Immunization with native surface protein NcSRS2 induces a Th2 immune response and reduces congenital Neospora caninum transmission in mice

• Published in: International journal for parasitology 2005-11, Vol.35 (13), p.1407-1415
• Main Authors: Haldorson, G.J., Mathison, B.A., Wenberg, K., Conrad, P.A., Dubey, J.P., Trees, A.J., Yamane, I., Baszler, T.V.
• Format: Article
• Language: English
• Subjects: Animals; antibody formation; Antigens, Protozoan - genetics; Antigens, Protozoan - immunology; Antigens, Protozoan - isolation & purification; Antigens, Surface - genetics; Antigens, Surface - immunology; Antigens, Surface - isolation & purification; Biological and medical sciences; Chromatography, Affinity - methods; Coccidiosis - congenital; Coccidiosis - immunology; Coccidiosis - prevention & control; Coccidiosis - transmission; congenital neosporosis; Congenital transmission; Female; Fundamental and applied biological sciences. Psychology; immune response; Immunity; Immunization; immunoglobulin G; Infectious Disease Transmission, Vertical - prevention & control; Interferon-gamma - biosynthesis; interferons; interleukin-4; Interleukin-4 - biosynthesis; Life cycle. Host-agent relationship. Pathogenesis; Mice; Mice, Inbred BALB C; Molecular Sequence Data; Mouse; Neospora - immunology; Neospora caninum; outer membrane proteins; Polymerase Chain Reaction - methods; Pregnancy; Pregnancy Complications, Parasitic - immunology; Pregnancy Complications, Parasitic - prevention & control; Protozoa; Protozoan Proteins - genetics; Protozoan Proteins - immunology; Protozoan Proteins - isolation & purification; Protozoan Vaccines - immunology; SRS2; surface antigens; Th2 Cells - immunology; transplacental transmission; vaccine development
• ISSN: 0020-7519; 1879-0135
• DOI: 10.1016/j.ijpara.2005.05.013

NcSRS2, a tachyzoite surface protein of Neospora caninum, is an immunodominant protein with respect to induction of antibody production and has a role in attachment and invasion of host cells. Native NcSRS2 was isolated from whole tachyzoite lysate antigen by affinity chromatography using NcSRS2 specific monoclonal antibody and used to immunize BALB/c mice in a congenital transmission study. NcSRS2 was a highly conserved protein as indicated by comparison of deduced amino acid sequence obtained from NcSRS2 gene sequences of 10 geographically distinct N. caninum isolates. Mice immunized with purified native NcSRS2 produced antigen-specific antibody, primarily of IgG 1 subtype. Following challenge during gestation with 10 7 tachyzoites, immunized mice had a statistically significant decreased frequency of congenital transmission compared to non-immunized mice ( P≤0.05) or mice inoculated with adjuvant alone ( P≤0.01). Decreased congenital transmission among immunized mice correlated with a predominately Th2 immune response compared to non-immunized mice as indicated by an increased ratio of interleukin 4 (IL-4) to interferon gamma (IFN-γ) secretion from antigen-stimulated splenocytes. The results provide a rationale for NcSRS2 as a candidate subunit vaccine antigen for reduction of N. caninum congenital transmission. Furthermore, the studies suggest that a Th2 immune response, if directed against an appropriate antigen, may induce protection against N. caninum congenital infection in mice.