What Is Antigenicity?

Antigenicity refers to the ability of an antigen to specifically bind to the antibodies or sensitized lymphocytes it induces. The strength of the antigenicity is closely related to the size of the antigen molecule, the chemical composition, the structure of the epitope, and the distance between the antigen and the immunized animal. It is generally believed that the larger the molecular weight of an antigen, the more complex its chemical composition, the more complete its three-dimensional structure, and the farther it is related to the animal to be immunized, the stronger its antigenicity. The physical state of the antigen also affects the antigenicity. For example, the polymerization state of the antigen is stronger than that of the monomer. Generally, the spherical molecule is stronger than the fibrous molecule. After adding the adjuvant to the antigen to change the physical state, the antigenicity is also enhanced. For example, gelatin with a molecular weight of up to 100,000 is poor in stability due to the lack of benzene ring amino acids, and is easily degraded by enzymes into low molecular substances after entering the body. If a small amount of tyrosine (benzene ring amino acids) is added, its antigenicity can be enhanced .

Antigenicity

Antigenicity refers to the antigen and the antibodies or antibodies it induces.

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flu virus

Divided into three types A, B, C. Type A is prone to cause a pandemic and the disease is severe; Type E and C are epidemic or sporadic and the disease is relatively mild. Due to the rapid changes in the antigenicity of influenza viruses, humans cannot obtain lasting immunity.

Viral Hepatitis A (HAV)

HAV virus has solid and hollow particles. Solid particles have intact virus and are infectious. Hollow ones are not infectious, but they are antigenic. HAV virus has four proteins, of which the VP1 gene is mainly the viral nucleocapsid protein gene and contains the epitopes of neutralizing antibodies. Although there are four genotypes, their antigenicity is similar, so HAV has only one serotype and one antigen-antibody system.

There are three major antigen-antibody systems for hepatitis B (HBV) in viral hepatitis.