Table 1.

Antibody response and percent survival

Initial inoculum and boost (PFU/mouse)AntibodyaNTbto influenza A/WSN virus at:% Survivalcafter challenge
Initial bleedSecond bleed
VSVrwt (106)−WSN-HA, +VSV<1:8<1:80
VSVrwt (105)−WSN-HA, +VSVNDND0
VSVrwt (104)−WSN-HA, +VSVNDND0
VSV-HA (106)+WSN-HA, +VSV≥1:512≥1:1,024100
VSV-HA (105)+WSN-HA, +VSV≥1:512≥1:1,024100
VSV-HA (104)+WSN-HA, +VSV≥1:512≥1:1,024100
  • a As determined by IFA. Primary antibody was pooled mouse serum diluted to 1:100 in PBS-glycine-BSA; secondary antibody was fluorescein isothiocyanate-conjugated goat anti-mouse antibody diluted to 1:50 in PBS-glycine-BSA.

  • b NT, neutralizing antibody titer. For initial bleed, pooled sera were collected 3 days prior to boost. For second bleed, pooled sera were collected 3 days prior to challenge. ND, not determined.

  • c % Survival indicates the percentage of mice surviving lethal challenge with influenza A/WSN virus. There were three mice in each of the six inoculum groups.