Streptococcus pneumoniae is a known notorious cause of invasive pneumococcal diseases as well as asymptomatic host carriage. Efforts have been made to curb this infectious organism through various vaccine strategies. ...Streptococcus pneumoniae is a known notorious cause of invasive pneumococcal diseases as well as asymptomatic host carriage. Efforts have been made to curb this infectious organism through various vaccine strategies. However, its several strains and serotypes have necessitated various vaccine schedules and updates in the USA and globally. The evolution in pneumococcal vaccine schedules is not without challenges, such as cost, vaccine hesitancy, uptake and global disparities. This narrative review synopsizes the history of the Pneumococcal Vaccine and changes in its schedules in the last two decades based on published data. We focused on the impact of pneumococcal vaccination on invasive pneumococcal diseases, historical limitations, current challenges and future directions. Despite advancements in vaccination against S. pneumoniae infections, some pertinent issues exist that need to be swiftly fixed, to reduce national and thus global burden of pneumococcal diseases.展开更多
【目的】猪圆环病毒3型(porcine circovirus type 3,PCV3)与母猪繁殖障碍、仔猪皮炎及心肌炎等疾病的发生密切相关。病毒在细胞上难以稳定传代,阻碍了PCV3动物感染模型的构建及其致病性的研究。【方法】利用PCV3阳性断奶仔猪的淋巴结病...【目的】猪圆环病毒3型(porcine circovirus type 3,PCV3)与母猪繁殖障碍、仔猪皮炎及心肌炎等疾病的发生密切相关。病毒在细胞上难以稳定传代,阻碍了PCV3动物感染模型的构建及其致病性的研究。【方法】利用PCV3阳性断奶仔猪的淋巴结病料接种PK-15细胞进行病毒分离,通过PCR、间接免疫荧光试验和透射电镜观察等方法对毒株进行鉴定,成功分离到一株PCV3毒株(PCV3-HK株),并测定了该毒株的全基因组。使用毒价为106.4TCID50/mL的第15代病毒细胞培养物在接种21日龄未断奶仔猪,通过临床症状、体重变化、排毒情况和病理变化等评价该毒株的致病性。【结果】病毒分离鉴定结果表明,PCV3-HK株基因组全长2000 bp,属于PCV3c基因亚型,病毒粒子为圆球形、无囊膜、直径约15-20 nm的颗粒,能够与PCV3 Cap蛋白单克隆抗体发生特异性反应;仔猪感染试验结果显示,PCV3-HK株感染猪出现皮炎、增重缓慢甚至消瘦等症状,以及淋巴结水肿、间质性肺炎等剖检变化;在感染的第7-21天,口拭子和肛拭子中均可检测到病毒核酸,并出现病毒血症。该病毒感染仔猪的心、肺、肾和淋巴结等器官,尤其在肾脏和淋巴结中观察到炎性细胞浸润、坏死细胞聚集等病理变化。【结论】本研究分离到一株PCV3c毒株,建立了仔猪感染模型,为PCV3致病机制研究和疫苗研发提供了关键材料。展开更多
【目的】确定广东某规模化猪场发病猪是否为猪圆环病毒2型(Porcine circovirus type 2,PCV2)感染,并评估病毒的遗传特性及其在猪群中的流行情况,为疫病的防控提供科学数据支持。【方法】采用实时荧光定量PCR和ELISA方法对猪场病猪的肾...【目的】确定广东某规模化猪场发病猪是否为猪圆环病毒2型(Porcine circovirus type 2,PCV2)感染,并评估病毒的遗传特性及其在猪群中的流行情况,为疫病的防控提供科学数据支持。【方法】采用实时荧光定量PCR和ELISA方法对猪场病猪的肾脏、淋巴结、脾脏等内脏组织及血清样本进行检测分析,并通过PCR扩增PCV2阳性样本的ORF2基因。利用DNAStar软件包中的MegAlign模块对所得ORF2基因序列与GenBank数据库中23株PCV2参考毒株进行相似性比对。运用Mega 7.0软件构建基于ORF2基因序列的遗传进化树,以明确鉴定毒株与参考毒株之间的遗传关系。【结果】流行病学调查、临床症状及病理解剖结果显示,该猪场病猪符合PCV2感染的特征。实时荧光定量PCR检测发现3份样本的Ct值分别为14.42、15.13和16.08,表明病毒载量较高,且PCV2检测结果为阳性。ELISA检测结果显示,不同日龄段猪群中Cap蛋白抗体阳性率介于60%~100%之间,而Rep蛋白抗体阳性率则在0~100%之间,特别是150日龄猪群的2种蛋白抗体阳性率均达到100%,表明PCV2感染强度较高。ORF2基因测序获得了3条序列,分别命名为LZC-2305-1、LZC-2305-2和LZC-2305-3。相似性分析结果显示,这3条序列间具有99.9%~100%的相似性,且与GenBank中的23株PCV2参考毒株序列的相似性为82.3%~99.7%,其中与CZ246序列相似性最高,为99.6%~99.7%。遗传进化树分析进一步证实,本研究获得的3条序列与CZ246序列具有最近的亲缘关系,归属于PCV2的2d分支。【结论】本研究确诊该猪场猪群发生了PCV2d分支的感染。本研究结果不仅为该猪场的PCV2防控提供了科学依据,也为其他规模化猪场的疫病监测与防控提供了参考。展开更多
文摘Streptococcus pneumoniae is a known notorious cause of invasive pneumococcal diseases as well as asymptomatic host carriage. Efforts have been made to curb this infectious organism through various vaccine strategies. However, its several strains and serotypes have necessitated various vaccine schedules and updates in the USA and globally. The evolution in pneumococcal vaccine schedules is not without challenges, such as cost, vaccine hesitancy, uptake and global disparities. This narrative review synopsizes the history of the Pneumococcal Vaccine and changes in its schedules in the last two decades based on published data. We focused on the impact of pneumococcal vaccination on invasive pneumococcal diseases, historical limitations, current challenges and future directions. Despite advancements in vaccination against S. pneumoniae infections, some pertinent issues exist that need to be swiftly fixed, to reduce national and thus global burden of pneumococcal diseases.
文摘【目的】确定广东某规模化猪场发病猪是否为猪圆环病毒2型(Porcine circovirus type 2,PCV2)感染,并评估病毒的遗传特性及其在猪群中的流行情况,为疫病的防控提供科学数据支持。【方法】采用实时荧光定量PCR和ELISA方法对猪场病猪的肾脏、淋巴结、脾脏等内脏组织及血清样本进行检测分析,并通过PCR扩增PCV2阳性样本的ORF2基因。利用DNAStar软件包中的MegAlign模块对所得ORF2基因序列与GenBank数据库中23株PCV2参考毒株进行相似性比对。运用Mega 7.0软件构建基于ORF2基因序列的遗传进化树,以明确鉴定毒株与参考毒株之间的遗传关系。【结果】流行病学调查、临床症状及病理解剖结果显示,该猪场病猪符合PCV2感染的特征。实时荧光定量PCR检测发现3份样本的Ct值分别为14.42、15.13和16.08,表明病毒载量较高,且PCV2检测结果为阳性。ELISA检测结果显示,不同日龄段猪群中Cap蛋白抗体阳性率介于60%~100%之间,而Rep蛋白抗体阳性率则在0~100%之间,特别是150日龄猪群的2种蛋白抗体阳性率均达到100%,表明PCV2感染强度较高。ORF2基因测序获得了3条序列,分别命名为LZC-2305-1、LZC-2305-2和LZC-2305-3。相似性分析结果显示,这3条序列间具有99.9%~100%的相似性,且与GenBank中的23株PCV2参考毒株序列的相似性为82.3%~99.7%,其中与CZ246序列相似性最高,为99.6%~99.7%。遗传进化树分析进一步证实,本研究获得的3条序列与CZ246序列具有最近的亲缘关系,归属于PCV2的2d分支。【结论】本研究确诊该猪场猪群发生了PCV2d分支的感染。本研究结果不仅为该猪场的PCV2防控提供了科学依据,也为其他规模化猪场的疫病监测与防控提供了参考。
