Snake venom metalloproteinases: structure/function relationships studies using monoclonal antibodies.

Area of Science:

• Biochemistry
• Toxicology
• Immunology

Background:

• Snake Venom Metalloproteinases (SVMPs) are key toxins responsible for hemorrhage.
• Jararhagin, a P-III SVMP from Bothrops jararaca venom, possesses catalytic, disintegrin-like, and cysteine-rich domains.
• The catalytic domain mediates hemorrhage, while disintegrin-like domains may enhance this activity and inhibit integrin binding.

Purpose of the Study:

• To investigate the functional relevance of the disintegrin-like domain in jararhagin's hemorrhagic activity.
• To identify specific epitopes within jararhagin that are critical for its function.
• To explore the potential of antibodies for neutralizing SVMP-induced hemorrhage.

Main Methods:

• Generation and characterization of mouse anti-jararhagin monoclonal antibodies (MAJars).
• Assays to measure jararhagin's hemorrhagic activity and its neutralization by MAJars.
• In vitro assays to assess the inhibition of jararhagin's binding to collagen by MAJars.
• Epitope mapping using additivity tests to determine antibody binding sites.

Main Results:

• MAJar 3 completely neutralized jararhagin's hemorrhagic activity, while MAJar 1 partially neutralized catalytic activity.
• MAJars 1 and 3 effectively inhibited jararhagin's collagen binding, with MAJar 3 showing higher potency (IC50 = 8.4 nM).
• Antibodies recognized the C-terminal region of the disintegrin domain, suggesting its proximity to the catalytic site.

Conclusions:

• The disintegrin-like domain of jararhagin plays a crucial role in its hemorrhagic activity, potentially through direct interaction or modulation of the catalytic site.
• Specific epitopes within the disintegrin-like domain are critical targets for neutralizing SVMP function.
• Monoclonal antibodies targeting these epitopes offer a promising strategy for developing antivenoms against SVMP-induced bleeding.