title: Evaluation of Toxoplasma gondii as a live vaccine vector in susceptible and resistant hosts.
abstract: BACKGROUND
  Toxoplasma gondii has been shown to trigger strong cellular immune responses to heterologous antigens expressed by the parasite in the inbred mouse model. We studied the immune response induced by T. gondii as an effective vaccine vector in chickens and rabbits.
  
  
  RESULTS
  T. gondii RH strain was engineered to express the yellow fluorescent protein (YFP) in the cytoplasm. A subcutaneous injection of the transgenic T. gondii YFP in chickens afforded partial protection against the infection of transgenic E. tenella YFP. T. gondii YFP induced low levels of antibodies to YFP in chickens, suggesting that YFP specific cellular immune response was probably responsible for the protective immunity against E. tenella YFP infection. The measurement of T-cell response and IFN-γ production further confirmed that YFP specific Th1 mediated immune response was induced by T. gondii YFP in immunized chickens. The transgenic T. gondii stimulated significantly higher YFP specific IgG titers in rabbits than in chickens, suggesting greater immunogenicity in a T. gondii susceptible species than in a resistant species. Priming with T. gondii YFP and boosting with the recombinant YFP can induce a strong anti-YFP antibody response in both animal species.
  
  
  CONCLUSIONS
  Our findings suggest that T. gondii can be used as an effective vaccine vector and future research should focus on exploring avirulent no cyst-forming strains of T. gondii as a live vaccine vector in animals.
authors.affiliation: National Animal Protozoa Laboratory, College of Veterinary Medicine, China Agricultural University, Beijing, 100193, China.
authors.forename: Jun
authors.initials: J
authors.lastname: Zou
authors.forename: Xiao-Xi
authors.initials: XX
authors.lastname: Huang
authors.forename: Guang-Wen
authors.initials: GW
authors.lastname: Yin
authors.forename: Ye
authors.initials: Y
authors.lastname: Ding
authors.forename: Xian-Yong
authors.initials: XY
authors.lastname: Liu
authors.forename: Heng
authors.initials: H
authors.lastname: Wang
authors.forename: Qi-Jun
authors.initials: QJ
authors.lastname: Chen
authors.forename: Xun
authors.initials: X
authors.lastname: Suo
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics / Q000276:immunology; D002645:Chickens; D004337:Drug Carriers; D005822:Genetic Vectors; D007074:Immunoglobulin G / Q000097:blood; D007279:Injections, Subcutaneous; D008164:Luminescent Proteins / Q000235:genetics / Q000276:immunology; D016052:Protozoan Vaccines / Q000008:administration & dosage / Q000276:immunology*; D011817:Rabbits; D011994:Recombinant Proteins / Q000235:genetics / Q000276:immunology; D013601:T-Lymphocytes / Q000276:immunology; D014122:Toxoplasma / Q000235:genetics / Q000276:immunology*; D014613:Vaccines, Attenuated / Q000008:administration & dosage / Q000276:immunology
chemical_list: D001426:Bacterial Proteins; D004337:Drug Carriers; D007074:Immunoglobulin G; D008164:Luminescent Proteins; D016052:Protozoan Vaccines; D011994:Recombinant Proteins; D014613:Vaccines, Attenuated; C054562:yellow fluorescent protein, Bacteria