FIG 4.
Viral titers in nasal tissues and lungs of challenged mice. Groups of five 7-day-old mice were immunized with either iFlu (1 μg) alone or with an adjuvant: GVI3000 (105 IU) or alum (Alhydrogel [1:5]). An additional PBS-immunized group was included. Five weeks after the single immunization, mice were challenged intranasally with 106 EID50 of influenza A/PR/8/34 virus. (A) Mice were euthanized 48 h postchallenge, and nasal tissues were collected in TRIzol. Following RNA extraction, real-time PCR was done with PR8 HA primer/probes. CT values were plotted on PR8 HA standard curve to calculate virus titer. (B) Mice were euthanized 3 days postchallenge, and their lungs were harvested. After homogenization of lung tissues, TCID50 assay was performed on MDCK cells. Cell supernatants were collected after 48 h of incubation, and hemagglutination assay was performed with 5% chicken red blood cells. TCID50/ml values were calculated using the Reed-Muench method (50). All data are presented as means plus SEM. Values that are significantly different by the Mann-Whitney test are indicated by bars and asterisks as follows: *, P < 0.05; **, P < 0.01.