VMC 221: Veterinary Immunology and Serology (1+1)

PRINCIPLE

• Viruses like Orthomyxo, Paramyxoviruses etc. have the property to clump the erythrocytes of certain species of birds or animals. This is not an antigen-antibody reaction but a network of erythrocytes formed by the bridging virions. The virions on their envelope have peplomers that binds with the receptors on the erythrocytes.
• If large quantities of virus are used for HA and allowed to act on red blood cells for a long period of time, the agglutinated red cells shed the virus particles which then float freely in the suspending fluid and neither attaches to the same red cells nor agglutinate them. This process of dissociation of virus from the red cells is known as elution, and is due to the destruction of receptors on red cells by the virion associated receptor destroying enzyme – neuraminidase. The elution will occur most rapidly if the temperature is raised to 37 ⁰ C as the enzyme neuraminidase will be more active at this temperature.

 Haemagglutination test