A team of scientists from the Indian Institute of Science (IISc) has developed a new method to deliver a vaccine candidate for Tuberculosis (TB). According to the scientists, this new method involves using spherical vesicles secreted by bacteria coated on gold nanoparticles which can then be delivered to immune cells. The scientists claims that this new method can potentially trigger an immune response and offer protection against the disease.
According to reports, Tuberculosis (TB) which is caused by the bacterium Mycobacterium tuberculosis, kills over a million people across the world every year. According to experts, the only effective vaccine currently in use is the BCG vaccine and it contains a weakened form of the disease-causing bacterium. When this vaccine is injected into our bloodstream, it triggers the production of antibodies that can help fight the disease.
Although the BCG vaccine works well in children, it is not as effective at protecting adolescents and adults, scientists claim. This motivated Rachit Agarwal, Assistant Professor at the Centre for BioSystems Science and Engineering (BSSE), IISc, and his team to develop a potential subunit vaccine candidate that contains only parts of the infectious bacterium to stimulate an immune response.
Reportedly, the scientists have earlier developed subunit vaccines based on just a handful of proteins from the disease-causing bacteria, but none of them have been effective so far. Instead, Agarwal’s group decided to use Outer Membrane Vesicles (OMVs). According to the scientists, OMVs are spherical membrane-bound particles released by some bacteria and contain an assortment of proteins and lipids which could induce an immune response against the pathogen.
“They’re safer compared to a live bacterium, and since they are membrane-derived, they contain all kinds of antigens,” explains Agarwal, the senior author of the paper. The findings of the study were published in Biomaterials Advances journal last month.
According to the researchers, subunit vaccines typically only contain a limited number of antigens. However, OMVs contain a variety of antigens and can induce a better immune response, according to the researchers.
Mycobacterium-derived OMVs are usually unstable and come in different sizes, making them unsuitable for vaccine applications. But the OMVs coated on gold nanoparticles (OMV-AuNPs) by the IISc team were found to be uniform in size and stable. The researchers also found that human immune cells showed a higher uptake of OMV-AuNPs than of OMVs or gold nanoparticles alone.
“To synthesise OMV-AuNPs, the OMVs and the gold nanoparticles are forced together through a 100 nm filter. The OMVs break up in the process and encapsulate the gold nanoparticles,” Edna George, a former postdoctoral fellow at BSSE, and co-first author of the study said in a statement.
Now the team is planning to develop gold-coated OMVs derived directly from Mycobacterium tuberculosis and test them on animal models to take the results forward for clinical applications.