Deadly Ebola virus disarmed by excising a single gene

Washington, Jan 22 : Researchers from the University of Wisconsin-Madison have managed to genetically disarm the lethal Ebola virus, an emerging public health concern in Africa and a potential biological weapon.

The virus ranks among the most feared of exotic pathogens and due to its virulent nature, scientists studying it have had to work under the most stringent biocontainment protocols, limiting research to a few highly specialized labs and hampering the ability of scientists to develop countermeasures.

Now, however, researchers from the university have found a way to genetically disarm the virus, effectively confining it to a set of specialized cells and making it safe to study under conditions far less stringent than those currently imposed.

"We wanted to make biologically contained Ebola virus. This is a great system," said Yoshihiro Kawaoka, a professor of pathobiological sciences in the UW-Madison School of Veterinary Medicine and the senior author of a paper.

The Ebola virus first emerged in 1976 in simultaneous outbreaks in Sudan and Zaire. Ebola is considered to be the deadliest virus of all time, but it is not as well known as Smallpox because Ebola outbreaks have been limited mainly to remote areas of the world.

Ebola hemorrhagic fever is potentially lethal and encompasses a range of symptoms including fever, vomiting, diarrhoea, generalized pain or malaise, and sometimes internal and external bleeding.

According to the new study, taming Ebola virus depends on a single gene known as VP30.

Like most viruses, Ebola is a genetic pauper and has only eight genes. It depends on host cells to provide much of the molecular machinery to make it a successful pathogen.

The virus's VP30 gene makes a protein that enables it to replicate in host cells. Without the protein, the virus cannot grow.

"The altered virus does not grow in any normal cells. We made cells that express the VP30 protein and the virus can grow in those cells because the missing protein is provided by the cell," said Kawaoka.

Kawaoka said that it took a lot of time to find which viral protein was not toxic to cells and could thus be used to develop a system, using monkey kidney cells, to confine the virus.

"We did this work in a BSL 4, and the altered cells didn't produce any infectious virus after many passages or replication cycles," said Kawaoka.

Research on live Ebola virus is confined to the very highest level of biosafety, known as Biosafety Level 4 (BSL 4).

With the exception that it is unable to grow in anything but cells engineered to express the VP30 protein, the virus is identical to the pathogen found in the wild, making it ideal for studies of basic biology, vaccine development and screening for antiviral compounds.

"This system can be used for drug screening and for vaccine production," said Kawaoka.

The study is published in the Proceedings of the National Academy of Sciences.

ANI