organisms risk progressing into virulent ones and these vaccines cannot be created quickly or efficiently for sudden outbreaks.
A Closer Look at ‘Programmable’ RNA Vaccines
These vaccines are attractive in combatting disease because they encourage their host cells to produce numerous copies of the proteins they encode, which initiates a stronger immune response than if the proteins were directly given on their own. The idea of using RNA in vaccines has been around ages, but finding safe and effective ways to deliver them has been an obstacle.
Chahal and Khan decided to package the RNA vaccines into a nanoparticle, or dendrimer (a branched molecule). This has many advantages. One, in particular, is that the final structure, size, and pattern can be controlled. In this case, the final product was a spherical vaccine particle with a diameter similar to many viruses, enabling these particles to enter cells and utilize the same proteins that viruses would. Additional advantages are that the RNA sequences can be customized to produce nearly any protein and they are fully synthetic. This means that they do not require living systems, such as cell cultures, to grow and produce the product.
Mice that received a single dose of one of these vaccines didn’t have any symptoms following exposure to real pathogens for Ebola, H1N1 influenza, or Toxoplasma gondii. A full antibody and T cell response were driven by these RNA vaccines.
What’s the Most Promising Aspect?
Possibly the most encouraging aspect to these vaccines is how quickly the RNA and nanomaterials can be manufactured. Since, these vaccines do not need to grow in cell culture, they can be produced in just seven days. This approach can generate vaccines against new diseases quickly and effectively, lending them to be advantageous in dealing with sudden outbreaks (just like that Ebola outbreak of 2014)!
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