Researchers at the Massachusetts Institute of Technology (MIT) have engineered a harmless virus into a nanoscale delivery platform that could help create personalized cancer vaccines. By controlling how densely cancer-targeting proteins are displayed on the virus, the team developed vaccine particles that significantly reduced tumor development in mice.

The platform uses a modified bacteriophage called M13, a virus that infects bacteria but is harmless to humans. It forms a long, thread-like structure called a nanofiber that can be coated with antigens, proteins that help the immune system recognize specific targets.

The researchers found that adjusting the concentration of these antigens on the viral structure changed how effectively the vaccine stimulated an immune response. This could allow scientists to customize the particles with different antigens to target individual patients’ tumors.

The study was led by researchers at MIT’s Koch Institute for Integrative Cancer Research. Angela Belcher, a professor of biological engineering and materials science and engineering, was the senior author, while research scientist Shengnan Huang led the work.

The M13 bacteriophage consists of a single strand of DNA surrounded by a protein shell, or capsid. The researchers modified a capsid protein called pVIII, attaching cancer antigens to its surface by incorporating the corresponding genetic instructions into the virus.

However, controlling how many antigen-bearing proteins appeared on the viral structure was important. The researchers found that adding one or two negatively charged amino acids to the pVIII protein increased antigen density. They could further adjust it by introducing a genetic mutation that slowed antigen production.

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