# Vaccine Assembly from Surface Proteins of Staphylococcus aureus

> **NIH NIH R01** · UNIVERSITY OF CHICAGO · 2020 · $445,500

## Abstract

ABSTRACT
Staphylococcus aureus is an invasive human pathogen, causing soft tissue, wound, lung, skeletal and
bloodstream infections in community- and hospital-settings. Infection with antibiotic-resistant strains,
designated methicillin-resistant S. aureus (MRSA), is associated with treatment failure and poor disease
outcomes. MRSA and methicillin-sensitive (MSSA) strains are frequent causes of infectious disease morbidity
and mortality in the United States. Hallmark of all S. aureus disease is its recurrence and the inability of
infected hosts to establish protective immunity. Persistent colonization of the human nasopharynx and
gastrointestinal tract is a key risk factor for invasive S. aureus disease. The development of a staphylococcal
vaccine that can block colonization and prevent invasive disease represents an urgent, unmet clinical need.
We have conducted studies in S. aureus infected humans and analyzed persistent colonization and invasive
disease in animals. Our data demonstrate that staphylococcal protein A (SpA), a sortase-anchored surface
protein, prevents development of protective immunity during S. aureus colonization and infection. When
anchored to the bacterial cell wall, SpA binds to the Fcγ domain of IgG, blocking the effector functions of
antibodies and inhibiting opsonophagocytic killing (OPK) of bacteria. Staphylococci also release peptidoglycan-
linked SpA into host tissues, thereby crosslinking VH3 idiotype B cell receptors (BCRs) and promoting non-
productive B cell proliferation as well as secretion of non-protective VH3 idiotype antibodies. Another sortase-
anchored product, adenosine synthase A (AdsA), converts ATP to adenosine and neutrophil NET DNA to
deoxyadenosine, triggering apoptosis of macrophages and preventing OPK of S. aureus. Immunization with
non-toxigenic SpA, which cannot bind IgG Fcγ or crosslink BCRs, elicits SpA-neutralizing antibodies that
promote OPK and block SpA-mediated B cell superantigen activity (BCSA) during S. aureus colonization and
invasive disease. SpA-neutralizing antibodies promote development of diverse pathogen-specific IgG
responses that block S. aureus colonization and prevent invasive disease. In this proposal, we seek to
characterize a non-toxigenic SpA variant devoid of BCSA in order to develop a human vaccine that blocks S.
aureus colonization and invasive disease. Further, we will explore the molecular and cellular mechanisms
whereby peptidoglycan-linked SpA activates B cells and CD4+ T cells to divert adaptive immune responses
during infection. Last, we will identify host determinants required for AdsA-mediated immune evasion of S.
aureus.

## Key facts

- **NIH application ID:** 9906158
- **Project number:** 5R01AI052474-16
- **Recipient organization:** UNIVERSITY OF CHICAGO
- **Principal Investigator:** Dominique Missiakas
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $445,500
- **Award type:** 5
- **Project period:** 2002-06-01 → 2023-03-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9906158

## Citation

> US National Institutes of Health, RePORTER application 9906158, Vaccine Assembly from Surface Proteins of Staphylococcus aureus (5R01AI052474-16). Retrieved via AI Analytics 2026-06-10 from https://api.ai-analytics.org/grant/nih/9906158. Licensed CC0.

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