"An international team of researchers has successfully deployed a Zika virus vaccine to target and kill human glioblastoma brain cancer stem cells which had been transplanted into mice. In a study published this week in mBio an openaccess journal of the American Society for Microbiology the team shows that a live attenuated version of the Zika virus could form the basis of a new treatment option for this fatal brain cancer.  Glioblastoma kills about  adults in the US each year and is currently incurable because patients experience a high recurrence rate of their cancer even after the standard treatments of surgery radiation and chemotherapy. Scientists suspect this recurrence is due to cancer stem cells called glioblastoma stem cells GSCs which hide out in nearby brain tissue even after the combination of therapies. During the Zika epidemic we learned that the virus preferentially infects neural progenitor cells in the fetus and causes the devastating microcephaly seen in babies born to infected mothers says PeiYong Shi a virologist at University of Texas Medical Branch in Galveston. He coled the current study with tumor biologist Jianghong Man of the National Center of Biomedical Analysis in Beijing and virologist ChengFeng Qin of the Chinese Academy of Military Medical Sciences in Beijing.  We made the connection that perhaps Zika virus could also specifically infect the GSCs because these cells have similar properties to neural stem cells says Man. In previous work Shi and his collaborators at Washington University in St. Louis showed that Zika virus did indeed attack and kill GSCs grown in the lab dish and in a mouse model of glioblastoma. In addition the Zika virus was much less efficient at attacking the differentiated healthy brain cells. image transmission electron micrograph of Zika virus NIAID If we could find a way to specifically target those GSCs that are the source of recurrence then that might provide an option to prevent recurrence or even a cure says Qin.  The teams first objective was to determine if there was a safe way to use Zika virus in patients to attack the cancer cells. Shis lab has developed a promising liveattenuated Zika vaccine candidate called ZIKVLAV that had been shown to be safe nonvirulent and effective in protecting against infection in mice and nonhuman primates. The ZIKVLAV has a small deletion from the viral genome that prevents it from replicating itself efficiently.  When the team injected this ZIKVLAV into the brains of mice they saw no health effects on the mice no weight loss and no behavioral abnormalities such as loss of appetite depression lethargy or selfinjury. The mice also functioned normally in tests for anxiety and motor function.  Next the team wanted to show whether the ZIKALAV could work to infect and kill human patientderived GSCs in a mouse model. So they mixed GSCs from two different human patient donors with the ZIKALAV and injected the mixture into the brains of mice. Mice that got the injection of the GSCs only rapidly developed tumors. Mice that got the ZIKVLAV injected as well saw a significant delay in tumor development. Coimplanting the virus along with the GSCs also prolonged the median survival time of the treated mice to around  days compared to around  days for the untreated mice who received GSCs alone. Qin says that perhaps in the future patients would be given the Zika vaccine at the same time as surgery to let the viruses hunt down the GSCs and eliminate them.  Finally the team investigated the cellular mechanisms that the modified Zika virus used to kill the GSCs. They took GSCs treated with the ZIKVLAV and those GSCs not treated and sequenced all the RNA messages being expressed in these two cell populations. Comparing those profiles the team found that in the treated cells the virus triggered a strong antiviral response in the cells which induced inflammation and eventually cell death.  Next the team will work with clinicians to develop safety tests of the ZIKVLAV in glioblastoma patients. They may also modify the Zika virus further to make it an even more potent cancer cell killing machine. For example Man explains the researchers could add an immune modulator as a cargo in the viral genome. Then once such a virus infects a cancer cell and kills it the immune modulator would be released to alert and activate the patients systemic immune system against the remaining cancer cells. As a virologist I see that we should take advantage of the bad side of viruses says Shi. They should have a role to play in cancer treatment.   The American Society for Microbiology is the largest single life science society composed of more than  scientists and health professionals. ASMs mission is to promote and advance the microbial sciences. ASM advances the microbial sciences through conferences publications certifications and educational opportunities. It enhances laboratory capacity around the globe through training and resources. It provides a network for scientists in academia industry and clinical settings. Additionally ASM promotes a deeper understanding of the microbial sciences to diverse audiences."