试验旨在探讨天蚕素对H9N2亚型禽流感病毒(AIV)与禽致病性大肠杆菌(APEC)共感染致炎性渗出的干预效果,为临床H9N2亚型AIV与APEC共感染的有效防治提供参考.试验选取150只14日龄白羽肉鸡,随机分为5组,每组3个重复,每个重复10只鸡.对照组肉鸡使用无菌生理盐水0.2 mL滴鼻,APEC感染组肉鸡使用含2.09 × 109 CFU APEC O2菌株肉汤0.2 mL滴鼻,H9N2感染组肉鸡使用H9N2病毒尿囊液(约105 EID50 H9N2病毒)0.2 mL滴鼻,H9N2+APEC感染组肉鸡使用0.2 mL APEC O2菌株肉汤离心后的沉淀与0.2 mL H9N2病毒尿囊液混匀得到的病毒尿囊液滴鼻,H9N2+APEC干预组肉鸡采用与H9N2+APEC感染组相同处理后,使用天蚕素饮水(300mg/kg)+基础饲粮饲喂,其余各组正常饮水+基础饲粮饲喂.正式试验期21 d.结果显示,H9N2+APEC感染组肉鸡临床症状极为明显,死亡率显著升高(P＜0.05),气管和肺脏病变最为严重.与H9N2+APEC感染组相比,H9N2感染组和APEC感染组在感染后第3、7、14、21 d时的H9N2病毒拷贝数和APEC载量均显著降低(P＜0.05);H9N2+APEC干预组在感染后第3、7、14、21 d时的H9N2病毒拷贝数均显著降低(P＜0.05),H9N2+APEC干预组在感染后第7、14、21d时的APEC载量均显著降低(P＜0.05).研究表明,天蚕素可以缓解H9N2亚型AIV、APEC以及两者共感染引起的肉鸡呼吸道症状,降低死亡率,其机制与天蚕素降低病原在组织内的载量及修复呼吸系统、改善呼吸机能有关.
Intervening effect of cecropin on co-infection of broiler with H9N2 subtype avian influenza virus and pathogenic avian Escherichia coli
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.
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