Western blot analyses were performed to study the expression of viral HA and NA proteins in differentiated THP-1 cells (lanes 1–9) and viral HA protein in BALB/C mice (lanes 10–15) treated with phosphate-buffered saline (PBS) only (PBS, lanes 1, 4, 7, 10, and 13), SL368 carrying the empty vector construct pVAX1 (Sal-vector, lane 2, 5, 8, 11, and 14) and constructs p5HA and p5NA (Sal-HA-NA, lanes 3, 6, 9, 12, and 15). Cells treated with PBS or Salmonella were harvested at 72 hours post treatment while spleens and cecums were harvested from BALB/C mice that were intragastrically inoculated with PBS or SL368 carrying different constructs at 4 days after inoculation. Protein samples (40 μg) were separated on denaturing gels, transferred to membranes, and stained with antibodies against viral HA (lanes 7–15) and NA (lanes 4–6) or actin (lanes 1–3), which serves as the loading control. Molecular markers are shown on the left.