The United States of America, As Represented by the Secretary, Department of Health and Human Services

Gowrisankar Rajam

George M Carlone

Sandra Steiner

Edwin W Ades

Jacquelyn S Sampson

Joseph E Martinez

Julie M Skinner

Nikkol Melnick

Nikkoj Melnick

Joseph J Caba

Patricia F Holder

Methods for enhancing opsonophagocytosis of a pathogen of interest are disclosed. The disclosed methods include administering to a subject an isolated P4 peptide, which includes the amino acid sequence set forth as SEQ ID NO: 1 and optionally an isolated opsonic antibody or a fragment thereof that specifically binds to an antigen present on the surface of the pathogen of interest. In some examples isolated complement protein or a fragment thereof (for example, a C3a, C3b, iC3b, C3d, C4b, or C5a fragment of a complement protein) is also administered. Compositions containing isolated P4 peptide and one or more isolated opsonic antibodies or a fragment thereof that specifically binds to an antigen present on the surface of a pathogen of interest are also disclosed. In some examples, the compositions also include isolated complement protein or fragment thereof, such as one or more of C3a, C3b, iC3b, C3d, C4b, or C5a.

Use of a pneumococcal P4 peptide for enhancing opsonophagocytosis in response to a pathogen

Methods for enhancing opsonophagocytosis of a pathogen of interest are disclosed. The disclosed methods include administering to a subject an isolated P4 peptide, which includes the amino acid sequence set forth as SEQ ID NO: 1 and optionally an isolated opsonic antibody or a fragment thereof that specifically binds to an antigen present on the surface of the pathogen of interest. In some examples isolated complement protein or a fragment thereof (for example, a C3a, C3b, iC3b, C3d, C4b, or C5a fragment of a complement protein) is also administered. Compositions containing isolated P4 peptide and one or more isolated opsonic antibodies or a fragment thereof that specifically binds to an antigen present of the surface of a pathogen of interest are also disclosed. In some examples, the compositions also include isolated complement protein or fragment thereof, such as one or more of C3a, C3b, iC3b, C3d, C4b, or C5a.

Provided is a P4 peptide, which contains functional epitopes of the PsaA protein of, and related methods and compositions. P4 peptide mimetics having a conformational structure identical or similar to the conformation of P4 (e.g., SEQ ID NO: 1 and SEQ ID NO:2) are provided. An antibody that specifically binds to the epitope defined by the disclosed peptides is provided. A P4-specific antibody is PsaA-specific since P4 defines an epitope specific for PsaA. Immunogenic compositions comprising the peptide of SEQ ID NO: 1 and a pharmaceutical carrier or the peptide of SEQ ID NO:2 and a pharmaceutical carrier are also provided. Methods of using the peptides and antibodies of the invention are provided.

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This application discloses a multivalent opsonophagocytosis assay that does not rely on counting of bacterial colonies to determine bacteria viability following opsonophagocytosis. Instead, the method uses a metabolic colorimetric indicator to determine if viable bacteria are present. Also disclosed are arrays that can be used to determine the viability of bacteria following opsonophagocytosis.

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Tucker, GA, United States of America

Gowrisankar Rajam