Cobra venom factor and human C3 share carbohydrate antigenic determinants

Area of Science:

• Immunology
• Glycobiology
• Complement System

Background:

• Cobra venom factor (CVF) and human complement component C3 share structural similarities, prompting investigation into their relationship.
• Monoclonal antibodies are valuable tools for probing protein structures and interactions.

Purpose of the Study:

• To produce and characterize murine monoclonal antibodies against CVF.
• To investigate the structural epitopes recognized by these antibodies on CVF and human C3.
• To elucidate shared structural features between CVF and human C3.

Main Methods:

• Production of murine monoclonal antibodies against CVF.
• Immunoblotting and enzyme-linked immunosorbent assay (ELISA) to assess antibody binding.
• Enzymatic deglycosylation using N-glycanase to determine epitope nature.
• Cross-reactivity studies with human C3.

Main Results:

• Two monoclonal antibodies, GV1.8 and GV1.10, were identified, both binding to carbohydrate epitopes on CVF.
• Antibody GV1.8 recognized epitopes on both alpha- and beta-chains of CVF, while GV1.10 recognized the alpha-chain.
• Both antibodies cross-reacted with human C3, binding to its chains, and lost binding after deglycosylation, confirming carbohydrate specificity.
• Shared carbohydrate epitopes were identified on homologous and nonhomologous chains of CVF and C3.

Conclusions:

• CVF and human C3 share common carbohydrate epitopes.
• Monoclonal antibodies GV1.8 and GV1.10 are specific for these shared carbohydrate structures.
• These findings provide insights into the structural relationships between CVF and human C3 within the complement system.