Analysis of humoral immune response and cytokines in chickens vaccinated with Eimeria brunetti apical membrane antigen-1 (EbAMA1) DNA vaccine

This study aimed to determine the changes of cytokines, specific serum IgG and several parameters in chickens vaccinated with DNA vaccine encoding Eimeria brunetti apical membrane antigen-1 (EbAMA1) antigen. Two-week-old chickens were divided into five groups (four groups for experiment) randomly. Experimental groups of chickens were immunized with DNA vaccine while control group of chickens were injected with pVAX1 plasmid alone or TE buffer solution. All immunizations were boosted 2 weeks later. The EbAMA1 specific IgG antibody responses were measured at weeks 1-6 post-second immunizations and several parameters were also identified. The result showed that the antibody titers in chickens vaccinated with DNA vaccines were significantly different from those of the control groups 1 week after the second immunization and reached the maximum values 3 weeks post-second immunization. IFN-γ concentration was increased the highest level against EbAMA1 of all chickens vaccinated with vaccines up to 56-fold, follow by the specific IgG antibody levels were increased 10-17-fold compared with those of TE solution and plasmid (pVAX1) control chickens 1-6 weeks post-second immunization. In case of the levels of IL-10 and IL-17 was increased in experimental chickens with 4-5-fold. Even though it was statistically significant, TGF-β and IL-4 levels were higher in vaccinated than unvaccinated chickens. The results suggested that DNA vaccines encoding E. brunetti apical membrane antigen-1 (EbAMA1) could increase serum specific IgG antibody and cytokines concentration and could give protection against E. brunetti infection.

Identification and immunogenicity of microneme protein 2 (EbMIC2) of Eimeria brunetti

There have been only a few antigen genes of Eimeria brunetti reported up to now. In this study, the gene encoding the microneme protein 2 (EbMIC2) was isolated from oocysts of E. brunetti by RT-PCR and the immunogenicity of recombinant EbMIC2 was observed. The EbMIC2 was cloned into vector pMD19-T for sequencing. The sequence was compared with the published EbMIC2 gene from GenBank revealed homology of the nucleotide sequence and amino acids sequence were 99.43 and 98.63%, respectively. The correct recombinant pMD-EbMIC2 plasmid was inserted into the pET-28a (+) expressing vector and transformed into competent Escherichia coli BL21 cells for expression. The expressed product was analyzed using SDS-PAGE and Western-blot. The results indicated that the recombinant EbMIC2 protein was recognized strongly by serum from naturally infected chicken with E. brunetti. Rat rcEbMIC2 antisera bound to bands of about 36 kDa in the somatic extract of E. brunetti sporozoites. The recombinant plasmid pVAX1-EbMIC2 was constructed and then the efficacies of recombinant plasmid and recombinant protein were evaluated. The results of IgG antibody level and cytokines concentration suggested that recombinant EbMIC2 could increase the IgG antibody level and induce the expressions of cytokines. Animal challenge experiments demonstrated that the recombinant EbMIC2 protein and recombinant plasmid pVAX1-EbMIC2 could significantly increase the average body weight gains, decrease the mean lesion scores and the oocyst outputs of the immunized chickens and presented high anti-coccidial index. All results suggested that EbMIC2 could become an effective candidate for the development of new vaccine against E. brunetti infection.

Morphological and molecular identification of Eimeria spp. in breeding chicken farms of Japan

There have been no reports of the prevalence of Eimeria spp. in poultry breeding farms in Japan unlike those of broiler farms. From 2017 to 2018, we examined the prevalence of Eimeria spp. on breeding farms in Japan by oocyst morphology and PCR analyses. A total of 143 samples was collected from 37 breeding farms in 21 prefectures of Japan. We detected oocysts of seven species at 34 of 37 breeding farms by PCR, and we identified E. brunetti at 51.5% of farms found to be positive for Eimeria. The differences in the identification of Eimeria spp. between the morphology and PCR assay methods of oocysts were pronounced for E. maxima and E. necatrix. We confirmed that molecular tools were more suitable for accurately estimating prevalence of Eimeria spp., and these findings suggest that E. brunetti could be widespread in Japan.