Construction of eukaryotic expression plasmid with Eimeria acervulina 3-1E gene and its immune protection efficacy against homologous Eimeria challenge

A 3-1E gene fragment was amplified from Eimeria acervulina SH strain sporozoite by RT-PCR,and it was cloned into eukaryotic expression vector pcDNA3.1(+) to construct the recombinant plasmid pcDNA3.1(+)-3-1E.The purified plasmid pcDNA3.1(+)-3-1E was transfected into 293T cells in vitro.The expressed 3-1E protein was detected by indirect immunofluorescence assay and immunohistochemistry.The plasmid pcDNA3.1(+)-3-1E and pcDNA3.1(+) was respectively used to immunize SPF chicks by injection intra-muscularly in thigh muscle at 14 and 21 days of age.Chicks in each group except that in the unchallenged control group were challenged with 5×104 E.acervulina sporulated oocysts at 28 days post-inoculation,and the immune protective efficacy was observed.The results showed that DNA vaccine pcDNA3.1(+)-3-1E could remarkably increase the number of CD8+ T lymphocyte after two immunizations,and also could provide partial immune protection against homologous Eimeria challenge,such as significantly decreasing oocyst shedding,reducing the average lesion score in duodenum,improving body weight gain and so on.