The analysis of mucosal immune responses induced by intranasal administration of an inactivated influenza virus vaccine in human. - The detection and analysis of neutralizing antibodies in nasal mucosa induced by intranasal administration of an inactivated whole-virus vaccine (H3N2 virus) in human.

Haemagglutination inhibition (HI) and neutralization (NT) titres as well as haemagglutinin (HA) specific antibody responses were examined in 50 healthy adults aged between 22 and 69 years old after two intranasal administrations of an inactivated A/Victoria/210/2009 whole virus vaccine (45 ug HA per dose) at 3 week intervals. Serum HI titres after two-doses of the nasal vaccine showed >2.5-fold rise in the ratio of geometric mean titre upon vaccination, >40% of subjects with a >4-fold increase in titre and >70% of subjects with a titre of >1:40, all parameters associated with an effective outcome of vaccination in the criteria defined by the European Medicines Agency. Serum neutralizing antibody responses correlated with HI antibody responses, although NT titres were about two-fold higher than HI titres. These high levels of serum responses were accompanied by high levels of HI and neutralizing antibody responses in nasal mucus as measured in concentrated nasal wash samples that were about 10 times diluted compared to natural nasal mucus. Serum and nasal HI and neutralizing antibody responses consisted of HA-specific IgG and IgA antibody responses, with IgG and IgA antibodies being dominant in serum and nasal responses, respectively. Hum Vaccin Immunother. 2013 Sep 1;9(9):1962-70. doi: 10.4161/hv.25458.