Chikungunya: Scientists identify receptor that causes arthritis pain

Scientists have identified the molecular handle that chikungunya grabs to get inside cells, an advance that could lead to ways to prevent or treat disease caused by the virus

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Washington, DC: Researchers at Washington University School of Medicine in the US have identified the molecular receptor that chikungunya grabs to get inside cells which can lead to ways to prevent or treat disease caused by the virus.

The receptor is located on cells that build cartilage, muscle and bone. Joints are filled with such cells, which helps explain patients’ painful symptoms. By creating a decoy receptor, the researchers showed that they could reduce chikungunya infection and signs of arthritis.

Chikungunya is an infection caused by the chikungunya virus (CHIKV). Symptoms include fever and joint pain. These typically occur two to twelve days after exposure. Other symptoms may include a headache, muscle pain, joint swelling, and a rash. Most people are better within a week; however, occasionally the joint pain may last for months.

Chikungunya is a viral disease that is spread by mosquitoes. Two important vectors are Aedes aegypti and Aedes albopictus, which also transmit dengue virus. These species bite during daylight hours with peak activity in the early morning and late afternoon. Both are found biting outdoors but Aedes aegypti will also readily bite indoors.

Observations during recent epidemics have suggested chikungunya may cause long-term symptoms following acute infection. This condition has been termed chronic chikungunya virus-induced arthralgia.

There are no specific treatments or vaccines for chikungunya and related viruses, known as arthritogenic alphaviruses, researchers said.

Doctors simply recommend rest, fluids and over-the-counter pain relievers such as acetaminophen or ibuprofen, they said.

Researchers have 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.

Since chikungunya uses Mxra8 protein as a handle to open a door into cells, the researchers tested whether preventing the virus from grabbing that handle could reduce infection. They deluged the virus with decoy handles, reasoning that chikungunya would grab the decoy and be locked out of cells.

Only a few individual viruses that lucked onto a true handle could infect cells, so the overall infection rate — and signs of arthritis — would fall, researchers said.

The results suggest that a compound that blocks the virus from attaching to Mxra8 on the surface of cells could prevent or reduce arthritis.