Virus titers in the lungs of mice challenged with H5N1 and H1N1 viruses.

<p>Mice were intragastrically immunized three times at day 0, 14, and 28 with PBS, the commercial H5N1 (cv-H5N1) and H1N1 vaccines (cv-H1N1), and <i>Salmonella</i> SL368 carrying the empty vector pVAX1 (Sal-vector) and constructs p5HA and p5NA (Sal-HA-NA), and then challenged intranasally with 20 LD₅₀ of lethal H5N1 (A/Viet Nam/1194R) and H1N1 (A/Puerto Rico/8/34) viruses at two weeks after final immunization. Lung tissues were harvested at 3 and 6 days post challenge and viral titers were determined. The experiments were performed in triplicate and were repeated three times, and the standard deviation is indicated by the error bar. The limit of detection was 1.0 log₁₀TCID₅₀/g.