Humoral immune responses specific to each purified LI antigen protein. Titers of serum IgG were measured in the mice immunized with the mixture of JOL1800 derivatives. Control, a group inoculated with PBS; immunized, groups immunized with a combined formula of four JOL1800 derivatives. The error bars indicate the standard deviation (sd). wpi: week post-immunization; *P < 0.05 compared to titers of the control group.