Antibodies with Attenuated Protein A Binding for S. aureus Treatment
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Solution Overview
Problem
Current treatments for Staphylococcus aureus infections, particularly those resistant to antibiotics, face challenges due to the bacterium's ability to evade the host immune system through Protein A binding, which hinders antibody-mediated killing and complement fixation, necessitating alternative therapeutic approaches.
Innovation Solution
Development of fully human monoclonal antibodies and antigen-binding fragments with attenuated Fc binding to Protein A and its homologues, specifically designed to target S. aureus antigens such as IsdA, IsdB, and others, which demonstrate high affinity and antibody-dependent killing capabilities, including cross-reactivity with S. pseudintermedius.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional antibodies are used to treat S. aureus infections, then antibody binding to bacterial antigens is achieved, but Protein A binding to the Fc region hinders antibody-mediated killing and complement fixation
Solution Approach 1:
The patent applies parameter changes by modifying the Fc region amino acid sequence of the antibody (specifically mutations at positions 435 and 436 in the EU numbering system) to alter its binding properties. This creates an Fc region that no longer binds to Protein A, thereby eliminating the harmful interference while preserving the antibody's ability to mediate bacterial killing through alternative mechanisms.
2Reliability
If antibiotic treatment is used for S. aureus infections, then bacterial growth is inhibited, but antibiotic-resistant strains (MRSA) evade treatment
Solution Approach 1:
The patent substitutes the mechanical/chemical action of antibiotics with a biological mechanism - antibody-mediated immunity. Instead of relying on antibiotics that target bacterial cell wall synthesis or protein production (which bacteria have evolved resistance against), the invention uses engineered antibodies that directly bind to bacterial antigens and trigger immune-mediated killing through complement fixation and opsonization, bypassing the antibiotic resistance problem entirely.
3Reliability
If S. aureus colonizes host tissue, then bacterial fitness and pathogenicity are enhanced, but host immune barriers (skin and mucous membranes) prevent infection
Solution Approach 1:
The patent introduces engineered antibodies as intermediary molecules that bridge the gap between the host immune system and the bacterial pathogen. These antibodies specifically recognize and bind to S. aureus surface antigens (such as Protein A, ClfA, ClfB, and other virulence factors), thereby marking the bacteria for immune clearance and preventing their ability to colonize and invade host tissues, effectively reinforcing the host's natural defense barriers.
Data Source
AI summary
Speciated antibodies or antigen-binding fragments that bind staphylococcal antigens are provided, where the antibodies and antigen-binding fragments have attenuated Fc binding to Protein A or homologous protein. Compositions comprising the antibodies and methods of use are also provided. The antibodies and compositions are useful for treating staphylococcal infection, reducing serum or kidney bacterial titers, and treating symptoms associated with staphylococcal infection. The antibodies may also prevent the severity and/or duration of the primary disease.