Tiger mosquito: why chikungunya hurts joints

American researchers have come to identify how the chikungunya virus penetrates inside the cells and causes severe joint pain.

Transmitted by the tiger mosquito, chikungunya is currently a growing threat in France as well as in other parts of the world. Tropical infectious disease due to an arbovirus, it takes its name from the makondé language, in Tanzania, where it means "who bends, who curls up". The translation of chikungunya into French means "disease that breaks the bones" or "curved man's disease".

And for good reason: besides high fever, headaches and sometimes rashes, chikungunya gives people infected very strong joint pain and sometimes incapacitating, especially around the wrists, ankles and knuckles.

Until now, scientists have struggled to understand how chikungunya and visible viruses can cause pain comparable to arthritis. Researchers at the University of Washington, St. Louis, may have found the answer. In an article published in the journal Nature, they explain having identified a molecular "handle" that the chikungunya operates to penetrate inside the cells. Their discovery could lead to ways to prevent or treat the disease.

Decoy the virus to prevent its spread in cells

This "handle" or receptor is located on cells that build cartilage, muscles and bones. They are also present in the joints, which explains the painful symptoms of people affected by chikungunya.

"We now know how chikungunya enters the cells, and we may have found a way to block the infection.If the virus can not enter the cell, it is unable to replicate and cause infection and disease, "says Professor Michael S. Diamond, lead author of the study.

The researchers found that the chikungunya virus used a protein called Mxra8 to invade human cells. He uses it as a "handle" to get inside the cells. But they also realized that it was possible to create "lure handles" so that the virus seizes them and does not enter the cells, which would reduce arthritis pain.

The experiment was successfully tested in mice: one day after infection, the level of virus in the ankles and calves of mice was ten times lower in animals treated with Mxra8 proteins or blocking antibodies than those who received a placebo. Three days after treatment, the mice that received the protein had significantly fewer ankle swellings than those receiving the placebo.

A hope for patients

For the researchers, this discovery is hope to prevent or reduce arthritis in people affected by chikungunya, but also to slow the spread of the virus.

However, further research is needed before developing any treatment. "We do not know much about what Mxra8 does in the human body, so we need more information before developing a drug that targets the protein," Pr Diamond says. "But we could develop more quickly a drug targeting the virus and preventing it from attaching to this protein."

Currently, there is no specific treatment or vaccine against chikungunya and related viruses. Doctors simply recommend rest, fluids and over-the-counter pain relievers such as paracetamol or ibuprofen.

Video: WHO official says chikungunya virus is in danger of spreading in the region (February 2020).