P-gp-2 Gene Research On Ivermectin Resistant And Sensitive Strains Of Haemonchus Contortus

Haemonchus contortus is the main parasitic nematode parasitizing the abomasum of ruminants,such as cattle and sheep.It feeds on the blood of the host.The diseased animals show symptoms such as anemia,edema,diarrhea,and weight loss.In severe cases,they can lead to death.The livestock industry has caused huge economic losses.At present,the control of Haemonchus contortus mainly uses anthelmintics such as ivermectin,but with the passage of time,the problem of drug resistance has become increasingly serious.The studies have shown that the P-gp-2 gene is related to drug resistance.This thesis combines the Haemonchus contortus strains we isolated with the international standard strains as controls to conduct in-depth research on this.(1)Using the larval migration inhibition test,with Haemonchus contortus international standard drug-resistant strain(Hc-R)and international standard sensitive strain(Hc-S)as a control,compared with domestic Haemonchus contortus isolates CYHHc-136 and YCHc-022 were tested for drug resistance.The results showed that the drug resistance ratio of Hc-R strain and Hc-S strain was 11.16;the drug resistance ratio of CYHHc-136 strain and Hc-S strain was 10.97;YCHc-022 strain and Hc-S strain were resistant.The drug ratio is 1.05;the drug resistance ratio of CYHHc-136 strain and YCHc-022 strain is 10.48;among domestic isolated strains,CYHHc-136 strain is resistant to ivermectin;while YCHc-022 strain belongs to a sensitive strain.(2)Using RT-qPCR technique,the domestic isolated strains CYHHc-136 and YCHc-022 of Haemonchus contortus,before and after the action of ivermectin and the international standard susceptible strain(Hc-S)and resistant strain(Hc-R)P-gp-2 gene expression was studied.The results showed that there was no significant difference in the expression of P-gp-2 gene between the two resistant strains and between the two sensitive strains before and after the ivermectin action,but the resistant strains of Haemonchus contortus before and after the ivermectin action(Hc-R,CYHHc-136)P-gp-2 gene expression was significantly higher than sensitive strains(Hc-S,YCHc-022).It showed that the expression of P-gp-2 gene in resistant strains was higher than that in sensitive strains.(3)Use RNAi technology to conduct an in-depth discussion on the P-gp-2 gene of Hc-R international standard drug-resistant strain and the isolated CYHHc-136 drug-resistant strain.The results showed that compared with before interference,the expression of Haemonchus contortus P-gp-2 gene was significantly down-regulated after RNAi(P<0.01).Under the action of ivermectin,the larval body bending frequency,head swing frequency and larval feeding rate after RNAi showed a downward trend,further indicating that P-gp-2 is indeed a resistance-related gene.The above research results provide important reference data for the establishment of ivermectin-resistant drug detection methods for nematodes and the resistance mechanism of the strains.