Liposomes containing glucosyl ceramide specifically bind T4 bacteriophage: a self-assembling nanocarrier formulation

Abstract

A unique formulation is described comprising liposomes containing glucosyl ceramide (GluCer) in the lipid bilayer to which bacteriophage T4 was attached. Binding of the phage T4 did not occur to glycolipids, such as galactosyl ceramide, containing an aldose in which the C-2 or C-4 conformations were not identical to glucose. These results strongly support previous proposals that glucose is a major receptor moiety for T4 binding to Escherichia coli. By using the binding of T4 to liposomal GluCer, we further describe a formulation that can be used as a self-assembling combined antigen and adjuvant carrier. A peptide antigen derived from C-trimer (Ct) of HIV-1 gp41 was fused to the highly antigenic outer capsid protein (Hoc), a nonessential protein of T4 that spontaneously binds to the T4 capsid. This resulted in display of the Ct-Hoc construct on the T4 capsid, and specific binding of a human monoclonal antibody that recognizes a peptide sequence of Ct was demonstrated. Liposomes containing monophosphoryl lipid A (MPLA) have been demonstrated to have potent adjuvant activities for experimental vaccines both in humans and animals, and because of this, mice were immunized with the Ct-Hoc-T4 construct that was bound to liposomes containing both GluCer and MPLA, resulting in the induction of high titers of Ct-specific antibodies. We conclude that liposomes containing both GluCer and MPLA can spontaneously bind to a construct of T4 that displays antigens that spontaneously binds to the capsid of T4 bacteriophage. This formulation could be utilized as an easily manufactured self-assembling antigen and adjuvant carrier.

Keywords::

• Adjuvant
• nanotechnology
• vaccines

Acknowledgments

The authors gratefully acknowledge the assistance of Ms. Elaine Morrison for immunization and sera collection and Ms. Sarah McCormack for performing the PA-specific IgG ELISAs. The authors also thank Drs. Taheri Sathaliyawala and Qin Li for their construction of recombinant gp41 and display on phage T4. The views and opinions expressed in this article are those of the authors and do not reflect the official policy of the Department of the Army, the Department of Defense, or the U.S. government. The study was conducted in compliance with the animal welfare act and adhered to the principles in the Guide for Care and Use of Laboratory Animals. The investigators used facilities accredited by the Association for Assessment and Accreditation of Laboratory Animal Care International. The Walter Reed Army Institute of Research Animal Care and Use Committee approved all animal experiments.

Declaration of interest

This work was supported through Cooperative Agreement no. DAMD17–93-V-3004 between the Henry M. Jackson Foundation for the Advancement of Military Medicine and the U.S. Army Medical Research and Material Command, working together with the Division of AIDS, National Institute for Allergy and Infectious Diseases, National Institutes of Health (Bethesda, Maryland, USA).