猪圆环病毒2型复制与转录模式研究进展

猪圆环病毒是一种单股负链环状DNA病毒,有PCV1和PCV2两种血清型,PCV1一般认为无致病性,而PCV2是导致断奶仔猪多系统衰竭综合症的重要病原,给养猪业造成了巨大的经济损失。PCV复制模式为坩埚滚环复制,须依赖于Rep和Rep,蛋白的共表达、病毒复制起始区和双链DNA片段的形成,三者缺一不可;其转录模式也较为复杂,可双向进行且通过选择性剪切从而产生不同的RNA。主要对PCV2复制模式和转录模式等方面进行综述,以期为PCV的相关研究提供借鉴和参考。     

猪圆环病毒基因组结构及其分子特征研究进展

目前,国际上已分离获得2个不同血清型的猪圆环病毒（PCV）,并命名为猪圆环病毒1型（PCV-1）和猪圆环病毒2型（PCV-2）。PCV-1对猪无致病性,而PCV-2被认为是引起断奶仔猪多系统衰竭综合征（PMWS）的主要病原。PCV基因组为单股环状双向DNA,由2个头一头相对排列的开放性阅读框和基因间隔区组成,包含rep基因、cap基因及病毒DNA复制起始区茎环序列。rep基因编码2种不同的复制酶相关蛋白,cap基因编码病毒结构蛋白或衣壳蛋白,茎环序列在病毒蛋白合成、DNA自身复制及子代病毒产生中发挥重要作用。PCV-2衣壳蛋白110位（P→A）和191位（R→S）氨基酸突变,提高PCV-2在体外组织培养中的增殖效率,而减弱其对动物的致病性和毒力。     

猪圆环病毒基因及其疫苗的研究进展

猪圆环病毒(PCV)感染是近几年新发现的一种猪的传染病,目前,国际上已分离获得2个不同血清型的猪圆环病毒(PCV),并命名为猪圆环病毒1型(PCV-1)和猪圆环病毒2型(PCV-2).PCV-1对猪无致病性,而PCV-2被认为是引起断奶仔猪多系统衰竭综合征(PMWS)的主要病原.该病在包括中国在内的各养猪国家广泛流行,发病猪死亡率10%～30%不等,较严重的猪场在暴发本病时死淘率高达40%,给养猪业造成严重的经济损失,同时也给各国科研人员带来了新的挑战和任务,现已受到国内外学者的高度重视,对此病的研究特别是对其疫苗的研究正日益受到关注.文章中就猪圆环病毒基因的结构特点、功能以及疫苗等方面进行了综述,以期为猪圆环病毒基因及其疫苗的研究提供一定依据.     

吉林省猪圆环病毒Ⅱ型血清流行病调查分析

猪圆环病毒（porcine circovirus，PCV）为圆环病毒科（Circoviridae）圆环病毒属成员，是单股环状DNA病毒，是迄今发现的最小的动物病毒。PCV存在2种基因型，即PCV-1和PCV-2。PCV-1未发现有致病性；PCV-2主要引起仔猪免疫缺陷的断奶仔猪多系统消耗综合症（Posl-weaning muhisystemic wasting syndrome，PMWS）的病原之一。猪是PCV的易感动物，主要是经口腔及呼吸道途径感染，少数怀孕母猪可经胎盘将PCV直接感染给仔猪。感染猪可从鼻液、粪、尿中排出病毒，并于2—15周龄时发生PMWS。     

荆州市猪圆环病毒2型主要流行亚型的鉴定

正猪圆环病毒(Porcine circovirus virus,PCV)属于圆环病毒科(Circoviridae)、圆环病毒属(Circovious)。PCV病毒的粒子直径为14~25 nm,呈二十面体对称,没有囊膜,它的基因组是一条单股负股环状DNA,并且以共价结合的形式呈闭合状态存在[1-2]。PCV主要分为PCV-1、PCV-2、PCV-3 3种,在这3种基因型中PCV-1不使猪发病,PCV-2对猪带来的影响最大,是对猪致病的主要PCV病原[2]。根据     

猪圆环病毒基因组结构与功能研究进展

猪圆环病毒(PCV)是单链环状DNA病毒,有PCV1和PCV2两种血清型,其中PCV2严重危害着世界养猪业。PCV2因其严重的危害性和精简而高效的基因组结构引起众多国内外专家学者的广泛研究,本文参考NCBI上公布的PCV2序列绘制了PCV2基因组结构图谱,就相关基因的结构和功能进行综述,并就与病毒复制、病毒免疫原性、病毒致病力等功能相关的基因进行了归纳和总结,以期能为PCV2分子生物学和新型疫苗的研究提供参考。     

浅谈猪圆环病毒2型（PCV-2）

PCV-2是近几年来一种新发现的病毒,它所致疾病能给养猪业带来很大的经济损失。 PCV为圆环病毒科圆环病毒属成员,单股环状DNA病毒。PCV存在两种血清型,即PCV-1(猪圆环病毒1型)和PCV-2(猪圆环病毒2型)。PCV-1经常存在于机体各组织器官和某些传代细胞中,不致病。PCV-2则是引起PMWS(猪断奶后多系统衰竭综合征)的主要病原。据发现,单     

猪圆环病毒2型引起急性肺水肿新症状

猪圆环病毒(PCV)是迄今发现的最小动物病毒之一,现已知PCV有两个血清型,即PCV-1和PCV-2。PCV-1为非致病性的病毒,PCV-2为致病性的病毒。PCV-2是断奶仔猪多系统衰竭综合征(PMWS)的主要病原,PMWS最早发现于加拿大。最近在美国有学者报道,猪圆环病毒出现一种新的表现症状,称为急性肺水肿型(APE),它主要影响刚出生和刚断奶的小猪,     

猪圆环病毒病防控策略

猪圆环病毒病病原是猪圆环病毒2型(PCV-2),PCV-2对外界和一般消毒剂的抵抗力较强,可通过胎盘垂直传播,公猪的精液带毒可通过配种传播. 1 特点 ①PCV2感染猪群免疫功能下降(免疫抑制);②PCV2感染猪群可并发或继发细菌或病毒感染;③PCV-2经常与猪繁殖与呼吸综合征病毒(PRRSV)等并发感染.     

猪圆环病毒病的临床症状及诊断要点与防治

猪圆环病毒(PCV)是迄今为止发现的一种最小的新的单链环状DNA动物病毒。现已知PCV有两个血清型,即PCV-1和PCV-2。研究认为PCV-1对猪无致病性,为非致病性病毒。PCV-2为致病性病毒,他是断奶仔猪多系统衰竭综合征的主要病原。本病最早发现于加拿大(1991年),很快在欧美及亚洲一些国家包括我国发生和流行。同     

华南地区猪圆环病毒和猪繁殖与呼吸综合征病毒检测分析

为了解华南地区猪圆环病毒及猪繁殖与呼吸综合征病毒的最新流行情况,采集了华南地区11个规模猪场各饲养阶段猪血清807份,用套式PCR(nPCR)检测猪圆环病毒1型(PCV-1)和猪圆环病毒2型(PCV-2);采集了若干猪场2010年1月至2011年8月期间有咳嗽、喘气、消瘦及疑似PDNS等临床症状的猪血清312份,以及无临床症状猪血清104份,以nPCR检测PCV-2,以一步法反转录PCR(RT-PCR)检测猪繁殖与呼吸综合征病毒。结果发现,所调查的11个规模猪场中只有5个检出PCV-1,所有猪场均检出PCV-2。PCV-2阳性率为30.61%,而PCV-1阳性率仅为4.21%;经产母猪和7周龄以上保育猪PCV阳性率最高;有临床症状的猪血清PCV-2阳性率为58.65%,PRRSV阳性率为37.82%,PCV-2阳性猪群中有39.89%的猪同时感染PRRSV;有症状猪群7月～9月的PCV-2感染率最高,而1月～3月最低;无临床症状猪血清PCV-2阳性率为27.9%,PRRSV阳性率为0.96%,PCV-2与PRRSV无混合感染。证明PCV尤其是PCV-2在华南地区仍广泛传播并流行,而且PCV-2与PRRSV混合感染致病情况较多。PCV-2的感染率与季节有一定的相关性,种猪带毒情况严重。     

Evaluation of a nested polymerase chain reaction assay to differentiate between two genotypes of Porcine circovirus-2.

Porcine circovirus-2 (PCV-2) is associated with several diseases in pigs, including postweaning multisystemic wasting syndrome (PMWS). A new genotype of PCV-2 was isolated from swine farms with and without clinical PMWS in North America. The new genotype was differentiated in a separate cluster by phylogenetic analyses and is now named PCV-2b compared with PCV-2a for the previously known genotype. The purpose of this study was to develop and evaluate a nested polymerase chain reaction (nPCR) assay to detect and differentiate between PCV-2a and PCV-2b. Genotype-specific primer sets were designed by using sequence data published for different PCV-2 strains. Specificity and sensitivity of the nPCR were examined by using PCV-2 isolates with known genotype. Nested PCR was found to be highly specific and sensitive for detecting and differentiating between the PCV-2 genotypes compared with the conventional 1-step PCR assay. Nested PCR was applied to detect PCV-2 and to identify the genotype in serum samples from swine farms with and without a clinical history of PMWS. Of 60 serum samples collected from 4 farms during clinical PMWS outbreaks, PCV-2a and PCV-2b were detected in 6 and 49 samples, respectively. Six of the 10 samples from one of the 4 farms had both PCV-2a and PCV-2b. Of 20 serum samples from 2 farms without PMWS, 11 were positive for PCV-2a only. These results suggest that the differential nPCR can be used to detect PCV-2 and to differentiate the 2 genotypes from field samples.     

Viral wasting syndrome of swine: experimental reproduction of postweaning multisystemic wasting syndrome in gnotobiotic swine by coinfection with porcine circovirus 2 and porcine parvovirus

One-day-old gnotobiotic piglets were inoculated intranasally with in vitro passaged porcine circovirus 1 (PCV-1), PCV-2, and porcine parvovirus (PPV) alone or in combination (PCV-1/PCV-2, PCV-1/PPV, and PCV-2/PPV). Piglets were evaluated for 1) the development of porcine postweaning multisystemic wasting syndrome (PMWS), 2) distribution of viral antigens by immunochemistry, and 3) viremia and the presence of viral DNA in nasal and ocular secretions and feces. All single agent-infected piglets and piglets infected with PCV-1/PCV-2 or PCV-1/PPV were clinically asymptomatic. They were transiently viremic and seroconverted to homologous virus(es). At termination of the study on postinfection day (PID) 35, microscopic lesions were restricted to focal inflammatory cell infiltrates in livers and myocardia. One piglet given PCV-1/PPV was PPV viremic for 2 weeks after infection and had lymphangiectasia of the spiral and descending colon associated with granulomatous inflammation. All four PCV-2/PPV-inoculated piglets developed PMWS, characterized by sudden onset of depression and anorexia, icterus, and submucosal edema. One piglet became moribund on PID 27, and the remaining three piglets were euthanatized between PID 27 and PID 30 because of severe disease. Lymph nodes were small and the livers were mottled. Disseminated angiocentric granulomatous inflammation was present in all tissues examined except the brain. Multiple lightly basophilic intracytoplasmic inclusion bodies were identified in macrophages and histiocytes. PCV-2 antigen was widely distributed within macrophages; PPV antigen was sparse. Hepatocellular necrosis and bile retention were prominent. PCV-2 DNA was identified in ocular, fecal, and nasal secretions. Terminal sera contained antibodies to PPV (4/4) and PCV-2 (3/ 4). Production of PMWS in gnotobiotic swine appears to require PCV-2 and additional infectious agents such as PPV for full disease expression in gnotobiotic piglets.     

我国部分地区猪圆环病毒2型和猪细环病毒混合感染的调查

为了解猪圆环病毒2型(PCV-2)和猪细环病毒(TTV)混合感染情况,用PCR方法对来自湖南、江西、广东、福建和广西五省区的193份猪组织样品进行PCV-2、TTV-1和TTV-2进行检测。结果显示,PCV-2感染率为61.1%(118/193),PCV-2和TTV-1混合感染率为32.1%(62/193),PCV-2和TTV-2混合感染率为16.9%(32/193),3种病原混合感染率为9.8%(19/193),2006年PCV-2和TTV的混合感染率最高。由此可见,目前猪群中存在PCV-2和猪TTV的混合感染,PCV-2和TTV-1型混合感染率高于和TTV-2型的混合感染率,且存在一定比例的三重感染情况。     

Prevalence of infection with porcine circovirus-2 (PCV-2) and porcine reproductive and respiratory syndrome virus (PRRSV) in an integrated swine production system experiencing postweaning multisystemic wasting syndrome

The objective of this study was to evaluate the prevalence of infection with porcine circovirus-2 (PCV-2) and porcine reproductive and respiratory syndrome virus (PRRSV) through a longitudinal study in an integrated swine production system (7 farms) experiencing postweaning multisystemic wasting syndrome (PMWS). Risk factors for PCV-2 infection and for PCV-2 and PRRSV coinfection were also evaluated. Fifteen sows from each herd and 4 non-cross-fostered piglets from each sow were randomly selected at farrowing and ear-tagged at birth. Serum samples were analyzed for antibodies to PCV-2 and for detection of the PCV-2 and PRRSV genomes. Statistical analyses involved 2 approaches. The 1st approach characterized the dynamics of PCV-2 infection and their relationship with PRRSV infection. The 2nd approach analyzed the probability of being infected by PCV-2 or by both PCV-2 and PRRSV through a generalized linear mixed model incorporating sow and farm characteristics. At the 1st sampling time (1 wk of age), there was a significant relationship between sow PCV-2 infection and piglet PCV-2 infection (P < 0.0001). The risk of PCV-2 and PRRSV coinfection was 1.85 times greater in piglets from a sow with low titers of PCV-2 antibodies than in piglets from sows with medium to high titers (P = 0.03) and was 2.54, 2.40, and 2.02 times greater, respectively, in piglets from primiparous sows, PCV-2-infected sows, and farms in an area of high pig density than in piglets from sows of higher parity (P = 0.004), noninfected sows (P = 0.04), and farms in a low-density area (P = 0.09).     

猪圆环病毒2b亚型的分离鉴定及基因组序列分析

为分离鉴定流行于重庆某猪场的猪圆环病毒2型,本研究从断奶仔猪多系统衰竭综合征猪的淋巴结病料中进行病毒学检测,病毒利用PK-15细胞增殖,其基因组序列经克隆、测序、拼接获得,并完成对全序列的生物信息学分析鉴定。结果获得了1株猪圆环病毒2型(命名PCV-2CQ1),该毒株的全序列大小为1 767bp,同源性分析发现该病毒与国内公布的PCV-2毒株同源性超过了90%,尤其与广西分离株同源性达100%;系统进化分析本分离病毒与浙江株(EU257511)、黑龙江株(HM038032)聚类到一起,形成一个进化分支,同属于PCV-2b型;对编码的衣壳蛋白分析发现,PCV-2CQ1Cap氨基酸发生了较大变异,与强毒株同源性较高,考虑到本病毒源自PMWS病猪,推测该毒株属于强毒株。     

猪圆环病毒检测技术研究进展

猪圆环病毒(PCV)分为1型(PCV-1)和2型(PCV-2).PCV-1一般认为无致病性,而PCV-2是断奶仔猪多系统衰竭综合征(PWMS)的主要致病因子;此外,猪皮炎肾病综合征(PDNS)、仔猪先天性震颤(CT)等疾病也与PCV-2有关.在临床上PCV-2常与猪繁殖与呼吸综合征病毒(PRRSV)、猪细小病毒(PPV)、猪流感病毒(SIV)等病毒混合感染,PCV-2相关疾病已经给世界养猪业造成了巨大的经济损失.然而,由于该病常常和上述几种疾病混合感染,且其临床症状十分类似,所以仅仅依靠单一的临床症状或者某一种实验室诊断方法并不能有效的检测该病.因此,将目前诊断PCV-2的各种方法集中起来,分析其优缺点,从而可以根据实验室的具体情况采取合适的方法是诊断该病的关键.论文就目前PCV-2的检测技术做一介绍.     

猪圆环病毒2型江西株的全基因组克隆和序列分析

为了解江西地区猪圆环病毒2型（PCV-2）的流行和进化情况,根据GenBank上已发表的PCV-2全基因序列设计1对引物,PCR扩增后得到9条PCV-2全基因序列,并对其全基因序列核苷酸和蛋白序列进行分析,绘制遗传进化树。结果表明,江西地区流行的9株PCV-2中,基因组序列全长分为8株1 767 bp和1株1 768 bp,9株PCV-2的核苷酸同源性为94.7%~99.9%,与GenBank己发表的PCV-2分离株全基因组同源性介于94.3%~99.8%之间,而9株PCV-2的ORF1核苷酸序列同源性为96.9%~100.0%。ORF2和ORF3编码的蛋白氨基酸序列存在部分位点突变。遗传进化树显示为3种基因型：5株PCV-2b、3株PCV-2d、1株PCV-2a。本研究有助于江西地区PCV-2的监测和防制。     

Cloning and Sequence Analysis of Complete Genomes of Porcine Circovirus Type 2 (PCV-2) Jiangxi Strains

In order to understand the epidemiology and evolution of PCV-2 in Jiangxi province, a pair of primers was designed according to the PCV-2 gene sequence published in GenBank. After PCR amplification, we got the whole genome sequence of 9 strains PCV-2 isolates, and the nucleotide and protein sequences were analyzed, the genetic evolutionary tree was constructed. The results showed that the complete genome of 8 out of the 9 strains were 1 767 bp in length and one strain was 1 768 bp. By analyzing the whole genome sequences of the nucleotide,the homology of nucleotide sequences of the 9 strains was 94.7% to 99.9%.Compared with other whole genome sequences of PCV-2 in GenBank, the homology was 94.3% to 99.8%. The homology of nucleotide sequences of the ORF1 of the 9 strain was 96.9% to 100.0%. ORF2 and ORF3 encoding protein amino acid sequence had some locus mutation. Phylogenetic tree analysis showed that the 9 strains could be divided into 3 genotypes,5 strains belonged to PCV-2b, 3 strains belonged to PCV-2d, and 1 strain belonged to PCV-2a. This study was helpful to monitor and control of PCV-2 in Jiangxi province.