What is meant by passive hemagglutination test?

What is meant by passive hemagglutination test?

n. Passive agglutination in which red blood cells are used to adsorb soluble antigen onto their surfaces; the red blood cells then agglutinate in the presence of antiserum specific for the adsorbed antigen. indirect hemagglutination test.

What is hemagglutination titer?

Titration to establish haemagglutinin (HA) titre of a suspension of virus. 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.

What is the difference between passive and active hemagglutination?

With active agglutination, the antigen occurs naturally on particle. With passive agglutination, the antigen must first be bound to an inert particle to detect an antibody.

How is hemagglutination titer calculated?

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.

How does hemagglutination occur?

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.

What is meant by antibody titer?

Definition. Antibody titer is a laboratory test that measures the level of antibodies in a blood sample.

Why is latex agglutination test used?

The latex agglutination test is a laboratory method to check for certain antibodies or antigens in a variety of body fluids including saliva, urine, cerebrospinal fluid, or blood.

What is the principle of hemagglutination assay?

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 the principle of hemagglutination?

What causes hemagglutination?

What causes an incorrect titer on a hemagglutination assay?

Non-specific factors in the sample can lead to interference and incorrect titer values. For example, molecules in the sample other than virus-specific antibodies can inhibit agglutination between virus and RBC’s, as well as potentially blocking antibody from binding to virus.

Is there a passive hemagglutination test for rheumatoid factor?

This is a passive hemagglutination test to detect rheumatoid factor. One of the features of human rheumatoid factor is that it can bind with human IgG as well as rabbit IgG.

How is viral hemagglutination used in the VDRL test?

This technique is used in VDRL test (venereal disease research laboratory test) to detect antibodies against Treponema pallidum, the bacteria that cause syphilis. Viral hemagglutination is a special category of erythro­cyte agglutination, which doesn’t involve antigen- antibody reaction.

How is hemagglutination expressed in an immunology laboratory?

If insufficient antibody is present, the cells roll down the sloping sides of the well to form a red pellet or “button” at the bottom of the well. Hemagglutination is expressed as titer: it is the inverse of the last dilution that is positive; e.g: 1/1000.

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