FIG 7.
Heterologous influenza virus challenge study following immunization using HA-ferritin nanoparticle cocktails in ferrets. (A) HAI titers (log2) of serum from ferrets (n = 12 per group) following two immunizations with immunogens and AF03 adjuvant: group 1, PBS alone; group 2, A/California/7/2009 IIV; group 3, NC99+CA09+HK77 HA-Nps; group 4, COBRA X6+COBRA P1+HK77 HA-Nps. The dashed line indicates the limit of detection. Horizontal gray bars mark the 1:40 to 1:80 ranges as a visual aid. (B) Heterologous challenge of ferrets immunized with HA-ferritin nanoparticle cocktails or PBS alone using 1947 Fort Monmouth virus. The challenge was performed 4 weeks after the last immunization by intranasal inoculation with 1 ml of A/Fort Monmouth/1/1947 virus, with a TCID50 of 104.65. Ferrets did not show significant weight loss after challenge. The dashed line indicates 0% change in weight. (C) Virus titers were quantified in the nasal washes over a time course after challenge. The dashed line indicates the assay limit of detection. Viral titers were significantly reduced at day 5 postchallenge in ferrets immunized with HA-Np combinations, but not with CA09 IIV, compared to vehicle (PBS) control by one-tailed unpaired t test and by one-way ANOVA [F(3, 44) = 5.18, P = 0.00375]. *, P ≤ 0.001 by Student's t test. The dashed line indicates the limit of detection.