北京发现丑鸭

正2017年2月10日,我们在北京市区的元大都城垣遗址公园内安贞门段(39°58′30.24″N,116°24′8.25″E)的护城河中发现一只野鸭。经实地观察、拍照,目测该鸟体长约40 cm,体形短圆敦实,头圆而嘴短,上体暗褐色,眼上、眼下污白色,耳羽处具一明显的白色斑点,两翅及尾暗褐色,下体污白色;虹膜深褐色,嘴灰色,脚灰色。     

三肽囊素(bursin)的鸡、鸭免疫器官组织学定位特征分析(简报)

三肽囊素(bursin)是法氏囊组织提取物中一种非常重要的活性因子,由Audhya T.等在1986年首次报道。近十几年,有关三肽囊素的研究取得了较大的进展,涉及对三肽囊素的生物学活性、组织学定位、功能机制及其应用前景。本研究分别探索了三肽囊素在鸡、鸭免疫器官中的定位,并对其特征进行分析,以期更深入理解三肽囊素的存在及其生物学意义。鸡用近交系(CB系),由12、14及20日龄胚、新生雏、1—9周龄鸡,采集法氏囊、法氏囊T细胞区、胸腺、哈德氏腺、脾脏及骨髓。鸭用北京鸭,由新生     

Effect of natural or vaccine-induced porcine circovirus type 2 (PCV2) immunity on fetal infection after artificial insemination with PCV2 spiked semen

The objectives of this study were to determine if vaccination against porcine circovirus type 2 (PCV2) or previous PCV2 infection of the dam are sufficient to prevent fetal infection when dams are artificially inseminated with PCV2-spiked semen. Nine sows (Sus domestica) were allocated into three groups of three dams each: The PCV2 naïve negative control Group 1 was artificially inseminated with extended PCV2 DNA negative semen during estrus, whereas the extended semen used in the vaccinated Group 2 (PCV2 vaccine was given 8 wk before insemination) and PCV2-exposed Group 3 (infected with PCV2 12 wk before insemination) was spiked with 5 mL of PCV2 inoculum with a titer of 10^4.2 tissue culture infectious dose (TCID₅₀) per milliliter at each breeding. The dams in the vaccinated and PCV2-exposed groups were positive for PCV2 antibody but negative for PCV2 DNA in serum at the time of insemination. Three negative control dams, two vaccinated dams, and three dams with previous PCV2 exposure became pregnant and maintained pregnancy to term. After artificial insemination, viremia was detected in one of three vaccinated dams and in two of three dams with previous PCV2 exposure. At farrowing, PCV2 infection was not detected in any piglets or fetuses expelled from the negative control dams or from dams with previous PCV2 exposure. In litters of the vaccinated dams, 15 of 24 live-born piglets were PCV2 viremic at birth, with 6 of 26 fetuses having detectable PCV2 antigen in tissues. In conclusion, vaccine-induced immunity did not prevent fetal infection in this sow model using semen spiked with PCV2.     

Molecular Characterization of the Duck Enteritis Virus UL4 Gene

Duck enteritis virus (DEV) is a herpesvirus that causes an acute, contagious and fatal disease. In the present article, the DEV UL4 gene was cloned and sequenced from a vaccine virus. A degenerate oligonucleotide primer for the consensus site of herpesvirus UL3 gene and a specific primer located in UL5 were used in the polymerase chain reaction (PCR) to amplify a DNA product 2 086 bp in size. DNA sequence analysis revealed that a 714 bp open reading frame (ORF) of DEV encoding a 237 amino acid polypeptide is homologous to the family of herpesvirus UL4 proteins and therefore has been characterized as a DEV UL4 gene. Alignment of the DEV UL4 protein sequence with those of other alphaherpesviruses showed that 10 amino acid residues are completely conserved. Phylogenetic tree analysis showed that the seventeen alphaherpesviruses viruses analyzed were classified into four large groups, and the duck enteritis virus branched separately, closely related to the Mardiviruses group comprising Gallid herpesvirus 2 (GaHV-2), Gallid herpesvirus 3 (GaHV-3) and Meleagrid herpesvirus 1 (MeHV-1). The present study showed that the evolutionary relationship of the UL4 protein could be used for classification of alphaherpesviruses.     

Epidemiological investigation and genome analysis of duck circovirus in Southern China

Duck circovirus (DuCV), a potential immunosuppressive virus, was investigated in Southern China from March 2006 to December 2009 by using a polymerase chain reaction (PCR) based method. In this study, a total of 138 sick or dead duck samples from 18 different farms were examined with an average DuCV infection rate of ∼35%. It was found that ducks between the ages of 40∼60 days were more susceptible to DuCV. There was no evidence showing that the DuCV virus was capable of vertical transmission. Farms with positive PCR results exhibited no regularly apparent clinical abnormalities such as feathering disorders, growth retardation or lower-than-average weight. The complete genomes of 9 strains from Fujian Province and 1 from Zhejiang Province were sequenced and analyzed. The 10 DuCV genomes, compared with others genomes downloaded from GenBank, ranged in size from 1988 to 1996 base pairs, with sequence identities ranging from 83.2% to 99.8%. Phylogenetic analysis based on genome sequences demonstrated that DuCVs can be divided into two distinct genetic genotypes, Group I (the Euro-USA lineage) and Group II (the Taiwan lineage), with approximately 10.0% genetic difference between the two types. Molecular epidemiological data suggest there is no obvious difference among DuCV strains isolated from different geographic locations or different species, including Duck, Muscovy duck, Mule duck, Cheery duck, Mulard duck and Pekin duck.     

Porcine circovirus type 2 (PCV2) vaccination is effective in reducing disease and PCV2 shedding in semen of boars concurrently infected with PCV2 and Mycoplasma hyopneumoniae

The objectives were to determine whether the amount of porcine circovirus type 2 (PCV2) shed in semen increased in boars experimentally coinfected with Mycoplasma hyopneumoniae (MHYO), and whether PCV2 vaccination of boars prior to PCV2 exposure reduced PCV2 viremia and virus shedding in semen. Twelve specific-pathogen-free PCV2- and MHYO-naïve boars were randomly and equally assigned to one of four groups. Six boars were vaccinated against PCV2 (VAC) on Day 0; three PCV2 vaccinated and three non-vaccinated boars were inoculated with MHYO on Day 21, and all boars were challenged with PCV2 on Day 35. The four treatment groups included PCV2-Infected (I), VAC-PCV2-I, MHYO-PCV2-Coinfected (CoI), and VAC-MHYO-PCV2-CoI. Semen, blood swabs, feces, and serum samples were collected weekly until Day 70. All vaccinated boars had seroconverted to PCV2 by Day 35. Between Days 28 and 35, MHYO boars developed moderate respiratory disease, characterized by coughing, respiratory distress, mucopurulent nasal discharge and loss of body condition. One MHYO-PCV2-CoI boar died on Day 50. Boars in the PCV2-I and MHYO-PCV2-CoI groups had significantly higher PCV2 DNA loads in blood swabs than the remaining boars. Moreover, PCV2 vaccination significantly reduced the incidence and amount of PCV2 shedding in semen and feces. In summary, although concurrent MHYO infection did not influence PCV2 shedding patterns, coinfection of boars with PCV2 and MHYO resulted in severe clinical disease and viral shedding was significantly decreased by PCV2 vaccination.     

Influence of in ovo thermal manipulation on lipid metabolism in embryonic duck liver

The growth and development of poultry embryos are easily affected by environmental factors, such as the incubation temperature and humidity. Metabolism, including lipid metabolism, during the embryonic stage is also important for the growth and development of poultry. Our study aimed to investigate the effects of incubation temperature on embryonic lipid metabolism in the liver of ducks. To fully evaluate the effects, thermal treatment was given between embryonic ages 11 and 24 days with a 1 °C higher incubation temperature than the control group, and lipid metabolism parameters in the liver and blood serum were analyzed both at embryonic stage day 20 and 2 weeks post-hatching. Our results showed no significant changes in the embryonic stage in total cholesterol (TC), triglycerides (TG), high-density lipoprotein cholesterol (HDL-C) and low-density lipoprotein cholesterol (LDL-C) in the blood serum (P>0.05). Additionally, the mRNA expression levels and enzyme activities of fatty acid synthase (FAS), acetyl CoA carboxylase (ACC), and elongase of very long chain fatty acids (ELOVL) did not show significant changes either in the embryonic stage or at hatching day 20 (P>0.05). However, there were significant changes in the gene expression and enzyme activities of TC, LDL-C and FAS at post-hatching stages (P≤0.05). These results may indicate that the thermal treatment has less influence on lipid metabolism in the embryonic stage but has a much stronger effect in the post-hatching stage.     

Comments on duck circovirus (DuCV) genotype definition

A standardised methodology has been used to define genotypes based on pairwise sequence comparisons (PASC). PASC is a widely accepted method in virus taxonomy, which is based on the histogram of pairwised differences among sequences. Recently, Zhang et al. (2013) concluded that the average p-distance of duck circovirus (DuCV) between genotypes 1 and 2 was 0.170, and subtype distance thresholds were 0.032 in DuCV-1 and 0.018 in DuCV-2, respectively. However, there might be some concerns on the methodology application to define the genotype of DuCV. Taking into account the concerns mentioned above, our authors conducted the PASC analyses of 54 capsid gene (ORF2) and genomic sequences including all the sequences from Zhang et al. (2013). Our results confirmed the existence of two DuCV genotypes (1 and 2) and, we suggest that DuCV ORF2 and genomic distance genotype thresholds were 0.061 and 0.038, respectively.     

PMWS病猪猪圆环病毒2型全基因组序列分析

根据GenBank中发表的猪圆环病毒2型(PCV2)全基因序列,设计一对特异性引物,用PCR方法直接从5省病料中分别扩增出5个PCV2毒株的全基因组,分别命名为FujianPCV、GuangxiPCV、HainanPCV、HunanPCV和ShandongPCV.将扩增片段克隆于pMD 18-T载体,进行序列测定,结果表明,除FujianPCV株核苷酸长度为1768bp,其余四株均为1767 bp.应用DNAstar序列分析软件分析表明,本实验的5个PCV2分离株与世界上其它地区的PCV2分离株密切相关,核苷酸序列同源性达93%～98.8%,与PCV1毒株的序列同源性只有68.4%～70%.其中ORF1和ORF2所编码的氨基酸序列与国内外PCV2毒株比较,同源性也很高,分别为98.1%～99.4%和88%～99.1%.     

猪圆环病毒2型流行株的分离及其感染性克隆的构建

【目的】通过分离一株猪圆环病毒2型(PCV2)流行毒株,并构建其感染性克隆,为研究PCV2基因功能提供操作平台。【方法】通过PCR方法,从疑似患断奶仔猪多系统衰竭综合症(PMWS)的仔猪淋巴结中鉴定为猪圆环病毒(Porcine circovirus,PCV)2型阳性。把阳性病料接种PK-15细胞传代培养,在培养物中扩增出PCV2的全基因序列。对扩增出的全序列进行序列测定,并与GenBank中公布的5株广东PCV2分离株(GD-pz、GD-gj、GD-jm、GD-ss和GD-sz)进行同源性分析。通过EcoRⅠ和SalⅠ将PCV2全基因组序列克隆进pUC18载体中,获得含PCV2 GD-zq株全基因组单拷贝的重组质粒pPCV2-GD-zq,再通过SalⅠ和HindⅢ把另一个全长拷贝克隆进pPCV2-GD-zq质粒中,使PCV2 GD-zq株基因组DNA以头尾相接的双重复方式克隆进pUC18载体中,获得重组质粒pPCV2-2GD-zq。将pPCV2-2GD-zq DNA纯化和定量后转染PK-15细胞,拯救PCV2 GD-zq病毒。【结果】从PMWS感染的猪淋巴结中分离到了一株PCV2,命名为GD-zq株;序列分析结果显示,GD-zq株全基因组为1 767 bp,与GenBank中公布的5株广东PCV2分离株ORF1核苷酸一致性为97.1%-99.7%,编码氨基酸一致性为98.7%-100%;ORF2核苷酸一致性为93.2%-99.6%,编码氨基酸一致性为92.3%-99.1%;全基因一致性为96.0%-99.6%。pPCV2-2GD-zq质粒转染PK-15细胞后,其通过间接免疫荧光实验(IFA)能从转染细胞及其传代细胞中,检测到拯救出的病毒。【结论】分离了一株PCV2广东株GD-zq,成功构建了PCV2 GD-zq株的感染性克隆。