The Zika Virus made headlines in 2015 and 2016 when there was an epidemic in South and Central America. Zika mainly attacks cells in the brain known as neural progenitor cells and is not particularly harmful to adults as they don’t have many of these cells. However, it is dangerous to unborn children as they have many neural progenitor cells and the virus causes a birth defect called microencephaly, which results in an unusually small head and can lead to complications including seizures.
Now scientists are hoping to use this devastating virus as a potential cancer therapy.
Glioblastoma is the most common form of malignant brain tumour. It is an aggressive type of cancer that is particularly difficult to treat, as it often resurges and is usually lethal within two years. The tumour’s ability to return once removed is thought to be connected to glioblastoma stem cells (GSCs) which hide out in the brain and avoid cancer treatments including radiotherapy and chemotherapy. GSCs share some properties with neural progenitor cells, and as Zika specifically infects the neural progenitor cells, researchers wanted to see if the virus could also infect the GSCs.
Previous research conducted in Brazil showed that Zika could kill GSCs in a dish, as they infected human glioblastoma cells with the virus and recorded microscopic images in order observe any changes. After 48 hours, the glioblastoma cells were swollen and had a loss of cell integrity which indicated cell death.
Now, new research has extended on this and successfully managed to kill human glioblastoma cells that were transplanted into mice.
They first wanted to ensure that they could find a safe way of introducing the Zika virus to patients, and developed an attenuated Zika vaccine called ZIKV-LAV. This virus is still ‘live’ but has been genetically engineered to neutralise the infectious Zika while preserving particles which induce the death of tumour cells. In tests, ZIKV-LAV protected both mice and non-human primates against Zika infection, and when injected into mice there appeared to be no physical or behavioural side effects.
To test the theory, half of the mice were injected with human-derived GSCs and the other half received the same GSCs but with the addition of ZIKV-LAV. The mice that received only GSCs developed tumours quickly, but the mice that also received the vaccine showed delayed tumour growth and survived significantly longer.
The researchers now plan on making their cancer-killing vaccine more potent and hope to work with clinicians to develop ways to test its safety in humans. The hope for the future is that the virus can be used as a cancer treatment to hunt down GSCs and eliminate them, thus preventing the recurrence of the brain tumour.