Leptospira is a bacterium that can cause disease in people and animals. Leptospira antigens mainly include LPS antigens, OMP antigens, Lipoprotein antigens, and Flagellin antigens, which can be recognized by the host immune system and produce antibodies. These antigens can be used to prepare diagnostic reagents and vaccines. Leptospira vaccines are typically inactivated or subunit vaccines that provide immune protection against multiple strains of Leptospira.