Abstract
Simple SummaryCoccidiosis caused by Eimeria tenella is a dreadful disease with a significant economic impact to the poultry industry. The disease has been controlled by routine medication of feed with synthetic chemicals or ionophore drugs. However, the rising appearance of drug resistance and public demands for reduced drug use in poultry production have driven a dramatic change, replacing anticoccidial drugs with alternative methods, such as vaccination with either virulent or attenuated Eimeria oocysts. Based on preliminary studies, the immune protection evaluating whole-sporozoites of E. tenella vaccine was verified. After this vaccine provided successful protection, the humoral response of a heterologous species like the rabbit was compared with the natural host immune response. Several B-cells antigens from the E. tenella sporozoite suitable for a genetically engineered vaccine were identified. Vaccination with newly identified recombinant antigens offers a feasible alternative for the control of avian coccidiosis into the broiler barns favoring the gradual withdrawal of the anticoccidial drugs.This study investigated protection against Eimeria tenella following the vaccination of chicks with 5.3 × 106 E. tenella whole-sporozoites emulsified in the nanoparticle adjuvant IMS 1313 N VG Montanide™ (EtSz-IMS1313). One-day-old specific pathogen-free (SPF) chicks were subcutaneously injected in the neck with EtSz-IMS1313 on the 1st and 10th days of age. Acquired immunity was assayed through a challenge with 3 × 104 homologous sporulated oocysts at 21 days of age. The anticoccidial index (ACI) calculated for every group showed the effectiveness of EtSz-IMS1313 as a vaccine with an ACI of 186; the mock-injected control showed an ACI of 18 and the unimmunized, challenged control showed an ACI of −28. In a comparison assay, antibodies from rabbits and SPF birds immunized with EtSz-IMS1313 recognized almost the same polypeptides in the blotting of E. tenella sporozoites and merozoites. However, rabbit antisera showed the clearest recognition pattern. Polypeptides of 120, 105, 94, 70, 38, and 19 kDa from both E. tenella life cycle stages were the most strongly recognized by both animal species. The E. tenella zoite-specific IgG antibodies from the rabbits demonstrated the feasibility for successful B cell antigen identification.
Highlights
Coccidiosis is a major parasitic disease that has a great economic impact on poultry production
Progress has been made toward the development of these vaccines using E. tenella antigens such as apical membrane antigen 1 (AMA1), immune mapped protein 1 (IMP1), microneme protein
The lesion score protective index of the chickens immunized with the whole sporozoites of E. tenella (81.78%) was substantially higher compared with the LSPI of the mock-immunized-challenged chickens (20.34%) or the LSPI of the unimmunized challenged chickens (0.0%, Table 1)
Summary
Coccidiosis is a major parasitic disease that has a great economic impact on poultry production. Eimeria tenella is probably the most important species of Eimeria that infects chickens; it is the causative agent of cecal coccidiosis, causing tissue damage that results in blood loss, dehydration, nutrient malabsorption, and increased susceptibility to other opportunistic pathogens [1,2]. A conventional control strategy is achieved by biosecurity measures combined with in-feed anticoccidial drugs or vaccination with live virulent or attenuated parasites [1,2]. Alternative control strategies are urgently needed due to the possible upcoming bans restricting the use of anticoccidials as feed additives [1,3]. Progress has been made toward the development of these vaccines using E. tenella antigens such as apical membrane antigen 1 (AMA1), immune mapped protein 1 (IMP1), microneme protein
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