Zika Virus Can Combat Central Nervous System Tumors

Researchers in Brazil recently reported proving the potential of the Zika virus to combat advanced-stage central nervous system tumors in dogs. 

Elderly dogs with spontaneous brain tumors were treated with injections of Zika by scientists affiliated with the Human Genome and Stem Cell Research Center (HUG-CELL) supported by São Paulo Research Foundation - FAPESP and hosted by the University of São Paulo (USP).

According to Oswaldo Keith Okamoto, a professor and a member of HUG-CELL, this data suggests viral therapy may be applicable to several types of central nervous system cancer, in both children and seniors over the age of 60. 

"These two groups tend to suffer more often than not from aggressive types of tumor, for which there are no effective treatments at present," he said in the related press release.

The study was published on Tuesday, March 10, in the journal Molecular Therapy.

"We observed a surprising reversal of the clinical symptoms of the disease, as well as tumor reduction and longer survival with quality, which matters most. We're genuinely excited by the results," Mayana Zatz, a professor at USP's Institute of Biosciences (IB) and HUG-CELL's principal investigator said in a press release.

"The findings confirm that the therapy acts via two mechanisms. The infection triggers an inflammatory reaction, and defense cells migrate to the site," said Carolini Kaid, who has a postdoctoral scholarship from FAPESP and is the first author of the article.

According to Kaid, central nervous system tumors respond poorly to immunotherapy because the blood-brain barrier that protects the brain from potentially toxic substances present in the blood hinders the migration of defense cells to the site.

However, post-mortem analysis of the dogs' brain tissue showed that T lymphocytes, macrophages and monocytes had infiltrated the tumor mass.

"The analysis also showed that Zika was present only at the edges of the tumor. No other brain cells were affected. This is a most important finding, enhancing our confidence that the treatment is safe," Kaid said.

In the group's prior experiments with mice, Zika destroyed tumor cell lines derived from medulloblastoma and atypical teratoid/rhabdoid tumor (AT/TR), central nervous system cancers of embryonic origin that usually manifest in children. 

The researchers also conducted in vitro tests in which they observed Zika's potential to infect and destroy glioblastoma and ependymoma cells.

The in vitro studies performed by the HUG-CELL group compared the virus's interactions with "tumor stem cells" and healthy neural progenitor cells, a type of brain stem cell that gives rise to neurons, astrocytes, and oligodendrocytes, among other nerve cells.

"When we infect the neural progenitor cells, Zika interrupts their proliferation, and some of them die. But the spheres [formed when progenitor cells cluster together in 3D culture] remain relatively intact. In the case of tumor stem cells, the destruction is far more prominent.” 

“Our in vitro tests also showed that the virus doesn't infect mature nerve cells such as neurons. That's a very positive finding," Kaid said.

According to Okamoto, groups in the United Kingdom and Greece are interested in leading collaborative projects in search of a better understanding of Zika's action mechanism in tumor stem cells.

The São Paulo Research Foundation (FAPESP) is a public institution with the mission of supporting scientific research in all fields of knowledge by awarding scholarships, fellowships and grants to investigators linked with higher education and research institutions in the State of São Paulo, Brazil. 

You can learn more about FAPESP here. 

Zika virus news published by Zika News.