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Research Institute Targets Ebola, Other Infectious Diseases

By Cheryl Pellerin
DoD News, Defense Media Activity

WASHINGTON, Oct. 30, 2014 – Ebola virus disease is a big focus among scientists at the U.S. Army Medical Research Institute of Infectious Diseases, where the mission since 1969 has been to protect warfighters from biological threats and to investigate disease outbreaks and other public-health threats.

Click photo for screen-resolution image
This digitally colorized transmission electron micrograph shows numerous Chikungunya virus particles that are composed of a central dense core surrounded by a viral envelope. Each virion is about 50 nanometers in diameter. CDC photo by Cynthia Goldsmith
  

(Click photo for screen-resolution image);high-resolution image available.

But Ebola is just one of the lethal pathogens on U.S. lists of high-priority bioterrorism agents that pose a risk to national security, and USAMRIID scientists conduct research on many of them, whether the pathogens appear on the battlefield or in nature.

At USAMRIID last week, DoD News interviewed Dr. Travis K. Warren, principal investigator in the Division of Molecular and Translational Sciences; Dr. John M. Dye Jr., Viral Immunology branch chief; and Army Maj. (Dr.) Matthew Chambers, chief of field studies in the Division of Medicine.

All discussed the USAMRIID mission and their work beyond Ebola.

“We are not the U.S. Army Medical Research Institute of Ebola, but we feel like it now. We are the U.S. Army Medical Research Institute of Infectious Diseases,” Dye said. “And although we’re focused on Ebola, we have programs on all Category A and Category B [bioterrorism] agents, and we’re looking at [those pathogens] for therapeutics, vaccines and diagnostics, trying to get ahead of the curve for the next bug that comes out to bother us.”

He added, “That's what our job is here -- to be prepared and to look ahead, and have the foresight to develop those assays ahead of time.”

Medical countermeasures

Chikungunya virus, dengue virus, Crimean Congo hemorrhagic fever virus, Lassa virus, Venezuelan equine encephalitis virus, Eastern equine encephalitis virus and many others are among the viruses for which USAMRIID is creating medical countermeasures for warfighter and public-health protection. All of these pathogens can be classified as creating emerging or re-emerging infectious diseases in people, and most originate in animals and cross over to people.

Nearly 75 percent of new emerging or re-emerging diseases that affect humans are zoonotic, meaning they spread from animals to people, according to the Centers for Disease Control National Center for Emerging and Zoonotic Infectious Diseases.

Emerging infectious disease outbreaks, Chambers explained, tend to happen in countries with unstable governments, encroachments by people on forests and other wildlife habitats, increased commercialization and trade, and a huge increase in transportation in and out of the country.

“Bam! An outbreak happens” when these factors collide, Chambers said, snapping his fingers for emphasis.

Many of these circumstances, along with weak health care systems, contributed to the historic Ebola virus disease outbreak in West Africa, for which the World Health Organization reports more than 10,000 confirmed and suspected cases and nearly 5,000 deaths.

“Viruses have a very high mutation rate, especially RNA viruses,” Dye said. “Therefore, their genetic material constantly changes, allowing them the possibility to mutate and [acquire the ability] to infect a new species.”

RNA viruses have ribonucleic acid as their genetic material and so are less genetically stable than DNA, or deoxyribonucleic acid, viruses, such as smallpox, herpes and chickenpox. For example, Dye said, the constantly mutating flu viruses are RNA viruses.

At USAMRIID, scientists are keeping their eyes on, among others, alphaviruses such as Chikungunya and Eastern equine encephalitis virus, and arenaviruses such as Lassa virus. All of these are RNA viruses, and all are zoonotic.

Warren said Eastern equine encephalitis virus occurs on the U.S. East Coast, and CDC says most cases of Eastern equine encephalitis have been reported from Florida, Georgia, Massachusetts and New Jersey. People get this virus from mosquitos that have bitten infected horses.

CDC says most people infected with the virus have no apparent illness, but for those who get encephalitis, or brain inflammation, Eastern equine encephalitis is one of the most severe mosquito-transmitted diseases in the United States. It has about a 33 percent mortality rate, and most who survive have brain damage. There’s no specific treatment for the disease.

“There's a Western version, there's a South American version of it,” Warren said. “We haven't discovered them all yet.”

Another alphavirus, Chikungunya virus, is transmitted to people by mosquitoes that picked up the virus by biting chimpanzees or other animals. The most common symptoms are fever and joint pain. The virus can be imported to new areas by infected travelers, and there is no vaccine to prevent it or medicine to treat it.

Since its discovery in Tanganyika, Africa, in 1952, Chikungunya outbreaks have occurred in countries in Africa, Asia, Europe and the Indian and Pacific oceans. In late 2013, it was found for the first time in the Americas on islands in the Caribbean.

From 2006 to 2013, an average of 28 people per year in the United States had positive tests for recent Chikungunya virus infection. All were travelers visiting or returning to the United States from affected areas, mostly in Asia, CDC said.

Beginning in 2014, cases were identified in travelers returning from the Caribbean. As of Oct. 21, 1,482 Chikungunya virus disease cases have been reported from U.S. states to ArboNET, a national surveillance system for arthropod-borne viruses in the United States, according to CDC.

Arenaviruses, also of interest to USAMRIID, often come from rodents and include Lassa virus, discovered in 1969 when two missionary nurses died in Nigeria. Its host is a West African rodent called the multimammate rat.

In some areas of Sierra Leone and Liberia, 10 percent to 16 percent of people admitted to hospitals have Lassa fever, CDC said. Ribavirin, an antiviral drug, has been used successfully in Lassa fever patients.

“Viruses basically usurp your own cellular machinery and take over your own cells, [turning them into] virus-producing factories,” Dye said. “It's brilliant, actually, because they don't have to have all the encumberments of other proteins.”

Most viruses just need an opportunity to infect people, Warren added.

“Once the Ebola outbreak has been controlled,” Dye said, “what's important for people to realize is that … we're still going to be here, working not just on filoviruses [such as Ebola], but all the other viruses.”

“A year from now when the last Ebola patient … recovers in the hospital, the work goes on here,” Chambers added, “and thank goodness it does, because we were doing it for years before the Ebola outbreak happened, and we'll be doing it after the outbreak [is over], and for that reason, we'll be a little bit more prepared than we were this time.”

(Follow Cheryl Pellerin on Twitter @PellerinDoDNews)

 

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