Figure 3.

 The antibody‐secreting cell response (ASC) induced after intranasal influenza vaccination. Groups of five mice were intranasally immunised twice (21 days apart) with a subunit (SU) influenza A H5N1 vaccine. The control group consisted of unimmunised mice. Three groups were vaccinated with different antigen doses (7.5, 15 or 30 μg HA) of the chitosan‐adjuvanted SU vaccine. One group was vaccinated with a non‐adjuvanted SU vaccine with 30 μg HA, and a further group was immunised with a non‐adjuvanted 15 μg HA whole virus vaccine. Animals were euthanised 4 days after the second immunisation, and splenocytes were used to enumerate the influenza‐specific ASCs by the ELISPOT assay. The data are presented as the mean number of class and IgG subclass influenza‐specific ASCs per 500 000 lymphocytes ± standard error of the mean (SEM). HA, haemagglutinin.