L-Asparagine is the essential factor for the susceptibility of Chinese pigs to Mycoplasma hyopneumoniae

Abstract Swine mycoplasma pneumonia caused by Mycoplasma hyopneumoniae is the most prevalent and frequently occurring chronic respiratory disease in pigs worldwide. Pig breeds in China are more susceptible to Mycoplasma hyopneumoniae, and understanding the reasons for their susceptibility is crucial for the prevention and control of swine Mycoplasma pneumonia, as well as for promoting the healthy development of the swine industry. Mycoplasma hyopneumoniae has limited biosynthesis and metabolism, and has harsh requirements for nutrients, thus it is necessary to add approximately 15%-20% porcine serum in medium during in vitro culture, and porcine serum plays an irreplaceable role in the growth and reproduction of Mycoplasma hyopneumoniae. In this study, growth titres of different Mycoplasma hyopneumoniae strains cultured in the serum medium from different Chinese pig breeds and introduced pig breeds were compared. Non-targeted metabolomics analysis of representative introduced and Chinese pig breeds, Large white pig and Bama miniature pig, respectively, screened of key serum metabolites. The results showed that, expression level of L-Asparagine in Bama miniature pigs was 15–18 times higher than in Large white pigs. Additionally, the contents of inositol and Arachidonic acid in Bama miniature pigs were significantly upregulated as well. A certain concentration of L-Asparagine significantly increased the growth titer, metabolic capacity and pathogenicity of Mycoplasma hyopneumoniae. In conclusion, Bama miniature pig and Large white pig are representative pig breeds that are susceptible and non-susceptible to Mycoplasma hyopneumoniae respectively. L-Asparagine is the essential factor and biomarker for the susceptibility of Chinese pigs to Mycoplasma hyopneumoniae. Graphical Abstract