This colorized, negative stained transmission electron microscopic (TEM) image, depicts a number of Marburg virus virions. [CDC/ Frederick Murphy]
This colorized, negative stained transmission electron microscopic (TEM) image, depicts a number of Marburg virus virions. [CDC/ Frederick Murphy]

Filoviruses such as Ebola often spread rapidly and lead to hemorrhagic fevers in humans with extremely high morbidity and mortality rates. The development of therapeutics to treat these deadly viral outbreaks are essential to help infected patients and minimize the public health threat. Now, a team of researchers from The University of Texas Medical Branch at Galveston, Mapp Biopharmaceutical, and Vanderbilt University have developed an antibody treatment that successfully protected nonhuman primates against the deadly Marburg and Ravn viruses, relatives of Ebola, even when administered five days after infection.

Findings from the new study showed that the experimental treatment cured 100% of guinea pigs and rhesus monkeys in late stages of infection with lethal levels of Marburg and Ravn viruses. The study results were published recently in Science Translational Medicine through an article entitled “Therapeutic treatment of Marburg and Ravn virus infection in nonhuman primates with a human monoclonal antibody.”

There are currently no vaccines or drugs approved for human use to protect against the Marburg and Ravn viruses. These two filoviruses cause severe and often lethal disease in people. The average case fatality rate of Marburg virus disease since the first recognized outbreak in 1967 is 80%.

Micrograph of the Marburg virus. [The University of Texas Medical Branch at Galveston]
Micrograph of the Marburg virus. [The University of Texas Medical Branch at Galveston]

In the current study, the investigators gave the animals a therapeutic candidate, MR191-N, which is a monoclonal antibody (mAb) derived from a person who survived Marburg disease. The authors report that two doses of MR191-N were able to confer protection of up to 100% when treatment was started up to five days post-infection. Prior studies of different experimental Marburg treatments involved daily dosing for 7 and 14 days, respectively, with treatment beginning closer to the time of infection.

“In this paper, we demonstrated that one monoclonal antibody is able to protect up to 100% of Marburg or Ravn virus-infected nonhuman primates when the antibody treatment is given up to five days following exposure to a lethal amount of the virus,” explained senior study investigator Thomas Geisbert, Ph.D., professor in the department of microbiology and immunology at UTMB. “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.”

Much of the study was conducted in Biosafety Level (BSL)-4 at UTMB's Galveston National Laboratory (GNL). BSL-4 is a highly-restricted area where scientists wear positive-pressure protective suits and study pathogens that cause severe and often fatal diseases. UTMB has the only functioning BSL-4 laboratory located on an American university campus.

The 2013 to 2016 Ebola virus epidemic highlighted the troubling lack of preventive or treatment options for filoviruses. Some of the therapeutics used to treat those infected with Ebola were developed and tested in the GNL.

“The level of protection observed by Dr. Geisbert's team with this antibody is very impressive. We plan to advance this product towards human safety testing as quickly as possible,” concluded co-senior study investigator Larry Zeitlin, Ph.D., president of Mapp Biopharmaceutical.







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