FIG. 2.

Humoral immune responses against influenza virus after intranasal immunization with chimeric SHIV-HA VLPs or a mixture of SHIV VLPs and inactivated influenza virus. Serum samples were collected at week 6 after the final immunizations, and antibodies were analyzed using ELISA plates coated with influenza virus. (A) Serum IgG specific to influenza virus. (B) Isotypes of IgG1 and IgG2a specific to influenza virus in sera after the third immunization (6 weeks). Error bars are given for six mice in a group. Naive, unimmunized mice; SHIV, SHIV VLPs alone; SHIV-HA, chimeric SHIV-HA VLPs; SHIV+Flu, SHIV VLPs coadministered with inactivated influenza virus; SHIV+CpG, SHIV VLPs coadministered with CpG DNA.