Engineers Take a Closer Look at How a Plant Virus Primes the Immune System to Fight Cancer

Side-by-side illustration of the cowpea mosaic virus (CPMV, left), which has potent cancer-fighting effects, and the closely related cowpea cholorotic virus (CCMV, right), which does not exhibit anti-tumor effects. Credit: Anthony Omole

July 25, 2025

A virus that typically infects black-eyed peas is showing great promise as a low-cost, potent cancer immunotherapy—and researchers are uncovering why.

In a study published in Cell Biomaterials, a team led by chemical and nano engineers at the University of California San Diego took a closer look at how the cowpea mosaic virus (CPMV), unlike other plant viruses, is uniquely effective at activating the body’s immune system to recognize and attack cancer cells.

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CPMV, the team found, stimulates type I, II and III interferons—proteins with well-known anti-cancer properties. “This is particularly interesting because some of the earliest cancer immunotherapy drugs were recombinant interferons,” noted Omole. Meanwhile, CCMV stimulates a set of pro-inflammatory interleukins that do not translate to effective tumor clearance. Another difference lies in how these viruses’ RNAs are processed within mammalian cells. CPMV RNAs persist longer and get delivered to the endolysosome, where they activate toll-like receptor 7 (TLR7), a critical component in priming antiviral—and more importantly—anti-tumor immune responses. CCMV RNAs, on the other hand, fail to reach this activation point.

CPMV also offers a unique advantage as a cost-effective immunotherapy. Unlike many other therapies that require complex and costly manufacturing, CPMV can be produced using molecular farming. “It can be grown in plants using sunlight, soil and water,” Omole said.

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