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agglutination of erythrocytes.
hemagglutination inhibition (HI, HAI) test
1. a highly sensitive procedure for the measurement of soluble antigens in biologic specimens; the amount of hemagglutination reflects the amount of free antibody present after reaction with the specimen and thus varies inversely with amount of antigen in the specimen.
2. a procedure for the measurement of serum antibodies directed against a hemagglutinating virus; the highest dilution of serum that completely inhibits hemagglutination by a standardized viral preparation is reported as the hemagglutination titer.


The agglutination of red blood cells; may be immune as a result of specific antibody either for red blood cell antigens themselves or other antigens that coat the red blood cells, or may be nonimmune as in hemagglutination caused by viruses or other microbes.
Synonym(s): hemoagglutination


/he·mag·glu·ti·na·tion/ (he″mah-gloo-tĭ-na´shun) agglutination of erythrocytes.


[hē′məglo̅o̅′tinā′shən, hem′-]
Etymology: Gk, haima + L, agglutinare, to glue
the agglutination of erythrocytes by an antigen-antibody reaction.


The agglutination of red blood cells; may be immune (as a result of specific antibody to red blood cell antigens or other antigens that coat the red blood cells), or nonimmune (as in hemagglutination caused by viruses or other microbes).
Synonym(s): haemagglutination.


The clumping or clustering of red blood cells caused by certain viruses, antibodies, or other substances.
Mentioned in: Rubella Test


agglutination of erythrocytes usually by either antibodies, viruses or certain plant lectins; abbreviated HA.

indirect hemagglutination test
see hemagglutination inhibition test (below).
hemagglutination inhibition (HI) test
an assay for the presence of specific antiviral antibodies in a test serum. The serum, usually a twofold dilution series, is mixed with a standard number, usually 4 to 8 HA units, of virus and incubated prior to the addition of a standard suspension of erythrocytes. The highest dilution of serum that inhibits hemagglutination is the HI titer of the serum.
passive hemagglutination test
see passive agglutination test.
hemagglutination (HA) test
hemagglutinating viruses directly agglutinate erythrocytes by binding to specific receptor sites on the surface of the erythrocyte and this characteristic can be used in detection, identification and quantitation of the virus.
hemagglutination viruses
viruses capable of agglutinating red blood cells of a variety of animals, e.g. adenoviruses, parvoviruses, togaviruses, some coronaviruses, picornaviruses, orthomyxoviruses and paramyxoviruses. Useful in classifying viruses and assaying amounts of virus and antibody. See also hemadsorption.
References in periodicals archive ?
However, Hemagglutination inhibition test was not sensitive enough to assess immune status against measles long after infection or vaccination (Neumann et.
The mixtures were incubated for 30 min at room temperature and, afterwards, the hemagglutination assay was performed.
Although indirect hemagglutination test has a higher false negative and false positive results due to cross reactivity with other parasitic infections.
Factors affecting hemagglutination activity of avian influenza virus subtype H5N1.
5) Careful serological investigations can shed light on the variation seen in hemagglutination, with some of these observations well documented by the manufacturer.
On the percentage inhibition of viral induced hemagglutination by the aqueous extract of Gynostemma pentaphyllum the 200 mg/mL (pre infection) gave the highest inhibition (85%) while the 2 mg/mL (pre infection) gave the lowest inhibition of 35%.
Hemagglutination inhibition (HI) and microneutralization (MN) assays were performed following standard procedures * using A/Minnesota/11/2010 (H3N2)v and seasonal influenza viruses, A/Wisconsin/67/2005 (H3N2), and A/Perth/16/2009 (H3N2).
The adhesion of microorganisms is carried out by the fimbriae of the common type giving mannose-sensitive hemagglutination in the different mannose-resistant adhesins.
Immunogenicity data from prelicensure clinical trials showed that people aged 65 and older who received the high-dose vaccine had significantly higher hemagglutination inhibition titers against all three influenza virus strains, compared with the standard-dose Fluzone vaccine.

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