Hemagglutination inhibition (HI) and neutralizing antibody (NAB) assays for PAV3-HA and AdHu5-HA.

<p>Serum was obtained from groups of PAV3-HA () or AdHu5-HA () vaccinated BALB/c mice and treated overnight at receptor-destroying enzyme (RDE), followed by complement inactivation the following day. (A) Kinetics of the HI antibody response. Serum was obtained from groups of 4 BALB/c mice on days 8, 10, 14, and 21 post-vaccination with 10¹⁰ vp/mouse of PAV3-HA or AdHu5-HA. Four agglutinating doses of H5N1-H05 virus were added to serial dilutions of serum and samples were incubated with horse red blood cells. HI antibody titre was determined as the reciprocal of the highest serum dilution which did not cause red blood cell agglutination. (B) Kinetics of the NAB response. Serum from obtained on 8, 10, 14, and 21 days post-vaccination with 10¹⁰ vp/mouse of PAV3-HA or AdHu5-HA. Serial dilutions of was also incubated with 100 pfu of H5N1-H05 virus, added to MDCK cells and monitored for the presence of cytopathic effects (CPE) over 48 hours. The NAB titre was scored as the highest serum dilution with the absence of CPE. (C) HI titre against H5N1-H05. Serum was obtained 25 days post-immunization from groups of 5–10 BALB/c mice were vaccinated with 10⁸, 10⁹, and 10¹⁰ vp/mouse of AdHu5-HA or PAV3-HA and the HI titre was assayed. (D) NAB titres against H5N1-H05. Serum from 25 days post-immunization was also monitored for NAB titre. The data represent average values and standard deviations from 3 to 5 experiments performed with 2 independent vector preparations of each vaccine (* represents p<0.05).