How a virus can cause joint-crippling arthritis

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Researchers have identified the molecular “handle” that the chikungunya virus grabs to get inside cells, potentially leading to a form of arthritis that persists for months or even years.



Scientists have understood little about how chikungunya and related viruses cause arthritis. The new findings, which appear in the journal Nature, could lead to ways to prevent or treat disease caused by chikungunya and related viruses.

The handle, or receptor, is located on cells that build cartilage, muscle, and bone. Joints are full of such cells, which helps explain patients’ painful symptoms. Further, by creating decoy handles, the researchers showed that they could reduce chikungunya infection and signs of arthritis.

“The name chikungunya comes from the Makonde language of Tanzania, and it means ‘to walk bent over.’ That’s how painful the arthritis can be,” says senior author Michael S. Diamond, professor of medicine at  Washington University in St. Louis School of Medicine. “We now know how chikungunya gets into cells, and we may have found a way to block the infection. If the virus cannot get into the cell, it is unable to replicate and cause infection and disease.

There are no specific treatments or vaccines for chikungunya and related viruses, known as arthritogenic alphaviruses. Doctors simply recommend rest, fluids, and over-the-counter pain relievers such as acetaminophen or ibuprofen.


Figuring out how the virus gets inside cells is considered a step toward slowing its spread. Diamond, first author and postdoctoral researcher Rong Zhang, and colleagues identified the protein on cells that chikungunya virus latches onto.

The protein is called Mxra8, and it is needed for chikungunya to invade both human and mouse cells, the researchers found. Additional experiments showed that not just chikungunya but its arthritis-causing relatives—Mayaro, Ross River, O’nyongnyong, and Barmah Forest viruses—require the protein to get into cells.



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“Not much is known about what Mxra8 does in the human body, so we need more information before developing a drug that targets Mxra8,” says Diamond, who also is a professor of molecular microbiology, and of pathology and immunology. “But we could more immediately develop a drug that targets the virus and prevent it from attaching to this protein.”


The National Institutes of Health (NIH) and the Defense Reduction Threat Agency funded this research.

Source: Washington University in St. Louis