As is the case with virus, researchers are apprehensive that the genetic makeup of Ebola in West Africa has undergone several mutations that could potentially make new drugs ineffective to treat the deadly virus.
“The (Ebola) virus mutates rapidly,” Jeffrey Kugelman of the US Army Medical Research Institute of Infectious Diseases (USAMRIID) said in a study. “And it’s an ongoing concern,” Xinhua quoted him as saying.
In the US journal mBio, Kugelman and other co-authors said the “genomic drift”, or natural evolution of the virus, may interrupt the action of potential therapies designed to target the virus’s genetic sequence.
Currently, three vaccines developed by Johnson & Johnson, GlaxoSmithKline and another from NewLink and Merck are undergoing second phase of clinical trials.
The study noted that there are three types of genetic sequence-based treatments — monoclonal antibody, small-interfering RNA and phosphorodiamidate morpholino oligomer drugs — being tested in clinical trials for evaluation still and all of them were developed using Ebola virus strains from two smaller outbreaks that occurred in 1976 and 1995.
When investigators from Harvard University and the Massachusetts Institute of Technology, the USAMRIID team compared the latest strain from the outbreak in West Africa, called EBOV/Mak, with the two previous strains in 1976 and 1995 in Zaire, now known as the Democratic Republic of the Congo, more than 600 genetic mutations have been found.
The mutations account for almost three percent of the genome, making it unviable to treat the latest strain which has outgrown the old strain, said researchers. The group also noted that 10 new mutations that might interfere with the mechanisms of the sequence-based drugs currently being tested and that three of these mutations appeared during the current West African outbreak.
The researchers urged that three drug developers currently conducting clinical trials should check whether these mutations affect the efficacy of their therapeutic drugs, which are being used to treat small numbers of patients under a World Health Organisation (WHO) emergency protocol.
“The virus has not only changed since these therapies were designed, but it’s continuing to change,” Kugelman said. “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.”
So far, more than 21,000 Ebola cases with more than 8,300 deaths have been reported since last year in Liberia, Sierra Leone and Guinea, according to the WHO.
(With inputs from IANS)