Identification and Characterization of chCR2, a Protein That Binds Chicken Complement Component 3d.

Area of Science:

• Immunology
• Avian Biology
• Molecular Biology

Background:

• Complement receptor type 2 (CR2) is crucial for linking innate and adaptive immunity in humans by binding complement component 3d (C3d).
• The chicken CR2 (chCR2) gene remained uncharacterized, hindering the study of avian immune mechanisms.

Purpose of the Study:

• To identify and characterize the chicken CR2 (chCR2) gene and protein.
• To investigate the function and expression of chCR2 in chickens.

Main Methods:

• Analysis of RNA sequencing data from chicken bursa lymphocytes.
• Gene sequencing, protein expression analysis, and binding assays.
• Flow cytometry, confocal microscopy, immunohistochemistry, and quantitative PCR.

Main Results:

• A novel chCR2 gene was identified, smaller than human CR2 but with high homology to avian CR2.
• chCR2 demonstrated significant binding activity to chicken C3d via its SCR1-4 region.
• chCR2 expression was confirmed on B lymphocytes and in various immune tissues, with variable expression linked to viral infection.

Conclusions:

• This study successfully identified and characterized chCR2, a distinct immunological marker in chicken B cells.
• chCR2 plays a role in chicken immunity, potentially bridging innate and adaptive responses.
• The findings provide a foundation for further research into avian complement systems and B cell immunology.