Method
1. Fill in recording sheets to record how samples will be dispensed into microwell plates.
2. Calculate the number of plates required and number each plate.
3. Dispense 25 µL of PBS into each well of the plates.
4. Shake each serum sample and dispense 25 µL into the first well and the last (control) well of a row of a microwell plate.
5. Use a multichannel pipette to make two-fold serial dilutions along the row until the second last well from the end. The last well is the serum control. Do not dilute this well. See Appendix 4 for instructions on carrying out two-fold serial dilutions.
6. Add 25 µL of the 4HA dilution of antigen to each well excluding the control wells in the last column. See Section 10 for preparation of 4HA units of antigen
7. Gently tap the sides of the microwell plates to mix the reagents. Cover plates with a lid. Allow to stand for 30 minutes at room temperature.
8. Add 25 µL of 1 percent washed red blood cells to each well including the control wells in the last column.
9. Gently tap the sides of the microwell plates to mix the reagents. Cover the plates with a lid. Allow to stand at room temperature for 45 minutes.
10. Read the settling patterns for each serum sample. Read the control serum well first then read the patterns in the other wells.
11. Record the pattern observed in each well on a microwell plate recording sheet. Determine the endpoint. This is the point where there is complete inhibition of haemagglutination.
12. Record the antibody level for each serum sample. This is expressed as a log base 2. For convenience, the titre is often recorded as just the log index. For example a titre of 26 would be recorded as 6.