Selection of a Monensin-resistant Strain of Eimeria tenella and Differences Analysis Between Resistant and Sensitive Strains by SNP Density Distribution
[Objective]The purpose of study was to determine the genetic differences between Eimeria tenella monensin-resistant and monensin-sensitive strains,and elucidate the molecular mechanism of monensin resistance.[Method]Resistance to monensin was induced in Eimeria tenella by simulating field infection.400 broilers were equally divided into two groups,group Ⅰ(inoculated and untreated group)and group Ⅱ(monensin recommended dose group).Monensin was added to the basal diet at 100 mg/kg.10 birds in group Ⅰ were inoculated with 5 000 oocysts on the first day.Litter containing feces with shed oocysts was randomly sampled from group Ⅰ and dispersed to the litter of group Ⅱ from the 8th day to the 25th day.33 days post inoculation,the caeca of 10 chickens in group Ⅱ were removed to collect the resistant oocysts.In the second experiment,100 broilers formulated the group m(monensin higher dose group).10 chickens of group Ⅲ were inoculated with 5 000 resistant oocysts.The chickens of group m were fed with gradient monensin(from 133 to 400 mg/kg).27 days post inoculation,the caeca of 10 chickens were removed to collect the resistant oocysts.The resistance was evaluated by ACI,POAA,RLS and POP.The genomes of resistant and sensitive strains were sequenced,then single nucleotide polymorphism(SNP)density was compared with the reference genome.[Result]In the first experiment,the resistant oocysts against 100 mg/kg monensin(1× monensin induced strain)were generated 33 days post inoculation.In the second experiment,the resistant oocysts against 400 mg/kg monensin 4 × monensin induced strain were harvested 27 days post inoculation.Evaluation result of resistance showed ACI,POAA and ROP of 4 × monensin induced strain were 121,25.4％,33％and 64％,respectively.Compared with the reference genome,there were 12 191 SNPs in the genome of the sensitive strain and 74 931 SNPs in the genome of the drug-resistant strain.The SNPs of the drug-resistant strain were enriched and distributed in the region of 3.3-4.2 Mb on chromosome 11,and the SNPs of three genes ETH2_1113700,ETH2_1113500 and ETH2_1113600 in the region were located in the coding region.[Conclusion]This study obtained a fully resistant strain of Eimeria tenella to monensin.On chromosome 11,there were significant differences in SNP distribution between resistant and sensitive strains,and three candidate genes for drug resistance were identified.
coccidiosisEimeria tenellamonensinresistanceSNP density
万方数据
维普
