Researchers at Texas Biomedical Research Institute will test what could become the first therapeutic for the measles virus, which is resurging in the U.S. amid declining vaccination rates.
Measles was declared eliminated in the U.S. in 2000. But as vaccination rates have fallen, measles cases have climbed, and the country now risks losing its elimination status as cases continue to surge past levels not seen since 1991.
There’s no specific treatment for measles, partly because of how successful the MMR vaccine was in eradicating the disease in the U.S., said Texas Biomed researcher Viraj Kulkarni.
“Because there’s such an effective vaccine, there’s not so much effort going into developing an antiviral,” Kulkarni said. “If successful, this is going to at least be an option for kids. We are worried about kids below 5, the very vulnerable population.”
Though deaths have fallen dramatically over the last several decades, measles is still a public health threat in developing countries where the vaccine is not widely available. The disease killed 95,000 people worldwide in 2024, according to the World Health Organization.
The new therapeutic candidate being tested in San Antonio is what’s known as a “monoclonal antibody,” essentially a lab-made protein that disrupts the virus during the infection process. Kulkarni and his lab will test the drug candidate in its rhesus monkey population next month.
Blocking measles at the door
Monoclonal antibodies are lab-made proteins identical to the ones our bodies produce to fight off viruses and bacteria. They have been approved by the U.S. Food and Drug Administration as treatments for cancer and a range of infectious diseases.
Unlike traditional antivirals, most of which impede viruses from replicating once they have already attached and burrowed themselves into human cells, monoclonal antibodies latch onto viruses and disrupt them from entering in the first place.
They can also reduce viral load and recruit the immune system after infection has taken place. As a result, they can be administered both as a preventative measure or as a therapeutic.
If eventually approved, the measles antibody could be administered in an outbreak area, treating the disease and preventing further spread, Kulkarni explained.
No specific FDA-approved antiviral treatment exists for measles. Instead, supportive care like extra fluids, fever reducers and antibiotics to control secondary infections are usually administered for patients.
Measles symptoms typically include fever, cough, inflamed eyes and a skin rash that usually starts on the face and then spreads to the rest of the body.
Serious complications include pneumonia, blindness and inflammation of the brain known as encephalitis. And secondary infections are a substantial risk since the disease weakens the immune system, according to the U.S. Centers for Disease Control and Prevention.
Testing the antibody in primates
In 2024, scientists at the La Jolla Institute for Immunology in California and Columbia University developed monoclonal antibodies that effectively attacked and neutralized the measles virus in lab and rodent studies. Their findings were published in Science.
These antibodies, known as mAb 77, target two proteins the measles virus uses to attach and enter our cells, resulting in infection.
“They target the membrane of the virus,” Kulkarni explained. “The antibody goes and binds to these molecules, and then the virus cannot enter.”
In 2025, Kulkarni and the other researchers teamed up to test their product at Texas Biomed, home to one of the largest primate centers in the U.S.
The drug candidate will be tested in juvenile rhesus monkeys — smaller monkeys common in biomedical research — instead of larger primates since measles poses the greatest risk to young children. If the early results of mAb 77 are validated in the study, the drug candidate will likely move into human clinical trials.
A preventable comeback
Before the introduction of the measles vaccine in 1963 and widespread immunization efforts that followed, measles was considered a nearly universal childhood disease, causing an estimated 2.6 million deaths globally each year.
Today, the MMR vaccine is one of the most effective childhood vaccines providing around 97% effectiveness after two doses.
Although the new antiviral candidate could help treat measles and prevent serious complications, especially in young children and infants, the need to find such a treatment was avoidable, Kulkarni said.
“It’s a big problem, and we have a simple solution for it,” he said. “We don’t have to even do this research — if you give the vaccine, it’s gone.”
