Introduction
-
Haemagglutinin is viral coded glyco proteins, on the outer surfaces of their envelope which confer the viruses to attach to red blood cells and link them together in large aggregates.
-
The red blood cells having receptor sites are chemically N-aectyl -Neuramic acid (NANA)
-
The linking together of the red blood cells by the viral particles results in clumping.
-
This clumping is known as haemagglutination.
-
The type of erythrocytes that is agglutinated varies from virus to virus .
-
The haemagglutination of virus varies with the composition of the suspending medium, range of pH (5.0-9.0) and temperature.
-
This is not an antigen antibody reaction but a network of any erythrocytes formed by bridging virions.It only indicate the presence of virus particles.
-
Hirst in 1941 first observed the haemagglutination of chicken RBC by influenza virus.
-
A large number of virus particles are needed to cause visible agglutination and so the test is comparatively insensitive and unsuitable for the detection of small number of virions.
-
Some virus family causing haemagglutination includes
-
Haemagglutinin and neruminidase are sero type specific in influenza virus and form the basis of typing of serum.
Note
-
The test does not discriminate between viral particles that are infectious and particles that are degraded and no longer able to infect cells. Both can cause the agglutination of red blood cells.
-
Some bacteria will also agglutinate chicken red blood cells.
|
Last modified: Monday, 4 June 2012, 8:17 AM