Objective:

To systematically characterize the TRD CDR3 immune repertoires of cattle and water buffalo and understand the specific mechanisms, such as V(D)J recombination and selection pressures, shaping γδ TCR diversity.

Key Findings:

• Cattle exhibited higher clonal evenness and overall diversity in TRD CDR3 repertoire compared to buffalo, suggesting a more robust immune response.
• Buffalo relied more on a limited number of highly expanded clonotypes, indicating potential vulnerabilities in their immune repertoire.
• Species-specific preferences were observed in TRDV gene usage, while TRDJ gene usage was highly conserved, highlighting evolutionary adaptations.
• CDR3 length distributions showed similar bell-shaped patterns in both species, suggesting structural constraints during evolution.
• Limited shared clonotype sequences were found between cattle and buffalo, indicating distinct immune repertoire development.

Interpretation:

The study provides insights into the structural and functional diversity of γδ TCRs in cattle and buffalo, highlighting species-specific immune repertoire characteristics and their implications for immune function.

Limitations:

• The study is limited to a small sample size of 7 cattle and 5 buffalo, which may not represent the broader populations.
• Findings may not be generalizable to other bovine species or populations, and selection bias may affect the results.

Conclusion:

This research offers fundamental data for understanding the mechanisms shaping γδ TCR diversity and their potential immunological functions in ruminants.