| haemagglutination inhibition | A variation of the haemagglutination technique. Some viral antigens, when coated on erythrocytes, spontaneously cause agglutination in the absence of antibody. In these situations, the specific antigen-antibody reaction actually prevents the agglutination of reagent RBCs. Haemagglutination inhibition cannot differentiate between isotypes of specific antibodies (IgG, IgA or IgM) although positive haemagglutination inhibition analysis of specimens treated with Staphylococcus aureus Protein A (discussed above under coagglutination) to remove the IgG isotype antibodies has been used to imply the presence of specific IgM antibodies to the specific viral antigen. The crude quantitation of the specific antibodies is possible using serial dilution (titre). (05 Mar 2000) |
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| haemagglutination inhibition test | <investigation> A clinical lab test used to detect the presence of a certain haemagglutinating virus or other haemagglutinin antigen based on whether the red blood cells in the sample lose the ability to clump together when the antibody to the virus or other antigen is added to it. If the virus or antigen is present, the antibody kills it and thereby stops it from being able to stick the red blood cells to each other. (09 Oct 1997) |
| haemagglutination inhibition tests | Serologic tests in which a known quantity of antigen is added to the serum prior to the addition of a red cell suspension. Reaction result is expressed as the smallest amount of antigen which causes complete inhibition of haemagglutination. (12 Dec 1998) |
| haemagglutination test | <investigation> A test in which an antigen and an antibody react to each other on the surface of a red blood cell. (09 Oct 1997) |
| haemagglutination tests | Sensitive tests to measure certain antigens, antibodies, or viruses, using their ability to agglutinate certain erythrocytes. (12 Dec 1998) |
| haemagglutination, viral | Agglutination of erythrocytes by a virus. (12 Dec 1998) |
| haemagglutinin | <haematology> Substance that will bring about the agglutination of erythrocytes. (18 Nov 1997) |
| haemagglutinin glycoproteins, influenza virus | Membrane glycoproteins from influenza viruses which are involved in haemagglutination, virus attachment, and envelope fusion. Fourteen distinct subtypes of ha glycoproteins and nine of na glycoproteins have been identified from influenza a virus; no subtypes have been identified for influenza b or influenza c viruses. (12 Dec 1998) |
| haemagglutinin-neuraminidase protein | <protein> A protein found in the capsid of the Sendai virus which is exceptionally good at binding to the cytoplasmic membranes of many animal cells. The protein is therefore used to make fusogenic vesicles for the purpose of delivering therapeutic drugs or other chemicals directly into cells. (09 Oct 1997) |
| haemagglutinin-protease | <enzyme> Soluble haemagglutinin/protease from vibrio cholerae; a zinc metalloendopeptidase Registry number: EC 3.4.24.- Synonym: ha-protease, vibrio cholerae haemagglutinin protease, vibrio cholerae non-o1 haemagglutinin-protease, nag-ha-p (26 Jun 1999) |
| haemagglutinins | <haematology, immunology> Agents that cause agglutination of red blood cells. They include antibodies, blood group antigens, lectins, autoimmune factors, bacterial, viral, or parasitic blood agglutinins, etc. (12 Dec 1998) |
| haemagogic | Promoting a flow of blood. (05 Mar 2000) |
| haemagogue | 1. An agent that promotes a flow of blood. Synonym: emmenagogue. Origin: hem-+ G. Agogos, leading (05 Mar 2000) |
| haemal | Having to do with the blood or blood vessels. (09 Oct 1997) |
| haemal arches | <anatomy> Three or four V-shaped bones located ventral to the bodies of the third to sixth coccygeal vertebrae; they represent intercentra and usually enclose the ventral caudal artery and vein. (05 Mar 2000) |