title: Protective efficacy of Toxoplasma gondii calcium-dependent protein kinase 1 (TgCDPK1) adjuvated with recombinant IL-15 and IL-21 against experimental toxoplasmosis in mice.
abstract: BACKGROUND
  Toxoplasma gondii can infect all warm-blooded animals including humans. Infection with T. gondii is probably the leading cause of posterior uveitis in humans and the most comment route of transmission is raw and undercooked meat from infected animals. T. gondii calcium-dependent protein kinase 1 (TgCDPK1) plays a critical role in direct parasite motility, host-cell invasion, and egress.
  
  
  METHODS
  We constructed a DNA vaccine expressing TgCDPK1 inserted into eukaryotic expression vector pVAX I and evaluated the immune protection induced by pVAX-CDPK1 in Kunming mice. Mice immunized with pVAX-CDPK1 intramuscularly and/or with a plasmid encoding IL-15 and IL-21 (pVAX-IL-21-IL-15). The immune responses were analyzed including lymphoproliferative assay, cytokine, antibody measurements, lymphocyte surface markers by flow cytometry and protective efficacy were measured as survival and cysts numbers after challenge 1 to 2 months post vaccination.
  
  
  RESULTS
  Immunization with pVAX-CDPK1 or pVAX-IL-21-IL-15 alone developed strong humoral responses and Th1 type cellular immune responses, and the significantly (P < 0.05) increase of both the percentages of CD4+ and CD8+ T cells compared with all the controls (blank control, PBS, and pVAX). Co-injection of pVAX-IL-21-IL-15 significantly increased humoral and cellular immune responses compared to the group of pVAX-CDPK1 or pVAX-IL-21-IL-15. Challenge experiments showed that co-administration of pVAX-IL-21-IL-15 and pVAX-CDPK1 significantly (P < 0.05) increased survival time (19.2 ± 5.1 days) compared with pVAX-CDPK1 (17.3 ± 4.3 days) or pVAX-IL-21-IL-15 (12.0 ± 2.0 days) alone, and pVAX-IL-21-IL-15 + pVAX-CDPK1 significantly reduced the number of brain cysts (72.7%) in contrast to pVAX-ROP13 (45.7%) or pVAX-IL-21-IL-15 alone (43.6%).
  
  
  CONCLUSIONS
  TgCDPK1 is identified to be a promising vaccine candidate for inducing a strong humoral and cellular response against T. gondii infection, and thus synergistic of mIL-21 and mIL-15 can induce non-specific immune responses, but also facilitate specific humoral as well as cellular immune responses elicited by DNA vaccine against acute and chronic T. gondii infection in mice.
authors.forename: Jia
authors.initials: J
authors.lastname: Chen
authors.forename: Zhong-Yuan
authors.initials: ZY
authors.lastname: Li
authors.affiliation: State Key Laboratory of Veterinary Etiological Biology, Key Laboratory of Veterinary Parasitology of Gansu Province, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, Gansu Province 730046, PR China. huangsiyang@caas.cn.
authors.forename: Si-Yang
authors.initials: SY
authors.lastname: Huang
authors.forename: Eskild
authors.initials: E
authors.lastname: Petersen
authors.forename: Hui-Qun
authors.initials: HQ
authors.lastname: Song
authors.forename: Dong-Hui
authors.initials: DH
authors.lastname: Zhou
authors.forename: Xing-Quan
authors.initials: XQ
authors.lastname: Zhu
mesh_terms: D000818:Animals; D000913:Antibodies, Protozoan / Q000276:immunology; D005260:Female; D006801:Humans; D007111:Immunity, Cellular; D007074:Immunoglobulin G / Q000276:immunology; D019409:Interleukin-15 / Q000008:administration & dosage / Q000235:genetics / Q000276:immunology*; D007378:Interleukins / Q000008:administration & dosage / Q000235:genetics / Q000276:immunology*; D051379:Mice; D011494:Protein Kinases / Q000008:administration & dosage / Q000235:genetics / Q000276:immunology*; D015800:Protozoan Proteins / Q000008:administration & dosage / Q000235:genetics / Q000276:immunology*; D016052:Protozoan Vaccines / Q000008:administration & dosage / Q000235:genetics / Q000276:immunology*; D018417:Th1 Cells / Q000276:immunology; D014122:Toxoplasma / Q000201:enzymology* / Q000235:genetics / Q000276:immunology; D014123:Toxoplasmosis / Q000276:immunology / Q000469:parasitology / Q000517:prevention & control*; D019444:Vaccines, DNA / Q000008:administration & dosage / Q000235:genetics / Q000276:immunology; D000098546:Interleukin-21; D017871:Calcium-Calmodulin-Dependent Protein Kinases
chemical_list: D000913:Antibodies, Protozoan; D007074:Immunoglobulin G; D019409:Interleukin-15; D007378:Interleukins; D011494:Protein Kinases; D015800:Protozoan Proteins; D016052:Protozoan Vaccines; D019444:Vaccines, DNA; D000098546:Interleukin-21; D017871:Calcium-Calmodulin-Dependent Protein Kinases