Food Additives as Novel Influenza Vaccine Adjuvants.

Influenza is a major threat to public health. Vaccination is an effective strategy to control influenza; however, the current inactivated influenza vaccine has mild immunogenicity and exhibits suboptimal efficacy in clinical use. Vaccine efficacy can be improved by the addition of adjuvants, but few adjuvants have been approved for human use. To explore novel and effective adjuvants for influenza vaccines, here we screened 145 compounds from food additives approved in Japan. Of these 145 candidates, we identified 41 compounds that enhanced the efficacy of the split influenza hemagglutinin (HA) vaccine against lethal virus challenge in a mouse model. These 41 compounds included 18 novel adjuvant candidates and 15 compounds with previously reported adjuvant effects for other antigens but not for the influenza vaccine. Our results are of value to the development of novel and effective adjuvanted influenza or other vaccines for human use.

Experimental infection of Cynomolgus Macaques with highly pathogenic H5N1 influenza virus through the aerosol route.

Several animal models are used to study influenza viruses. Intranasal inoculation of animals with a liquid inoculum is one of the main methods used to experimentally infect animals with influenza virus; however, this method does not reflect the natural infection with influenza virus by contact or aerosol route. Aerosol inhalation methods have been established with several influenza viruses for mouse and ferret models, but few studies have evaluated inoculation routes in a nonhuman primates (NHP) model. Here, we performed the experimental infection of NHPs with a highly pathogenic H5N1 influenza virus via the aerosol route and demonstrated that aerosol infection had no effect on clinical outcome, but caused broader infection throughout all of the lobes of the lung compared with a non-aerosolized approach. Aerosol infection therefore represents an option for inoculation of NHPs in future studies.