FAVN (Fluorescent Antibody Virus Neutralisation)
The FAVN is a classical virus neutralisation test and is the method of choice for determining the levels of antibody to rabies virus in serum.
In the rabies FAVN test, multiple serial dilutions of test serum are incubated with 100TCID50 of the CVS strain of rabies virus. After the initial serum virus incubation, BHK-21 cells are added and the test plate is incubated for 48 hours at 37 degrees Celsius. As the strain of virus used in the test causes little or no Cytopathic effect, the test is then read by immunofluorescence.
A D50 endpoint titre (i.e. where 50% of the wells at that serum dilution show the presence of virus) is calculated for each test serum and the control sera by the Spearman Karber method. By international convention, this titre is converted to a value in IU/mL by comparison to a standard serum of known titre.
For more information on virus neutralisation tests visit our VNT page.