HSPD1 and leptospirosis: As documented by Guerreiro et al. [59], various leptospiral antigens are involved in the humoral immune response towards leptospirosis—namely, LipL32 and LipL4 in the outer membrane portion, heat shock proteins (GroEL and DnaK) in the cytoplasmic fraction and P37 in the periplasmic portion.