Investigation On Main Pathogens Of Calf Diarrhea In Henan Province And Verification Of Microfluidic Chips For Calf Diarrhea

Calf diarrhea is one of the main causes of the death of newborn calves,and it is also one of the reasons for the economic loss of the cattle industry worldwide.There are many causes of diarrhea in calves,and infectious factors are considered to be the main cause of diarrhea.The four pathogens E.coli K99~+,Rotavirus A group,Coronavirus,and Cryptosporidium are considered to be the main pathogens causing diarrhea in calves.In recent years,domestic and foreign scholars have used a variety of methods to isolate and identify the main pathogens of calf diarrhea,and at the same time actively explored a rapid diagnostic method for calf diarrhea.This study investigated the main pathogens of diarrhea in calves in Henan Province and verified the microfluidic gene chip of calf diarrhea,which provided a scientific basis for prevention and control of diarrheal diseases in calves and provided a new technical method for diagnosing calf diarrhea in calves.Research 1:Establishment of a PCR identification method for the main pathogens of calf diarrhea.To establish a PCR assay for the major pathogens,ELISA was used as a control.Among 100 calf diarrhea samples,the detection rate of Rotavirus ELISA method was 15%,and the detection rate of Rotavirus A group PCR method was 16%.The detection rate of Coronavirus ELISA method was 5%,the detection rate of PCR method was 7%,the detection rate of E.coli K99~+ ELISA method was 2%,and the detection rate of PCR method was 3%.The results showed that the detection rate of PCR method was higher than that of ELISA method.The detection rate of Cryptosporidium parvum ELISA method and PCR method were all 14%.However,PCR method also identified Cryptosporidium bovis and Cryptosporidium ryanae?Research 2: Investigation of main pathogens of diarrhea in calves in Henan Province.To investigate the pathogenic conditions of diarrhea in calves in Henan Province,the above four pathogens were screened using the PCR method established in research 1 for 147 diarrhea calves and 65 non-clinical calf fecal specimens.Among the 147 diarrhea samples,44 were positive for Cryptosporidium,and the detection rate was 29.93%.Eighteen positive samples of Rotavirus A group were detected,and the detection rate was 12.24%.Seven positive samples of coronavirus were detected with a detection rate of 4.76%.The positive of E.coli K99~+ was 3,and the detection rate was 2.04%.Twelve positive samples of Cryptosporidium were detected in 65 non-clinical calf fecal samples,and the detection rate was 8.16%.Three positive samples of Rotavirus A group were detected,and the detection rate was 2.04%.No Coronavirus and E.coli K99~+ were detected.In 147 diarrhea calves,59 calves were single pathogen infections,12 calves were mixed by two pathogens,and one calf was mixed by three pathogens.There were regional differences in pathogen detection.Research 3: Validation of microfluidic gene chip related indicators for diarrhea in calves.In order to verify the accuracy of calf diarrhea microfluidic gene chip,147 diarrheal calf feces samples were screened by microfluidic gene chip,and two indicators of Cryptosporidium and Coronavirus on microfluidic gene chip authenticating.A total of 44 positive samples of Cryptosporidium and 5 positive samples of coronavirus were detected.After comparing the two methods positive samples have a higher consistency.There was no difference in the detection rate of the two pathogens between the PCR method and the microfluidic gene chip method(P>0.05).Although the number of samples in this research is small,the verification of these two testing indicators by this experiment shows that the microfluidic gene chip technology has certain application value in the diagnosis of diarrhea in calves.