Salmonella vaccination with iron-regulated membrane proteins

DESCRIPTION (provided by applicant): Salmonella are a leading cause of illness in humans worldwide and also represent one of the few pathogens that have been used in a bioterror attack in the United States, highlighting the urgent need for developing effective methods for the prevention and control of this major pathogen. Preliminary studies and previous investigations have demonstrated that membrane proteins derived from Salmonella grown under iron-restricted conditions protect against oral and systemic Salmonella infections, and furthermore, provide cross-protection against different serotypes of Salmonella. These results have led us to hypothesize that one or more proteins present in the Salmonella membrane composition are effective immunogens. To test this hypothesis, and work towards our overall goal of developing a safe and cross-protective Salmonella vaccine, we here propose to carry out Phase I feasibility studies with three specific aims: In Aim 1, we will separate and identify the membrane proteins derived from Salmonella enterica serotype Newport grown under iron-limiting conditions; in Aim 2, we will test the separated fractions for their ability to stimulate specific antibody and cytokine responses in mice, and in Aim 3, we will formulate vaccines with the antigenic fractions identified in Aim 2 and test their ability to promote cross-protection in a murine model of oral infection. These investigations will determine which of the separated fractions provide protection against oral Salmonella challenge, and the type of immune responses elicited by vaccine components. Taken together, we believe that the proposed Phase I feasibility studies will provide enabling information for the formulation of rational strategies for developing safe and effective vaccines against Salmonella infection. Salmonella infects over a million people annually in the U.S., is increasingly antibiotic-resistant, and is one of the few pathogens that have been successfully used in a bioterror attack in the United States. For these reasons, the development of a vaccine that prevents infections by Salmonella would provide considerable benefit to public health as well as provide a means to protect citizens from a Salmonella bioterror attack. The proposed studies aim to separate the components of a demonstrably effective Salmonella vaccine, and to test those separated fractions for the ability to stimulate specific immune responses and the ability to protect mice against Salmonella infections. If successful, these investigations will identify new candidate antigens for the development of human vaccines for prevention of salmonellosis.