Are the Australian poultry industries vulnerable to large outbreaks of highly pathogenic avian influenza?

Objective   To describe the structure of the Australian poultry industry and discuss the potential for highly pathogenic avian influenza (HPAI) to spread between Australian poultry farms.
Procedure   High densities of poultry farms, frequent contacts between farms by service providers, the supply of live poultry markets (LPM) and the presence of free-range duck flocks in affected regions have been identified as risk factors for the spread of HPAI between flocks in outbreaks causing the death or destruction of over 1 million poultry overseas. Data on 1,594 commercial Australian chicken meat, chicken egg, duck and turkey farms were collected by a telephone questionnaire of farm managers to assess the risk of a HPAI outbreak in Australia.
Results and Discussion   Five regions of Australia had farm densities comparable to overseas regions that experienced widespread HPAI. Common service providers routinely contacted different classes and types of farms over wide geographic areas. However, no responding farms supplied LPM and the majority of duck farms did not produce free-range ducks.
Conclusion   Outbreaks of HPAI have the potential to cause serious impacts on the Australian poultry industry. The risk posted by LPM and free-range ducks is limited, but the movement of genetic stock and common service providers could spread infection between companies, industries or geographical regions. Biosecurity measures are therefore considered critical to limit the secondary spread of infection should an outbreak occur.     

益生菌对致病性大肠杆菌在雏鸡消化道内的作用效果

1日龄雏鸡120只,随机分为6组,用不同的方法处理后,对各组雏鸡7个部位（嗉囔、腺胃、十二指肠、空肠、回肠、盲肠、直肠）消化道黏膜黏附的O78进行分离计数,研究禽致病性大肠杆菌在雏鸡消化道的分布,比较益生菌对禽致病性大肠杆菌O78在不同雏鸡动物模型中的抑制作用。结果表明：禽致病性大肠杆菌O78主要定植在雏鸡的嗉囔、盲肠和直肠;抗生素处理组和非处理组在灌服益生菌后24、48、72、96h与对照纽相比,各消化道部位定植的O78均有不同程度的降低,说明益生菌对禽致病性大肠杆菌O78。具有较强的抑制能力;未处理组的雏鸡消化道内黏附的O78菌数低于抗生素处理组,说明益生菌在抑制病原菌同时可促进消化道有益菌群的生长,从而防止致病菌的感染。     

实验感染肉鸡组织中J亚群禽白血病病毒的抗原定位

从实验感染J亚群禽白血病病毒(ALVJ)的髓细胞性白血病肉鸡病例中,选取典型病例,用J亚群禽白血病病毒单克隆抗体通过免疫酶组化试验对不同组织进行了抗原定位观察。结果显示:在实验感染阳性肉鸡体内实质组织细胞及瘤细胞的核膜和细胞浆里可见不同程度的棕黄色阳性反应,可为探讨ALVJ对体内组织细胞的嗜性提供依据。     

The fat content of milk from dairy cattle infected with bovine leukosis virus

Two groups of cows infected with the bovine leukosis virus (BLV) were kept on two different diets and the fat content of their milk was assayed. The results were compared with those obtained from two comparable groups of BLV-free cows. The cows in each group were of similar ages, those in the groups on the poorer diet being 1–4 months post partum, while those on the richer diet were 5–7 months post partum. The mean percentage of fat in the milk from uninfected cows on the poorer diet was 2.94 while that from the similar infected cattle was 3.06. Uninfected cows on the richer diet produced milk containing 3.39% fat, while those that were infected produced milk containing 3.30% fat. No statistical differences in milk fat production were observed between the BLV seropositive and seronegative cows.     

免疫剂量和母源抗体对禽流感重组鸡痘病毒活载体疫苗免疫效力的影响

利用表达 H 5亚型禽流感病毒 (AIV)血凝素基因的重组鸡痘病毒 (r FPV- HA)以不同剂量免疫 1日龄 SPF鸡、有或无母源抗体 (FPV、AIV H5)的商品鸡 ,并于免疫后 2 1d利用同亚型 AIV通过肌肉注射进行致死性攻击 ,通过检测免疫后 HI抗体应答、比较攻毒后发病率和死亡率评价免疫剂量和母源抗体对 r FPV- HA免疫效力的影响。结果发现 ,免疫后 2 1d,15 %～ 2 0 %的 SPF鸡和无母源抗体商品鸡可检出 HI抗体 ,而含母源抗体商品鸡检测不到 HI抗体。利用H5亚型 AIV致死性攻击后 ,10 3～ 10 6 PFU的 r FPV- HA可保护 95 %～ 10 0 %的 SPF鸡和无母源抗体商品鸡抵御强毒攻击 ,使之免于发病和死亡 ;而不同剂量 r FPV- HA接种的含母源抗体商品鸡有 80 %～ 90 %发病和死亡。结果表明 ,在较宽的免疫剂量范围内 ,r FPV- HA对 SPF鸡和无母源抗体商品鸡可提供良好的保护 ,显示出一定的应用前景 ;母源抗体影响 r FPV- HA诱导的免疫应答 ,且提高免疫剂量亦不能克服其干扰作用 ,这提示在实际应用中需优化免疫程序 ,避免母源抗体干扰。     

鸡流行性腹泻病原的分离鉴定及特性研究

用胰蛋白酶处理发病鸡的粪便和肠内容物，接种Marc145细胞，盲传数代后，从山东不同地区发生流行性腹泻的鸡群中分离到轮状病毒，并对分离的轮状病毒的生物学特性和理化特性进行了部分研究。结果表明病毒粒子的形态呈车轮状、大小为70-80nm；其病毒基因组的电泳图谱为5：1：3：2；病毒在Marc145细胞上传到第9代时的TCID50为10^-4.62／0．1mL；该分离株病毒对氯仿、乙醚有抵抗力；对pH3．0处理60min稳定；50℃ 30min能使其感染力下降10^2；1mol／L MgCl2不能增强其对50℃ 60min的抵抗力。动物回归试验中接种两周龄SPF鸡，24h后陆续发病，表现为持续性水样腹泻，与自然发病相同；剖检可见病鸡脱水、小肠内有大量的液体和气泡、肠粘膜变薄；组织学变化为肠绒毛上皮坏死、脱落，绒毛平均长度减少而隐窝深度增加，固有层中淋巴细胞浸润。其临床症状及病理组织学变化与自然发病相同。因此确定发生在山东鸡流行件腹泻的病原为轮状病毒．     

禽肺病毒病

从病原学、流行病学、临床症状、病理变化方面对禽肺病毒病进行了详尽的分析和和论述，并提出了诊断和防治应注意的问题。     

种鸡场鸡白血病净化的研究(Ⅲ)-ALV检测不同样品种鸡场净化效果的比较

应用双抗体夹心酶联免疫吸附试验 (DAS- EL ISA)在种鸡白血病的净化中 ,针对同一种鸡群 ,同时采用蛋清和肛拭作为试验材料 ,实验反映的结果不同 ;将产第一枚蛋为阳性的鸡隔离饲养 ,检测其以后蛋中 AL V的状况 ,结果发现 :在随后的 2 5天左右的每一枚蛋清中都能检测到 AL V:在不同种鸡场分别采用蛋清、蛋清和肛拭同时作试验样品进行净化 ,跟踪结果发现 :在不同种鸡场中 ,AL V阳性感染率都有不同幅度的下降。另一方面 ,检测雏鸡的胎粪 ,淘汰阳性者 ,到其产蛋期抽检蛋清 ,该群鸡 AL V阳性率有所下降     

实验性鸡大肠杆菌病病理学动态变化

用致病性大肠杆菌O18分离株和／或低致病性禽流感病毒（Mildly pathogenic avian influenza virus ,MPAIV)接种10－12日龄SPF鸡。在接种后1－96h进行临床症状与大体病理变化、组织学观察发现：大肠杆菌接种组、MPAIV接种组和健康接种组除扑杀鸡外未见鸡死亡，MPAIV与大肠杆菌混合接种组除扑杀鸡外死亡率为24％。混合接种组的病变比大肠杆菌接种组出现的时间早，恢复也慢，各脏器的病理变化更严重。MPAIV主要引起各实质器官的坏死，结果表明，大肠杆菌经气管内接种后试验鸡主要表现为呼吸道的炎症反应；MPAVI可使鸡大肠杆菌病严重化。     

应用ELISA双抗体夹心法检测鸡病毒性关节炎病毒的研究

本试验建立了检测鸡病毒性关节炎病毒的ELISA双抗体夹心法.取代反应、阻断试验均为阴性,与NDV、MDV和IBDV无交叉反应,对已知阳性标本的检测均为阳性;其敏感性比琼扩试验高80倍以上,这表明ELISA夹心法具有较高的特异性和敏感性.在人工感染后2～27d,关节滑膜、腱鞘和脾脏中病毒检出率为100％;还从肝脏、法氏囊和脑组织中检测到病毒.