猪圆环病毒免疫学研究进展

猪圆环病毒(PCV)在世界范围内广泛存在,可引起断奶仔猪多系统衰竭综合征(PMWS)、猪皮炎-肾病综合征(PDNS)和猪呼吸系统疾病症候群,给养猪业造成重大经济损失.已有研究表明,PCV-2感染和免疫刺激作用在PMWS发生中起关键作用,母源抗体对PMWS发生有被动保护作用,通过对初产母猪和经产母猪进行PCV-2免疫,增加母源性免疫和降低病毒血症的措施可以减少PMWS对仔猪死亡的影响.PCV-2疫苗现在已经在商业上应用,疫苗对PCV-2复制和PCVD的诱导增强作用似乎依赖于疫苗佐剂的类型和疫苗的接种时间.因此,基于有效的试验,在发生过PMWS感染的猪群,应该根据PCV-2感染的时间有目的地制定免疫接种方案,以控制或者减少PMWS的发生.     

2型猪圆环病毒研究进展

猪圆环病毒2型(Porcine circovirus type 2,PCV2)是一种基因组较小,但有较高进化速率的DNA病毒,其是影响养猪业经济发展的重要病原体。到目前为止,PCV2具有5种基因型-PCV2a到PCV2e,但对PCV2流行株的基因序列的检测发现,PCV2的基因型仍在持续的发展。自2012年以来,PCV2d基因型的圆环病毒在北美取代了以前主导的PCV2b基因型感染,同时在中国和韩国也有了类似的趋势。圆环病毒的新兴基因型,其毒力存在增强的可能性,基于PCV2a基因型制备的疫苗,是否对PCV2d基因型圆环病毒的感染具有保护作用,已引起各国学者的重视。本文通过对PCV2的生物学特性、抗体变异情况以及其基因进化情况进行综合的分析总结,从而为PCV2疫苗的开发与研制奠定理论基础。     

猪圆环病毒2型疫苗研究进展

猪圆环病毒2型(PCV2@@)是引起断奶仔猪多系统衰竭综合征(PMWS)、猪皮炎与肾病综合征(PDNS)和猪呼吸道疾病综合征(PRDC)等多种疾病的主要病原,并在猪群中广泛存在,给世界养猪业造成了巨大的经济损失.疫苗预防是当前PCV2防制的主要举措之一.目前PCV2商品化疫苗主要包括灭活疫苗和亚单位疫苗,临床应用结果表明,这些疫苗确实获得一定的免疫保护效果,并在有效防控PCV2感染中发挥了重要作用.PCV2传统疫苗也存在一定的局限性,抗原含量偏低、成本偏高、无法有效诱导细胞免疫等,因此研制更安全、高效、廉价的新型基因工程疫苗是未来发展的趋势.文章就PCV2商品化疫苗的应用效果和新型疫苗的研究成果进行了详细阐述,以期为PCV2的防控提供参考.     

猪圆环病毒2型疫苗研究进展

猪圆环病毒2型主要引起断奶仔猪多系统衰竭综合征,在包括中国在内的各养猪国家广泛流行,造成严重的经济损失,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.文章就猪圆环病毒2型的灭活疫苗、弱毒疫苗和基因工程疫苗的研究进展做了详细的阐述.     

猪圆环病毒2型ORF2基因及其编码蛋白的研究概况

结合国内外对猪圆环病毒2型(porcine circovirus2,PCV2)的研究,重点对猪圆环病毒2型ORF2基因及其编码蛋白的抗原表位和功能应用研究进行简要综述,为猪圆环病毒2型新型疫苗研究和建立诊断检测方法研究方面提供参考。     

猪圆环病毒2型疫苗研究进展

猪圆环病毒2型(PCV2)感染后会导致断奶仔猪多系统衰竭综合征(PMWS)等"猪圆环病毒相关疾病"(PCVADs),给全球养猪业造成了巨大的经济损失。疫苗免疫是防控该病的有效手段,近年来市场上推出了PCV2灭活疫苗、嵌合疫苗和亚单位疫苗。PCV2变异较快,主要临床流行毒株从PCV2b逐渐演变为PCV2d,现有商业化疫苗免疫效果需进一步研究证实。论文就近年来国内外PCV2传统疫苗、新型基因工程疫苗、PCV2疫苗与其他疫苗联合免疫的研究进展进行综述,旨在为猪圆环病毒相关疾病的防控及疫苗的开发与利用提供参考。     

猪圆环病毒2型疫苗研究进展

猪圆环病毒2型(PCV-2)感染是一种新发现的猪传染病,以5周龄～12周龄仔猪高发病率、高死亡率及导致机体淋巴系统损伤与免疫缺陷为主要特征。PCV-2感染在世界各养猪国家广泛流行,给各国养猪业造成了巨大的经济损失。PCV-2疫苗研究已成为国内外学者的研究焦点。迄今为止,西欧与美国已有PCV-2疫苗注册上市,主要为灭活疫苗与亚单位疫苗。由于灭活疫苗与亚单位疫苗成本高,且注射次数多,容易造成机体应激,因此,弱毒疫苗、活载体疫苗及核酸疫苗等新型疫苗是目前研究的重点,并取得了长足的进展。论文主要概述了PCV-2疫苗研究的最新进展,以期为PCV-2疫苗研究提供一定的参考资料。     

猪圆环病毒2型病毒样颗粒研究进展

猪圆环病毒2型(PCV2)是引起猪圆环病毒相关疾病的主要病原体,给养殖业造成重大经济损失。一直以来,对于PCV2的防控主要通过疫苗接种。目前使用的疫苗可大致分为全病毒灭活疫苗、嵌合病毒疫苗、重组亚单位疫苗三大类。病毒样颗粒(VLPs)作为一种伪病毒,以其高免疫原性、高安全性成为新型疫苗的研究热点。本文综述了VLPs在国内外的最新研究动态、研究和开发的意义,提出了VLPs作为一种基因转载工具,其研究为疫苗研发开拓了新的方向。     

猪圆环病毒2型疫苗的研究进展

猪圆环病毒2型(PCV2)是引起断奶仔猪多系统衰竭综合征(PMWS)的主要病原,给全球养猪业造成了巨大经济损失.PCV2感染可以破坏动物机体的免疫系统,造成严重的免疫抑制,容易诱发多种细菌及病毒的混合感染与继发感染,给疾病的诊断和治疗带来巨大的困难.疫苗免疫接种是防控PCV2感染的有效手段,有关PCV2疫苗的研究已成为国内外学者的关注热点.迄今为止,欧美几家跨国公司已先后推出商品化的PCV2灭活疫苗、亚单位疫苗及嵌合病毒疫苗,国内也已研制出PCV2灭活疫苗,这些疫苗的推广应用为有效防控猪圆环病毒病发挥了重要作用.鉴于这些疫苗尚不能完全阻断PCV2传播,无法彻底清除体内感染的病毒,因此,开发高效、价廉的新型活载体疫苗、核酸疫苗及标记疫苗是今后研究的趋势.笔者在本文中概括地介绍了目前商品化的PCV2疫苗的特性和免疫效力,并对近年来有关PCV2活载体疫苗、核酸疫苗及标记疫苗等新型疫苗的研究进展进行综述,以期为猪圆环病毒病的防制提供参考.     

3个猪圆环病毒1型衣壳蛋白型特异性抗原表位的鉴定

猪圆环病毒1型(PCV1)感染猪肾细胞PK-15,血清学和遗传学研究结果表明,PCV1广泛存在于家猪中。本研究用杆状病毒系统表达的重组PCV1衣壳蛋白(PCV1-Cap)诱导产生单克隆抗体(mAbs)和多克隆抗体(pAbs)。用PEPSCAN分析来鉴定mAbs和pAbs识别的PCV1-Cap表位,结果精确定位了对PCV1-Cap特异的3个B细胞线性表位,包括85 GGTNPLP91、162 FTPKPELDKTIDWFH-PNNK180和219 YVQFREFILKDPLNK233。本研究结果将有助于PCV1和PCV2的抗原差异调查和鉴别诊断。     

猪圆环病毒2型检测与免疫技术研究进展

对年近来国内外对猪圆环病毒2型(PCV2)的检测技术进展和疫苗研究进展作了简要回顾。PCV2实验室检验技术有间接免疫荧光(IFA)、间接酶联免疫吸附试验(ELISA)、免疫过氧化物酶单层细胞试验(IPMA)、单克隆抗体以及多种聚合酶链式反应(PCR)技术等。在疫苗研究方面,国外已研发多种PCV2灭活疫苗,国内亦有人正在研发PCV2灭活苗(SH株)。在PCV2基因工程疫苗研究方面主要有重组活载体疫苗和核酸疫苗两类。     

猪圆环病毒研究进展

猪圆环病毒(porcine circovirus，PCV)是迄今发现的一种最小的动物病毒。PCV具有PCV1和PCV2两种基因型。PCV1无致病性，但广泛存在猪体内及猪源传代细胞系；PCV2具有致病性，可以引起断奶仔猪多系统衰竭综合征(post-weaning multisystemic wasting syndrome，PMWS)。它是一种新的传染病。1991年加拿大首次暴发该病，随后世界上许多国家和地区都有该病的报道，给养猪业造成严重的经济损失。我国是养猪大国，对该病及其病原有一个全面的了解，意义重大。     

Focus on research:New porcine circovirus

1新型圆环病毒2008年9月,一批组织样本从患有严重猪繁殖与呼吸综合征(PRRS)的仔猪体内成功采集,该样本的PCR检测结果并不如预期的那样,但发现了猪圆环病毒2型(PCV2)病毒基因组的变异型(Vet.Microbiol.14418～23).     

聚焦研究动态

1新型圆环病毒2008年9月,一批组织样本从患有严重猪繁殖与呼吸综合征(PRRS)的仔猪体内成功采集,该样本的PCR检测结果并不如预期的那样,但发现了猪圆环病毒2型(PCV2)病毒基因组的变异型(Vet.Microbiol.144 18～23)。     

Infectivity of porcine circovirus 1 and circovirus 2 in primary porcine hepatocyte and kidney cell cultures

Infectivity of porcine circovirus (PCV) 1 and PCV2 was examined in primary porcine hepatocyte culture by comparing that of PCV in primary kidney cell culture. The virus titer of PCV2-infected hepatocyte cultures was higher than that of the PCV1-infected hepatocyte cultures and the PCV-infected kidney cell cultures. The number of virus-positive cells was most abundant in PCV2-infected hepatocyte cultures as determined by immunohistochemistry and/or in situ hybridization. The results of our data suggest that PCV2 preferably infects cultured hepatocytes as observed in the liver of pigs with postweaning multisystemic wasting syndrome.     

Characterization of porcine circovirus type 2 in Taiwan

In an effort to understand the genetic diversity of porcine circovirus type 2 (PCV2) and the prevalence of PCV2 infection in Taiwanese herds, we have sequenced the complete genomes from PCV2-infected specimens and individually measured the antibody titer against PCV2 from pigs reared in Taiwan between the years 2000 and 2002. A total of 623 specimens originating from pigs displaying varied clinical signs were screened with the polymerase chain reaction (PCR). Results showed that 309 pigs (49.6%) tested positive for PCV2. Eight of the positive specimens were used for the amplification of the complete viral genome. Sequence comparison of the complete genomes indicated that the 8 Taiwanese PCV2 isolates shared 95-99% similarity. Phylogenetic analysis of all 40 PCV2 isolates from North America, Europe, Asia and Taiwan revealed that those isolates were grouped together in one large group containing two minor subgroups. The Taiwanese PCV2 isolates were classified into the two minor subgroups. The prevalence of serum antibodies to PCV2 in pigs was investigated, and results showed that approximately 83.5% of the pigs in Taiwan were seropositive. Finishing pigs possess the highest titers of antibodies, while 9-week-old pigs contained the lowest titers for specific antibodies. Our results suggest that PCV2 infections have become common in Taiwanese pig farms.     

Association of porcine circovirus 2 with porcine respiratory disease complex

A retrospective study was performed on natural cases of porcine respiratory disease complex (PRDC) to determine the association and prevalence of PRDC with porcine circovirus 2 (PCV2) and other co-existing pathogens in Korea. Histologically, alveolar septa were markedly thickened by infiltrates of mononuclear cells. Moderate to marked multifocal peribronchial and peribronchiolar fibrosis were present and often extended into the airway lamina propria. Among the 105 pigs with PRDC, 85 were positive for PCV2, 66 were positive for porcine reproductive and respiratory syndrome virus (PRRSV), 60 were positive for porcine parvovirus (PPV), and 14 were positive for swine influenza virus (SIV). There were 80 co-infections and 25 single infections. A co-infection of PCV2 with another additional bacterial pathogen is frequently diagnosed in PRDC. The combination of PCV2 and Pasteurella multocida (38 cases) was most prevalent followed by PCV2 and Mycoplasma hyopneumoniae (33 cases). The consistent presence of PCV2, but lower prevalence of other viral and bacterial pathogens in all pigs examined with PRDC, has led us to speculate that PCV2 plays an important role in PRDC.     

Enteritis associated with porcine circovirus 2 in pigs

This report describes the diagnosis of porcine circovirus 2 (PCV2)-associated enteritis in 6 weaned pigs without postweaning multisystemic wasting syndrome by histopathology, virus isolation, and in situ hybridization. The most unique lesions were granulomatous inflammation affecting Peyer's patches, characterized by infiltrates of epithelioid macrophages and giant multinucleated cells. Large, multiple, basophilic or amphophilic, grape-like intracytoplasmic inclusion bodies were often seen in the cytoplasm of histiocytic cells and giant multinucleated cells. No microscopic lesions were observed in the lymphoid tissue, such as lymph node, spleen, and tonsil. A strong hybridization signal for PCV2 was detected in the cytoplasm of histiocytes and giant multinucleated cells in Peyer's patches. Porcine circovirus 2 was isolated from homogenates of the small and large intestines in 2 weaned pigs. The presence of diarrhea and granulomatous enteritis, and abundant PCV2 DNA associated with the microscopic lesions is suggestive of PCV2-associated enteritis. Thus, PCV2-associated enteritis could be a distinct clinical manifestation of PCV2.     

猪圆环病毒的研究进展

圆环病毒能引起猪的传染性、先天性颤抖和断奶仔猪多系统衰弱综合症,现已成为严重影响养猪业发展的病毒之一.作者从猪的圆环病毒所引起疾病的流行现状、致病机理、病理变化、临床诊断、预防等方面进行了论述.     

Association of porcine circovirus type 2 with vascular lesions in porcine pneumonia

The aim of this study was to evaluate the vasculature in porcine circovirus type 2-infected (PCV2-infected) lungs and to identify the PCV2 subtypes involved in porcine pneumonia. Pulmonary samples from 140 pigs, 2 weeks to 7 months of age, from 36 Hungarian commercial herds with clinical signs of respiratory disease were examined for the presence of respiratory pathogens, with bacterial culture, pathologic evaluation, and immunohistochemistry for PCV2, porcine reproductive respiratory syndrome virus, and swine influenza virus. PCV2 was the most commonly identified pathogen (49 cases) among the 74 of 140 cases (53%) with respiratory pathogens. PCV2 was detected immunohistochemically in the wall of 13% to 100% of pulmonary vessels (mean, 89%) in 38 of 49 cases (78%). Detection of PCV2 antigen was positively correlated with the presence of vascular lesions (P < .001, odds ratio [OR]: 159.54). Other pathogens capable of vascular injury in swine were found in 29 of 49 of the PCV2-positive cases (59%). The probability of detecting vascular lesions in PCV2-infected lung was higher than in infection with porcine reproductive respiratory syndrome virus (P < .002, OR: 14.63), Pasteurella multocida infection (P < .001, OR: 5.75), or Streptococcus spp. infection (not significant, OR: 1.45). Sequence analysis of open reading frame 2 amplicons was possible in 6 PCV2-positive cases, from which 5 cases proved to be PCV2b subtype and 1 case, PCV2a subtype. In conclusion, PCV2 antigen was commonly colocalized with pulmonary vascular lesions in pneumonia in Hungarian swine, and PCV2b was the dominant subtype.