Preliminary Study On Screening For Inhibitors Of Eimeria Tenella Infection In Vitro

Chicken coccidiosis is a commonly self-limiting disease found in poultry production,which can cause extensive damage to the intestinal wall of chicken.When the disease is outbreak,it will cause a high mortality rate,decrease of feed ratio,decline of quality of meat and eggs,etc,which will seriously affect the healthy development of the poultry.Eimeria tenella is the The greatest harm to chicken.Currently,the prevention of chicken coccidiosis mainly relies on anticoccidial drugs and vaccines.Due to the widespread emergence of drug resistance,people have to look for new drugs.This study choosed E.tenella,the most pathogenic strain,as the study object.The compounds was screened by the MDBK cell in vitro system.Negative controls included uninfected host cells,and infected cultures received 1% DMSO only.Positive controls used a known anticoccidial drug sulfachloropyrazine sodium.The final concentration of the compounds is 20 umol/L,and the reaction time of the compound was 48 hours.RNA was then extracted and Real-Time RT PCR is performed.The the invasive rate of sporozoites was calculated by ΔΔCT method,the inhibition rate of different compounds was used to evaluate the anticoccidial efficacy of the compounds.In this study,20 compounds were screened out from 400 compounds,whose inhibition rate against E.tenella in vitro was greater than 50%.These are 4’-Hydroxychalcone,4-Hydroxychalcone,Baicalein,Andrographolide,Methyl orsellinate,Clovanedioldiacetate etc.Then we set the final concentration of the compound at 20 umol/L,15 umol/L,1.5 umol/L,0.5 umol/L,150 umol/L,50 umol/L,and made three replicates for each concentration.The IC50 of 12 compounds was determined,such as 4’-Hydroxychalcone,4-Hydroxychalcone,Baicalein,Andrographolide etc.These findings provid new options for the development of new drugs.Most of the 20 compounds screened come from traditional Chinese medicines.These raw materials of compounds are relatively economical except Thymoquinone.The inhibition rates of seven compounds in vitro such as Methyl Deoxycholate,Andrographolide,Helenine,5,2’-dimethoxy-flavone,4’-Hydroxychalcone,4-hydroxychalcone and Larixyl acetate were all higher than 70%.It is recommended that the anticoccidial effect be further studied.These findings provid new options for the development of new drugs.