Transcutaneous immunization with a novel lipid-based adjuvant protects against Chlamydia genital and respiratory infections

Mucosal adjuvants are important to overcome the state of immune tolerance normally associated with mucosal delivery and to enhance adaptive immunity to often-weakly immunogenic subunit vaccine antigens. Unfortunately, adverse side effects of many experimental adjuvants limit the number of adjuvants approved for vaccination. Lipid C is a novel, non-toxic, lipid oral vaccine-delivery formulation, developed originally for oral delivery of the live Mycobacterium bovis Bacille Calmette-Guerin (BCG) vaccine. In the present study, murine models of chlamydial respiratory and genital tract infections were used to determine whether transcutaneous immunization (TCI) with Lipid C-incorporated protein antigens could elicit protective immunity at the genital and respiratory mucosae. BALB/c mice were immunized transcutaneously with Lipid C containing the chlamydial major outer membrane protein (MOMP), with and without addition of cholera toxin and CpG-ODN 1826 (CT/CpG). Both vaccine combinations induced mixed cell-mediated and mucosal antibody immune responses. Immunization with Lipid C-incorporated MOMP (Lipid C/MOMP), either alone or with CT/CpG resulted in partial protection following live challenge with Chlamydia muridarum as evidenced by a significant reduction in recoverable Chlamydia from both the genital secretions and lung tissue. Protection induced by immunization with Lipid C/MOMP alone was not further enhanced by the addition of CT/CpG. These results highlight the potential of Lipid C as a novel mucosal adjuvant capable of targeting multiple mucosal surfaces following TCI. Protection at both the respiratory and genital mucosae was achieved without the requirement for potentially toxic adjuvants, suggesting that Lipid C may provide a safe effective mucosal adjuvant for human vaccination

An Oral Mycobacterium bovis BCG Vaccine for Wildlife Produced in the Absence of Animal-Derived Reagents▿

Cultures of Mycobacterium bovis BCG, comprising predominantly single-cell bacilli, were prepared in broth without animal-derived reagents. When formulated into a vegetable-derived lipid matrix, the vaccine was stable in vitro and was immunogenic in vivo upon feeding it to mice. This formulation could be useful for oral vaccination of wildlife against tuberculosis, where concern over transmissible prions may preclude the field use of vaccines containing animal products

Oral Delivery of Mycobacterium bovis BCG in a Lipid Formulation Induces Resistance to Pulmonary Tuberculosis in Mice

A lipid-based formulation has been developed for oral delivery of Mycobacterium bovis bacille Calmette-Guérin (BCG) vaccine. The formulated M. bovis BCG was fed to BALB/c mice to test for immune responses and protection against M. bovis infection. The immune responses included antigen-specific cytokine responses, spleen cell proliferation, and lymphocyte-mediated macrophage inhibition of M. bovis. Oral delivery of formulated M. bovis BCG to mice induced strong splenic gamma interferon levels and macrophage inhibition of virulent M. bovis compared with results with nonformulated M. bovis BCG. Formulated oral M. bovis BCG significantly reduced the bacterial burden in the spleen and lungs of mice following aerosol challenge with virulent M. bovis. Our data suggest that oral delivery of formulated M. bovis BCG is an effective means of inducing protective immune responses against tuberculosis. Lipid-based, orally delivered mycobacterial vaccines may be a safe and practical method of controlling tuberculosis in humans and animals

N-Terminal E-Cadherin Peptides Act as Decoy Receptors for Listeria monocytogenes

The observation that E-cadherin is the principal epithelial receptor for the bacterial pathogen Listeria monocytogenes led us to investigate whether N-terminal fragments of E-cadherin containing the L. monocytogenes binding domain could inhibit entry of the bacteria into cultured epithelial cells. Here we demonstrate that a conditioned medium from a gastric cancer cell line (Kato III) that carries a truncating CDH-1 mutation 3′ of the L. monocytogenes binding domain can inhibit the uptake of the bacteria into Caco-2 cells. The inhibitory activity of the Kato III conditioned medium could be mimicked by incubation of the bacteria with a recombinant 26-kDa N-terminal E-cadherin peptide prior to infection. Furthermore, these data suggest that cleavage of the 80-kDa extracellular domain of E-cadherin from the cell surface may provide an innate form of pathogen defense by acting as a decoy receptor for L. monocytogenes

Oral vaccination with Liporale™-BCG increases the number of Ag85B-specific CD4⁺ T cells in the spleen.

<p>Lymphocytes from the spleens of naïve, Liporale™-BCG vaccinated (BCG oral) or subcutaneously vaccinated (BCG s.c.) mice were stained with an Ag85B/MHCII tetramer and enriched for tetramer positive cells by magnetic bead isolation. (A) Representative flow cytometry plots show Ag85B-specific CD4⁺ T cells in the spleens of naïve or BCG vaccinated mice at 4, 8 and 30 weeks post immunization. (B) Bar graphs show the number of Ag85B-specific CD4⁺ T cells in the spleens of naïve or BCG vaccinated mice at 4, 8 and 30 weeks post vaccination. Results are displayed as mean +SEM of n = 5 for each group, significance expressed relative to naïve: *p<0.05, **p<0.01, ***p<0.001 (one way ANOVA with Tukey post test). The 8 and 30 weeks results are representative of 2 independent experiments.</p