RESUMO
Coccidiosis is a costly intestinal disease of chickens caused by Eimeria species. This infection is associated with high mortality, reduced feed efficiency, and slowed body weight gain. The diagnosis and control of coccidiosis becomes challenging due to the fact that chickens can be infected by seven different Eimeria species and often occur mixed-species co-infections. Grasping the epidemiology of Eimeria species is crucial to estimate the efficiency of poultry management. This study aimed to explore the distribution of Eimeria species in broiler chickens in China after administering live anticoccidial vaccines. A total of 634 samples were obtained, and the survey results showed that the prevalence of Eimeria was 86.12% (546/634), and the most common species were E. acervulina (65.62%), E. necatrix (50.95%), E. mitis (50.79%), E. tenella (48.42%), and E. praecox (41.80%). Most samples indicated mixed-species infections (an average of 3.29 species per positive sample). Notably, 63.98% of samples contain 3 to 5 Eimeria species within a single fecal sample. The most prevalent combinations were E. acervulina-E. tenella (38.96%) and E. acervulina-E. necatrix (37.22%). Statistical analysis showed that flocks vaccinated with trivalent vaccines were significantly positive for E. necatrix in grower chickens (OR = 3.30, p < 0.05) compared with starter chickens, and tetravalent vaccinated flocks showed that starter chickens demonstrated a higher susceptibility to E. tenella-E. brunetti (OR = 2.03, p < 0.05) and E. acervulina-E. maxima (OR = 2.05, p < 0.05) compared with adult chickens. Geographically, in the case of tetravalent vaccine-immunized flocks, a substantial positive association was observed between E. necatrix infection rates and flocks from eastern (OR = 3.88, p < 0.001), central (OR = 2.65, p = 0.001), and southern China (OR = 3.17, p < 0.001) compared with southwestern China. This study also found a positive association between E. necatrix (OR = 1.64, p < 0.05), E. acervulina (OR = 1.59, p < 0.05), and E. praecox (OR = 1.81, p < 0.05) infection and coccidiosis occurrence compared with non-infected flocks in tetravalent vaccinated flocks. This molecular epidemiological investigation showed a high prevalence of Eimeria species in the field. The emergent species, E. brunetti and E. praecox, might be incorporated into the widely-used live vaccines in the future. These insights could be useful in refining coccidiosis control strategies in the poultry industry.
RESUMO
Objective To express prokaryotically the non-structural protein 1 (NS1) of duck Tembusu virus (DTMUV) and prepare NS1-specific polyclonal antibodies. Methods The NS1 gene of DTMUV strain AH-F10 was amplified by PCR, followed by subcloning and expression in the prokaryotic vector pET-32a. The recombinant NS1 protein was successfully expressed in Escherichia coli BL21 (DE3), and purified with hydroxymethyl urea and renatured by gradient centrifugation. The BALB/c mice were immunized with the purified recombinant NS1 protein to prepare polyclonal antibodies against the NS1 protein. Furthermore, the titer of the polyclonal antibodies was determined by agar diffusion test (AGP), and the specificity of the polyclonal antibodies was verified by Western blotting and indirect immunofluorescence assay (IFA). Results Polyclonal antibodies against NS1 protein in serum was successfully obtained with an AGP titer of 1:8. Western blotting and IFA demonstrated that the serum with polyclonal antibodies had a high-level specificity and reactivity to the NS1 protein of DTMUV. Conclusion Polyclonal antibodies against DTMUV NS1 protein were successfully prepared and validated in this study.