2009]. Another virosome vaccine containing inactivated hepatitis A virus (HAV), Epaxal (Crucell NV, Leiden, The Netherlands), was developed as hepatitis A vaccine. It is excellently tolerable Raf pathway and highly immunogenic, conferring protection of at least 9–11 years in vaccinated individuals [Ambrosch et al. 1997; Gluck and Walti, 2000; Bovier et al. 2010]. Immunogenicity and safety of Epaxal was evaluated in Thai children with HIV infection. Prevalence of HAV protective antibodies was 100% after vaccination, showing that Epaxal is an effective HAV vaccine for HIV-infected children [Saksawad et al. 2011].
Another vaccine contains an aspartyl proteinase 2 (Sap2) of Candida albicans incorporated into IRIVs. Following intravaginal administration, anti-Sap2 antibodies were detected in vaginal fluids of rats, inducing long-lasting protection [De Bernardis et al. 2012]. Walczak and colleagues demonstrated that a heterologous prime boost with Semliki Forest virus encoding a fusion protein of E6 and E7 of HPV16 and virosomes containing the HPV16-E7 protein resulted in higher numbers of antigen-specific CTL in mice than homologous protocols [Walczak et al. 2011]. Today, a second generation of influenza virosomes has evolved for various preclinical and clinical stage
vaccine candidates. Additional components are included to optimize particle assembly and stability and to enhance immunostimulatory effects [Moser et al. 2013]. GPI-0100, a saponin derivative,
enhanced immunogenicity and protective efficacy of a virosomal influenza vaccine, providing full protection of infected mice at extremely low antigen doses [Liu et al. 2013]. A combination of reconstituted respiratory syncytial virus (RSV) envelopes with incorporated MPLA (RSV-MPLA) virosomes was studied by Kamphuis and colleagues in enhanced respiratory disease prone rats. Vaccination with RSV-MPLA induced higher antibody levels and protection against infection [Kamphuis et al. 2013]. Jamali and colleagues developed a DNA vaccine using cationic influenza virosomes (CIV). CIV-delivered epitope-encoding DNA induced equal numbers of IFNγ and granzyme B-producing T cells than a 10-fold higher dose of naked pDNA [Jamali et al. 2012]. Another DNA/virosome vaccine was reported by Kheiri and colleagues, who prepared a vaccine complex containing an influenza NP-encoding plasmid that induced much higher T-cell responses and protection than plasmid alone [Kheiri Batimastat et al. 2012]. In clinical trials, IRIVs have shown vast potential for delivery of peptides derived from Plasmodium falciparum antigens [Peduzzi et al. 2008]. An IRIV-formulated fusion protein composed of two malaria antigens was described by Tamborrini and colleagues. Compared with other vaccines, the adjuvant-free formulation elicited specific IgG1 antibody profiles in mice and cross reactivity with blood-stage parasites [Tamborrini et al.