Enhancement of the Immunogenicity and Protective Efficacy of a Mucosal Influenza Subunit Vaccine by the Saponin Adjuvant GPI-0100

Abstract

Identification of safe and effective adjuvants remains an urgent need for the development of inactivated influenza vaccines for mucosal administration. Here, we used a murine challenge model to evaluate the adjuvant activity of GPI-0100, a saponin-derived adjuvant, on influenza subunit vaccine administered via the intranasal or the intrapulmonary route. Balb/c mice were immunized with 1 µg A/PR/8 (H1N1) subunit antigen alone or in combination with varying doses of GPI-0100. The addition of GPI-0100 was required for induction of mucosal and systemic antibody responses to intranasally administered influenza vaccine and significantly enhanced the immunogenicity of vaccine administered via the intrapulmonary route. Remarkably, GPI-0100-adjuvanted influenza vaccine given at a low dose of 2×1 µg either in the nares or directly into the lungs provided complete protection against homologous influenza virus infection.

Advax augments B and T cell responses upon influenza vaccination via the respiratory tract and enables complete protection of mice against lethal influenza virus challenge

“…Hemagglutination inhibition (HI) assay was performed as described previously [30]. Briefly, sera were pooled from each experimental group and 4 hemagglutination units (4 HAU) of inactivated virus were added to two-fold diluted serum samples.…”

Passive inhalation of dry powder influenza vaccine formulations completely protects chickens against H5N1 lethal viral challenge

“…Serum samples and lung washes were used for the determination of IgY and IgA antibody titers. For the determination of IgY titers, ELISA was performed as previously described [36], except that the secondary antibody consisted of goat anti chicken IgY-HRP (Southern Biotech, Birmingham, USA). IgY titers were determined as log 10 of the reciprocal of the sample dilution corresponding to an absorbance of 0.2 at the wavelength of 492 nm.…”

Advancements in the development of subunit influenza vaccines

“…For example, a saponin-derived adjuvant, GPI-0100, may improve the immunogenicity and protective efficacy of a mucosal influenza HA subunit vaccine in immunized mice [95]. Moreover, a recombinant cholera toxin B subunit (rCTB) significantly increased serum IgG and mucosal IgA immune responses and serum neutralizing antibody titers of mice intranasally immunized with a recombinant baculovirus surface-displayed HA (BacHA) compared with those from the mice administered with unadjuvanted BacHA [96].…”