In order to establish a method for the detection of serum antibodies to donkey-derived e-quine coronavirus(ECoV),recombinant ECoV N protein was expressed in E.coli system,purified by nickel column affinity chromatography and identified by Western blot.After optimizing the re-action conditions,the indirect ELISA(iELISA)detection method was established using the puri-fied recombinant protein as coating antigen and used to detect 143 clinical serum samples.The re-sults showed that the recombinant N protein,which has good reaction activity with serum antibod-y,was successfully expressed.The optimum conditions of the established iELISA method were as follows:the amount of antigen coated was 0.2 μg/well and overnight at 4 ℃,10％skimmed milk powder solution was sealed at 37℃ for 1.5 h,the dilution concentration of serum was 1∶200,and the enzyme-labeled secondary antibody diluted at 1∶10 000.The sensitivity test results showed that the positive serum could be diluted to 1∶6 400.The specificity test results showed that all an-tibodies to several donkey pathogens were negative.The repetitive test results showed that the in-tra-and inter-batch coefficients of variation were 2.90％-6.12％and 2.29％-7.88％respectively.The positive rate of clinical donkey serum was 57.3％.The iELISA established in this study pro-vides a technical support for epidemiological investigation and antibody surveillance.

In order to establish a method for the detection of serum antibodies to donkey-derived e-quine coronavirus(ECoV),recombinant ECoV N protein was expressed in E.coli system,purified by nickel column affinity chromatography and identified by Western blot.After optimizing the re-action conditions,the indirect ELISA(iELISA)detection method was established using the puri-fied recombinant protein as coating antigen and used to detect 143 clinical serum samples.The re-sults showed that the recombinant N protein,which has good reaction activity with serum antibod-y,was successfully expressed.The optimum conditions of the established iELISA method were as follows:the amount of antigen coated was 0.2 μg/well and overnight at 4 ℃,10％skimmed milk powder solution was sealed at 37℃ for 1.5 h,the dilution concentration of serum was 1∶200,and the enzyme-labeled secondary antibody diluted at 1∶10 000.The sensitivity test results showed that the positive serum could be diluted to 1∶6 400.The specificity test results showed that all an-tibodies to several donkey pathogens were negative.The repetitive test results showed that the in-tra-and inter-batch coefficients of variation were 2.90％-6.12％and 2.29％-7.88％respectively.The positive rate of clinical donkey serum was 57.3％.The iELISA established in this study pro-vides a technical support for epidemiological investigation and antibody surveillance.

Objective To study the effect of contusion and exhaustive exercise on satellite cells' activation and Pax7/CBF1/DAPT contents in skeletal muscles of rats,and reveal the repair mechanism of the skeletal muscle injury.Methods Twenty-four seven-week-old male Sprague-Dawley(SD)rats were randomly divided into a control(C)group,an immediately after exhaustive exercise(E0)group,a 24 hours after exhaustive exercise(E24)group and a 48 hours after exhaustive exercise(E48)group,each of 6.Other 18 SD rats were randomly divided into 3 groups,6 rats in each group:an immediately after contusion group(D0),a 24h post-contusion group(D24)and a 48h post-contusion group(D48).All groups were killed at different time points after exhaustive exercise and the contusion respectively while the control group was at resting state,and their serum was extracted.The right gastrocnemius muscles were resected and divided into 2 parts:one was used immediately for culturing satellite cells,while the other was stored in the bridge at-80℃.All the serum and gastrocnemius muscles were tested for Pax7,CBF1 and DAPT contents using the enzyme-linked immunosorbent assay(ELISA).Moreover,three-day-old newborn rats were also slaughtered for the above experiment.Results The results of culture in vitro showed that one day after the culture began a small amount of spindle satellite cells could be seen in the newborn rats,but the satellite cells of other groups were growing slowly.However,on the third day and the fifth day,the spindle satellite cells of each group began to proliferate in quantity and reached the peak.Then all the satellite cells had a good proliferation until the seventh day after serial passage,and some patial fusions to microtubules occurred.The biggest cell number and proliferation rate was in newborn rats,but no skeletal muscle satellite cell was found in the control group.At the same time,the number and the proliferation rate of skeletal muscle satellite cells in contusion groups were significantly higher than the exhaustive exercise groups.The results of Elisa showed that the contents of CBF1 and Pax7 in skeletal muscles in exhaustive groups and contusion groups,were significantly upregulated,compared to the control group(P＜0.05).Amomg them,the CBF1 content in group D0,together with the Pax7 content in group D24 and D48,was significantly higher than that of the other groups(P＜0.05).On the other hand,the content of DAPT in skeletal muscles of exhaustive groups and contusion groups,compared to the control group,was significantly downregulated (P＜0.05).To be more specific,the value of group D0 was significantly lower than that of the other groups (P＜0.05).However,there was no significant difference in it among group E0,E24 and E48.Conclusions Contusion and exhaustive exercise can activate the skeletal muscle satellite cells to proliferate and differentiate.The number of activated skeletal muscle satellite cells in the contusion groups is significantly larger than that of exhaustive groups maybe due to the stronger stimulating by contusion.Both contusion and exhaustive exercise increase the contents of Pax7 and CBF1 in skeletal muscles,but decrease that of DAPT.The Pax7 and CBF1 may play a positive regulating role in terms of activating skeletal satellite cells and repairing skeletal muscle injury,while DAPT may play a negative regulating role.