A nasal diphtheria vaccine formulated with Endocine™ (1 or 4%) was evaluated in a phase I study in 2002, and was found to be safe find more and tolerable. Subjects receiving the diphtheria vaccine with 4% Endocine™ had a higher increase in neutralization titers compared to subjects receiving unadjuvanted vaccine (unpublished data). An inactivated whole virus influenza vaccine and

an HIV vaccine, and was shown to be safe and tolerable in all studies [19] and [20]. Pre-clinical studies with split virion influenza vaccines showed that Endocine™, (previously known as L3B), significantly increases both local and systemic immune responses after intranasal immunization [21].

Addition of the adjuvant to a subunit influenza antigen given intranasally to mice conferred protection (measured by detection of viral RNA) against homologous virus challenge [22]. To further investigate the potential of Endocine™ to adjuvant inactivated nasal influenza vaccines we used the ferret as a model for influenza. Ferrets are considered to be the most suitable animal model for the different forms of Selleckchem GSK1210151A human influenza and are naturally susceptible to infection with all wildtype human influenza A viruses causing clinical changes in ferrets similar to those observed in humans. Also the pathogenesis and antibody responses observed in ferrets are quite similar to those in humans [23] and [24]. Furthermore ferrets share similarities in lung physiology and airway morphology with humans [25] and [26] and the pattern of influenza virus Thymidine kinase attachment and replication in the ferret respiratory tract is largely similar to that in humans [27]. In the current study the efficacy of nasal Endocine™ adjuvanted split virion and whole virus pH1N1/09 candidate vaccines was evaluated using the homologous wildtype H1N1 A/The Netherlands/602/2009 (wt-pH1N1) virus as a challenge. Humoral, hemagglutination

inhibiting (HI) and virus neutralizing (VN) antibody responses against homologous and three distant swine H1N1 viruses were evaluated. Efficacy was measured by evaluating clinical, virological and pathology parameters. In addition computed tomography (CT) imaging was performed as a newly developed read out parameter of efficacy by quantifying alterations in aerated lung volumes (ALV) [28] and [29]. Vaccine nasal drops: Endocine™ 20 mg/ml formulated inactivated H1N1/California/2009 split virion antigen at 5, 15 and 30 μg HA/0.2 ml and whole virus antigen at 15 μg HA/0.2 ml were provided by Eurocine Vaccines AB (Stockholm, Sweden). Parenteral vaccine: Fluarix®, season 2010/2011, also containing inactivated H1N1/California/2009 (GlaxoSmithKline).