仔猪伪狂犬病的病理学研究

实验用三周龄健康哺乳仔猪18头,随机分为三组,以三种接种途径(脑内注射、滴鼻和肌肉注射)、不同剂量感染三株伪狂犬病毒株(PrV-S、Pry-闽A和PrV-Shope)。发病仔猪于体温升高至41～12℃后反复出现神经症状。尸体剖检除脑膜充血水肿外,一些病例肺和肝出现小的坏死灶。病理组织学变化主要为淋巴细胞性脑膜脑脊髓炎和神经节的神经元广泛变性坏死。在大脑、神经节、扁桃体、肺和淋巴结发现核内包涵体。     

辽西地区猪伪狂犬病的病理学特征及病毒组织嗜性

应用PCR方法结合病理剖检和组织学观察对辽宁省辽西地区猪伪狂犬病流行病例进行诊断和病理学观察。结果表明:该地区猪伪狂犬病表现多种病理类型,包括脑炎型、脑炎兼内脏型、母猪繁殖障碍型和公猪睾丸炎型4种;主要特征性剖检病变:脑炎,肺、肝、肾、脾、淋巴结的出血和灰白色坏死斑点;主要特征性组织病理变化:非化脓性脑炎,间质性肺炎,肺、肝、肾、脾、淋巴结的局灶性核碎裂性坏死和出血。患猪临床死亡率很高,其病理变化发生于脑和多种内脏器官,并呈现显著的坏死和出血变化,免疫组化试验显示该株伪狂犬病毒(PRV)可侵袭脑、肺、脾等多种器官,说明该地区的PRV流行毒株属于强毒株,可能出现新的变异而毒力增强。     

猪伪狂犬病的防治

某猪场是一个年出栏万头商品瘦肉猪的出口基地,1997年3~4月份发生伪狂犬病,造成58头母猪流产、早产及产木乃伊胎.占能繁母猪的10%;哺乳仔猪发病55窝,死亡仔猪348头,仔猪发病死亡率70.3%,其中20窝新生仔猪产后数天内整窝发病死亡,病死率100%.现作如下报道:     

猪伪狂犬病的研究进展

猪伪狂犬病 (Ｐｓｅｕｄｏｒａｂｉｅｓ,Ｐｒ)是由猪疱疹病毒Ｉ型 (ＰｏｒｃｉｎｅＨｅｒｐｅｒｖｉｒｕｓＴｙｐｅＩ)引起的一种以发热、脑脊髓炎为主症的急性传染病。本病主要引起母猪流产、产死胎或木乃伊胎 ;初生仔猪表现出神经症状 ,最后麻痹、衰竭而死亡 ,死亡率可达 1 0 0 % ;成年猪多耐过而呈隐性感染 ,是该病主要的传染源。猪Ｐｒ自 1 90 2年匈牙利奥耶斯基 (Ａｕ ｊｅｓｋｙ)首先发现以来 ,目前世界上已有 40 0多个国家发生此病 ,虽然许多国家都采取了不同措施进行防制 ,但疫情仍不断扩大蔓延。发达国家已将本病列为重点防制疫病…     

猪伪狂犬病防控与净化

伪狂犬病（Aujeszky’s Disease）是由伪狂犬病毒（Pseudorabies virus PRV）引起的多种家畜和野生动物以发热,奇痒（猪除外）及脑脊髓炎为主要特征的一种重要传染病;猪是伪狂犬病毒的自然宿主,可造成种猪繁殖障碍、仔猪早期大量死亡、商品猪生长迟滞,给畜牧业带来巨大损失。本病曾在全世界流行,中国自1947首次报道以来,目前已扩大到全国各地,隐性感染、临床发病及混合感染日趋严重,每年因为该病造成巨大的经济损失。世界上主要的养猪国家都已开始实施猪伪狂犬病的控制和净化项目,并在一些国家取得成功;借鉴国外成功的经验,根据我国猪伪狂犬病的流行状况及研究进展,并提出我们国家伪狂犬病防控策略和净化方案。     

猪伪狂犬病一例

1998年12月,河南省某地养猪场发生怀孕母猪流产、死胎及黑胎现象,新生仔猪大量死亡。经现场观察、尸体剖检、实验室检查,确诊为猪伪狂犬病。经对全群猪紧急接种猪伪狂犬病弱毒苗和灭活苗,小猪配合使用病愈母猪血清,疫情很快得到了控制。1发病情况该猪场存栏母猪210头...     

PCR法对伪狂犬病病猪不同部位的检测及敏感性试验

应用ＰＣＲ方法对ＰＲＶ感染细胞及自然发病猪不同组织样品进行检测,感染细胞毒最低检出量为１０５个ＴＣＩＤ５０病料组织样品最低取样为０１ｍｇ时,仍能得到阳性结果其敏感性显著高于微量血清中和试验。ＰＲＶ在自然发病猪体内分布很广,脑、三叉神经节（三叉Ｎ节）、嗅球、扁桃体、心脏、肝、脾、肺、肾均有ＰＲＶ的存在,ＰＲＶ检出率最高的组织为三叉神经节,其检出率为１００％。其它对照病毒及传代细胞ＰＣＲ反应产物电泳结果均为阴性。     

A retrospective study into characteristics associated with the seroprevalence of pseudorabies virus-infected breeding pigs in vaccinated herds in the southern Netherlands

Vaccination programs to eradicate pseudorabies virus (PRV) are being considered in several countries. Knowledge of factors that influence PRV transmission within vaccinated breeding herds may contribute to the success of these programs. A multivariate analysis of variance of the PRV-seroprevalence in sows in 209 herds (average seroprevalence 67.0% per herd) in the southern Netherlands revealed the following risk indicators: (1) presence of finishing pigs; (2) production type (producers of finishing piglets had a higher seroprevalence than producers of breeding stock); (3) vaccination of the sows during nursing (in comparison with vaccinating all sows simultaneously at 5 month intervals, or vaccination during the second half of gestation); (4) pig density in the municipality where the herd was located (seroprevalence increased with higher pig density); (5) herd size less than 100 sows; (6) average within-herd parity (seroprevalence increased with higher withinherd parity); (7) replacement pigs raised on the premises; (8) vaccine strain administered to the sows. Purchase policy (breeding pigs purchased between 10 weeks and 7 months of age, or use of home-bred gilts only) did not significantly contribute to the multivariate model.     

Aujeszky's disease (pseudorabies) virus detection in cerebrospinal fluid in experimentally infected pigs

The presence of Aujeszky's disease virus in cerebrospinal fluid of experimentally infected pigs was studied using the techniques of virus isolation and PCR. Pigs, some of which were previously vaccinated against Aujeszky's disease, were inoculated with different doses of the Aujeszky's disease NIA-3 strain. At the time of death or sacrifice, a sample of cerebrospinal fluid was taken and tested for the presence of virus using the mentioned techniques. Virus was isolated only from one sample, while it was detected by PCR in most of them. The higher sensitivity of the PCR technique and the possible presence of antiviral antibodies in the cerebrospinal fluid are reasons that can be argued to explain this fact. By PCR, the virus was detected more efficiently when digested cerebrospinal fluid cells were used as DNA source than when using whole cerebrospinal fluid, suggesting that the virus could be cell-associated. Aujeszky's disease virus could not be detected by PCR in pigs which survived the acute phase of the infection and were euthanased at 8 weeks post-inoculation, when they were latently infected. This indicated that the cerebrospinal fluid is not an adequate sample for the diagnosis of latency. Since Aujeszky's disease virus was detected from most of the tested samples, we believe that this could be an adequate procedure for the quick diagnosis of Aujeszky's disease.     

种公猪精液伪狂犬病野毒的筛查

本文基于1 100头基础母猪的规模化场进行公猪精液伪狂犬病病毒筛查,农业部规定伪狂犬病病原学检测方法是通过ELSIA方法检测猪伪狂犬病gE野毒抗体。由于抗体检测具有滞后性,导致正在发生感染的猪群g E抗体检测往往呈阴性,但此时通过病原学检测精液已经正在排毒。本文互补了ELSIA抗体检测方法与荧光定性PCR检测病原的优劣,成功实现种公猪精液伪狂犬病病毒的筛查。     

闽北地区猪伪狂犬病抗体检测分析

为了解猪伪狂犬病在闽北地区的流行情况,整理并分析2015年度血清抗体检测数据。采用ELISA检测方法对闽北地区45个规模化猪场进行检测分析,通过检测样品血清中伪狂犬病gE抗体和gB抗体的水平进行结果判定。结果显示：送检的45个规模化猪场,伪狂犬病gE抗体阳性场达25个,猪场阳性率达55.6%;共检测1304份血清,其中伪狂犬病gE抗体阳性213份、可疑24份、阴性1067份,抗体阳性率达20.6%。从伪狂犬病gE抗体阴性猪场抽检猪伪狂犬gB抗体380份,gB抗体阳性258份,猪群伪狂犬病抗体保护率仅有67.9%。     

Implications derived from a mathematical model for eradication of pseudorabies virus

Simple mathematical models based on experimental and observational data were applied to evaluate the feasibility of eradicating pseudorabies virus (PRV) regionally by vaccination and to determine which factors can jeopardise eradication. As much as possible, the models were uncomplicated and our conclusions were based on mathematical analysis. For complicated situations, Monte-Carlo simulation was used to support the conclusions. For eradication, it is sufficient that the reproduction ratio R (the number of units infected by one infectious unit) is < 1. However, R can be determined at different scales: at one end the region with the herds as units and at the other end compartments with the pigs as units. Results from modelling within herds showed that contacts between groups within a herd is important whenever R between individuals (R_ind) is 1 in one or more groups. This is the case within finishing herds. In addition, if the R_ind is more than 1 within a herd, the size of the herd determines whether PRV can persist in the herd and determines the duration of persistence. Moreover, when reactivation of PRV in well-vaccinated sows is taken into account, R_ind in sow herds is still less than 1. In sow herds with group-housing systems, it is possible that in those groups R_ind is 1. Results from modelling between herds showed that whether or not R_herd is < 1 in a particular region is determined by two factors: (1) the transmission of infection between nucleus herds and rearing herds through transfer of animals and (2) contacts among finishing herds and among rearing herds. The transmission between herds can be reduced by reduction of the contact rate between herds, reduction of the herd size, and reduction of the transmission within herds.     

Correlation between the nature of immunity induced by different immunogens and the establishment of latent infection by wild-type pseudorabies virus

To assess the correlation between the nature of immunity induced by different types of immunogens and the establishment of latent infection by wild-type pseudorabies virus (PrV), we used a murine model immunized with different immunogens, the PrV modified live vaccine (MLV), inactivated vaccine (IAV), and commercial oil-adjuvant subunit vaccine (OSV), via either intranasal (i.n.) or intramuscular (i.m.) route. Both MLV and IAV induced a different nature of immunity biased to Th1- and Th2-type, respectively, as judged by the ratio of PrV-specific IgG isotypes (IgG2a/IgG1) and the profile of cytokine IL-2, IL-4, and IFN-gamma production. In contrast, the OSV induced a lower isotype IgG2a to IgG1 ratio and higher level of IL-2 production. The MLV (inducing Th1-type) provided more effective protection against a virulent wild-type PrV challenge than IAV and OSV (inducing Th2- and mixed type, respectively). In addition, the MLV impeded the establishment of a latent infection with wild-type PrV, and the decrease in the PrV latency load by immunization with the MLV appeared to be mediated by the immune T-cells. These results demonstrate the substantial role of the immune responses driven by preceding vaccination in modulating the establishment of PrV latency caused by the post-infection of a field virus.     

珠江三角洲地区春季草坪杂草群落组成及其特征

在春季用样方法对珠江三角洲5个城市32个样点草坪绿地杂草群落进行调查,并分析了不同样地杂草群落的发生规律。调查共发现84种杂草,属30科,68属。其中,水蜈蚣重要值最大,为20．332／6,其次是三点金,为11．369,6;狗牙根、崩大碗、香附子、天胡荽等杂草为珠江三角洲地区草坪绿地恶性杂草,其重要值均大于5．00％。广州市形成以水蜈蚣＋天胡荽＋狗牙根为主的杂草群落;珠海市以三点金＋狗牙根＋水蜈蚣为主;惠州市以水蜈蚣＋狗牙根十三点金为主;中山市以水蜈蚣＋崩大碗＋天胡荽为主;肇庆市以水蜈蚣＋香附子＋狗牙根为主。通过聚类分析可以将32个样点分成5个组。结果表明：在相似管理水平下,地理环境是影响杂草群落结构的最重要因素。     

Diagnosis and gI antibody dynamics of pseudorabies virus in an intensive pig farm in Hei Longjiang Province

BackgroundPseudorabies (PR), caused by the pseudorabies virus (PRV), is an endemic disease in some regions of China. Although there are many reports on epidemiological investigations into pseudorabies, information on PRV gI antibody dynamics in one pig farm is sparse.ObjectivesTo diagnose PR and analyze the course of PR eradication in one pig farm.MethodsTen brains and 1,513 serum samples from different groups of pigs in a pig farm were collected to detect PRV gE gene and PRV gI antibody presence using real-time polymerase chain reaction and enzyme-linked immunosorbent assay, respectively.ResultsThe July 2015 results indicated that almost all brain samples were PRV gE gene positive, but PRV gI antibody results in the serum samples of the same piglets were all negative. In the boar herd, from October 2015 to July 2018 three positive individuals were culled in October 2015, and the negative status of the remaining boars was maintained in the following tests. In the sow herd, the PRV gI antibody positive rate was always more than 70% from October 2015 to October 2017; however, it decreased to 27% in January 2018 but increased to 40% and 52% in April and July 2018, respectively. The PRV gI antibody positive rate in 100-day pigs markedly decreased in October 2016 and was maintained at less than 30% in the following tests. For 150-day pigs, the PRV gI antibody positive rate decreased notably to 10% in April 2017 and maintained a negative status from July 2017. The positive trend of PRV gI antibody with an increase in pig age remarkably decreased in three tests in 2018.ConclusionsThe results indicate that serological testing is not sensitive in the early stage of a PRV infection and that gilt introduction is a risk factor for a PRV-negative pig farm. The data on PRV gI antibody dynamics can provide reference information for pig farms wanting to eradicate PR.