Avian Influenza Assays

We offer assay support for research and development of avian influenza vaccines and antivirals for both human and animal health. Available methods include the hemagglutination inhibition (HAI) assay to assess antibody response, the neuraminidase inhibition (NAI) assay (ELLA) to evaluate antiviral activity, and the microneutralization (MN) assay to measure virus-neutralizing antibodies. Assays are available for both low pathogenic (LPAI) and current highly pathogenic (HPAI) influenza A strains, including H5N1 and H7N9.

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Plaque Assay

The Plaque Assay determines infectious virus particles in a sample. Virus is sequentially diluted and dilutions are plated on susceptible cells. Cultures are overlaid with nutrient agarose and plaques or pocks formed by cytopathic viruses can be quantitated.

Plaque Inhibition Assay

This assay is requested frequently to test the efficacy of antiviral drug candidates. Drug is included in the agarose overlay and if effective will reduce the size and / or number of plaques observed.

TCID₅₀ Assay

The TCID₅₀ assay quantitates infectious virus particles in a sample. Virus is sequentially diluted and dilutions are plated in replicate wells of susceptible cells. The TCID₅₀ (50% Tissue Culture Infectious Dose) is that dilution of virus which will produce pathological change in fifty percent of cell cultures inoculated at a particular dilution. TCID₅₀ values are normally very close to the Plaque Assay values for most cytopathic viruses.

IC50 Assay

This assay is requested frequently to test the efficacy of antiviral drug candidates. Drug is included in the agarose overlay and if effective will reduce the size and / or number of plaques observed.

Fluorometric Neuraminidase Assay

This assay measures a fluorogenic substance released by the active influenza neuraminidase enzyme. It is used to screen for antiviral drug activity against neuraminidase and determine the 50% Drug Inhibitory Dose.

Hemagglutination Assay

This assay detects the presence of certain viruses that agglutinate red blood cells. This assay can be used to quantitate or type many virus strains. In some labs, the hemagglutination assay is preferred for detecting influenza virus growth. The hemagglutination titer of an influenza virus sample can be determined when dilutions of virus are mixed with human or turkey red blood cells. The presence of virus will hold the red cells in a diffuse matrix and prevent them from settling out to the bottom of the well.

Hemagglutination Inhibition Assay

This test is based on the inhibition of viral agglutination by a specific antibody and can be used for virus identification and for determining quantitative antibody titers. This assay is still used as a standard for measuring the efficacy of influenza vaccines and potency of neutralizing antibodies.

Microneutralization Assay

This test is used to determine if an antibody may have therapeutic effects. This assay measures the ability of an antiserum to inhibit cytopathogenic effect of about 100 virus infectious units. The antibody / virus mixture is plated on susceptible cells and inhibition is tracked.

Textiles and Plastics Assay (AATP)

The antiviral activity of textiles and plastics (AATP) test measures antiviral activity of plastics and other non-porous surfaces treated with antiviral agents. This assay will determine the log reduction of virus compared to the customer supplied untreated control.