Pseudorabies virus latency and reactivation in vaccinated swine

Latency and reactivation of pseudorabies virus in swine was studied. Thirty-one pigs were assigned to 5 groups and were given 1 of 4 vaccines; 10 remained unvaccinated controls. All pigs were then challenge exposed with a sublethal dose of virulent pseudorabies virus. One hundred one days after challenge exposure, all pigs were treated with dexamethasone to reactivate the virus. Virus-positive tonsil and nasal mucus isolates were recovered from 29 of the 31 pigs over a 12-day period. Frequency and duration of virus-positivity were significantly (P less than 0.05) and consistently lower among vaccinated pigs than among the unvaccinated controls. It was concluded that vaccination before challenge exposure had little or no effect on the rate of establishment of virus latency, but that vaccination reduced shedding after subsequent reactivation of the virus.     

Pseudorabies virus antibodies in swine slaughtered in Iowa.

Sera from butcher swine (1,246 total) were evaluated qualitatively by the microimmunodiffusion test and quantitatively by the virus neutralization test for antibody to pseudorabies virus. Ten percent of the sera had antibody to pseudorabies virus. Follow-up contact with veterinarians whose clients included the farms from which the positive swine originated revealed that few feeder swine are vaccinated against pseudorabies and that most infections with pseudorabies virus are subclinical.     

广西猪伪狂犬病毒感染状况调查报告

为了解广西猪伪狂犬病毒的感染状况,应用PCR技术对来自广西46个种猪场的1940份公猪精液进行了猪伪狂犬病毒(PRV)的检测,阳性率为0;同时对广西25个已使用猪伪狂犬病病毒gE基因缺失疫苗猪场的1455份送检血清,采用了猪伪狂犬病基因缺失鉴别ELISA方法进行了血清学抗体监测,结果检出猪伪狂犬gE抗体阳性11份,阳性率为0.76%。结果表明,广西猪群中存在猪伪狂犬病野毒感染,但感染率较低。     

猪伪狂犬病毒PCR检测方法的优化

猪伪狂犬病是由伪狂犬病毒(Pseudorabies virus,PRV)引起的一种疱疹病毒性疾病,在世界大部分地区都是地方性家畜流行病。而且猪伪狂犬病与其他猪传染病不易区分,因此,建立一个特异性强的检测方法对于其诊断具有重要意义。实验是在实验室已经建立伪狂犬病毒单项PCR检测方法的基础上,对扩增条件进行优化后对其特异性进行了验证。结果发现,优化后的方法特异性好,只有猪伪狂犬病毒扩增为阳性,其余DNA病毒:猪细小病毒、猪圆环病毒Ⅰ型(PCV1)、猪圆环病毒Ⅱ型(PCV2)均呈现阴性。因此,本研究方法可以为今后实验室检测猪伪狂犬病毒提供参考。     

猪伪狂犬病病毒流行株遗传进化及序列比对分析

为了了解我国不同地区规模化猪场2014年以来猪伪狂犬病病毒(PRV)流行株的现状、分子生物学特点和遗传演化规律,本试验从我国15个省份不同地区分离得到29株PRV,并对其gB,gC和gE基因进行遗传变异分析。结果显示,这29株PRV分离株主要为PRV变异毒株,与Bartha株等国外经典毒株亲缘关系较远,与Ea株等国内经典毒株亲缘关系较近。氨基酸序列比对发现,29株PRV变异毒株在gB,gC及gE基因上均发生了多个位点的突变:gB氨基酸序列均存在75S、76P和77G的连续缺失,94位点均存在甘氨酸(G)的插入;gC氨基酸序列存在多处改变,其中P87Q和Y142C使gC糖蛋白与宿主细胞表面的硫酸乙酰肝素受体结合功能域发生改变;gE氨基酸序列第48位点均存在天冬氨酸(D)的插入。这些特征性变异位点可作为分子诊断依据,并且从分子水平揭示了临床Bartha-K61株等经典毒株疫苗免疫效果下降的可能原因。     

Endometrial nitric oxide production and nitric oxide synthases in the equine endometrium: Relationship with microvascular density during the estrous cycle

Nitric oxide (NO) plays an important role in angiogenesis and in the regulation of the blood flow. This study was carried out to investigate (i) the effects of endogenous estrogens and progestins and exogenous progesterone (P₄) (5 ng/ml or 1 μg/ml) or estradiol 17β (E₂β) (50 pg/ml or 1 μg/ml) on in vitro endometrial NO synthesis; (ii) the presence of different isoforms of NO synthase; (iii) and their relationship to microvascular density in the equine endometrium during the estrous cycle. NOS expression was also evaluated in the myometrium. Expression of endothelial and inducible forms of NOS in the uterus was assessed by Western blot and immunocytochemistry. Vascular density in endometrial tissue was determined on histologic sections. In the luteal phase, compared to the follicular phase, endometrial NO production increased without exogenous hormones and with exogenous E₂β (1 μg/ml). Although immunocytochemistry revealed iNOS and eNOS expression in the endometrium, no positive signal for iNOS was detected by Western blot. Endothelial NOS was observed in endometrial glands, endothelial cells, fibroblasts, blood and lymphatic vessels. Endometrial eNOS expression was the highest in the follicular and mid-luteal phases while it was found to be the lowest in the early luteal phase. In the follicular phase, hyperplasia of endometrial tissue with respect to myometrium was detected. No difference in vascular density was present between phases. All together, NO may play some roles in both proliferative and secretory phases of endometrial development in the mare.     

猪中枢神经系统疾病的诊断方法

猪中枢神经系统疾病是临床常见病,通常由传染性疾病引起,也可能由先天性遗传或中毒所致.神经紊乱一般表现为步态异常、共济失调、瘫痪、肌肉震颤、角弓反张、抽搐、惊厥和眼球震颤等症状.     

Replication and immunosuppressive effects of Pseudorabies virus on swine peripheral blood mononuclear cells.

The infectivity and potential immunosuppressive effects of Pseudorabies virus (PRV) was evaluated in swine peripheral blood mononuclear cells (PBMC). Virus progeny titers and viral DNA synthesis at various intervals post-inoculation revealed the replication of PRV in both peripheral blood monocytes and lymphocytes; however, replication in lymphocytes was restricted compared with monocytes. PRV infection resulted in the damage and death of monocytes. Although PRV did not appear to affect the viability of the lymphocytes, PRV infection suppressed lymphocyte functions such as proliferation and interleukin-2 (IL-2) synthesis in response to Concanavalin A. This immunosuppression was dependent upon the multiplicity of infection (MOI) of infectious PRV. UV-inactivated PRV was not immunosuppressive. There was no effect of PRV on natural killer (NK) cell activity. The reduction of lymphocyte proliferation by PRV was not reversible by the addition of supernatant containing porcine IL-2 and non-infected monocytes to the infected cultures. The results from these in vitro studies demonstrate that PRV can infect and cause immunosuppressive effects on swine PBMC. These effects may explain the potential role of PRV in predisposing infected pigs to secondary infection and support the hypothesis that PRV can spread systemically by infected PBMC in blood and lymph.     

伪狂犬病毒感染ST细胞的增殖抑制及对细胞周期的影响

以猪伪狂犬病毒(PRV)容A株感染体外培养的ST细胞为模型,采用体外细胞培养技术、噻唑蓝(MTT)还原法、流式细胞计数检测梯度剂量的PRV病毒感染ST细胞株过程中细胞的增殖抑制及对细胞周期的影响.结果显示,PRV感染前期(8h和16h)促进ST细胞的增殖,24h以后可显著抑制细胞增殖,这种抑制与时间密切相关,与感染剂量无显著相关.PRV感染ST细胞可显著地改变细胞周期各时相分布,24 h时细胞G1、S期所占比例明显升高,48 h细胞停滞在G2期,出现明显的凋亡峰.结果表明,PRV在感染过程中对细胞生长的影响与时间紧密联系,最终可显著使细胞停滞在G2期,诱发细胞调亡.     

Antiviral effect of Saccharomyces cerevisiae beta-glucan to swine influenza virus by increased production of interferon-gamma and nitric oxide

The aim of these experiments was to investigate the potential antiviral effect of Saccharomyces cerevisiae beta-glucan on the pneumonia induced by swine influenza virus (SIV). Forty colostrum-deprived 5-day-old piglets were randomly divided into four groups of 10. The 20 pigs in groups 1 and 2 were administered Saccharomyces cerevisiae beta-glucan orally (50 mg/day/pig; En-Bio Technology Co., Ltd) for 3 days before SIV infection and those in groups 3 and 4 were given culture medium/diluent alone. Groups 1 and 3 were inoculated intranasally with 3 ml of tissue culture fluid containing 2 x 10(6) tissue culture infective doses 50% (TCID(50))/ml of SIV and those in groups 2 and 4 were exposed in the same manner to uninfected cell culture supernatant. The microscopic lung lesions induced by SIV infection (group 1 pigs) were significantly more severe than those induced by infection in animals pre-administered beta-glucan (group 3) (P < 0.05). Significantly more SIV nucleic acid was detected in the lungs of pigs experimentally infected with SIV only (group 1) at 5, 7 and 10 days post-inoculation (dpi) compared with lungs from pigs pre-administered beta-glucan and infected with SIV (group 3) (P < 0.05). The concentrations of interferon-gamma (IFN-gamma) and nitric oxide (NO) in bronchoalveolar lavage fluid from pigs pre-administered beta-glucan and infected with SIV (group 3) were significantly higher than for any other group at 7 and 10 dpi for IFN-gamma, and at 5, 7 and 10 dpi for NO (P < 0.05). Saccharomyces cerevisiae beta-glucan reduced the pulmonary lesion score and viral replication rate in SIV-infected pigs. These findings support the potential application of beta-glucan as prophylactic/treatment agent in influenza virus infection.     

ELISA在猪伪狂犬病诊断中的应用

近年来 ,猪伪狂犬病不断传播蔓延 ,给世界养猪业带来了巨大危害 ,因此开发特异性强、敏感性高、简便、快速、能区别疫苗毒和野毒、能检出潜伏感染的诊断方法是防制该病的关键之一。EL ISA方法具有特异、敏感、快速、稳定等特点 ,为广大兽医工作者所关注。目前 ,国内外关于 EL ISA在猪伪狂犬病诊断中的应用方面的研究已有不少 ,已有试剂盒出售。笔者综述了应用于猪伪狂犬病诊断的多种 EL ISA方法 ,如直接 EL ISA、间接 EL ISA、竞争 EL ISA、斑点EL ISA、SPA-EL ISA、双抗体夹心 EL ISA、单抗夹心 L AB-EL ISA、血清学鉴别 EL ISA等。这些方法中 ,有测病毒的 ,有测抗体的 ;有单抗介导的 ,有多抗介导的 ;有的还引入了 SPA和 L AB;有的以分子生物学为基础并能够鉴别疫苗毒和野毒。此外 ,还总结了目前所用 EL ISA诊断方法的优点和缺点 ,并预测了其发展前景     

Nitric oxide synthase expression and nitric oxide/cyclic GMP pathway in swine granulosa cells

The present investigation was undertaken to verify if the two nitric oxide synthase isoforms, eNOS and iNOS, are present in swine granulosa cells and whether the enzyme soluble guanylate cyclase is functionally active in the same cells and can account for NO effects. Using western blotting, the presence of endothelial NO synthase was demonstrated in freshly collected cells; on the contrary, iNOS expression was not observed in the same cells either before or after culture with the inflammatory cytokine hTNF-. The treatment with a strong NO donor (S-Nitroso-L-acetyl penicillamine, SNAP) determined an increase of cGMP levels in culture media, which was attenuated by the combined treatment with an inhibitor of NO-sensitive soluble guanylate cyclase, 1H-[1,2,3]oxadiaziolo [4,3a]quinoxaline −1-one (ODQ). The cGMP analog, 8 bromo-cGMP, mimicked the strong inhibitory effect exerted by SNAP on estradiol 17 β and progesterone production, while ODQ did not modify steroids concentrations in culture media. These observations demonstrate the presence of a follicular NO-generating system, which in swine granulosa cells seems to include only the endothelial NOS isoform. Furthermore, the nitric oxide/cyclic GMP system seems to be functionally active in these cells, since cGMP appears to mediate NO action, even if it cannot account completely for NO inhibitory effect on steroidogenesis.     

Taq Man实时荧光定量PCR检测猪伪狂犬病病毒方法的建立与初步应用

根据猪伪狂犬病病毒gE基因保守序列,设计合成引物和探针,优化反应条件,建立实时定量荧光PCR方法.实验结果表明,当50 pmol/L的引物O.3μL和5 pmol/L的探针0.5μL时,反应体系获得的CT值较小,而荧光强度增加值最大;制作的标准曲线显示各浓度范围内具有良好的线性关系;可检测到相当于20拷贝/μL的病毒DNA;与猪细小病毒、圆环病毒和猪瘟病毒等不发生交叉反应;敏感性比常规PCR电泳检测高约100倍.该方法具有快速、特异、敏感、可定量,并可同时检测大量样品等优点.     

Yeast-expressed classical swine fever virus glycoprotein E2 induces a protective immune response

Classical swine fever (CSF) is an economically important swine disease worldwide. The glycoprotein E2 of classical swine fever virus (CSFV) is a viral antigen that can induce a protective immune response against CSF. A recombinant E2 protein was constructed using the yeast Pichia pastoris expression system and evaluated for its vaccine efficacy. The yeast-expressed E2 (yE2) was shown to have N-linked glycosylation and to form homodimer molecules. Four 6-week-old specified-pathogen-free (SPF) piglets were intramuscularly immunized with yE2 twice at 3-week intervals. All yE2-vaccinated pigs could mount an anamnestic response after booster vaccination with neutralizing antibody titers ranging from 1:96 to 1:768. Neutralizing antibody titers at 10 weeks post booster vaccination ranged from 1:16 to 1:64. At this time, the pigs were subjected to challenge infection with a dose of 1 × 10⁵ TCID₅₀ (50% tissue culture infective dose) virulent CSFV strain. At 1 week post challenge infection, all of the yE2-immunized pigs were alive and without symptoms or signs of CSF. Neutralizing antibody titers at this time ranged from 1:4,800 to 1:12,800 and even to 1:51,200 one week later. In contrast, the control pigs continuously exhibited signs of CSF and had to be euthanized because of severe clinical symptoms at 6 days post challenge infection. All of the yE2-vaccinated pigs were E^rns antibody negative and had seroconverted against E^rns by post challenge day 11, suggesting that yE2 is a potential DIVA (differentiating infected from vaccinated animals) vaccine. The yeast-expressed E2 protein retains correct immunogenicity and is able to induce a protective immune response against CSFV infection.     

Pseudorabies virus infection in mink: a host-specific pathogenesis

Pseudorabies virus (PRV) is an alphaherpesvirus that causes a neurological disease in many wild and domestic animals. The neuropathology elicited by PRV is quite consistent regardless of the host with the only exception of mink, in which it is characterized by a vasculopathy rather than by an encephalitis. In this study, we aimed to investigate the underlying pathogenic mechanism(s) of PRV infection in mink by using immunohistochemistry and laser capture microdissection (LCM) on material from naturally and experimentally infected animals. The inflammatory reaction induced by PRV was minimal or absent not only in the nervous system, where we identified a low number of macrophages and a few T lymphocytes, but also in the primary replication site, the oropharyngeal mucosa; however, the number of PRV-infected cells detected by immunohistochemistry was extremely high both in the peripheral mucosa and in the nervous tissue. On the other hand, the vascular pathology included parenchymal hemorrhages of various degrees and, in specific cortical areas of the brain, fibrinoid degeneration of the capillary walls. Detection of viral antigens by immunohistochemistry revealed infection of endothelial cells of capillaries situated both in the oropharyngeal mucosa and in the brain stem; the presence of PRV DNA in vessels was further demonstrated by PCR performed on LCM samples of brain capillaries. These results can be interpreted as supporting the idea that the different pathology of the disease in mink may be the consequence of an increased endotheliotropism of PRV in this species. Infection of the vessel wall may then lead to vascular pathology and impairment in endothelial cell function, resulting in a weak immune response to infection.     

Evidence of nitric oxide synthase 2 activity in swine naturally infected with Actinobacillus pleuropneumoniae

Evidence of nitric oxide synthase (NOS) 2 activity was determined by formation of nitrotyrosine (a reaction product of peroxynitrite) and by activation of poly(ADP-ribose) synthetase (PARS) in NOS2-expressed pleuropneumonic lungs from 20 pigs naturally infected with Actinobacillus pleuropneumoniae using immunohistochemistry. Intense immunostaining for nitrotyrosine residue was seen within the lung lesions from A. pleuropneumoniae-infected pigs, but it was minimal in the unaffected parts of the lung from A. pleuropneumoniae-infected pigs and in the normal lung from control pigs. Staining was especially strong in neutrophils and macrophages in the periphery of the lesions and within the alveolar spaces. There was close cell-to-cell correlation when serial sections were examined by immunohistochemistry for NOS2 and nitrotyrosine in each of the 20 lung samples. Expression of PARS was always present within inflammatory lesions but was minimal in the unaffected lung of A. pleuropneumoniae-infected pigs. Macrophages in alveolar spaces frequently exhibited strong staining for PARS. Colocalization of nitrotyrosine and PARS antigen was especially prominent in macrophages in the periphery of lesions. NOS2 expression in pleuropneumonic areas associated with protein nitrosation and PARS suggests that NOS2 is functionally active during infections caused by A. pleuropneumoniae.