Lamei Wu1, Huijian Yang2, Jianglin Wang3, Xiuwen Yu3, Yanhong He4, Shenxia Chen5. 1. Department of Clinical Laboratory, Anting Hospital, Jiading District, Shanghai, 201800, China. 2. Department of Laboratory Medicine, Shanghai East Hospital, Tongji University School of Medicine, Shanghai, 200120, China. 3. Department of Clinical Laboratory, Jiading District Central Hospital Affiliated Shanghai University of Medicine and Health Sciences, Jiading District, Shanghai, 201800, China. 4. Department of Clinical Laboratory, Anting Hospital, Jiading District, Shanghai, 201800, China. athlab@163.com. 5. Department of Microbiology, Medical College of Jiangsu University, ZhenJiang, 212013, China. Chensx313@163.com.
Abstract
PURPOSE: Antigens expressed by Toxoplasma gondii (T. gondii) during its life cycle trigger various immune responses in the host. Recently, toxoplasma vaccine research focused on T. gondii surface antigen 1 (SAG1) and Rhoptry Protein 18 (ROP18) to establish a safe and efficacious DNA vaccine. METHOD: We constructed two eukaryotic expression plasmids: p3 × FLAG-Myc-CMV™-24-SAG1 and p3 × FLAG-Myc-CMV™-24-ROP18. BALB/c mice were randomly divided into six groups and immunized with these DNA vaccines either separately or in combination. The combination vaccine was administered at either the full dose or at half-strength dose. Control mice were immunized with empty vector or with phosphate-buffered saline. RESULTS: The frequency of CD4+ cells in the spleen was consistent among all groups, whereas that of CD8+ T cells was the highest in the group immunized with the combination vaccine at half-strength dose (p < 0.05). Importantly, the mRNA expression levels of interleukin-12 (IL-12) and interferon-gamma (INF-γ) were closely correlated (r = 0.6, p < 0.0001) and both were upregulated in the group that was immunized with the combination vaccine at half-strength dose (p < 0.0001). The survival time of the mice subjected to a lethal dose of toxoplasma was significantly extended by prior immunization with DNA vaccines expressing either SAG1 or ROP18 or a combination of both (p < 0.05). The group that was immunized with the combination vaccine at half-strength dose demonstrated the best efficacy (p < 0.05). CONCLUSION: These results showed that the combination DNA vaccine provided better immune protection than the single gene vaccines, and that optimizing the dosing of the vaccine can improve the immune response.
PURPOSE: Antigens expressed by Toxoplasma gondii (T. gondii) during its life cycle trigger various immune responses in the host. Recently, toxoplasma vaccine research focused on T. gondii surface antigen 1 (SAG1) and Rhoptry Protein 18 (ROP18) to establish a safe and efficacious DNA vaccine. METHOD: We constructed two eukaryotic expression plasmids: p3 × FLAG-Myc-CMV™-24-SAG1 and p3 × FLAG-Myc-CMV™-24-ROP18. BALB/c mice were randomly divided into six groups and immunized with these DNA vaccines either separately or in combination. The combination vaccine was administered at either the full dose or at half-strength dose. Control mice were immunized with empty vector or with phosphate-buffered saline. RESULTS: The frequency of CD4+ cells in the spleen was consistent among all groups, whereas that of CD8+ T cells was the highest in the group immunized with the combination vaccine at half-strength dose (p < 0.05). Importantly, the mRNA expression levels of interleukin-12 (IL-12) and interferon-gamma (INF-γ) were closely correlated (r = 0.6, p < 0.0001) and both were upregulated in the group that was immunized with the combination vaccine at half-strength dose (p < 0.0001). The survival time of the mice subjected to a lethal dose of toxoplasma was significantly extended by prior immunization with DNA vaccines expressing either SAG1 or ROP18 or a combination of both (p < 0.05). The group that was immunized with the combination vaccine at half-strength dose demonstrated the best efficacy (p < 0.05). CONCLUSION: These results showed that the combination DNA vaccine provided better immune protection than the single gene vaccines, and that optimizing the dosing of the vaccine can improve the immune response.
Authors: Ernest J Mui; Guy A Schiehser; Wilbur K Milhous; Honghue Hsu; Craig W Roberts; Michael Kirisits; Stephen Muench; David Rice; J P Dubey; Joseph W Fowble; Pradipsinh K Rathod; Sherry F Queener; Susan R Liu; David P Jacobus; Rima McLeod Journal: PLoS Negl Trop Dis Date: 2008-03-05