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As an expert in providing solutions to assist virology and microbiology research, Creative Diagnostics recently introduced Hemagglutination Inhibition Assay services to determine relative concentrations of viruses, bacteria, or antibodies.

Hemagglutination inhibition (HI or HAI) is an experimental method invented by the American virologist George Hearst in 1941. This assay utilizes surface proteins of various viruses, such as hemagglutinin (HA) of the influenza virus, to agglutinate red blood cells (RBCs). The reaction of viral hemagglutinin with RBCs creates a lattice of aggregated cells. However, if RBCs and virus are mixed in the serum of a virally infected patient, the RBCs will not agglutinate. This phenomenon is called hemagglutination inhibition.

Moreover, antibodies present in the serum of infected persons were shown to neutralize the virus, leading to a positive result. If the patient’s serum does not contain antibodies against the surface protein of the tested viruses, hemagglutination occurs because the surface molecule is free for hemagglutinin RBC (negative result).

HAI Procedures of Creative Diagnostics

1) Obtain a virus preparation (e.g., influenza viruses) of known or determined HA titers;

2) Prepare two-fold dilutions of patient/test serum to be tested, e.g., from 1:4 to 1:1024;

3) Add a fixed amount of viruses to a 96-well plate, equivalent to 4 HA units (varies according to the virus), except for serum control wells;

4) Allow the plate to stand at room temperature for 60 minutes (time varies according to specific requirements);

5) Add RBCs and incubate at 4 °C for 30 minutes;

6) Read wells.

HAI is closely related to HA analysis, mainly through antiviral antibodies as “inhibitors” that interfere with the interaction of viruses and RBCs. The goal is to characterize the concentration of antibodies in antisera or other antibody-containing samples. Meanwhile, HAI assays are typically performed by serially generating dilutions of antisera in a 96-well microtiter plate. A standard amount of virus or bacteria is added to each well, and the mixtures are incubated at room temperature. It is necessary to set up a negative control without the addition of viruses for each experiment. During the incubation, the antibodies will bind to the virus particles. Lastly, if the antibody concentration and the binding affinity are high enough, they can effectively block the coagulation reaction.

Creative Diagnostics combines infection and analytical expertise to provide its clients with the strongest portfolio of antiviral and antibacterial in vitro testing services. In confront with a growing need for novel antiviral and antibacterial compounds for the treatment of infectious diseases, Creative Diagnostics is leveraging its expertise to perform in vitro testing for compounds to estimate their potential in vivo efficacy.

If you need more information regarding the Hemagglutination Inhibition Assay services or have questions related to the in vitro antiviral testing, please visit Creative Diagnostics.

About Creative Diagnostics

Headquartered in New York, Creative Diagnostics is a consulting and experimental service provider specializing in virology and microbiology. It provides comprehensive solutions to conquer obstacles in virology and microbiology research, including the need for high-security infrastructures, an understanding of biosafety regulations, and expertise in multiple virus systems.

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