FIG. 6.
ELISPOT results of cytokine-producing lymphocytes in response to stimulation with influenza virus HA protein or nucleoprotein peptide. Splenocytes isolated at week 6 were stimulated for 2 days with EL-4 cells infected with rVV expressing influenza virus HA protein or nucleoprotein peptides. (A) IFN-γ-producing spots. H-2b-restricted major histocompatibility complex class I peptide NP1 (ASNENMDTM) was used for IFN-γ stimulation as a nucleoprotein peptide. (B) IL-4-producing spots. H-2b-restricted class II peptide NP2 (ARSALILRGSVAHKSCLPACVYGP) was used for IL-4 stimulation. Naive, unimmunized control; SHIV, SHIV VLPs alone; SHIV-HA, chimeric SHIV-HA VLPs; SHIV+Flu, SHIV VLPs plus inactivated influenza virus. The statistical significance of the difference between the SHIV VLP group and the other groups was calculated by Student's t test: *, P < 0.05.