Project Summary
Pseudomonas aeruginosa (PA) is an opportunistic pathogen that causes a diverse array of disease
manifestations. It is a major cause of healthcare associated infections worldwide, chronic lung infection in
patients with cystic fibrosis (CF), and burn wound infections. There is a high rate of antimicrobial resistance in
PA, leading to significant morbidity and mortality from infection. The World Health Organization has classified
multidrug resistant (MDR) PA as a priority 1 pathogen for research. As infections with MDR strains of PA have
become commonplace, treatment options have become limited. We propose to develop a vaccine to prevent PA
infection in high-risk individuals. Prior attempts to develop a PA vaccine have focused on protection from
respiratory infection, most notably ventilator-associated pneumonia and lung infection in CF patients. These
attempts have been unsuccessful despite the induction of detectable vaccine-specific antibody responses in
immunized patients. We and others hypothesize that the parenteral immunization scheme and adjuvants used
in these studies do not produce the full spectrum of balanced humoral and cellular immunity necessary for
effective protection from PA in the respiratory tract. This can be overcome through direct immunization at the
mucosal surface with an adjuvant that can induce Th17 immunity, as Th17 immunity has been shown to be a
critical component for protection to PA. Furthermore, vaccines administered at mucosal surfaces have also been
shown to generate protective systemic immune responses. We are developing a vaccine that can be
administered mucosally, providing complete protection not only against respiratory infection with PA, but also
against non-mucosal disease manifestations; thus, providing complete immunity to the pathogen. The vaccine
will consist of a minimum of four virulence factors to provide broad protection against the large number of PA
serotypes present in nature. In this application, we will evaluate PcrV, OprF, OprI, and Exotoxin A toxoid as
vaccine targets. These antigens will be conjugated to Tobacco Mosaic Virus, which we have previously
demonstrated to be an effective delivery platform for the mucosal delivery of subunit vaccine antigens. In a pilot
study, we demonstrated that IN delivery of TMV-PcrV protected 66% of mice from lethal challenge with 10xLD50
of PA in an acute lung infection model, whereas all uninfected mice succumbed to infection. In the present study
we will optimize vaccine immunogenicity for each of the four TMV conjugates, evaluating functional antibody and
T cell responses following IN vaccination, and testing protective efficacy in an acute lung infection model of PA.
We will then test the ability of a combined multivalent vaccine against five different strains of PA using both the
lung infection model, and a foreign implant biofilm model. Using this we will establish proof of principle for our
approach and develop a prototype vaccine to move into preclinical development in a subsequent R01 application.