Worked example
Preparation of 4HA units of antigen for HI test in 10 microwell plates:
The HA titre of the antigen was tested according to the protocol described above. The HA titre = 128
Calculation of dilution factor to prepare 4 HA units: 128/4 = 32
Calculation of volume of 4HA unit dilution of antigen required:
Allow 2.5 mL per plate; total volume required = 10 × 2.5 mL = 25 mL
Apply dilution factor = 25 mL/32 = 0.781 mL = 781 µL
Preparation of the diluted antigen: mix 781 µL of original virus suspension with 24.219 mL of diluent. PBS is a suitable diluent.