August 6, 2021 – Find it. Kill it. This is the simple premise behind new biomaterial-based vaccines that experts are developing to ward off future pathogens or germs that could threaten human health.
When designing next-generation vaccines, scientists rely on the idea that the structure of a future pathogen will, on a pandemic scale, be the same as those they already know.
The new class of vaccines is being developed to boost the immune system so that the body can respond quickly to a range of pathogens.
The new biomaterial-based vaccines are also shelf-stable, which means they don’t need to be refrigerated like some of the COVID-19 syringes. This is encouraging news for faster vaccine adoption and will help poorer countries lacking refrigerated supplies.
New biomaterial vaccines harness the body’s natural immune response, explains Michael Super, PhD, of the Wyss Institute at Harvard University in Boston, who is the lead author of a new study examining what the vaccines can do.
Previous research has shown that scientists can create a depot under the skin that acts like a protective lymph node or small bean-shaped structure that, as part of the body’s immune system, helps fight infection and disease.
Strengthening the immune system
This opens up the possibility that a biomaterial like silica, an important trace element already present in the body’s connective tissue, could be used to inject a pathogen that will help the body produce antibodies against it and aid immune system recovery explains super.
“We recruit the immune system at this point, and then the dendritic cells take in the antigen that you put into this biomaterial,” he says. “This creates a danger signal that activates these dendritic cells in a very natural way. The immune system doesn’t overproduce, but it reacts, and we have found that it reacts very quickly. “
As the cells at the deposit site mature, they learn what signals to send to the rest of the immune system in order for it to respond to the pathogen attacked by the vaccine. These cells then travel around the body and stimulate other immunoreactive cells.
In their study, Super and his research team went one step further and used their biomaterial vaccine to introduce live, weakened pathogens into the body. This process kept the pathogen viable but harmless.
This process is different from the recombinant spike protein vaccines used for COVID-19, which use genetically modified drugs to produce antibodies that target the coronavirus.
“We found that we can take live pathogens and kill them with an antibiotic or something else and use that directly as part of the vaccine of our choice,” says Super. “You don’t have to go through this complex manufacturing process; you can just take it, capture it, kill it and mix it with the biomaterial and inject it or implant it. We have seen that then you have these native antigens” to “fight the pathogen.”
The team used this process to fight a form of E. coli, a type of bacteria scientifically known as Escherichia coli that is particularly dangerous to farm animals. They infected a pig and then gave it an antibiotic to kill the infection. They extracted these dead bacteria from the pig’s blood and combined them with a biomaterial, in this case mesoporous silicon, to make a vaccine.
After giving this vaccine to mice, they exposed the mice to a different strain of E. coli and the mice fought the infection.
“It’s not just the pig-to-mouse aspect that is exciting, but that we were able to protect ourselves from a deadly challenge from another variety,” says Super. The results were similar when the vaccine was tested on mice infected with Staphylococcus aureus, he says.
Most of this study, which focused on immune responses to bacteria, was completed before the COVID-19 pandemic began. However, the researchers say the work has important implications for preparing for future pandemics.
Stockpiling for future threats
“One of the problems is that very often you do not know which pathogen you are dealing with, especially when there is a bio-threat,” emphasizes Super. But “we believe that the structure of a microbial pathogen will be similar to the native, normal pathogens we already know.”
If so – and research suggests – a vaccine against an under-studied pathogen could be made with pathogens that attack structurally similar but well-studied bacteria.
Biomaterials can be inexpensively produced in large quantities and dried for future use.
“We see this as something that can be manufactured, stored and ready to use at any time,” explains Super.
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Nature Biomedical Engineering: “Biomaterial vaccines that capture pathogen-associated molecular patterns protect against bacterial infections and septic shock.”
Michael Super, PhD, senior senior scientist at the Wyss Institute, Harvard University, Boston.
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