Saturday, March 7, 2015

Using Nanobodies to Identify Norovirus: a Glimpse into the Future?

A research team at the German Cancer Research Center (DKFZ) discovered “nanobodies” that could bind to intact norovirus-like particles (VLPs) in culture and
be used to better characterize the structural makeup of the virus. They discovered that these nanobodies could identify the virus in some of the clinical stool samples and disassemble intact norovirus particles.

The researchers led by Hansman found that a “nanobody” called Nano-85 was able to bind to intact norovirus-like particles (VLPs) in culture. While nano bodies have some similarities to antibodies, they "are much smaller, more stable, easier to produce, and cost-effective than traditional monoclonal antibodies.” Interestingly, Nano-85 was able to recognize the VLPs from a variety of different norovirus strains.

While nano bodies could potentially be used as a diagnostic tool to detect noroviruses, at the present they only detect the virus in one third of the samples already known to be positive for noroviral RNA.

Nano-85 recognized the P domains from a variety of strains of norovirus. The group of researchers also determined the shape and molecular components of the Nano-85/P domain complex, and the specific sites where Nano-85 and the P domain formed bonds. Hansman indicates that this is the first time that scientists have figured out the molecular structure of a nanobody-P domain complex for norovirus.

When the researchers tried to create high-magnification images of the interaction of the  Nano-85 with the P domain complex using electron microscopy, they they could not find any intact VLPs. Based on these findings they hypothesize that Nano-85 itself was actually causing the VLPs to break apart. 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.”

-Mariam Kyarunts

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