A Naturally Occurring Antibody Fragment Neutralizes Infectivity of Diverse Infectious Agents

Area of Science:

• Immunology
• Infectious Diseases
• Biochemistry

Background:

• Antibodies are crucial for adaptive immunity, but their role in innate immunity is less understood.
• Naturally occurring antibody fragments may possess intrinsic antimicrobial properties.
• The constant region of Immunoglobulin M (IgM) is a potential source of such fragments.

Purpose of the Study:

• To identify and characterize novel peptide fragments derived from human serum IgMs.
• To investigate the antimicrobial and antiviral activities of the identified peptide K40H.
• To explore the potential therapeutic applications of K40H against infectious agents.

Main Methods:

• Detection of K40H in human serum using liquid chromatography and high-resolution mass spectrometry.
• Synthesis of K40H peptide for in vitro and ex vivo testing.
• Assessment of K40H activity against fungal pathogens and HIV-1 replication.
• Evaluation of K40H therapeutic effect in a Galleria mellonella infection model.

Main Results:

• A phosphorylated peptide, K40H, was identified and synthesized.
• K40H demonstrated potent in vitro activity against fungal pathogens.
• K40H inhibited HIV-1 replication in vitro and ex vivo.
• K40H exhibited therapeutic effects against Candida albicans infection in Galleria mellonella.

Conclusions:

• K40H serves as proof of concept for the innate immune role of naturally occurring antibody fragments.
• This discovery sheds new light on the posthumous functions of antibodies.
• It opens new perspectives on the multifaceted roles of humoral immunity in combating infections.