Vaccine Protects Monkeys from Ebola, Marburg Viruses

(HealthDay News) -- An experimental combination vaccine that uses so-called virus-like particles (VLPs) fully protected monkeys against the deadly Ebola and Marburg viruses, U.S. researchers say.

Ebola and Marburg are viral hemorrhagic fevers, the only two known members of the filovirus family of viruses, according to the U.S. Centers for Disease Control and Prevention. These often fatal infections have triggered highly publicized outbreaks in Africa over the past few decades.

"VLPs are one of the most promising candidates for protecting humans against Ebola and Marburg virus infections," and could be safer than other vaccine candidates, researcher Dr. Kelly Warfield, of the U.S. Army Medical Research Institute of Infectious Diseases, said in a prepared statement.

Traditional vaccines against viral diseases contain whole viruses -- either dead or weakened versions of the virus that causes the disease or a virus that's genetically similar to the one that causes the disease. But these vaccines do carry a slight risk of viral reactivation and resulting infection of a patient.

"Since the VLP vaccine does not use a whole virus, there is no chance of infection," Warfield said. Some VLP-based vaccines, such as the human papillomavirus (HPV) vaccine, are already in use.
In this study, Warfield and colleagues infected insect cells with specially engineered baculoviruses. The infected cells then produced VLPs for either Ebola or Marburg, which were purified and mixed together to create the vaccine.

Two groups of monkeys were exposed to Ebola and Marburg viruses. The group that had been vaccinated with the combination VLP vaccine showed no signs of infection, while the monkeys in the non-vaccinated group became infected and died.

The findings were presented Tuesday at the 2008 American Society for Microbiology Biodefense and Emerging Diseases Research Meeting in Baltimore. The researchers hope to begin human clinical trials of the Ebola/Marburg VLP vaccine within a few years.

More information
The U.S. Centers for Disease Control and Prevention has more about viral hemorrhagic fevers.