Intervening effect of cecropin on co-infection of broiler with H9N2 subtype avian influenza virus and pathogenic avian Escherichia coli
WANG Xu-gang
LU Jia-hui
YUAN Jia-xin
CHANG Jia-yi
FAN Yu-xin
LI Long-fei
ZHANG Rui-hua
XU Tong
Abstract：This study aimed to explore the intervention effect of cecropin on the inflammatory exudation caused by co-infection with H9N2 subtype avian influenza virus(AIV)and pathogenic avian Escherichia coli(APEC),providing a reference for the effective prevention and treatment of clinical co-infections of H9N2 subtype AIV and APEC.The experiment selected 150 white-feathered broilers at 14 days old,randomly divided into five groups,with three replicates per group and 10 chickens per replicate.The control group was administered 0.2 mL of sterile saline nasally.The APEC infection group was administered 0.2 mL of broth containing 2.09 x 109 CFU of APEC O2 strain nasally.The H9N2 infection group was administered 0.2 mL of H9N2 viral allantoic fluid(approximately 105 EID50 H9N2 virus)nasally.The H9N2+APEC infection group was administered 0.2 mL of the pellet from the centrifugation of APEC O2 broth mixed with 0.2 mL of H9N2 viral allantoic fluid nasally.The H9N2+APEC intervention group was treated in the same way as the H9N2+APEC infection group and fed with cecropin in drinking water(300 mg/kg)+basic feed.The rest of the groups were fed with normal water+basic feed.The formal experimental period was 21 days.The results showed that the H9N2+APEC infection group had very obvious clinical symptoms and a significantly increased mortality rate(P＜0.05),with the most severe tracheal and pulmonary lesions.Compared with the H9N2+APEC infection group,the H9N2 virus copy number and APEC load on the 3rd,7th,14th,and 21st days after infection were significantly reduced in the H9N2 infection group and the APEC infection group(P＜0.05),the H9N2+APEC infection group,the H9N2 virus copy number on the 3rd,7th,14th,and 21st days after infection was significantly reduced(P＜0.05),and the APEC load on the 7th,14th,and 21st days after infection was significantly reduced(P＜0.05).The study showed that cecropin can significantly alleviate respiratory symptoms caused by H9N2 subtype AIV,APEC,and their co-infection,and reduce mortality rates.Its mechanism is related to the reduction of pathogen load in tissues and the repair of the respiratory system,improving respiratory function.
Keywords：broilersH9N2 subtype avian influenza viruspathogenic avian Escherichia colico-infectioncecropin
Publication Date：2024-08-15
Online Publishing Date：2025-08-15(First online date of this platform, not the publication date of the document)
Pages：6( 73-78 )