黄芪多糖对PCV2阳性猪外周血免疫细胞及相关细胞因子的影响

检测外周血T淋巴细胞、嗜中性粒细胞、CD4+、CD8+细胞百分数及IL-2、IL-4和IFN-γ含量的变化,研究黄芪多糖(APS)对PCV2阳性猪免疫功能的调节作用。结果显示,APS能显著增加外周血T淋巴细胞、NBT阳性细胞、CD4+T细胞百分数及IL-2、IL-4、IFN-γ含量,显著降低CD8+T细胞百分数,推测APS通过上调CD4+细胞百分数、CD4+/CD8+及Th1反应恢复正常免疫机能。     

乳酸菌制剂对小鼠血清中IgG及肠道内SIgA影响的研究

试验以2株乳杆菌MG2 1、L casei zhang按不同剂量分别饲喂小鼠,在5,10,15,20,25,30天测定其血清中IgG及肠道内SIgA含量。结果表明:饲喂不同剂量2株菌的乳悬液均能极显著地提高IgG、SIgA的含量(P<0.01)。在提高IgG含量方面,2菌株均表现出低、中剂量饲喂组随着饲喂时间的不断增加,有超过高剂量组的趋势。在第25天时,菌株MG2 1中剂量组极显著地高于高剂量组;L casei zhang低剂量组极显著地高于中、高剂量组。而SIgA高剂量组比低、中剂量组高。     

PCV2、PCV3和PCV4三重荧光PCR鉴别检测方法的建立及应用

根据猪圆环病毒2型(porcine circovirus 2,PCV2)、猪圆环病毒3型(porcine circovirus 3,PCV3)和猪圆环病毒4型(porcine circovirus 4,PCV4)保守区域基因序列合成特异性的引物和TaqMan探针,通过优化反应条件,建立了一种可同时快速高效鉴别检测PCV2、PCV3和PCV4的三重荧光PCR方法。结果显示,所建立的三重荧光PCR方法仅对PCV2、PCV3和PCV4出现阳性扩增,与猪伪狂犬病毒(PRV)、猪细小病毒(PPV)、猪繁殖与呼吸综合征病毒(PRRSV)、猪瘟病毒(CSFV)、猪支原体肺炎(M.hyo)、猪流行性腹泻病毒(PEDV)和猪传染性胃肠炎病毒(TGEV)等猪常见病原无交叉反应;对PCV2、PCV3和PCV4的最低检出限分别为1.69×10¹,1.38×10²,1.42×10²拷贝;组内和组间试验变异系数均小于1.6%,重复性好。进一步应用所建立的PCV2、PCV3和PCV4三重荧光PCR方法对263份猪临床样品进行检测,结果检出168份PC...     

太子参多糖对环磷酰胺所致肠道黏膜损伤小鼠SIgA、IL-2、IL-6含量的影响

试验将36只18~22 g雄性昆明小鼠随机分为空白对照组、太子参多糖对照组(400 mg/kg体重)、环磷酰胺(CY)模型组、太子参多糖低、中、高剂量组(100、200、400 mg/kg体重),上述各组分别灌喂蒸馏水和多糖,连续灌胃19 d,第20天,除空白对照组和太子参多糖对照组小鼠腹腔注射生理盐水外,其余4组均腹腔注射CY(100 mg/kg体重),24 h处死小鼠,取十二指肠和回肠,放免法测定分泌型免疫球蛋白A(SIgA)、白细胞介素-2(IL-2)、白细胞介素-6(IL-6)的含量,研究太子参多糖对CY所致肠道黏膜损伤小鼠中SIgA、IL-2、IL-6分泌的影响。结果显示,与CY模型组相比,太子参多糖高、中剂量组十二指肠SIgA含量显著升高(P<0.05),太子参多糖高剂量组回肠SIgA含量极显著升高(P<0.01);太子参多糖高剂量组中十二指肠和回肠IL-2含量显著升高(P<0.05),十二指肠IL-6含量极显著升高(P<0.01),回肠IL-6含量显著升高(P<0.05)。上述结果表明太子参多糖在一定程度上能颉颃CY所致的肠道黏膜免疫损伤。     

猪圆环病毒2型(PCV2)遗传变异与疫苗免疫、发病机理及诊断的关系

猪圆环病毒相关疾病(PCVAD)的发生依赖猪圆环病毒2型(PCV2)的感染,表现为一群复杂的多因子综合征。目前在野外流行的PCV2被分为PCV2a和PCV2b两个亚群。北美和其它国家PCVAD的暴发通常与主要基因型从PCV2a转变为PCV2b有关。因此,有人提出基因型存在致病性和抗原性差异。总体来说,毒力是特定PCV2分离株的特性,与基因型无关。此外,报道证实只有少数抗原差异。就免疫病理学而言,位于衣壳蛋白C端一个保守的诱骗表位为不能鉴定基因型之间的致病力差异提供了解释。最后本文讨论了PCV2的遗传变异对疫苗和诊断方法的影响。     

PCV2对体外培养仔猪脾细胞分泌细胞因子的动态影响

为进一步了解猪圆环病毒2型(PCV2)引起断奶仔猪多系统衰竭综合征的机理,选取5头35日龄PCV2血清抗体阴性的断奶仔猪,无菌取脾脏制成单个细胞悬液,体外培养,分PCV2感染组与对照组。分别在培养后0 h、6 h、12 h、24 h收获细胞培养上清,用猪特异性ELISA试剂盒测定上清中白细胞介素-1β(IL-1β)、肿瘤坏死因子-α(TNF-α)、白细胞介素6(IL-6)和白细胞介素10(IL-10)的含量。结果显示:病毒组IL-1β和IL-6在不同时间点的含量变化均不显著(P>0.05),IL-1β在6 h、24 h略高于对照组,12 h则低于对照组;IL-6除在6 h高于对照组外,其余时间点均低于对照组;病毒组TNF-α和IL-10的含量在6 h、12 h、24 h均高于对照组,且TNF-α在6 h和24 h极显著升高(P<0.01),而IL-10在12 h显著高于对照组(P<0.05)。上述结果表明:PCV2能影响体外培养的仔猪脾细胞某些细胞因子的分泌,而且可能通过TNF-α的高表达促使机体产生全身炎症反应综合征甚至多系统衰竭,而通过IL-10的高表达促使机体产生免疫抑制。     

猪圆环病毒2型(PCV2)遗传变异与疫苗免疫、发病机理及诊断的关系(续)

<正>上期回顾:上一期主要介绍了PCV2分离株的进化和分类,包括圆环病毒的起源、PCV2的出现和PCV2的分类和系统发生的关系。2分子差异与PCV2的致病性PCV1、PCV2a和PCV2b的基因组大小分别为1 759、1 768和1 767个核苷酸(Tischer等,1986;Meehan等,1998)。PCV1和PCV2在核苷酸水平上序列有70%的相同,PCV2a和PCV2b基因型有95%的相似性。PCV2各基因型主要差异在ORF2,该处核苷酸和氨基酸序列的相似度有90%。有报道指出肽段的不同造成了致病力的差异,导致低致病性的PCV2a被PCV2b取代。序列比较发现ORF2内有一对基序可以区别PCV2a和PCV2b分离株(cheung等,2007)。PCV2b病毒基因组1 486~1 472位序列为TCA/AAC/CCC/CG,PCV2a在1 487~     

乳酸杆菌对鸡肠道免疫功能的影响

本文以乳酸杆菌为研究对象，观察乳酸杆菌对鸡肠道黏膜SIgA分泌的影响，研究乳酸杆菌对鸡免疫功能的作用。     

RT-PCR法对福州周边猪PCV2流行情况调查

2009年7月至12月,收集福州周边猪场送检的71份病料,采用荧光定量RT-PCR法进行PCV2检测。结果表明,7～9月份送检病料的PCV2阳性率为34.37%,而10～12月份送检病料的PCV2阳性率高达94.87%,从检测的结果来看,冬天寒冷季节PCV2感染率明显高于夏季。     

猪圆环病毒2型（PCV2）：遗传变异与疫苗免疫、发病机理及诊断的关系（续）

上期回顾：上一期主要介绍了PCV2分离株的分子差异与PCV2的致病性,包括猪圆环病毒间致病差异、ORF1和ORF2对致病性的影响、CP内的抗体表位、PCV2基因型间的抗原性差异。     

Effect of porcine circovirus type 2 (PCV2) vaccination on PCV2-viremic piglets after experimental PCV2 challenge

The objective of this study was to evaluate the effect of porcine circovirus type 2 (PCV2) vaccines on PCV2-viremic and -seropositive piglets born from naturally PCV2-infected sows against postnatal PCV2 challenge. The experimental design was aimed at mimicking commercial swine rearing conditions to evaluate the response of the PCV2 vaccine on PCV2-viremic and -seropositive piglets after experimental PCV2 challenge. PCV2a (or 2b)-viremic piglets received a PCV2 vaccine at 21 days of age followed by a PCV2b (or 2a) challenge at 49 days of age (28 days post vaccination). The PCV2 vaccines elicited a high level of humoral (as measured by immunoperoxidase monolayer assay and neutralizing antibody titers) and cellular (as measured by the frequency of PCV2-specific interferon-γ-secreting cells) immune response in the PCV2-viremic piglets after vaccination even in the presence of maternally derived antibodies (MDA). The initial infection of PCV2 in the pigs was not affected by PCV2 vaccination, however the challenging PCV2 was reduced by PCV2 vaccination on PCV2-viremic pigs. The results from this study demonstrate that the PCV2 vaccine used in this study is effective at reducing PCV2 viremia and lymphoid PCV2 DNA, even for PCV2-viremic pigs with passively acquired MDA at the time of vaccination.     

微生态制剂对樱桃谷肉鸭免疫器官指数、十二指肠黏膜SIgA含量和肠道组织形态的影响

本试验旨在研究微生态制剂对樱桃谷肉鸭免疫器官指数、十二指肠黏膜分泌型免疫球蛋白A（SIgA）含量和肠道组织形态的影响。选取540羽1日龄樱桃谷肉鸭（公鸭）,随机分成3组,每组6个重复,每重复30羽。Ⅰ组为空白对照组,饲喂基础饲粮;Ⅱ组为抗生素对照组,在基础饲粮中添加10%杆菌肽锌400 mg/kg;Ⅲ组为试验组,在基础饲粮中添加300 mg/kg微生态制剂,试验期42 d。于21、42日龄进行屠宰取样,测定樱桃谷肉鸭免疫器官指数、十二指肠黏膜SIgA含量和肠道组织形态。结果表明：1）Ⅲ组42日龄的胸腺指数和脾脏指数分别比Ⅰ组提高了35.00%（P<0.05）、25.39%（P<0.05）;2）Ⅲ组42日龄的十二指肠黏膜SIgA含量比Ⅰ组提高了12.50%（P<0.05）;3）Ⅲ组21日龄的十二指肠绒毛高度、绒毛高度与隐窝深度的比值（V/C）分别比Ⅰ组提高了4.47%（P>0.05）、10.68%（P<0.05）;4）Ⅲ组42日龄的空肠隐窝深度比Ⅰ组降低了10.17%（P<0.05）、空肠V/C值比Ⅰ组提高了12.43%（P<0.05）;5）Ⅲ组42日龄的回肠绒毛高度、V/C值比Ⅰ组分别提高了3.66%（P<0.05）、16.32%（P<0.05）,隐窝深度比Ⅰ组降低了11.18%（P<0.05）。由此可见,微生态制剂可以提高樱桃谷肉鸭胸腺指数和脾脏指数,提高十二指肠SIgA含量,并能够提高肠道（十二指肠、空肠、回肠）绒毛高度、降低隐窝深度。     

党参多糖可溶性粉对肉仔鸡血清ND抗体水平、IgG及肠道SIgA含量的影响

为了研究党参多糖可溶性粉对肉仔鸡免疫功能的影响。将300只罗斯308白羽肉仔鸡分为党参多糖可溶性粉高、中、低剂量组,阳性药对照组,疫苗对照组和空白对照组,每组50只。党参多糖可溶性粉在每千克饮水中添加0.4、0.2和0.1 g药物,阳性药对照组在每千克饮水中添加0.2 g黄芪多糖粉,疫苗对照组和空白对照组不添加任何药物。除空白对照组外,7日龄首免用鸡新城疫低毒力活疫苗(La Sota株)滴鼻点眼,21日龄二免,在每次免疫的同时给药,连续三天。结果显示,党参多糖可溶性粉可显著增加肉仔鸡胸腺、脾脏和法氏囊指数;显著提高接种新城疫(ND)疫苗后肉仔鸡血清中ND抗体水平、免疫球蛋白G(Ig G)含量和肠道分泌型免疫球蛋白A(SIg A)含量(P0.05)。此外,饮水中添加党参多糖可溶性粉对肉仔鸡有明显增重作用(P0.05)。因此,党参多糖可溶性粉不仅有增强肉仔鸡免疫功能的作用,而且对肉仔鸡体重增长有一定促进作用;其中以中剂量药物组,即在每千克饮水中添加0.2 g党参多糖可溶性粉效果最好。     

通过检测血清中的病毒载量评估不同圆环病毒疫苗对母猪的免疫效果

为了给规模化猪场圆环病毒2型(PCV2)的感染和疫苗评价提供科学合理的评判标准,本研究建立了一套成熟敏感的real-time PCR检测方法,通过检测母猪免疫前后血液中病毒载量变化,来评价不同类型圆环病毒疫苗的免疫效果。结果显示:4个厂家疫苗对降低病毒载量的效果差异很大,其中原核表达的PCV2疫苗效果最佳,降幅比例为97.78%,离散度为49.8。此外,PCV2疫苗免疫能够降低猪繁殖与呼吸综合征(PRRS)的抗体水平,有助于猪场PRRS疫情的控制。以上试验证明:PCV2病毒载量的降低是控制PCV2感染的关键;抗体水平不能作为疫苗的评价标准;不同厂家的PCV2疫苗效果存在很大差异。     

钼对小鼠免疫球蛋白和细胞因子含量的影响

旨在探讨钼对小鼠血清免疫球蛋白和细胞因子含量的影响,选用30d健康昆明小鼠60只,随机分为4组,分别饮用钼水(mg/L),Ⅰ组(0)、Ⅱ组(400)、Ⅲ组(800)、Ⅳ组(1 200),试验周期42d,定期剖杀取样。采用ELISA法检测小鼠血清中免疫球蛋白和细胞因子含量的变化,结果显示:与Ⅰ组相比,整个试验中,Ⅱ、Ⅲ、Ⅳ组小鼠血清IgE含量差异不显著(P0.05),第14天Ⅲ、Ⅳ组IgG、IL-4均极显著降低(P0.01),Ⅲ组IFN-γ、IL-6均显著升高(P0.05),第28天Ⅱ、Ⅲ、Ⅳ组IgG,Ⅲ、Ⅳ组IgM、IL-4,Ⅳ组IL-2均显著或极显著降低(P0.05或P0.01),第42天Ⅱ、Ⅲ、Ⅳ组IgG、IL-2、IL-4均显著或极显著降低(P0.05或P0.01),且小鼠血清IgG、IgM、IL-2、IL-4含量随时间的延长呈下降趋势,IFN-γ、IL-6含量随时间的延长先上升后下降。结果表明:饮水中钼(≥400mg/L)可引起小鼠血清免疫球蛋白、抗炎细胞因子下降,促炎细胞因子先上升后下降,且具有一定的时-效和量-效关系,影响动物的体液免疫和细胞免疫功能。     

Effect of porcine circovirus type 2 (PCV2) vaccination on porcine reproductive and respiratory syndrome virus (PRRSV) and PCV2 coinfection

The objectives were to determine if PCV2 vaccination is effective in reducing disease and lesions associated with PRRSV and PCV2 coinfection and if there is a difference between intradermal (ID) and intramuscular (IM) route of PCV2 vaccination. Seventy-four, 21-day-old pigs were randomly allocated into one of six groups. On day 0, pigs were vaccinated with 2ml Suvaxyn((R)) PCV2 One Dose (Fort Dodge Animal Health, Inc.) by intramuscular (VAC-M-COINF) or intradermal (VAC-D-COINF) routes. On day 28, pigs were either singularly (PRRSV-only, PCV2-only) or coinfected (COINF) with PRRSV and PCV2. All pigs in all groups were necropsied on day 42. All vaccinated pigs seroconverted (IgM, IgG, and neutralizing antibodies) to PCV2 between 14 and 28 days post-vaccination. After challenge, all groups inoculated with PRRSV had reduced average daily gain compared to CONTROLS and PCV2-only (P<0.001). COINF pigs had significantly (P<0.05) reduced anti-PCV2-IgG antibody levels and neutralizing antibody levels compared to both vaccinated groups. COINF pigs had more severe lung lesions compared to VAC-M-COINF (P<0.05). COINF pigs had higher amounts of PCV2 DNA in serum samples and feces (P<0.05) and increased amounts of PCV2 in lymphoid tissues (P<0.05) compared to both vaccinated groups. In summary, PCV2 vaccination was effective at inducing a neutralizing antibody response and significantly reducing PCV2-associated lesions and PCV2 viremia in pigs coinfected with PCV2 and PRRSV. Differences between intradermal and intramuscular routes of vaccine administration were not observed.     

Detection of porcine Circovirus type 2 (PCV2) variants PCV2-1 and PCV2-2 in Brazilian pig population

In the present study whole genome of six Brazilian isolates of PCV2 were sequenced, analyzed and compared with 35 other sequences (24 from other countries and 17 from Brazil). The phylogenetic analysis showed that mostly Brazilian variants of PCV2 were grouped as PCV2-1. Two isolates among the six analyzed here could not be grouped with any other PCV2-2 analyzed in this study. One of these isolates was from an aborted fetus with myocarditis and the other from a PMWS affected pig. The results pointed here showed that both groups of PCV2 are present in Brazilian pig population without any clear geographical correlation.     

Porcine reproductive and respiratory syndrome virus (PRRSV) influences infection dynamics of porcine circovirus type 2 (PCV2) subtypes PCV2a and PCV2b by prolonging PCV2 viremia and shedding

The objective of this study was to determine the effect of porcine reproductive and respiratory syndrome virus (PRRSV) infection on porcine circovirus type 2 (PCV2) subtypes a (PCV2a) or b (PCV2b) viremia and shedding characteristics in oral, nasal and fecal samples in experimentally infected pigs. Twenty-three, 2- to 6-week-old pigs were randomly divided into five groups: negative control (n=3), PCV2a-I (n=5), PCV2a-PRRSV-CoI (n=5), PCV2b-I (n=5), and PCV2b-PRRSV-CoI (n=5). Blood, oral, nasal and fecal swabs were collected in regular intervals from day post inoculation (dpi) 0 until dpi 70 and tested by quantitative real-time PCR for the presence and amount of PCV2 DNA and by ELISA for the presence of PCV2-specific antibodies. The results indicate that there were significantly (P<0.05) higher loads of PCV2a and PCV2b DNA in serum, oral swabs, nasal swabs and fecal swabs and a higher prevalence of detectable PCV2 antigen in tissues of pigs concurrently infected with PCV2 and PRRSV compared to pigs singularly infected with PCV2 further confirming that PRRSV enhances replication of PCV2. Moreover, PRRSV infection significantly prolonged the presence of PCV2 DNA in serum and increased the amount of PCV2 DNA in oral and nasal secretions and fecal excretions in the later stages of infection between dpi 28 and 70. Shedding patterns were similar between groups infected with PCV2a and PCV2b, indicating that there was no subtype-specific interaction with the PRRSV isolate used in this study. The results from this study highlight the interaction between PRRSV and PCV2 and the importance of controlling PRRSV infection in order to reduce PCV2 virus loads in pig populations.     

PCV2疫苗对仔猪体重和死亡率的影响

许多养猪生产者发现,在开始对仔猪接种猪圆环病毒2型(PCV2)疫苗后,猪场生产效益要好于PCV2感染之前。这是怎么回事呢?     

Porcine circovirus type 2 (PCV2) vaccination reduces PCV2 in a PCV2 and Salmonella enterica serovar Choleraesuis coinfection model

We previously reported that prior porcine circovirus type 2 (PCV2) infection potentiates the severity of clinical signs, lung lesions, and fecal shedding and tissue dissemination of Salmonella enterica serovar Choleraesuis in infected pigs. Here, we evaluated whether PCV2 vaccination is effective in reducing fecal shedding and tissue dissemination of S. Choleraesuis and improving clinical signs associated with PCV2 and S. Choleraesuis infection in 15 Cesarean-derived, colostrum-deprived pigs randomly assigned to 3 groups (n = 5/group). The vaccinated and co-infected (VAC-COINF) group received 2 ml of a commercial PCV2 vaccine at age 3 weeks. The VAC-COINF and co-infected (COINF) groups were inoculated intranasally with PCV2 and S. Choleraesuis at 5 and 7 weeks of age, respectively. The CONTROL group pigs received a similar volume of PBS for sham-vaccination and sham-inoculation. PCV2 vaccination clearly reduced PCV2 DNA load in the serum and postmortem tissue samples and decreased PCV2 antigen levels in tissue samples of the VAC-COINF group. After S. Choleraesuis infection, the incidence of several clinical signs increased in the VAC-COINF group compared to that in the COINF group. The microscopic lung lesions and weight gain, fecal shedding and tissue dissemination of S. Choleraesuis except in the spleen were not significantly different in the VAC-COINF and COINF groups. Thus, PCV2 vaccination reduced PCV2 in the S. Choleraesuis and PCV2 coinfection model and the effects on S. Choleraesuis were minimal.