Figure 1: Neutralizing antibody response following RSV-G protein, FI-RSV and live RSV experimental infection.
(A) Schematic representation of cotton rat immunization and challenge schedule. Inbred female Sigmodon hispidus cotton rats between 6 and 8 weeks of age were immunized i.m. with PBS (Gps A-B), 5 μg of unadjuvanted or Emulsigen-adjuvanted REG (Recombinant E . coli produced G) (Gps C-D), or with FI-RSV (Gp E) on days 0 and 28 in groups A thru E, or were infected intranasally (i.n.) with 0.1 ml of RSV/A2 at 105 pfu per rat (Gp F). Blood was collected by eye-bleed on days 0, 28 and 49. On day 49, animals were either mock challenge intranasally with 0.1 ml of PBS (Gp A), or with 0.1 ml of RSV-A2 virus at 105 pfu per animal (10 animals per group) (Gps B-F). Cotton rats were sacrificed on days 2 or 5 post-challenge wherein lungs and nose tissues were collected. (B) Sera from individual cotton rats collected at pre-vaccination (day 0) and 3 weeks post second immunization (day 49) were tested for neutralization in a plaque reduction neutralization test (PRNT) against the homologous RSV-A2 strain and heterologous RSV-B1 strain. Neutralizing antibody titers represent 50% inhibition of plaque numbers. Statistical significance was tested with one-way ANOVA and Bonferroni multiple comparisons tests. ***p < 0.0001.
