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March 23, 2009
Researchers close on vaccines to slay viruses

By Quinn Eastman

Effective vaccines against some of the world’s deadliest viruses are within reach, top virologists reported at the Emory Conference Center March 16.

The Emory Vaccine Center organized a day-long symposium featuring research on “viral hemorrhagic fevers,” illnesses caused by viruses such as Ebola, Marburg, hantavirus, lassa, dengue and yellow fever.

Ebola and Marburg are swift-acting and deadly enough to have inspired science fiction movies and best-selling thrillers (see: Richard Preston’s “The Hot Zone”). Less deadly but still fearsome mosquito-borne dengue infects millions of people every year and is a major public health threat in developing countries, according to the World Health Organization. A troubling feature of dengue is “antibody-dependent enhancement,” where previous exposure to one strain of dengue can make infection by a related strain worse.

“Viral hemorrhagic fever” describes a severe syndrome affecting multiple organs. Symptoms commonly include fever, fatigue, dizziness, muscle pain and weakness. Sometimes blood vessels break down, causing internal bleeding leading to shock.

Most of the viruses naturally are found in animals which are transmitted to humans via insects notably mosquitoes and are geographically restricted to the areas where their host species live. However, their true reservoir remains to be defined. For example, the natural host of Marburg virus appears to be bats, although one of the way humans usually get infected is from contact with monkeys.

At the conference, researchers from the U.S. Centers for Disease Control and Prevention described their recent investigation of a gold mine in Uganda where several miners had been infected with Marburg. Inspection of the mine demonstrated that bats infected with Marburg lived inside these gold mines.

In addition, scientists from the CDC, the National Institutes of Health and several universities reported on animal models for studying viral hemorrhagic fevers, experimental vaccines, and new viruses isolated from field research and how they are related to previously known viruses.

The symposium was the first convened on the subject of hemorrhagic fever viruses by the Emory Vaccine Center, with support from a grant from the National Institute of Allergy and Infectious Diseases at the NIH.