Final answer:
Viral neutralization assays measure the ability of neutralizing antibodies to prevent viruses from binding to host cells, while hemagglutination assays detect viruses that cause agglutination of red blood cells. Hemagglutination inhibition assays determine the antibody titer by adding antibodies to a sample to block agglutination.
Step-by-step explanation:
The main difference between viral neutralization and hemagglutination assays lies in their purposes and outcomes. Viral neutralization involves the body's neutralizing antibodies that bind to and inhibit the infectivity of viruses, thereby preventing them from binding to host cell receptors. This can be quantified using a viral neutralization assay, where the level of virus-neutralizing antibodies in a patient's serum is determined by observing the decrease in the number of infectious virions, often measured by the absence of viral plaques or hemagglutination.
On the other hand, hemagglutination is a phenomenon where viruses, such as influenza, which have hemagglutinin surface proteins, cause red blood cells to clump together or agglutinate. The direct hemagglutination assay (HA) is used to detect the presence of these viruses. Hemagglutination is visible as a dispersed pink precipitate, unlike a clear pellet formed in the absence of agglutination.
A related concept is the hemagglutination inhibition assay (HIA), which determines the titer of antiviral antibodies in the patient's serum. The HIA utilizes the patient's antibodies to prevent the virus-bound hemagglutinins from clumping the red blood cells, therefore, no agglutination is observed. The highest serum dilution that blocks agglutination indicates the titer of the patient's antibodies.