Identification of an antilymphocyte transformation substance from Pasteurella multocida

Area of Science:

• Immunology
• Microbiology
• Biochemistry

Background:

• Pasteurella multocida causes significant animal diseases.
• Bacterial components can modulate host immune responses.
• Understanding bacterial virulence factors is crucial for disease control.

Purpose of the Study:

• To investigate the immunomodulatory effects of Pasteurella multocida extracts.
• To identify and characterize bacterial components responsible for immune cell inhibition.
• To determine the role of identified components in bacterial virulence.

Main Methods:

• Purification of bacterial protein using chromatography techniques (cation/anion exchange, hydroxyapatite).
• Molecular weight determination by SDS-PAGE.
• N-terminal amino acid sequencing and BLAST analysis for protein identification.
• Cloning and expression of the identified gene in E. coli.
• Purification of recombinant protein using Ni affinity chromatography.
• Assessment of antiproliferative activity on mouse spleen cells and HT-2 cells.
• Evaluation of IL-2 production in stimulated spleen cells.
• Thermal stability assays.

Main Results:

• Crude Pasteurella multocida extracts inhibited mouse spleen cell proliferation stimulated by Con A.
• A 27 kDa protein, PM27, was purified and identified as uridine phosphorylase (UPase).
• PM27 and recombinant UPase (rUPase) exhibited significant antiproliferative activity against Con A-stimulated mouse spleen cells.
• The antiproliferative activity was heat-labile, lost after heating to 100°C for 20 min.
• PM27/UPase did not directly inhibit IL-2-dependent T cells or affect IL-2 production.

Conclusions:

• Pasteurella multocida uridine phosphorylase (PM27/UPase) possesses significant antiproliferative activity on activated mouse spleen cells.
• The heat-labile nature of this activity suggests a protein-based mechanism.
• PM27/UPase may function as a virulence factor contributing to Pasteurella multocida pathogenesis in animals.