November 14, 2016

Research Roundup: Treating drug-resistant infections, Ebola virus mutations, and Zika vaccine clinical trials

Kat Kelley
Senior Program Assistant

Researchers at the US National Institutes of Health (NIH) have developed a test that can rapidly screen chemical compounds for their ability to treat drug-resistant infections. The team at NIH has already put the test to use, evaluating approved medicines, promising compounds, and drug combinations against common drug-resistant bacteria. After screening an estimated 4,000 drugs and compounds, the researchers identified 25 that effectively killed drug-resistant Klebsiella pneumoniae in the lab, including not only antibiotics, but also antifungals, antivirals, antiseptics, and even anticancer medicines. The test has also revealed three drug cocktails—each comprised of three different medicines—that can effectively treat ten common multidrug-resistant bacteria. These findings will enable clinicians to prescribe drug combinations with near certainty that they will treat a drug-resistant infection without waiting on lab results. While the tool is not yet commercialized, it can be mobilized to rapidly respond to emerging drug-resistant infections.

A new study has revealed that during the 2014–2015 Ebola outbreak in West Africa, the virus evolved, enhancing its ability to infect humans. Previously, Ebola was thought by many scientists to be relatively static; however, researchers at the University of Massachusetts Medical School and University of Nottingham have independently identified a mutation in the Ebola genome—A82V—that appeared during the outbreak and could have made the virus two to four times more virulent. The mutation affects the cells on the surface of the virus that are responsible for infiltrating a host’s cells. For viral cells, shape matters, as it enables them to latch onto host cells like a key in a lock. The researchers suspect that A82V adjusts the shape of these surface proteins, allowing them to better fit into human cells. The mutation also enhances the virus’ ability to infect the cells of chimps and monkeys, while hampering its ability to infect bats, dogs, cats, rats, and mice. The team also discovered that patients with the new, mutated strain of Ebola were 27 percent more likely to die. Further research is needed to confirm this finding.

A vial of the National Institute of Allergy and Infectious Diseases (NIAID) Zika Virus Investigational DNA Vaccine, taken at the NIAID Vaccine Research Center’s Pilot Plant in Frederick, Maryland. (Photo: NIAID)

Last week, the NIH and the Walter Reed Army Institute of Research (WRAIR) initiated clinical trials of an experimental Zika vaccine—the first of five phase 1 trials evaluating the vaccine. The vaccine platform was first used by WRAIR in developing a vaccine against Japanese encephalitis, a fellow flavivirus. The Zika Purified Inactivated Virus (ZPIV) contains complete, inactivated virus particles that will not cause disease but train the immune system to recognize and mount a robust response to the Zika virus. In preclinical trials, the vaccine candidate successfully induced an immune response and protected animals against the virus. The five phase 1 clinical trials will test the vaccine compared to placebos in different doses and schedules, as well as in different populations, including individuals previously exposed to flaviviruses (including Zika, yellow fever, dengue, Japanese encephalitis, and West Nile) and dengue, individuals who have received yellow fever or Japanese encephalitis vaccines, and those who have received the NIH’s experimental DNA-based Zika vaccine.