Objective In mammals, Toll-like receptors and antimicrobial peptide genes are important components of the innate immune system, which play a crucial role in fighting against pathogen attacks. The study was conducted to explore the expression differences of Toll-like receptor and antimicrobial peptide genes between different immune organs or tissues in Tibetan pigs and Duroc-Landrace-Yorkshire pigs, with an aim to reveal the potential contribution of these genes to disease resistance and immune response and provide theoretical support for the screening of molecular markers for disease resistance.

Method The mRNA abundance of Toll-like receptors genes (TLR1-TLR9) and two types of antimicrobial peptide genes (PBD-1 and PR-39) in lungs, mesenteric lymph nodes, inguinal lymph nodes, submandibular lymph nodes and spleens of 6-month-old Tibetan and Duroc-Landrace-Yorkshire pigs were detected by qPCR.

Result The mRNA expression of Tolllike receptors and antimicrobial peptide genes in most of the immune organs or tissues of Tibetan pigs was significantly higher than that of Duroc-Landrace-Yorkshire pigs. Among them, the mRNA expression of TLR1 and TLR2 in lungs was increased by about 50%, and PR-39 was increased by 2.6 times; the expression of TLR4 in mesenteric lymph nodes was increased by 40%, and the expression of TLR1 and PR-39 was increased by 88% and 3 times, respectively. In the inguinal lymph nodes, the expression of TLR1 and TLR2 was increased by about 2 times, and the expression of TLR9 and PR-39 was increased by 70%, especially, the expression of PR-39 increasing by 7 times; The expression of TLR1, TLR2, TLR4 and TLR7 in submandibular lymph nodes was increased by more than 2 times, and the expression of PR-39 was increased by nearly 7 times, which was similar to that in inguinal lymph nodes; the expression of TLR1 in the spleen rose by 3.5 times, which was similar to that in submandibular lymph nodes. The expression of TLR4 and TLR9 increased by about 50%, and the expression of PR-39 increased by 2.5 times.

Conclusion Tibetan pigs show higher expression levels of Toll-like receptors and antimicrobial peptide genes in multiple immune organs or tissues compared to Duroc-Landrace-Yorkshire pigs. It is implied that Tibetan pigs may possess stronger innate immunity and be able to generate more effective local or systemic immune responses against pathogenic microbial infections. The results of this study provide important theoretical support for the identification of disease resistance molecular markers and are expected to provide a scientific basis for further improvement of disease resistance in Tibetan pigs and other pig breeds.