In general

inactivated whole virion vaccines are more immunogenic than split/subunit vaccines [56]. However, it has been shown that whole virion vaccines may be more effective without an additional adjuvant [57], and it was mentioned that the neutralizing activity of an adjuvanted whole virion H5N1 vaccine was lower than that of an adjuvanted split-virion H5N1 vaccine [58]. The intratracheal route of virus inoculation establishes a reproducible severe pneumonia in the ferret model [36]. Ferrets immunized with nasal Endocine™ formulated vaccines, but not ferrets immunized with parenteral TIV were protected from severe pneumonia. Protection from pneumonia corresponded with the absence of detectable virus replication in the lung and absent or significantly reduced virus replication in the upper respiratory tract. Also the previously developed CT-scanning [14], [15], [28] and [29], confirmed

that nasal Endocine™ formulated Luminespib price vaccine, but not parenteral TIV protected the ferrets from severely affected and see more inflamed lungs and marked alterations in ALVs. Current candidate influenza vaccine design has a strong focus on mucosal immunity and the crucial role of mucosal adjuvants in the development of effective inactivated or subunit nasal vaccines [14], [15], [16], [17] and [18]. Adjuvanted nasal vaccines may have the advantage to induce systemic as well as mucosal immunity, including specific secretory IgA (S-IgA) [6]. Locally produced antibodies, particularly S-IgA have been demonstrated to play an important role in responses to natural infection. Pre-existing S-IgA antibodies can prevent infection by neutralizing

influenza virus before it passes the mucosal barrier, can through effectively prevent infection of epithelial cells and have been shown to contribute to the establishment of cross-protection [59]. In the present ferret study, nasal wash and swab samples were collected for detection of antibodies against influenza. Interestingly, the nasal wash procedure clearly yielded higher antibody titers than the nasal cotton swabs. Endocine™ formulated split antigen (15 μg HA) induced significantly (p < 0.05) higher nasal Ig titers in nasal wash samples after two immunizations compared to the parenteral vaccine (manuscript in preparation). Furthermore, the present study showed that the Endocine™ formulated inactivated pH1N1/09 influenza vaccines administered nasally induced broad specific systemic antibody responses in naïve ferrets. The Endocine™ formulated split antigen (15 μg HA) vaccine induced cross reactive HI antibody titers of >40 (GMT) against distant viruses of swine origin already after one immunization and both HI and VN cross reactive titers>200 (GMT) was achieved after two immunizations. Overall this study shows the feasibility to induce protective systemic immunity after intranasal administration of relatively low doses inactivated pH1N1/09 antigens when formulated with Endocine™.