Virus-like particles have been produced that bind to cancer cells, delivering a treatment drug to tumors, and avoiding the need to expose the whole body to toxic chemicals. The work is still at proof of concept stage, carrying fluorescent proteins not chemotherapy, but it holds the potential for cancer treatment with greatly reduced side-effects.
Viruses are excellent at carrying proteins, and at finding their ways in the body to specific locations. Medical researchers have been experimenting for years with putting this to use by adding cancer-fighting drugs to viruses as “payloads” so that the rest of the body doesn't need to be exposed to their effects. There's an obvious downside, however, since the virus could make the patient sick in the process, although there are a number of ways to avoid this.
Dr Frank Sainsbury of the University of Queensland, Australia, has addressed this issue by creating virus-like nanoparticles (VNPs) with shells based on those of real viruses, but no genetic material inside, so they can't multiply inside the body.
“Viruses have evolved to contain and protect bioactive molecules,” Sainsbury said in a statement. “They’ve also evolved smart ways to get into cells and deliver these bioactive molecules.
Sainsbury based his VNPs on the Bluetongue virus, which infects ruminants, but not humans. He told IFLScience the live virus has three shells, but his VNPs only use the inner two. These shells not only protect the payload while navigating the bloodstream, but the outer shell (or middle shell in the natural virus) binds to molecules that are over-expressed in breast cancers.
Consequently, Sainsbury's VNPs travel through the body largely unhindered but become absorbed into cells when they encounter breast cancers. Sainsbury told IFLScience the process by which the VNP disassembles within the cancer to release the payload is not well understood so “the exact delivery mechanism remains to be investigated.”
Nevertheless, having published in ACS Nano that the test molecules can be incorporated into his VNPs, Sainsbury hopes to use chemotherapy drugs as a real payload. If successful, the work would allow doctors to administer far lower drug doses, since rather than hitting much of the body at random, these drugs would predominantly end up where they are needed.
According to Sainsbury, VNPs based on plant viruses have been tested before in similar ways, but his team is the first to make use of the Bluetongue virus's configuration.
The VPNs were produced by modifying Nicotinia benthamiana, a wild tobacco relative, to manufacture them in its leaves with the fluorescent protein already inside.
Sainsbury said the work is unrelated to the most famous virus-like particles, also invented at the University of Queensland, which form the basis of vaccines against the Human Papillomavirus.