Kiwi study could aid new weapon against cancer

Dr Mihnea Bostina looks at a Seneca Valley Virus attached to its cancer cell specific receptor. Photo / Supplied

Kiwi scientists have used high-resolution images to reveal how an anti-cancer virus interacts with tumour cells, increasing its potential to save lives.

Seneca Valley Virus (SVV), a newly discovered virus which infects cancer cells but not normal tissue, has become a focus of Dr Mihnea Bostina's OMNI Electron Microscopy unit at the University of Otago.

He hoped the results of a just-published study might help develop the virus for clinical use against cancer.

Working with researchers from Japan's Okinawa Institute of Science and Technology, the group used cryo-electron microscopy to capture thousands of images of the virus bound to its receptor, using them to reconstruct a high resolution structure of the complex.

The structure demonstrated how SVV discriminated between its preferred receptor - cancer cells - and other similar proteins, such as healthy tissue.

"We can see exactly how the virus breaks into the cancer cells, while leaving other cells untouched," Bostina explained.

The virus was a strong contender for effective virotherapy because it selectively targeted a receptor found only in tumour cells in more than 60 per cent of human cancers.

The receptor, a protein called ANTXR1, was expressed on tumours, but it had a cousin, ANTXR2, that only appeared on healthy tissues.

SVV didn't bind with the similar receptor on healthy cells, and only showed a strong affinity for ANTXR1.

SVV had already demonstrated its cancer-fighting abilities in clinical trials, but there was one problem – the body built up immunity to the virus within just a couple of weeks.

"This structure teaches us which part of the virus is essential for binding to the receptor and which is not," Bostina said.

"If we want to make the virus more efficient at invading cancer cells, we can leave intact the part that interacts with the cancer cells and modify the rest so the virus can escape the attack of the immune system."

Study lead author and Otago University PhD candidate Nadishka Jayawardena said he'd "always been intrigued" by how naturally occurring micro-organisms could be used for human benefit.

"Being able to work on a virus that can kill cancers is very rewarding, especially knowing that one day our findings could potentially lead to tackling a major global health issue."