Influenza virosomes as a combined vaccine carrier and adjuvant system for prophylactic and therapeutic immunizations

Abstract

Influenza virosomes are an efficient antigen carrier and adjuvant system that are approved for the use in human vaccines. Structurally, virosomes are spherical vesicles of approximately 150 nm in diameter, composed of a lipid membrane with integrated envelope proteins derived from influenza virus, predominantly hemagglutinin. The particle structure, together with the functions of hemagglutinin--receptor binding, pH-dependent fusion activity and immunostimulation--is responsible for the adjuvant effect of virosomes. In contrast to most other virus-like particles, virosomes are semisynthetic particles reconstituted in vitro from lipids and from virus-derived proteins. The production process has proven to be robust at industrial scale and fully compatible with Good Manufacturing Practice guidelines. At the same time, the formulation procedure is sufficiently flexible to allow modifications of the composition and structure for the intended use, including the positioning of the antigens of interest.

Delivery strategies to enhance oral vaccination against enteric infections

“…In addition, VLPs require the addition of adjuvants in order to elicit enhanced immune responses. However, virosomes may not require the addition of adjuvants and so may be the more attractive of the two options as oral delivery vehicles [183]. Results in mice following intra-nasal application of Noravirus-based VLPs have been encouraging and will perhaps in time lend themselves to the oral route [184,185] although it may be essential to incorporate these lipid based systems in enteric capsule based formulations to enhance their oral effectiveness and protect them from the lipid digesting gastrointestinal environment.…”

Immunization with HIV-1 gp41 Subunit Virosomes Induces Mucosal Antibodies Protecting Nonhuman Primates against Vaginal SHIV Challenges

“…In this study, we used market-approved virosomes (Moser et al, 2007;Herzog et al, 2009) as a carrier-in use for humans for more than 10 years-to deliver two distinct HIV-1 gp41 antigens: a recombinant, truncated, trimeric gp41 (rgp41) antigen (Delcroix-Genê te et al, 2006) and the P1 peptide (Alfsen and Bomsel, 2002;Magé rus-Chatinet et al, 2007;Yu et al, 2008;Coutant et al, 2008). P1 corresponds to the extended MPER region of gp41 and includes the binding site to the mucosal receptor galactosyl-ceramide that is present on epithelial and dendritic cells (Alfsen and Bomsel, 2002;Magé rus-Chatinet et al, 2007;Yu et al, 2008;Coutant et al, 2008).…”

Safety and Mechanism of Action of Licensed Vaccine Adjuvants

“…Virosomes are expected to allow antigen presentation in the context of both MHC I and MHC resulting in both Band T-cell responses (Herzog et al, 2009;Moser et al, 2007;Arkema et al, 2000). Because of their capacity to induce cytokines such as GM-GSF, TNF-α, IFN-γ and IL-2 in PBMCs and to allow antigen depot, virosomes are capable of improving the immunogenicity of a variety of antigens (Cusi, 2006;Moser et al, 2007). Virosomes interact directly with cells of the immune system, particularly Blymphocytes and dendritic cells.…”