ASAP1 gene InDel variants are associated with enhanced goat resistance against Brucella infection

OBJECTIVE: This study aimed to investigate the potential of the ASAP1 gene as a genetic biomarker for brucellosis resistance/susceptibility in goats. METHODS: This study collected samples from female Shaanbei white cashmere (SBWC) goats to investigate the association between the ASAP1 gene and brucellosis susceptibility. Peripheral blood mononuclear cells (PBMCs) were isolated from goats with various haplo types and Brucella statuses, and the association was evaluated using polymerase chain re action (PCR), quantitative reverse transcription (qRT)-PCR, and lipopolysaccharide (LPS) stimulation assays. RESULTS: The ASAP1 gene was expressed most in th e spleen, significantly more than in the kidney and heart (p<0.05). In the SBWC goats population, three genotypes insertion/insertion (II), insertion/deletion (ID), and deletion/deletion (DD) were identified at the P2, P5, and P7 sites of goat ASAP1 gene. Association analysis showed that P2 and P7 sites variants were associated with host resistance to Brucella infection with the II genotype used as reference (p<0.05; p<0.01) and maintained after multiple testing correction. The ASAP1 gene was observed lower expression in testicular tissues of Brucella-infected adult SBWC goats compared to healthy controls (p<0.01). Haplotype analysis revealed Hap3 and Hap5 were associated with brucellosis-resistant compared to Hap1 (p<0.05). PBMCs were isolated from goats carrying Hap1, Hap3, and Hap5. After LPS stimulation, significantly reduced ASAP1 expression was detected in the susceptible haplotype Hap1 compared to the resistant haplotypes. The highest expression level was exhibited by the most resistant haplotype, Hap5. Furthermore, resistant haplotypes showed more rapid activation of key inflammatory pathways and pro-inflammatory cytokines (NF-κB, IL-6, TNF-α, IFN-γ) compared to susceptible Hap1, with faster resolution of the inflammatory response observed, particularly in the most resistant haplotype Hap5. CONCLUSION: The present study demonstrates that ASAP1 gene InDel variants influence brucellosis resistance in SBWC goats, providing a theoretical basis for breeding resistant populations.