Swayne D E, Beck J R, Mickle T R
USDA, Agriculture Research Service, Southeast Poultry Research Laboratory, Athens, GA 30605, USA.
Avian Dis. 1997 Oct-Dec;41(4):910-22.
Internationally and nationally, governments and the poultry industries have used various strategies to control avian influenza (AI), ranging from a minimum of living with mildly pathogenic AI virus (AIV) infections to the other extreme of implementing a total quarantine-slaughter approach for eradication of highly pathogenic (HP) forms of the disease. However, recent economic considerations in various countries have prompted a broader reevaluation of vaccination as one of several tools to be used in AI control programs, including H5 and H7 HP AI. In the current study, 1-day-old chickens were immunized with a recombinant fowl poxvirus vaccine containing a hemagglutinin gene insert (Vector-HA) from an H5 AIV. Vector-HA- and negative control (vector-control)-vaccinated chicks were challenged with a HP H5N2 AIV isolated from chickens in Mexico. All immunized chickens were antibody negative on the agar gel precipitin test, indicating that vaccination would not interfere with routine AI serologic surveillance programs in the United States. However, in the hemagglutinin-inhibition test, a few immunized chickens (8%) had low serologic titers. Protection against illness (90-100%) and death (90-100%) was provided by the vector-HA vaccine from 3 wk of age to the end of the 20-wk study. The number of chickens shedding the challenge AIV from their enteric tracts was significantly reduced (50-75%) and the quantity of challenge AIV shed from respiratory and enteric tracts was significantly reduced (10(1)-10(2.1) mean embryo lethal dose/ml) in most vector-HA vaccine groups when compared with vector-control groups. Furthermore, vector-HA vaccination reduced in contact transmission of HP AI challenge virus to both vector-HA- and vector-control-vaccinated chickens. These findings indicate the recombinant fowl poxvirus vaccine can be a useful tool in an AI control program by preventing illness and death in chickens and reducing intestinal and respiratory shedding of H5 AIV. However, for an AI control program to be successful, enhanced biosecurity and surveillance must be practiced, and the vaccine's use must be controlled by an industry and/or government task force.
在国际和国内，政府及家禽行业已采用各种策略来控制禽流感（AI），范围从最少地应对低致病性禽流感病毒（AIV）感染，到另一个极端，即实施全面检疫-扑杀方法以根除高致病性（HP）形式的该疾病。然而，各国近期的经济考量促使人们更广泛地重新评估疫苗接种，将其作为禽流感防控计划中可使用的多种工具之一，包括H5和H7高致病性禽流感。在本研究中，用含有来自H5禽流感病毒血凝素基因插入片段（载体-HA）的重组禽痘病毒疫苗对1日龄雏鸡进行免疫接种。用从墨西哥鸡中分离出的高致病性H5N2禽流感病毒对接种载体-HA疫苗和阴性对照（载体对照）疫苗的雏鸡进行攻毒。所有免疫接种的鸡在琼脂凝胶沉淀试验中抗体均为阴性，这表明疫苗接种不会干扰美国常规的禽流感血清学监测计划。然而，在血凝抑制试验中，少数免疫接种的鸡（8%）血清学滴度较低。从3周龄到20周研究结束，载体-HA疫苗提供了针对疾病（90 - 100%）和死亡（90 - 100%）的保护。与载体对照组相比，在大多数载体-HA疫苗组中，从肠道排出攻毒禽流感病毒的鸡的数量显著减少（50 - 75%），并且从呼吸道和肠道排出的攻毒禽流感病毒的量显著减少（平均胚致死剂量/毫升为10（1） - 10（2.1））。此外，载体-HA疫苗接种减少了高致病性禽流感攻毒病毒向接种载体-HA疫苗和载体对照疫苗的鸡的接触传播。这些发现表明，重组禽痘病毒疫苗通过预防鸡的疾病和死亡以及减少H5禽流感病毒的肠道和呼吸道排出，可成为禽流感防控计划中的一种有用工具。然而，要使禽流感防控计划取得成功，必须加强生物安全和监测，并且疫苗的使用必须由行业和/或政府特别工作组进行管控。
