What is meant by hemagglutination test?

(hemagglutination assay) An in vitro assay used to measure the relative concentration of viruses, bacteria, or antibodies in which serial dilutions of solution containing virus, bacteria, or antibody are applied to red blood cells in culture to look for the presence of hemagglutination.

What is the principle of haemagglutination test?

The principle behind the hemagglutination test is that the nucleic acids of viruses encode proteins, such as hemagglutinin, that are expressed on the surface of the virus (Figs. 51.1 and 51.3).

What is hemagglutination test used for?

The haemagglutination test is used to quantify the amount of Newcastle disease virus in a suspension. This is done by carrying out two-fold serial dilutions of the viral suspension in a microwell plate and then testing to determine an end point.

How do you do a hemagglutination test?

To carry out a hemagglutination assay, a twofold serial dilution of virus-containing samples is dispensed into individual wells of a 96-well microtiter plate (Fig. 4.7B). Then, aliquots of RBC are added to each well. The highest dilution at which clumping is observed is regarded as the HA titer of the sample.

What is hemagglutination unit?

By multiplying the dilution fold, the viral titer can be determined. Generally, 1 hemagglutinin unit corresponds to 104 viral particles per milliliter of sample. Hemagglutination is a widely used assay for detecting and titrating the influenza virus.

How is high titer calculated?

For the appropriate amount of antigen, divide the calculated volume by the titer corresponding to 4 HA units. For example, 4 HA units correspond to a dilution of 1/64, and we needed 15,000 µL of antigen solution are needed: 15,000/64 = 234.4 µL of the dissolved lyophilized influenza antigen are added.

What causes hemagglutination?

Hemagglutination is a reaction that causes clumping of red blood cells in presence of some enveloped viruses, such as the influenza virus. A glycoprotein on the viral surface, namely hemagglutinin, interacts with red blood cells, leading to the clumping of red blood cells and the formation of a lattice.

How does hemagglutination assay work?

Who invented hemagglutination assay?

virologist George Hirst
The hemagglutination assay or haemagglutination assay (HA) and the hemagglutination inhibition assay (HI or HAI) were developed in 1941–42 by American virologist George Hirst as methods for quantifying the relative concentration of viruses, bacteria, or antibodies.

What does titer stand for?

A titer is a laboratory test that measures the presence and amount of antibodies in blood. A titer may be used to prove immunity to disease. A blood sample is taken and tested. If the test is positive (above a particular known value) the individual has immunity.

What is HAI titer?

The HAI assay measures the highest dilution of serum that prevents influenza virus-induced hemagglutination of erythrocytes [44]. The reciprocal of this dilution was defined as the HAI titer.

How is the hemagglutination inhibition ( HI ) assay used?

The hemagglutination inhibition (HI) assay is used to titrate the antibody response to a viral infection. The HI assay takes advantage of some viruses’ ability to hemagglutinate (bind) red blood cells, therefore forming a “lattice” and preventing the red blood cells from clumping.

What’s the best way to test for hemagglutination?

Add a fixed amount of virus to every well of a 96-well plate, equivalent to 4 HA units (varies according to the virus), except for the serum control wells. Allow the plate to stand at room temperature for 60 minutes (time varies according to specific requirements). Add red blood cells (RBC) and incubate at 4°C for 30 minutes. Read the wells.

How are red blood cells used in hemagglutination?

If red blood cells are used as a source of antigen, the assay is called hemagglutination. An animal receiving Sheep red blood cells (SRBC) will develop antibodies against SRBC. In the experiment, SRBC are added to serially diluted serum from this immunized animal.

How does a negative control well work in a haemagglutination test?

Negative control well (no haemagglutinin) Every time a haemagglutination test is carried out, it is necessary to test the settling pattern of the suspension of red blood cells. This involves mixing diluent with red blood cells and allowing the cells to settle. 1. Dispense diluent. 2. Add red blood cells and mix by gently shaking. 3.