Integrated Single-Cell and TCR Profiling Reveals Protection-Associated CD8⁺ T Cell Subsets Linked to Viral Control in...

Area of Science:

• Immunology
• Virology
• Vaccinology

Background:

• Porcine reproductive and respiratory syndrome virus (PRRSV) poses a significant threat to the global swine industry.
• The immune mechanisms behind effective PRRSV vaccination are not fully understood.

Purpose of the Study:

• To characterize immune responses to PRRSV vaccination using integrated single-cell RNA sequencing and T cell receptor profiling.
• To identify immune cell subsets and mechanisms associated with protective vaccination outcomes against PRRSV.

Main Methods:

• Integrated single-cell RNA sequencing and T cell receptor (TCR) profiling in a PRRSV vaccination-challenge model.
• Analysis of CD8+ T cell subsets, cytotoxic transcriptional programs, and functional activity.
• Investigation of the role of viral structural proteins (SP) and innate signaling pathways (TLR4, TLR8) in T cell activation.

Main Results:

• Distinct CD8+ T cell subsets with enhanced cytotoxic activity and clonal expansion were found in protected animals.
• Non-protected animals exhibited dysfunctional CD8+ T cells with exhaustion markers.
• Protection-associated CD8+ T cell responses were primarily driven by viral structural proteins (SP).
• Replacing the SP-coding region altered the T cell landscape towards a protective profile.
• Optimal CD8+ T cell activation required innate signaling from macrophages/monocytes and CD4+ T cell help.

Conclusions:

• Specific CD8+ T cell states are linked to effective viral control in PRRSV infection.
• Viral structural proteins play a key role in inducing protective T cell responses.
• Findings provide insights for designing more effective PRRSV vaccines targeting CD8+ T cell immunity.