Infection with highly contagious noroviruses, while not usually fatal, can lead to a slew of unpleasant symptoms such as excessive vomiting and diarrhea. Current treatment options are limited to rehydration of the patient.
Electron micrograph of norovirus virus-like particles (VLPs) and a cartoon representation of a nanobody, termed Nano-85 (orange). Nano-85 binds to the VLPs and causes the VLPs to disassemble. Image courtesy of Dr. Grant Hansman, DKFZ.
Infection with highly contagious noroviruses, while not usually fatal, can lead to a slew of unpleasant symptoms such as excessive vomiting and diarrhea. Current treatment options are limited to rehydration of the patient.
"Additionally, noroviruses come in a variety of constantly evolving strains," says Dr. Grant Hansman, a virologist who leads the CHS Research Group on Noroviruses at the German Cancer Research Center (Deutsches Krebsforschungszentrum, DKFZ) and Heidelberg University. "This makes the development of an effective vaccine to protect against infection, as well as antiviral therapy to combat already-existing infections, particularly challenging."
Hansman's research team recently discovered that a "nanobody" called Nano-85 was able to bind to intact norovirus-like particles (VLPs) in culture. Nanobodies are very similar to antibodies, which recognize and bind to antigens. "However, nanobodies are much smaller, more stable, easier to produce, and cost-effective than traditional monoclonal antibodies," says Hansman. Interestingly, Nano-85 was able to recognize the VLPs from a variety of different norovirus strains.
The researchers then tested the nanobody on stool samples from patients infected with the virus. In this context, Nano-85 was able to detect virus in one-third of the samples already known to be positive for noroviral RNA. "Because noroviruses are changing all the time, there is a need for more powerful tools to detect emerging noroviruses. We still need to optimize detection using Nano-85, but we hope that it could potentially be used as a diagnostic tool further on down the road," explains Hansman.
In solution, Nano-85 was also able to bind to a specific portion of the VLP known as the protruding (P) domain. As with the VLPs, Nano-85 recognized the P domains from a variety of strains. Hansman describes the P domain as a structure that "essentially sticks out like a spike from the virus. Therefore, it has some degree of flexibility - like grass on a hill on a windy day. This ability to change shape likely allows the virus to evade recognition by the immune system - but could also make it more vulnerable to attack."
Using a technique called X-ray crystallography, the researchers were able to determine the shape and molecular components of the Nano-85/P domain complex, as well as specific sites where Nano-85 and the P domain formed bonds. According to Hansman, "this is, as far as we know, the first instance in which the molecular structure of a nanobody-P domain complex has been determined for norovirus."
Interestingly, the investigators found that the site where Nano-85 bound to the P domain was actually hidden under the viral particle's surface. "From the virus's point of view, this could be a strategy to keep potentially vulnerable sites protected from attack," explains Hansman. However, when they tried to create high-magnification images of the interaction using electron microscopy, they were surprised that they could not find any intact VLPs. This led them to believe that Nano-85 itself was actually causing the VLPs to break apart.
In describing the significance of these findings, Hansman says: "If Nano-85 is indeed causing intact VLPs to disassemble, this could be a very promising lead in developing norovirus antiviral therapy. This could be especially beneficial to immunosuppressed individuals such as cancer patients. Administering a vaccine to protect against infection would overwhelm the patient's immune system. However, if he or she has the option of receiving an antiviral to eliminate the infection, the norovirus becomes much less dangerous."
Reference: Anna D Koromyslova and Grant S Hansman: A nanobody binding to a conserved epitope promotes norovirus disassembly. Journal of Virology 2015, DOI:10.1128/JVI.03176-14
Source: German Cancer Research Center (Deutsches Krebsforschungszentrum, DKFZ)
Stay prepared and protected with Infection Control Today's newsletter, delivering essential updates, best practices, and expert insights for infection preventionists.
Flawed From the Start: Why Many IFUs for Surgical Instruments Fail in Real-World Sterile Processing
July 23rd 2025At the 2025 HSPA Annual Conference & Expo, Cori L. Ofstead, MSPH, highlighted critical flaws in manufacturers’ instructions for use (IFUs) for orthopedic and neurosurgical instruments. From contradictory directions to unrealistic cleaning expectations, these IFUs often fail under real-world conditions, jeopardizing both patient safety and sterile processing workflows.
US Withdrawal From UNESCO Signals a Dangerous Step Back for Global Science
July 22nd 2025In a decision heavy with consequence and light on foresight, the US has once again chosen to walk away from UNESCO, leaving behind not just a seat at the table, but a legacy of global scientific leadership that now lies in question.
Pathogen Pulse: Facilities Need the SPD, Yersinia Enterocolitica Outbreak, and More
July 22nd 2025From unsterilized surgical tools in Colorado to a years-long methicillin-resistant Staphylococcus aureus (MRSA) outbreak in Virginia and a surging measles crisis in Canada, recent headlines reveal the fragile front lines of infection prevention and the high stakes when systems fail.
Telemedicine's Transformative Role in PPE Distribution and Sterile Equipment Management
July 22nd 2025In an era defined by digital transformation and post-pandemic urgency, telemedicine has evolved beyond virtual visits to become a vital infrastructure for delivering personal protective equipment (PPE) and managing sterile supplies. By enabling real-time forecasting, remote quality control, and equitable distribution, telemedicine is revolutionizing how health care systems protect both patients and providers.
Reducing Hidden Risks: Why Sharps Injuries Still Go Unreported
July 18th 2025Despite being a well-known occupational hazard, sharps injuries continue to occur in health care facilities and are often underreported, underestimated, and inadequately addressed. A recent interview with sharps safety advocate Amanda Heitman, BSN, RN, CNOR, a perioperative educational consultant, reveals why change is overdue and what new tools and guidance can help.
New Study Explores Oral Vancomycin to Prevent C difficile Recurrence, But Questions Remain
July 17th 2025A new clinical trial explores the use of low-dose oral vancomycin to prevent Clostridioides difficile recurrence in high-risk patients taking antibiotics. While the data suggest a possible benefit, the findings stop short of statistical significance and raise red flags about vancomycin-resistant Enterococcus (VRE), underscoring the delicate balance between prevention and antimicrobial stewardship.