Mutations let JC polyomavirus evade antibodies, offering clues for vaccines and treatments

by Corrie Pikul, Brown University

edited by Stephanie Baum, reviewed by Andrew Zinin

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In people with severely compromised immune systems, JC polyomavirus can trigger an untreatable, often fatal brain disease. An international research team has identified how virus mutations can strategically interfere with how human antibodies recognize the virus, allowing it to evade an immune response. The new insights into the interactions between the JC polyomavirus and the human immune system, published in PNAS, could lay the foundation for the development of treatments and vaccines.

The research was led by scientists at the University of Tübingen in Germany, in collaboration with researchers from Brown University and the University Hospital of Zürich in Switzerland.

"This work is the culmination of a 10-year international project between our institutions," said Walter Atwood, a professor of biology and medicine at the Warren Alpert Medical School and the lead researcher from Brown University. "There's now the possibility of therapeutic antibodies to be able to block an infection in patients who develop the disease. That's been the thought and the goal, but getting to this point has been a significant challenge for a very long time."

When a common virus turns deadly

Polyomaviruses are a family of small DNA viruses that establish persistent, lifelong infections in a wide range of vertebrate hosts. Human polyomavirus 2, commonly referred to as the JC polyomavirus (after the initials from a patient from whom it was first isolated and identified) is widespread, infecting more than 60% to 70% of the population worldwide.

The virus usually remains dormant, but in some people — especially patients with AIDS and people whose immune systems have been modulated by strong medications designed to treat autoimmune conditions — it can reactivate and spread to the brain. There, it infects and destroys specialized glial cells in the central nervous system that produce the myelin sheath. The resulting disease, called progressive multifocal leukoencephalopathy (PML), is severely debilitating and often fatal, and there are no effective treatments.

Neutralizing antibodies

For the study, the research team drew on the observation that some patients are able to survive PML.

"Their bodies manage to neutralize the attacking JC polyomaviruses so that they can no longer penetrate the body's cells; the infection is stopped," said study author Thilo Stehle, a professor of biochemistry at the Interfaculty Institute of Biochemistry at the University of Tübingen.

The immune system achieves this neutralization by producing precisely tailored antibodies, Stehle explained. The antibodies attach like a lock to binding sites on the viral capsid, which prevents the virus from binding to cells.

Tracing how antibodies bind

At the University Hospital of Zürich, researchers isolated specialized antibodies against the protective protein shell of JC polyomavirus from PML patients. In Atwood's lab at Brown, a team of researchers tested the antibodies for their binding and neutralization properties. Stehle's team in Tubingen then analyzed the binding mechanism of the most promising antibodies to the virus using high-resolution structural analysis with atomic precision.

By studying the genetic mutations that can occur at the binding sites that antibodies use to defend themselves against the virus, the researchers developed insights into the structure and mechanisms of action between JC polyomaviruses and the human immune system that can be used to develop therapeutics and vaccines.

One antibody hits two viruses

Atwood's team showed that one of the antibodies protected cells against infection by both the JC polyomavirus as well as the related BK polyomavirus. BK polyomavirus is also common in humans, and while it does not cause brain disease, it leads to nephropathy and hemorrhagic cystitis in kidney and bone marrow transplant patients, respectively.

"A potential vaccine could protect high-risk patients from infection with both polyomaviruses," Atwood said.

Publication details

Christina Harprecht et al, Structural characterization of human neutralizing antibodies against JC and BK polyomaviruses, Proceedings of the National Academy of Sciences (2026). DOI: 10.1073/pnas.2603048123

Journal information: Proceedings of the National Academy of Sciences

Key medical concepts

JC VirusLeukoencephalopathy, Progressive MultifocalAntibodiesMutation

Clinical categories

Infectious diseasesCommon illnesses & PreventionAllergy and immunology Provided by Brown University Who's behind this story?

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Citation: Mutations let JC polyomavirus evade antibodies, offering clues for vaccines and treatments (2026, July 6) retrieved 6 July 2026 from https://medicalxpress.com/news/2026-07-mutations-jc-polyomavirus-evade-antibodies.html This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.