SH3PXD2B is the critical host factor promoting the entry of mycobacteria

ABSTRACT Bovine tuberculosis (bTB), caused by Mycobacterium bovis , causes major economic losses in the global livestock industry and threatens public health. Macrophages are essential for pathogen clearance, yet serve as the primary intracellular niche for mycobacterial survival. These characteristics emphasize the importance of identifying host factors that regulate macrophage functions during infection. To systematically uncover such factors, we constructed a genome-wide CRISPR-KO library in Bomac cells (the bovine macrophage cell line) and performed iterative infection screening under high selective pressure. Here, the host protein SH3PXD2B was identified as a key host factor to promote mycobacterial invasion: SH3PXD2B was significantly enriched in the screening. M. bovis infection significantly increases the expression of SH3PXD2B. The phagocytic activity of macrophages is enhanced in an SH3PXD2B-dependent manner, and the high expression of SH3PXD2B inhibits the migration of macrophages, causing macrophages to remain at the site of infection and promoting the entry of more mycobacteria into macrophages to establish infection. Further results indicate that macrophage migration inhibitory factor is positively regulated by SH3PXD2B and plays an important role in SH3PXD2B-mediated macrophage migration and phagocytic activity. These results indicate that SH3PXD2B is a critical host factor manipulated by M. bovis to promote infection. It provides a new potential target for genetic breeding against bTB. IMPORTANCE There is a complex interaction between Mycobacterium bovis and the host, which has an important impact on the occurrence and development of bTB. However, the host gene regulatory network for M. bovis infection is still incomplete, and the specific genes that play a key role in the infection process are still unclear. Bovine tuberculosis remains a major economic and public health burden worldwide. This study identifies SH3PXD2B as a novel host factor that is exploited by M. bovis to promote macrophage phagocytosis and inhibit migration, thereby facilitating bacterial invasion. These findings reveal a new pathogenic strategy and suggest that SH3PXD2B may represent a potential target for host-directed therapy and genetic breeding against bTB.