Abstract: 　Objective To observe the immunoprotection of recombinant plasmids of λMzp5-7 to chicken challenged with Eimeria tenella(E.t) oocysts. Methords All the chicken were immunized with the recombinant plasmids by different inoculation pathways, three times on d7, d14 and d21, and challenged with E.t oocysts. The response of specific humoral and cell immunity were detected by the immunological methods such as the specific antibody response, the ratio of CD4+/CD8+ T cells. Results The results showed that the recombinant plasmids can induce immune response. The specific immune responses were strengthened with the increase of immunization times. The difference of the immunity indexes among experiment groups was not significant, while the ratio of CD4+/CD8+ T cells and antibody titer were significantly higher in experiment groups than those in the control groups. The number of oocysts shed in experiment groups decreased and the shedding duration was shorter significantly. The body weight of the chicken in experiment groups increased significantly and the lesion in cecum was slighter than that of control groups. Conclusion The recombinant plasmids of λMzp5-7 show an immunoprotection to chicken challenged with E.t oocysts.

Key words: Recombinant plasmids pVAX1-Mzp5-7, Immunoprotection, Eimeria tenella