Jee Loon Look

Options for Inactivation, Adjuvant, and Route of Topical Administration of a Killed, Unencapsulated Pneumococcal Whole-Cell Vaccine

ABSTRACT We previously reported that ethanol-killed cells of a noncapsulated strain of Streptococcus pneumoniae, given intranasally with cholera toxin as an adjuvant, protect rats against pneumonia and mice against colonization of the nasopharynx and middle ear by capsulated pneumococci of various serotypes. The acceleration of pneumococcal clearance from the nasopharynx in mice is CD4+ T cell-dependent and interleukin 17A (IL-17A) mediated and can be antibody independent. Here, anticipating human studies, we have demonstrated protection with a new vaccine strain expressing a nonhemolytic derivative of pneumolysin and grown in bovine-free culture medium. Killing the cells with chloroform, trichloroethylene, or beta-propiolactone—all used without postinactivation washing—produced more-potent immunogens than ethanol, and retention of soluble components released from the cells contributed to protection. Two sequential intranasal administrations of as little as 1 μg of protein (total of cellular and soluble combined) protected mice against nasopharyngeal challenge with pneumococci. Nontoxic single and double mutants of Escherichia coli heat-labile toxin were effective as mucosal adjuvants. Protection was induced by the sublingual and buccal routes, albeit requiring larger doses than when given intranasally. Protection was likewise induced transdermally with sonicates of the killed-cell preparation. Thus, this whole-cell antigen can be made and administered in a variety of ways to suit the manufacturer and the vaccination program and is potentially a solution to the need for a low-cost vaccine to reduce the burden of childhood pneumococcal disease in low-income countries.

Transcutaneous immunization with Intercell's vaccine delivery system.

Transcutaneous immunization (TCI) has become an attractive alternate route of immunization due to increase understanding of the skin immune system and to recent technical innovations in skin patch delivery systems. Basic principles of TCI have been demonstrated in animal and human studies, covering a variety of bacterial, viral, and cancer diseases. At Intercell, we have advanced two major platforms of TCI: 1) a needle-free vaccine delivery patch (VDP) and 2) a vaccine enhancement patch (VEP). Simplified, the VDP contains an antigen with or without an adjuvant that is administered on the skin; while the VEP contains only the adjuvant and is used in combination with an injected vaccine. In many of our TCI studies, the VDP or VEP is routinely applied on pretreated skin, in which the stratum corneum has been partially removed by mild abrasion. Recently, we have achieved technical breakthroughs in formulating and stabilizing vaccines in a dry patch format. For instance, a microplate-based screening process has been implemented to rapidly identify excipients, singularly or in combination, to stabilize biological macromolecules in patch blend formulations. A second technical innovation is our nonwoven (patch) disc matrix-supported drying technology, which allows efficient drying of our patch formulation blend to produce dry stable dosage forms of VDP or VEP. The low cost and the facileness in the manufacturing of VDP (or VEP) combined with the development of thermostable dry patches should improve the supply chain efficiency and reduce the dependence on cold chain.

Transcutaneous delivery and thermostability of a dry trivalent inactivated influenza vaccine patch.

A patch containing a trivalent inactivated influenza vaccine (TIV) was prepared in a dried, stabilized formulation for transcutaneous delivery. When used in a guinea pig immunogenicity model, the dry patch was as effective as a wet TIV patch in inducing serum anti‐influenza IgG antibodies. When the dry TIV patch was administered with LT as an adjuvant, a robust immune response was obtained that was comparable with or better than an injected TIV vaccine. When stored sealed in a nitrogen‐purged foil, the dry TIV patch was stable for 12 months, as measured by HA content, under both refrigerated and room temperature conditions. Moreover, the immunological potency of the vaccine product was not affected by long‐term storage. The dry TIV patch was also thermostable against three cycles of alternating low‐to‐high temperatures of −20/25 and −20/40°C, and under short‐term temperature stress conditions. These studies indicate that the dry TIV patch product can tolerate unexpected environmental stresses that may be encountered during shipping and distribution. Because of its effectiveness in vaccine delivery and its superior thermostable characteristics, the dry TIV patch represents a major advance for needle‐free influenza vaccination.