Scientists at the La Jolla Institute for Immunology (LJI) have made an important discovery about the chikungunya virus (CHIKV), a mosquito-borne virus that affects people in over 110 countries.
While CHIKV usually causes flu-like symptoms, it can lead to chronic, severe joint pain in some people. This new study may explain why that happens — and how it resembles autoimmune diseases like rheumatoid arthritis.
In their study, published in Cell Reports Medicine, the researchers found that a type of immune cell called CD4+ T cells reacts strongly to the virus. These cells, which normally help the body fight infections, may also cause long-term inflammation, leading to lasting joint pain.
The researchers tested blood samples from people in Colombia who had been infected with CHIKV. They studied how their immune cells responded to small parts of the virus and discovered that CD4+ T cells had a strong and long-lasting memory of the infection.
Even six years later, 87% of the patients still had CHIKV-specific memory CD4+ T cells in their blood. In contrast, only 13% had memory CD8+ T cells, which are usually more active in fighting viruses.
This pattern is unusual for a virus but common in autoimmune diseases. Lead researcher Dr. Daniela Weiskopf noted that this T-cell response looked very similar to what is seen in conditions like rheumatoid arthritis.
The researchers also found that in patients with chronic joint pain, these CD4+ T cells were mostly ‘monofunctional.’
That means the cells mainly produced one type of inflammatory molecule, called TNF-alpha, instead of many different types. While TNF-alpha helps fight infections, it can be harmful when it sticks around too long, causing inflammation and pain.
This could explain why some people continue to suffer joint pain long after the virus is gone. The team believes that therapies that block TNF-alpha might help relieve arthritis-like symptoms caused by CHIKV.
Co-first author Rimjhim Agarwal is now researching why women in their 40s seem to be more likely to develop long-term joint pain after CHIKV infection. She received a special grant to study how CD4+ T cells might be attacking the body’s own tissues in these women.
This work is part of a growing effort to understand how viral infections might lead to autoimmune diseases. Other viruses, such as dengue and SARS-CoV-2 (the virus that causes COVID-19), are also known to trigger chronic, autoimmune-like symptoms in some people.
“More people are realizing that viral infections can have long-term effects,” said Agarwal. “We still have many questions, but this research is an important step toward understanding how viruses can lead to lasting inflammation and disease.”
If you care about pain, please read studies about Chronic morphine use for cancer pain may increase bone loss and findings of Scientists find a new hope for chronic pain.
For more about pain, please read studies about What you need to know about diabetes and joint pain and findings of Understanding the connection between liver disease and joint pain.
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