Neospora caninum: Application of apical membrane antigen 1 encapsulated in the oligomannose-coated liposomes for reduction of offspring mortality from infection in BALB/c mice

摘要

Liposomes coated with neoglycolipids constructed with mannopentaose and dipalmitoylphosphatidylethanolamine (Man3-DPPE), referred to as M3-DPPE liposomes, have been shown to induce cellular immunity against antigens encapsulated therein. To evaluate whether these M3-DPPE liposomes have an adjuvant capacity against Neospora caninum infection, a novel immunization method utilizing soluble N. caninum apical membrane antigen 1 (NcAMA1) encapsulated in the M3-DPPE liposomes (M3-NcAMA1) was employed. The intent was to reduce offspring mortality from N. caninum infection in susceptible, pregnant BALB/c mice. The results revealed that BALB/c mice developed IgG antibodies specific to N. caninum. A significant amount of interferon (IFN)-γ production was detected in culture supernatants of NcAMA1 protein- or N. caninum lysate-stimulated spleen cells obtained from the mice one week after the third immunization with M3-NcAMA1. This suggested that the T helper-type 1 (Th1) immune response was induced in the mice. The parasite burden in the dams’ brain tissue was decreased in M3-NcAMA1-immunized mice. Moreover, the survival rate of offspring increased significantly in mice immunized with M3- NcAMA1. Taken together, the results demonstrated that a parasite-specific Th1 immune response was successfully induced in the pregnant mice immunized with M3-NcAMA1. Thus, an effective reduction of offspring mortality from N. caninum infection was triggered.