Combination vaccines can reduce the number of injections and simplify the immunization schedule required to prevent different diseases. Here we assessed the immunogenicity in a mouse model of a vaccine composition comprising inactivated influenza viruses (H5N1/H1N1), enterovirus 71 (EV71), and/or Japanese encephalitis virus (JEV) and investigated whether the vaccine formulations can overcome the immunologic interference between the individual vaccine components. We demonstrated that the antigenic competition happens between H5N1/H1N1 or H5N1/EV71 inactivated virions when the vaccine combinations either formulated with Alum suspensions or without adjuvant. In the presence of PELC emulsified particles, EV71-specific immune responses before and after incorporating H5N1 virus into EV71 vaccine were detected of no significant difference; in addition, H5N1- and EV71-specific immune responses were found at the same level when H5N1/EV71/JEV consolidating into combination vaccine. Emulsified vaccine formulation was represented as a potential tool that is found to reduce the number of injections required to prevent multiple infectious strains causing the same disease (H5N1/H1N1) and/or that protect against different diseases (H5N1/EV71). Combination vaccines can also include a third component to protect against H5N1/EV71/JEV at the same time.
Keywords: Japanese encephalitis; adjuvant; combination vaccine; enterovirus 71; influenza.