Gold Nanoparticles Coated with Antibodies Bind to Flu Viruses

Influenza can be detected in minutes by measuring how the particles scatter laser light.

The gold nanoparticle-antibody complex aggregates with any virus present in a sample, and a commercially available device measures the intensity with which the solution scatters light. The clustering of the virus with the gold nanoparticles causes the scattered light to fluctuate in a predictable and measurable pattern.

“We’ve known for a long time that you can use antibodies to capture viruses and that nanoparticles have different traits based on their size,” said Professor Ralph Tripp, Georgia research alliance eminent scholar in vaccine development in the University of Georgia (UGA) College of Veterinary Medicine (Athens, GA, USA). “What we’ve done is combine the two to create a diagnostic test that is rapid and highly sensitive.”

“This test offers tremendous advantages for influenza, but we really don’t want to stop there,” Prof. Tripp said. “Theoretically, all we have to do is exchange our anti-influenza antibody out with an antibody for another pathogen that may be of interest, and we can do the same test for any number of infectious agents.”

The current standard for definitively diagnosing flu is the polymerase chain reaction (PCR). PCR can only be done in highly specialized labs and it requires that specially trained personnel incubate the sample for three days, extract the DNA, and then amplify it many times. The entire process, from sample collection to result, takes about a week and is too costly for routine testing.

A rapid test known as the lateral flow assay is cost effective and can be used at the point-of-care, but it cannot identify the specific viral strain. It also misses up to 50% of infections and is especially error-prone when small quantities of virus are present.

By overcoming the weaknesses of existing diagnostic tests, the UGA scientists hope to enable more timely diagnoses that can help halt the spread of flu by accurately identifying infections and allowing physicians to begin treatment early, when antiviral drugs, such as Tamiflu, are most effective.

The new detection method using antibodies coated with gold nanoparticles developed at the University of Georgia was described in the August 2011 edition of the journal Analyst.

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University of Georgia College of Veterinary Medicine