Antibody cures animals of Ebola-related viruses

Marburg virus, shown here, isn't as well known as Ebola, but can also cause severe illness and death.Dr. Tom Geisbert, University of Texas Medical Branch

The closely related Marburg and Ravn viruses aren’t as well known as Ebola, but these Filoviridae family viruses all cause similar symptoms and outcomes. They typically affect multiple organs in the body, and infections often cause hemorrhage (bleeding). They can lead to severe illness and death in people and other primates. Once one of these viruses is transmitted from an animal host to a human, it can spread through person-to-person contact.

Researchers have been searching for effective ways to prevent and treat these diseases. One potential approach is to use monoclonal antibodies, which are derived from immune system molecules that bind to a specific substance, such as an invading virus. Previously, researchers were able to create a set of monoclonal antibodies from a person who had survived Marburg disease.

A group led by Dr. Thomas W. Geisbert at the University of Texas Medical Branch and Dr. Larry Zeitlin of Mapp Biopharmaceutical, Inc., chose three of these antibodies for further testing. The antibodies each bind to a different part of the Marburg virus. The work was funded by NIH’s National Institute of Allergy and Infectious Diseases (NIAID) and National Center for Advancing Translational Sciences (NCATS). Results appeared in Science Translational Medicine on April 5, 2017.

The scientists first tested the antibodies in guinea pigs. One of the antibodies, MR191-N, completely protected the animals from either the Marburg or Ravn viruses when given up to four days after infection.

The team next tested MR191-N in rhesus monkeys. Two doses of MR191-N given four and seven days after infection protected all tested monkeys from the Marburg virus. Even when doses began five days after infection, the antibodies protected all five monkeys infected with Ravn virus and four out of five monkeys infected with Marburg.

Studies of other experimental Marburg treatments have involved daily dosing regimens for seven and 14 days, with treatment beginning closer to the time of infection. “These findings extend the growing body of evidence that monoclonal antibodies can provide protection during advanced stages of disease with highly dangerous viruses and could be useful during an epidemic,” Geisbert says.

The researchers are now working to perform safety testing to advance the monoclonal antibody treatment to initial human clinical studies. Public health officials aim to have a treatment available in case of a large-scale Marburg or Ravn outbreak similar to the 2014-15 Ebola outbreak in West Africa.

—by Harrison Wein, Ph.D.