雏鸡母源抗体滴度与抗禽网状内皮增生病病毒感染间的相关性分析

为分析雏鸡母源抗体滴度与抗禽网状内皮增生病毒(REV)感染之间的相关性.将蛋用型海兰褐种鸡在用REV弱毒疫苗免疫接种,种鸡均在2周内产生REV特异性抗体.来自免疫REV疫苗种鸡的雏鸡均呈母源抗体阳性,而且母源抗体滴度与对应种鸡的抗体滴度呈正相关性.分别对有母源抗体和无母源抗体的雏鸡人工接种REV低代毒,比较它们的生长速度和对新城疫病毒(NDV)和禽流感病毒(AIV)灭活苗免疫后的抗体反应.结果表明,种鸡提供的母源抗体,不仅可预防REV野毒感染引起的生长迟缓,也可预防REV引起的对NDV和AIV灭活疫苗免疫反应的抑制作用.雏鸡的REV母源抗体水平与对NDV和AIV的灭活疫苗免疫后的抗体滴度呈正相关性.     

不同来源禽网状内皮增生病病毒株的致病性比较

本研究旨在探讨不同来源的禽网状内皮增生病病毒(REV)对1日龄SPF鸡的致病性.用包括分子克隆化病毒REV-C99在内的不同来源的6个REV株人工感染1日龄SPF鸡,以禽流感病毒灭活疫苗(H9-AIV、H5-AIV)与新城疫病毒灭活疫苗(NDV)免疫后HI抗体滴度的测定结果为指标,比较不同REV株的致病性.结果表明,分别用3000TCID_(50)·只~(-1)的剂量人工感染1日龄SPF鸡,6个REV感染组与对照组相比,H9-AIV、H5-AIV与NDV免疫后4、5与6周的HI抗体水平均极显著降低(P<0.01).但6个REV感染组之间差异不显著(P>0.05).研究结果显示,不同来源REV株感染1日龄SPF鸡后均造成生长迟缓,并对体液免疫反应有明显的抑制作用,同时,这也揭示出REV感染可能是免疫失败的重要原因之一.     

海兰褐蛋鸡新城疫、禽流感母源抗体消长规律的研究

本研究应用血凝抑制试验对不同日龄的海兰褐蛋鸡进行新城疫、禽流感母源抗体水平的检测,掌握雏鸡AI和ND母源抗体的分布和消长规律。结果表明,雏鸡出壳后,新城疫、禽流感母源抗体水平大都在7日龄内出现高峰,之后随着日龄的增长,抗体水平逐渐下降,新城疫、禽流感H9亚型母源抗体35日龄已基本消失,而禽流感H5亚型Re-4株和Re-5株母源抗体下降较快,20日龄左右母源抗体水平接近0。     

猪瘟母源抗体衰减及保护水平分析

为分析仔猪体内猪瘟母源抗体的衰减规律及母源抗体保护水平,测定了断奶时母猪和仔猪抗体水平,并监测仔猪母源抗体水平至81日龄;分别对12头81日龄仔猪（来自5头母猪）和25头35日龄仔猪（来自5头母猪）进行了攻毒试验,并用RT—nPCR进行了跟踪检测,对7头攻毒耐过猪用兔体中和法测定了中和效价。结果表明,母猪抗体水平不均衡会导致仔猪群体母源抗体水平不均衡;仔猪群体抗体到60日龄时仍然有67％（12／18）的个体用ELISA检测阻断率在50％以上：81日龄攻毒组有3头（3／12）耐过,35日龄攻毒组能全部耐过（25／25）,但有2头（2／25）在攻毒27d后仍然呈PCR阳性,此时中和抗体水平从低于1：4到1：16不等,推测中和抗体水平1：8～1：16是母源抗体保护的临界线。     

鸡新城疫母源抗体消长规律和免疫保护抗体临界值的测定

通过对初生雏鸡的新城疫母源抗体不同时间检测,发现初生雏鸡5日龄时母源抗体出现最高值7.7log2,并选择母源抗体在4log2、5log2、6Log2和7log2时分别攻新城疫强毒。结果显示,初生雏鸡母源抗体达到6Log2日龄时能有效抵御强毒的攻击。     

清远麻鸡H5亚型禽流感母源抗体消长规律的探讨

本试验试图通过对不同日龄的清远麻鸡H5亚型禽流感母源抗体的检测,找出母源抗体消长规律,确定本地区清远麻鸡H5亚型禽流感首免日龄,为制定合理免疫程序提供科学依据。分别于2、6、10、15、20、24、28日龄颈静脉或翅静脉采血,每个日龄整体随机采集30份样品。结果表明,2、6、10、15日龄的禽流感H5亚型母源抗体抗体合格率为100%,能够保护禽群抵御风险;20日龄时抗体保护率为96.7%,仍然能够很好地保护禽群;24日龄时抗体保护率为76.7%,接近临界值;28日龄时抗体保护率为30%,此时母源抗体已经不足以保护禽群抵御感染风险。     

蛋鸡禽流感和新城疫母源抗体消长规律的研究

为了探讨种鸡场禽流感和新城疫母源抗体消长规律,制定科学的免疫程序,本试验对父母代种鸡和出壳当日蛋雏鸡进行禽流感和新城疫抗体检测以及对1、8、15、22及29日龄蛋雏鸡进行禽流感H5、H9亚型和新城疫母源抗体跟踪检测。结果表明,父母代种鸡禽流感和新城疫免疫抗体水平较高,且通过卵黄传递给蛋雏鸡,使其产生较高的母源抗体抵抗病毒侵袭。同时发现蛋雏鸡在出壳当日禽流感和新城疫母源抗体水平最高,均达到6log2以上,且群体抗体合格率均达90%以上,随后母源抗体逐渐下降,在15日龄时禽流感H5亚型和新城疫母源抗体下降到抗体保护水平以下,22日龄时禽流感H9亚型母源抗体也已下降到抗体保护水平以下,因此在15日龄时进行禽流感H5亚型和新城疫首免,在22日龄时进行禽流感H9亚型首免,可以有效降低禽流感H5和H9亚型和新城疫的发生风险。     

母源抗体对鸡新城疫疫苗免疫的影响

该试验旨在通过在不同日龄分别选用不同的疫苗组合 ,对有鸡新城疫母源抗体的雏鸡进行免疫 ,探讨不同疫苗组合克服母源抗体的效果。结果表明 :有 ND母源抗体的雏鸡用弱毒疫苗免疫后 ,母源抗体对弱毒疫苗免疫干扰较大 ,只有当 ND母源抗体降到较低水平 (小于 3log2 ,一般要到 1 5～ 2 0日龄后 )时 ,对弱毒疫苗免疫影响才非常小 ,方可产生较为可靠的免疫力 ;用ND弱毒疫苗 油乳剂疫苗进行免疫 ,可有效地克服母源抗体的干扰 ,获得理想的免疫效果。但母源抗体对 ND油乳剂疫苗免疫的影响在日龄越小的雏鸡越明显 ,因此于 8～ 1 0日龄之后用 ND弱毒疫苗 油乳剂疫苗进行免疫是最佳选择 ,为雏鸡免疫程序的制定奠定了理论基础     

商品肉雏鸡H5亚型禽流感母源抗体变化规律

通过血凝抑制(HI)试验,对市售商品肉雏鸡血清H5亚型禽流感母源抗体进行调查,结果显示,该批商品肉雏鸡H5禽流感母源抗体仅持续13d,峰值出现在3～5日龄,达到6.4～6.6(log2)。从6日龄起母源抗体水平开始下降,13日龄后下降到临界值4(log2),从20日龄开始几乎检不出母源抗体。     

禽脑脊髓炎弱毒疫苗不同免疫期的种鸡及其后裔雏鸡母源抗体的衰减规律

艾维菌父母代肉种鸡经禽脑脊髓炎病毒(AEV)弱毒疫苗免疫后，用琼脂扩散试验对不同免疫期种鸡的后裔雏鸡的母源抗体进行动态监测。结果发现，26周龄种鸡禽脑脊髓炎(AE)抗体阳性率为86．79／6～1009／6．其后裔雏鸡在1～7日龄时母源抗体阳性率为83．3％～100％；14日龄时降至30．0％～70．09／6；多数在21日龄时转阴。36周龄种鸡AE抗体阳性率为56．7％～76．79／6，其后裔雏鸡在1日龄时母源抗体阳性率只有50．0％～76．7％；7日龄时降至10．0％～50．0％；14日龄时全部转阴。表明，雏鸡AE母源抗体水平及其衰减规律受种鸡抗体水平的影响。攻毒保护试验发现，低母源抗体雏鸡(1日龄母源抗体阳性率为50．0％)，不但7～28日龄脑内攻毒后6～11d全部发病，而且14日龄颈部皮下攻毒后11～13d也有6／10雏鸡发病；而高母源抗体雏鸡(1日龄的母源抗体为1009／6)，虽然14～28日龄对脑内攻毒易感，但是颈部皮下攻毒后观察45d均未发病。证实，雏鸡1日龄的AE母源抗体为50．0％时，很难保护其免受AEV的侵袭。     

种鸡接种网状内皮组织增生病病毒弱毒疫苗的安全性和免疫效果观察

在正常饲养条件下，在肉种鸡鸡群中试用网状内皮增生病病毒（reticuloendotheliosis virus，REV）的弱毒疫苗，观察其对体重增长、产蛋生产性能、对其他疫苗应答有无影响。同时连续定期测定种鸡血清REV抗体，并测试抗体阳性鸡的后代有无病毒垂直传播。结果表明，该疫苗接种18周龄种鸡后，对生长、产蛋率、受精率和孵化率等生产性能均无不良影响，对正常疫苗免疫的抗体应答也无影响。经免疫接种REV弱毒疫苗的种鸡，在开产后及产蛋高峰期，均不表现病毒的垂直传播。免疫种鸡后，其激发的抗体可持续280d以上，且雏鸡血清中母源抗体可持续至少7d。结果表明，该REV弱毒在开产前种鸡应用时有很高的安全性，并能为雏鸡提供足够的特异性母源抗体。     

Influence of maternal immunity on vaccine efficacy and susceptibility of one day old chicks against Egyptian highly pathogenic avian influenza H5N1

In Egypt, continuous circulation of highly pathogenic avian influenza (HPAI) H5N1 viruses of clade 2.2.1 in vaccinated commercial poultry challenges strenuous control efforts. Here, vaccine-derived maternal AIV H5 specific immunity in one-day old chicks was investigated as a factor of vaccine failure in long-term blanket vaccination campaigns in broiler chickens. H5 seropositive one-day old chicks were derived from breeders repeatedly immunized with a commercial inactivated vaccine based on the Potsdam/H5N2 strain. When challenged using the antigenically related HPAIV strain Italy/98 (H5N2) clinical protection was achieved until at least 10 days post-hatch although virus replication was not fully suppressed. No protection at all was observed against the Egyptian HPAIV strain EGYvar/H5N1 representing a vaccine escape lineage. Other groups of chicks with maternal immunity were vaccinated once at 3 or 14 days of age using either the Potsdam/H5N2 vaccine or a vaccine based on EGYvar/H5N1. At day 35 of age these chicks were challenged with the Egyptian HPAIV strain EGYcls/H5N1 which co-circulates with EGYvar/H5N1 but does not represent an antigenic drift variant. The Potsdam/H5N2 vaccinated groups were not protected against EGYcls/H5N1 infection while, in contrast, the EGYvar/H5N1 vaccinated chicks withstand challenge with EGYvar/H5N1 infection. In addition, the results showed that maternal antibodies could interfere with the immune response when a homologous vaccine strain was used.     

Effect of breeder vaccination on immunization of progeny against Newcastle disease

Two experiments were conducted to determine the effect of breeder vaccination program and maternal antibody on the efficacy of Newcastle disease immunization of 1-day-old chicks. Experimental protocol was the same for both. In the first experiment, broilers were from breeders that were 32 weeks old, and in the second experiment, broilers were from breeders 50 weeks old. Breeders received three live Newcastle disease virus (NDV) vaccines and either a killed vaccine at 18 weeks or continual live boosting at 60-to-70-day intervals through lay. Broilers were vaccinated at 1 day of age with a commercial coarse-spray machine; they were bled, sera were examined for antibody against NDV, and broilers were challenged with virulent NDV at 2, 4, and 6 weeks of age. In the first experiment, maternal antibody was higher in chicks from the younger breeders given the inactivated vaccine, and in the second experiment maternal antibody was higher in chicks from older breeders given continual live vaccines. Higher antibody in 1-day-old broilers resulted in fewer vaccine-induced reactions, less vaccine virus shed, and decreased duration of vaccine-induced immunity from coarse-spray vaccination.     

Antibody response of chickens to serotype 1, 2, or 3 Marek's disease vaccines based on ELISA with infected cells as antigen

An enzyme-linked immunosorbent assay (ELISA) was applied to evaluate the antibody response of commercial White Leghorn chickens to vaccination against Marek's disease (MD) at hatch (day 0) with serotype-1 (Rispens), -2 (SB-1), or -3 (turkey herpesvirus, HVT) vaccine virus and to challenge on day 21 with MD virus. Antigens for the test were whole chicken embryo fibroblast cells infected with Rispens, SB-1, or HVT. The chickens were progeny of stock that had been vaccinated with HVT, and on day 21 the nonvaccinated group had higher levels of maternal antibodies to HVT than to other antigens (P < 0.05). Only SB-1 vaccine had induced antibodies by day 21, and this was detected only against homologous antigens. On day 49, all three vaccines had induced higher levels of antibodies to homologous than to heterologous antigens. Marek's Disease virus (MDV) induced antibodies to all three antigens, but challenging vaccinated chicks did not significantly increase levels of antibodies on day 81 to any of the three antigens. It was concluded that an ELISA using whole cells as antigens would have potential value for monitoring the antibody response induced by MD vaccines and virulent MDV.     

Evaluation of the hemagglutination-inhibition test for measuring the response of chickens to avian infectious bronchitis virus vaccination

An infectious bronchitis virus (IBV) hemagglutination-inhibition (HI) test was used to assay serum-antibody titers after IBV vaccination of IBV-susceptible specific-pathogen-free broilers and commercial layers. Three-week-old broilers were vaccinated via eye-drop with IBV strains that represent the antigenic spectrum of commercial vaccines--Holland, Massachusetts 41 (41 Ms), Connecticut 46, Florida 18288, or JMK strain--and revaccinated 3 weeks later with either the same or a heterologous strain. Weekly serum samples were tested by IBV HI with homologous and heterologous antigens. Vaccinates, except for those vaccinated with the Holland strain, were HI-positive with homologous but not heterologous antigens by 1 to 2 weeks postvaccination. Sixteen-week-old IBV-vaccinated commercial layers were revaccinated with IBV Holland 52 (H 52) strain and subsequently infected with Arkansas 99 (Ark 99) and SE 17 strains. In contrast to the limited HI cross-reactivity of serum from IBV-vaccinated broilers, there were extensive cross-reactions in HI tests with 41 Ms, H 52, Ark 99, and SE 17 antigens of revaccinated layers. These results demonstrate that the IBV HI test is more strain-specific than previous reports indicate, especially when the test samples are from early postvaccination.     

CAV与REV共感染SPF鸡对疫苗免疫反应的抑制作用

用1日龄SPF鸡人工感染鸡贫血病毒(CAV)和禽网状内皮增生病病毒(REV),探讨病毒感染对鸡体疫苗免疫反应的影响。结果表明,在用禽流感病毒(AIV,H5和H9)疫苗免疫后,CAV与REV单独感染均显著抑制了鸡体对H5和H9亚型禽流感病毒灭活疫苗的HI抗体反应,在CAV与REV共感染后,这种抑制作用更为明显。CAV单独感染后鸡体对新城疫病毒(NDV)和传染性法氏囊病病毒(IBDV)疫苗的免疫反应受到抑制,但与对照组在统计学上的差异不显著,然而,CAV可以显著加重REV感染对鸡体在NDV和IBDV疫苗免疫后抗体反应的抑制作用。从而证实CAV与REV共感染在疫苗免疫抑制上有协同作用。     

Immunization of broiler breeder chickens against Newcastle disease with an oil-emulsion vaccine

Antibody response was rapid and high in broiler breeder chickens receiving 1 or 2 vaccinations with oil-emulsion vaccine against Newcastle disease at 23 or at 23 and 26 weeks old. The antibody titers remained high during the 41-week experimental period. At 64 weeks old, about 41 weeks after vaccination, the geometric mean hemagglutination-inhibition antibody titer was 67 from the single vaccination, and 103 from the double vaccination. The immune response to live-virus vaccine given at 2, 9, 20, 30, 42, or 54 weeks of age via the drinking water was high, but uniformity was lacking in the antibody response in the breeders and maternal antibody response in the progeny. Maternal antibody levels in one-day-old chicks were related to the titers of antibody in the dams. Maternal antibody titers of chicks originated from breeder flocks that were vaccinated with the oil-emulsion vaccine remained high for all hatches.     

Resistance of broiler chickens to Escherichia coli respiratory tract infection induced by passively transferred egg-yolk antibodies

Egg-yolk antibodies induced by immunizing hens with selected Escherichia coli antigens were evaluated for their ability to protect broiler chickens against respiratory/septicemic disease caused by avian pathogenic E. coli (APEC). Seven groups of broiler breeder hens were vaccinated three times, 1 week apart with live E. coli, killed E. coli, E. coli antigens [lipopolysaccharide (LPS), type 1 pilus adhesin (FimH), P pilus adhesin (PapG), aerobactin outer membrane receptor (IutA)] or phosphate buffered saline (PBS). An O78 APEC strain was used for preparation of all the antigens. Egg yolk immunoglobulins (IgY) were purified from eggs of each group and antibody activity in serum and purified IgY was determined by enzyme-linked immunosorbent assay (ELISA). IgY (100mg) was injected intramuscularly into 11-day-old broiler chickens, which were challenged 3 days later with homologous (O78) or heterologous (O1 or O2) E. coli by the intra-air sac route. Mortality was recorded and surviving chickens were euthanized 1 week after the challenge and examined for macroscopic lesions. Passive antibodies against all antigens except FimH were protective (90-100%) against the homologous challenge, but only anti-PapG and anti-IutA were effective against heterologous challenge. Anti-PapG IgY provided the greatest protection against the three serogroups of E. coli used for challenge. Hence vaccination of broiler breeders to induce anti-PapG and anti-IutA antibodies may provide passive protection of progeny chicks against respiratory/septicemic disease caused by APEC.     

我国白羽肉用型鸡群中CAV、REV和REOV感染状况的血清学调查

为了解鸡传染性贫血病毒（CAV）、禽网状内皮增生病病毒（REV）和呼肠孤病毒（REOV）在我国白羽肉用型鸡中的感染状态，在2003—2004年，检测了来自5省市8个公司不同年龄鸡群血清样品中3种病毒抗体的存在状况。结果表明，在送检的75个鸡群中，对CAV、REV和REOV呈现抗体阳性的鸡群分别有64个（85．3％）、36个（48％）和74个（96％）。在总共检测的1764份血清样品中，对这3种病毒的平均抗体阳性率分别为51．4％、9．8％和75．1％。在1日龄雏鸡，对CAV和REOV的平均母源抗体阳性率可达100％和81．1％，但对REV只有7．4％。抗体阳性率随年龄变化的动态分析表明，对REV和REOV的母源抗体在出壳后2～3周内消失，而对CAV的母源抗体则可持续3～4周。对CAV和REOV的抗体从5周龄起再次出现，到20周龄时，所有送检鸡群全部阳性，平均阳性率在90％以上。有近一半送检鸡群对REV呈现抗体阳性，抗体阳性率普遍较低，即使在达到开产年龄后，仍还有很高比例鸡为抗体阴性，即对REV仍为易感鸡。研究表明，我国多数鸡群中都同时存在着这3种病毒的感染，但它们在感染的程度和动态等流行病学特点上显著不同，应根据鸡群中抗体的阳性率分别采取不同的措施。