By Robert Preidt, HealthDay Reporter

(HealthDay)

TUESDAY, Jan. 20, 2015 (HealthDay News) -- Genetic changes that have occurred in the Ebola virus over the last few decades could make it more difficult for scientists to find ways to treat the deadly pathogen, a new study says.

Many of the most promising experimental drugs being developed to fight Ebola bind to and target a section of the virus's genetic sequence or a protein derived from that genetic sequence. If there are significant changes in Ebola's genetic sequence, these drugs may not work, the researchers explained.

The researchers compared the genetic makeup of the Ebola strain causing the current outbreak in West Africa with the genetic makeup of strains that caused outbreaks in Africa in 1976 and 1995. Compared to the older strains, the current strain had changes in about 3 percent of its genetic structure, the study authors said.

The findings were published Jan. 20 online in the journal mBio.

"Our work highlights the genetic changes that could affect these sequence-based drugs that were originally designed in the early 2000s based on virus strains from outbreaks in 1976 and 1995," study senior author Gustavo Palacios said in a journal news release. He is director of the Center for Genome Sciences at the U.S. Army Medical Research Institute of Infectious Diseases in Frederick, Md.

Study lead author and U.S. Army Captain Jeffrey Kugelman, a viral geneticist at the institute, said, "The virus has not only changed since these therapies were designed, but it's continuing to change."

Three of the mutations found by the researchers appeared during the current West African epidemic.

"Ebola researchers need to assess drug efficacy in a timely manner to make sure that valuable resources are not spent developing therapies that no longer work," Kugelman said.

While genetic sequence-based drugs are considered to be the best hope for future treatment of Ebola outbreaks, none has been approved by the U.S. Food and Drug Administration or any other regulator. However, some of the drugs are being tested on some patients, and a clinical trial of one of the drugs is scheduled to begin in Sierra Leone in the coming months.

Sierra Leone, along with Guinea and Liberia, are the three West African nations at the epicenter of the current outbreak that has led to nearly 21,300 infections and more than 8,400 deaths.

More information

The U.S. Centers for Disease Control and Prevention has more about Ebola.