University California, San Diego - Vaccines & Immunotherapy

Nicole Steinmetz, Professor of NanoEngineering and Director of the Center for Nano-Immuno-Engineering at the University of California San Diego (UC San Diego) takes a unique approach by engineering plant-virus-based nanomaterials. In her research, Dr. Steinmetz pushes to new frontiers in medicine and bio-nanotechnology through the design, development and testing of plant-derived materials and biologics, with a focus on human and plant health. Her vision is to translate promising plant-derived materials and biologics into clinical and commercial applications.

The Steinmetz Lab repurposes plant viruses to yield nanoparticles that interface with the immune system for applications such as vaccines and immunotherapy. Her extensive research includes vaccines for COVID-19, for which her lab produces the nanoparticles in plants, and post-harvest turns them into vaccine candidates. Her lab also focuses on preventing and treating cancer, where they have already transitioned to treating canine patients in collaboration with Dartmouth College. For cancer therapy her lab develops vaccines that use a plant virus as a stimulatory agent injected directly into the cancerous tumour to restart the cancer immunity cycle and therefore not only treat the disease but protect from recurrence and outgrowth of metastatic disease.

Other areas of research include cardiovascular applications, as well as living materials and agricultural nanotechnology solutions targeting plant health. The lab’s research is funded by agencies and associations such as National Institute of Health (NIH), National Science Foundation (NSF), Department of Defense (CDMRP) and the United States Department of Agriculture (USDA).

What makes plants suitable for developing vaccines?

From a more global perspective, researchers and companies alike have turned to plants for a particular advantage: plant molecular farming is scalable. For any research that takes the approach of fermentation, for example, going from a small to large scale can easily change the production process. However, when plants are being used as the “production factory” and the team needs more product, they simply grow more plants. In addition, since her research relies on using plant viruses, it makes sense to produce them on the original host which are plants.

Also, in terms of safety, one advantage is that certain pathogens do not affect plants and plant viruses are considered safer to work with and they are not pathogens.

Choosing the right plants

Because the type of research demands making live virus particles -- meaning that they are infectious towards plants -- they often use the live virus which allows the virus to make copies of itself. To achieve this, the Steinmetz Lab uses Cowpea mosaic virus and Tobacco mosaic virus (amongst several others), which propagate in black eyed peas or Nicotiana benthamiana (Australian Tabaco); the latter plant is susceptible to many plant viruses.

Using chambers for research

Currently, the Steinmetz Lab uses six Conviron plant growth chambers and one plant growth room with additive humidification and dehumidification. The specific Conviron equipment selected was driven from a process identifying the Lab’s overall condition requirements coupled with growth stages and type of plants.

During her career, Dr. Steinmetz has relied on using greenhouses and a number of controlled environments. Steinmetz stressed that most of the experiments they conduct can be done in a greenhouse or in fully controlled environments. However, she points out that reach-in and walk-in chambers have the advantage of providing a more reliable environment to exactly reproduce the desired conditions which are harder to achieve in a greenhouse.