禽流感免疫水平低下的原因剖析

近几年,世界许多国家相继发生禽流感疫病,禽流感疫情形势十分严峻。2004年来,禽流感油乳剂灭活苗在我市得到了广泛应用,从东阳市畜牧兽医局化验室对大批次、大批量的家禽进行的禽流感抗体监测情况来看,一些家禽养殖专业户的的禽流感免疫效果并不理想。为此本人就禽流感免疫水平低下的原因及对策进行了分析。1免疫程序不科学建立科学合理的免疫程序是保证免疫效果的前提。一个合理的免疫程序的制定必须建立在对当地疫情流行情况的了解,以及母源抗体监测工作的基础上。但有些养禽户对免疫程序的确立并不重视,进行免疫接种的时间安排随意性较大…     

禽流感油乳剂灭活苗免疫效力试验

用禽流感病毒（ＡＩＶ）Ｆ株尿囊腔接种非免疫鸡胚,取死亡胚的胚液、尿囊膜、胚体及三者混合处理物,分别制成油乳剂灭活苗,免疫５日龄普通蛋雏鸡,免疫后一周开始检测ＡＩ血凝抑制（ＨＩ）抗体。检测结果是：免疫后２１ｄ,各免疫组鸡的ＨＩ抗体效价均达到５ｌｏｇ２以上,２５ｄ左右达高峰,后维持较高水平３０ｄ以上,１８日以制苗用Ｆ株攻毒,４９日龄和６４日时用Ｆ株和禽源病原大肠杆菌（Ｏ１８）单独或联合攻毒,结果是：１     

高致病性禽流感免疫水平低下的原因分析与预防

近年来,随着畜牧业不断发展,高致病性禽流感等重大动物疫病在国内外频繁发生,防控形势十分严峻。为此,做好畜禽疫苗免疫工作是防控重大动物疫病最有效的措施之一。笔者在化验室对多批次、多批量的家禽进行的禽流感抗体监测情况来看．一些家禽养殖专业户的禽流感免疫效果并不理想。带着这个问题,笔者进行分析和探讨,就禽流感免疫失败的原因及预防作了分析,供大家参考。     

H9亚型禽流感油乳剂灭活苗免疫、免疫后攻毒及人工感染鸡抗体的监测

本研究采用ＡＧＰ、ＨＩ等试验方法，对经Ｈ９亚型禽流感油乳剂灭活苗免疫、免疫后攻毒以及经Ｈ９Ｎ２活毒人工感染后的ＳＰＦ鸡抗体产生、消长规律进行了测定，结果表明人工感染ＳＰＦ鸡和免疫鸡一周后，ＡＧＰ的检出率即可达到１００％；Ｈ９亚型禽流感油乳剂灭活苗自免疫后一周内即可产生ＨＩ抗体，２１－２８天达到高峰，并能对相同亚型病毒感染引发良好的免疫反应。     

H9亚型禽流感油乳剂灭活苗免疫产生期内T淋巴细胞表型亚类的检测与研究

采用免疫荧光法、使用流式细胞检测仪对经H9亚型禽流感病毒人工感染SPF鸡、H9亚型禽流感油乳剂灭活苗免疫SPF鸡以及经免疫后使用H9亚型禽流感病毒攻毒后的SPF鸡外周血、脾脏、胸腺中T细胞表型亚类(CD4+、CD8+、TCR1+)的变化规律进行了监测,结果表明,H9亚型禽流感油乳剂灭活苗免疫后抗原的缓慢释放可在一定程度上激发机体的细胞免疫应答,使免疫活性T淋巴细胞得到活化,免疫后鸡体外周血中CD4+、CD8+和TCR1+T细胞的数量呈现出一明显升高的过程;同时,人工感染免疫鸡后,脾脏和胸腺TCR1+T细胞的数量上升,外周血CD4+、CD8+和TCR1+T细胞的数量少量降低或维持不变,随后短期即恢复正常;而人工感染SPF对照鸡后,外周血CD4+、CD8+和TCR1+T细胞的数量呈现下降趋势.     

鸡群免疫失败原因剖析

在实际生产中,接种疫苗后未能获得满意的免疫效果的情况时有发生。究其原因,有以下方面:1疫苗质量①疫苗质量不合标准,如病毒的含量不足;②疫苗制备过程中冻干或密封不佳,疫苗已过期失效;③油乳剂疫苗乳化不良,水油分层或氢氧化铝颗粒过大;④疫苗在运输或保管过程中,因温度过高或反复冻融失效。     

禽流感-新城疫重组二联活疫苗(rl-H5株)免疫效果初步观察

目前我市使用的禽流感疫苗均为油乳剂灭活苗,由于油乳剂疫苗使用矿物油作为载体,注射后吸收较为缓慢,肉鸡胸肌注射禽流感油乳剂疫苗0．5ml,30d后才基本上完全吸收,因肉鸡特别是快速型肉鸡饲养时间短,油乳剂疫苗在肌肉中残留,严重影响鸡肉的品质,一定程度上影响了养禽场（户）进行禽流感二免的积极性。因此,在2006年4月开始,     

禽流感H9亚型灭活油乳剂疫苗不同剂量的免疫效果比较

将47只28日龄SPF鸡分为4组，第1～3组为试验组，每组12只，分别肌肉注射禽流感H9亚型灭活油乳剂疫苗0．1、0．3、0．5mL／只，第4组11只为对照组。各组鸡在免疫后1、2、3周采血，测定H9抗体水平；在免疫后3周用1：10稀释的AIV H9N2攻毒，0．2mL／只。攻毒后第2、3、4周继续测定H9抗体水平，观察了疫苗对鸡的保护效果。结果显示，0．5mL／只剂量的免疫效果比0．1mL／只和0．3mL／只剂量的免疫效果好；攻毒用的AIV H9N2的致病力低，对所有试验鸡均不致死。     

高致病性禽流感免疫抗体水平的监测与分析

云浮市是畜牧生产大市,2007年全市家禽饲养量22856.3万只,上市量17542.7万只,其中肉鸡上市量16668.4万只,全市畜牧业产值52.8亿元,占农业总产值41.6%。为了保障畜牧业的健康发展,有效控制和预防禽流感疫情的发生,我所按照省总所的具体任务要求,在2007年     

禽流感难于预防的原因剖析

禽流感是流行性感冒病毒引起人和多种动物的一种急性、热性、败血性、高度接触性传染病。禽流感无论是对鸡、鸭等禽类的安全生产,还是对人类的生命安全,都会造成很大的危害。     

禽流感的疫苗接种

巴基斯坦的研究人员近年来已对使用当地自家脏器灭活疫苗及鸡胚尿囊液灭活疫苗(均未加油佐剂)在控制禽流感的有效性方面进行了试验性评估。结论是这两种疫苗只对降低鸡群的死亡率有暂时的和有限的改善作用。     

Antiviral efficacy of oseltamivir against avian influenza virus in avian species

Avian influenza is one of the most contagious viral diseases in bird species and, increasingly, interspecies transmission to mammalian species has been reported. Prevention and eradication of avian influenza virus (AIV) infection in birds may require vaccines as part of a comprehensive program including biosecurity, culling, diagnostics, and surveillance. However, for valuable bird species in zoos, novel eradication strategies are needed, including antiviral treatments. The present study evaluated the anti-influenza efficacy of the potent neuraminidase inhibitor oseltamivir in avian species using the orders Galliformes (chickens) and Anseriformes (ducks). Viral replication of low pathogenic AIV was significantly reduced in the chicken model and completely reduced in the duck model. Anti-influenza drug administration to valuable bird species with an appropriate extrapolation approach could be useful for control of AIV in combination with active surveillance and vaccination strategies. Further, evaluation of oseltamivir against highly pathogenic avian influenza (HPAI) using avian models would be needed to optimize the oseltamivir application guideline for HPAI control.     

Yeast-derived sigma C protein-induced immunity against avian reovirus

Avian reoviruses (ARVs) can result in disease and economic losses in the poultry industry. Vaccines against ARV may not provide full protection and can cause adverse reactions. The coding sequence of the sigma C protein from strain S1133 of avian reovirus was expressed in Schizasaccharomyces pombe. Sigma C protein expression was demonstrated by Western blotting, and the protein was evaluated for its ability to protect specific-pathogen-free (SPF) chickens against challenge with the virulent S1133 strain. Serologic and challenge-infection data showed the efficacy of the recombinant vaccine administered orally each week for 3 consecutive wk. Sigma C protein induced antibody, as determined by enzyme-linked immunosorbent assay. Percentage (%) protection induced by the low dose (125 microg purified yeast-expressed sigma C protein/chicken) or the high dose (250 microg purified yeast-expressed sigma C protein/chicken) was 64 and 91, respectively. The commercial vaccine administered once or twice provided 82% protection. Results supported the feasibility of a plant-derived vaccine for use in poultry immunization schemes.     

禽流感病毒的致病性和免疫性研究进展

介绍了禽流感病毒的病原、基因结构及其对禽类、人类的致病机理和危害，探讨了感染病毒后宿主的反应、机体的体液免疫和细胞免疫，在一定程度上概述了禽流感病毒的固有特点和规律，为进一步研究打下了基础。     

Salmonella flagellin enhances mucosal immunity of avian influenza vaccine in chickens

Flagellin, a bioactive Toll-like receptor (TLR) 5 ligand, may trigger the innate immunity that in turn is important for subsequent adaptive immune responses. In the present study, the adjuvant effects of the monomeric and polymeric forms of Salmonella flagellin (mFliC and pFliC, respectively) were examined in specific-pathogen free (SPF) chickens immunized intramuscularly (i.m.) or intranasally (i.n.) with formalin-inactivated avian influenza virus (AIV) H5N2 vaccines. Results showed that mFliC cooperating with the 64CpG adjuvant significantly induced influenza-specific antibody titers of plasma IgA in the i.m.-vaccinated animals. The nasal IgA levels in the i.n.-mFliC-coadministrated AIV vaccinated chickens were significantly elevated compared to levels observed in the control group (H5N2 vaccine alone). The pFliC cooperating with the 64CpG adjuvant significantly enhanced cell proliferation of splenocytes in the i.m.-vaccinated animals. TLR3 and TLR5 expressions were activated by flagellin stimulation in vitro and in vivo. These results suggest that flagellin can be used as an adjuvant in an AIV H5N2 vaccine, especially for mucosal immunity.     

Duck MDA5 functions in innate immunity against H5N1 highly pathogenic avian influenza virus infections

Melanoma differentiation-associated gene 5 (MDA5) is an important intracellular receptor that recognizes long molecules of viral double-stranded RNA in innate immunity. To understand the mechanism of duck MDA5-mediated innate immunity, we cloned the MDA5 cDNA from the Muscovy duck (Cairina moschata). Quantitative real-time PCR analysis indicates that duck MDA5 mRNA was constitutively expressed in all sampled tissues. A significant increase of MDA5 mRNA was detected in the brain, spleen and lungs of ducks after infection with an H5N1 highly pathogenic avian influenza virus (HPAIV). We investigated the role of the predicted functional domains of MDA5. The results indicate the caspase activation and recruitment domain (CARD) of duck MDA5 had a signal transmission function through IRF-7-dependent signaling pathway. Overexpression of the CARD strongly activated the chicken IFN-β promoter and upregulated the mRNA expression of antiviral molecules (such as OAS, PKR and Mx), proinflammatory cytokines (such as IL-2, IL-6, IFN-α and IFN-γ, but not IL-1β and IL-8) and retinoic acid-inducible gene I (RIG-I)-like receptors (RLR) (RIG-I and LGP2) without exogenous stimulation. We also demonstrate the NS1 of the H5N1 HPAIV inhibited the duck MDA5-mediated signaling pathway in vitro. These results suggest that duck MDA5 is an important receptor for inducing antiviral activity in the host immune response of ducks.