Although most of the world is protected from the polio virus thanks to a vaccine developed decades ago, some countries remain vulnerable to the disease thanks to challenges posed by a vaccine that requires repeat dosing.
Researchers from the Massachusetts Institute of Technology want to change that with a nanoparticle vaccine that can deliver multiple doses of the therapy in a single injection.
“The goal is to ensure that everyone globally is immunized,” senior author Ana Jaklenec told MIT News. “Children in some of these hard-to-reach developing world locations tend to not get the full series of shots necessary for protection.”
The injectable Salk vaccine, developed in the 1950s, requires as many as four shots to ensure full immunization. There is an oral vaccine that is still used in some developing countries thanks to its ease-of-administration, but most countries avoid using the product since it contains a viable virus that can mutate and cause infection.
With funding from the Bill & Melinda Gates Foundation, Robert Langer’s lab at MIT set out to create an injectable vaccine that could give multiple doses with a single shot.
They turned to a biodegradable polymer, PLGA, to encapsulate the vaccine. The polymer degrades over time, giving an initial burst of the vaccine at the time of injection, followed by a secondary dose a month later.
To stop the vaccine-loaded polymer from breaking down within the body, the team of researchers added positively-charged polymers to soak up protons and keep the local environment from becoming too acidic.
In a study published this week in the Proceedings of the National Academy of Sciences, Langer’s team described how the injectable vaccine performed in a rat model. The researchers sent blood samples from immunized rats to the Centers for Disease Control & Prevention and reported that the rats’ antibody response was comparable to the immune response from rats given the traditional Salk vaccine.
In their latest study, the researchers used a method that delivers the vaccine on day one and day 25 – but they noted that it would be possible to deliver three or more doses by mixing particles that are designed to deliver drugs at varying rates.
The team is hoping to advance their product to clinical trials soon, according to MIT News. They are also working a single-injection delivery approach for Ebola and HIV vaccines.