Tobacco Mosaic Virus as a mucosal delivery platform for an intranasal vaccine against Pseudomonas aeruginosa

Pseudomonas aeruginosa (PA) is a gram-negative opportunistic pathogen that is one of the most prominent causes of healthcare acquired infections worldwide. It is also a significant cause of morbidity and mortality associated with burn wounds, and in chronic lung infections associated with cystic fibrosis (CF). PA has a wide variety of virulence mechanisms and can cause many different types of mucosal and soft tissue infections. It is one of the most common causes of ventilator associated pneumonia, and a top ten cause of surgical site infections, catheter associated urinary tract infections, and blood infections from central lines. The spread of antimicrobial resistance has made PA infections increasingly difficult to treat, and multi-drug resistant (MDR) PA is considered a critical threat to public health by the World Health Organization and the Centers for Disease Control and Prevention. New approaches for the treatment and/or prevention of PA are needed. Vaccines are one of the most successful medical interventions in history. Most vaccines are giving parenterally via injection, a route of administration that does not provide strong protection at mucosal surfaces, which is the site of entry for most pathogens. Mucosal vaccination provides strong protection at mucosal sites, such as the respiratory tract, as well as systemically. This is ideal for a pathogen like PA which can cause disease at different sites. A challenge for mucosal vaccination is the need for delivery methods that can overcome the natural tolerogenic mechanisms that occur at these sites, while not inducing overt inflammatory reactions. We are developing an intranasal protein subunit vaccine against PA, using tobacco mosaic virus (TMV) as a delivery platform. TMV is a plant pathogen that does not infect animal cells and is highly immunogenic, being an optimal size and composition for recognition by the immune system. We have developed a recombinant TMV that expresses a surface exposed lysine on the coat protein allowing for the conjugation of vaccine antigens to the viral surface. In preliminary studies we demonstrated that IN vaccination with TMV conjugated to PcrV, the tip protein of the PA type III secretion system, in the presence of the Th17 skewing adjuvant curdlan, protected mice against lethal respiratory challenge with PA. Protection was associated with production of anti-PcrV antibody and elevated IL-17 and IFNγ in the lungs and spleens of mice following infection. In the present study we will define additional vaccine antigens to create a multi-valent vaccine that will provide broad protection against multiple strains of PA. We will also identify the mechanism(s) of vaccine mediated protection to provide additional pathways that can be targeted for improving vaccine efficacy. PA is a major public health threat that requires new and innovative methods to protect patients in health care settings, first responders and our military, and CF patients from disease and death. The goal of this project is an effective mucosal vaccine that will provide broad coverage against different types of PA infections for use in at risk patients to limit the impact of MDR PA and improve patient outcomes.