Researchers a step closer to decoding dengue and West Nile

University of Michigan and Purdue University researchers released study results on Thursday that show how dengue fever and West Nile fever replicate and manipulate their host's immune system.

Researchers discovered a common protein structure in the viruses that assists in replication and spreading infection. Lead researcher Janet Smith of University of Michigan Life Sciences Institute said that discovering the protein provides a potential target for vaccines or therapeutic drugs.

The protein is called NS1, and is produced inside infected cells. It is released into the bloodstream, which may play a part in disguising the virus from the immune system. It may also be a reason for hemorrhaging that is seen in dengue virus infections.

Smith said the researchers used X-ray crystallography to create images of the protein.

"Isolating the protein in order to study it has been a challenge for researchers," Smith said. "Once we discovered how to do that, it crystallized beautifully."

The research team studied the NS1 protein because of its role in infection.

"Understanding how the protein is designed provides an easier pathway to understanding its roles in the virus life cycle," Richard Kuhn, professor and biological sciences department head at Purdue, said. "We now know which portions of the protein to target in drug development to shut it down and stop the progression of infection."

Dengue is caused by four related viruses. If a person is infected with one type of virus, they may experience only flu-like symptoms. If they are then infected with a different but related virus, the exposure can lead to serious illness or death. Smith said this process greatly complicates vaccine development.

"We don't want to prime people for severe dengue disease by delivering their first exposure to the virus in the form of a vaccine," Smith said.

Kuhn said that researchers will be able to manipulate the protein for certain funcitons now that they better understand it.

"This could lead to a way to prevent any harmful priming of the immune system," Kuhn said.