C基因型牛副流感3型病毒的分离鉴定

为了对宁夏地区患有呼吸系统疾病的舍饲牛进行病原鉴定,试验主要利用RT-PCR方法对样品进行牛副流感3型病毒(BPIV3)M基因序列扩增,将扩增产物连接在pMD18-T载体后转化到大肠杆菌DH5α感受态细胞中进行亚克隆。通过氨苄青霉素平板筛选,将鉴定为阳性的克隆菌进行核苷酸序列测定并利用分子生物学软件与GenBank上参考序列进行同源性比对。测序结果表明,从样品中分离到了1株BPIV3,并命名为NX49,其M基因全长为1056bp;进化分析表明,NX49隶属于BPIV3C基因型,其M基因与中国山东C型分离株SD0835具有较高同源性,核苷酸同源性为99.4%;理化分析表明,该毒株对温度、酸及有机物均敏感,高温孵育下Mg²⁺对该病毒无保护力;血凝试验表明,NX49对豚鼠红细胞凝集效价仅为1∶4,且仅在4℃孵育时出现凝集反应。本研究成功分离得到一株BPIV3C型毒株,这将有助于中国BPIV3分子进化规律及病毒流行特点的进一步研究。     

Studies on the pathogenesis of a Chinese strain of bovine parainfluenza virus type 3 infection in Balb/c mice

To date, three genotypes A, B, and C of bovine parainfluenza virus type 3 (BPIV3) have been isolated from cattle and only limited studies on the pathogenesis of the genotype A of BPIV3 infection in calves and laboratory animals have been conducted. The pathogenesis of the genotypes B and C of BPIV3 infection in calves and laboratory animals have not been reported. To alleviate the difficulties associated with sourcing suitable calves for infection studies, the establishment of BPIV3 infection model using laboratory model animals could aid in increasing the knowledge of the pathogenesis of this virus. Therefore thirty Balb/c mice were intranasally inoculated with a Chinese BPIV3 strain SD0835 which was classified as genotype C. Virus replications in mice were demonstrated by using virus isolation and titration, immunofluorescent staining, and immunohistochemistry and had occurred in the respiratory tissues as early as 24h after intranasal inoculation. The results of immunofluorescent staining and IHC implicated that the lungs and tracheas might be the major tissues in which the SD0835 infected and replicated. The histopathologic examinations revealed that alveoli septa thickening and focal cellulose pneumonia were seen in the lungs of experimentally infected mice. The aforementioned results indicated that the SD0835 of the genotype C was pathogenic to Balb/c mice and the mouse infection model could cast light on the genotype C of BPIV3 infection process and pathogenesis.     

牛副流感病毒3型毒株的分离鉴定及基因组遗传变异分析

从新疆地区某牛场出现发热、咳嗽等症状的多例病牛的肺组织中分离得到3株牛副流感病毒3型,分别命名为XJ03、XJ022、XJ023,对其中两株病毒XJ03和XJ023的基因组进行序列测定,测序结果显示,XJ03和XJ023毒株基因组全长分别为15474 bp(Gen Bank登录号为KU198929)和15475 bp,其核苷酸同源性为99.89%。同代表性的牛副流感病毒基因组比对发现,与我国的山东毒株SD0835同源性最高为99.3%,均属C型BPIV。在C型毒株中,与南韩12Q061分离株(C型)同源性最低为97.5%。F、N、HN、L、P、M蛋白基因氨基酸序列分析显示,与SD0835毒株相应序列对比,同源性分别为99.63%、92.15%、99.48%、99.28%、98.50%和100%,部分氨基酸发生了新的变异。试验结果将为今后更好地开展BPIV3防控奠定基础。     

Isolation and genetic characterization of bovine parainfluenza virus type 3 from cattle in China

Bovine parainfluenza virus type 3 (BPIV3) is one of the most important of the known viral respiratory pathogens of both young and adult cattle. However BPIV3 has not been detected or isolated in China prior to this study. In 2008, four BPIV3 strains were isolated with MDBK cells from cattle in China and characterized by RT-PCR, nucleotide sequence analysis, transmission electron microscope observation, hemadsorption and hemagglutination tests. Nucleotide phylogenetic analysis of partial hemagglutinin-neuraminidase (HN) gene for four isolates and the complete genome for the SD0835 isolate implicated that the four Chinese BPIV3 strains were distinct from the previously reported genotype A (BPIV3a) and genotype B (BPIV3b) and might be a potentially new genotype, which was tentatively classified as genotype C (BPIV3c). This is the first study to report the isolation and genetic characterization of BPIV3 from cattle in China.     

牛副流感病毒3型HNex蛋白表达及其多克隆抗体的制备

本研究旨在获得牛副流感病毒3型（BPIV3）的HNex蛋白及其多克隆抗体。以提取的BPIV3细胞毒的RNA为模板，利用RT-PCR方法扩增包含血凝素神经氨酸酶（HN）的基因片段，然后以此为模板扩增编码HN蛋白膜外区片段（HNex基因），并进行氨基酸序列测定。将HNex基因插入克隆载体pEASY-Blunt Simple中，经双酶切连接至pET-30a（+）表达载体中，构建重组原核表达载体pET-30a-BPIV3-HNex，转化大肠杆菌Rosetta^TM（DE3）pLysS感受态细胞，IPTG诱导后，用SDS-PAGE和Western blotting方法鉴定表达产物。经亲和层析方法纯化的HNex蛋白作为免疫原，制备兔抗BPIV3-HNex多克隆抗体。结果显示，本研究成功克隆BPIV3 HNex基因。原核表达蛋白结果表明，53 ku处有特异条带出现，并且可以与鼠抗His发生特异性免疫反应。免疫兔的血清中BPIV3 HNex抗体效价为1：819 200。Western blotting结果表明，制备的兔抗BPIV3 HNex多克隆抗体能与BPIV3蛋白发生特异性反应。总之，本研究利用原核表达系统表达BPIV3 HNex蛋白，并获得兔抗BPIV3 HNex多克隆抗体，为进一步探索BPIV3 HN蛋白的功能及亚单位疫苗研制提供参考。     

鸡传染性支气管炎病毒广西株N、M基因的克隆与序列分析

为研究鸡传染性支气管炎病毒(IBV)广西流行株的遗传变异情况,本研究从广西发病鸡中分离鉴定了1株IBV。参照GenBank中IBV的核苷酸序列设计2对引物,利用RT-PCR技术对分离毒株的N、M基因进行了克隆、序列测定,并与GenBank中发表的国内外参考毒株进行比对分析。结果显示,N基因序列全长为1 230 bp,编码409个氨基酸,M基因序列全长为678 bp,编码225个氨基酸。与参考毒株相比,分离株的N基因核苷酸序列同源性为87.2%~93.3%,推导的氨基酸序列同源性为90.0%~94.4%;M基因的核苷酸序列同源性为83.6%~91.0%,推导的氨基酸序列同源性为82.7%~92.9%。在遗传进化树中,本试验分离株Guangxi156株与BJ株和LX4株两个参考株位于同一个分支上,亲缘关系较近,而与其他参考株属于不同的分支,亲缘关系较远。结果表明,本试验分离株是一株新的IBV变异株。     

Cloning and Sequence Analysis of N and M Genes of Avian Infectious Bronchitis Virus Guangxi Strain

To investigate genetic variation of avian infectious bronchitis virus (IBV) in Guangxi province,one strain of IBV was isolated from chicken.Two pairs of primers for amplifying the N and M genes of IBV were designed according to the sequences in GenBank.The N and M genes of the strain were amplified by RT-PCR,and they were proved to be the N and M genes of IBV by cloning,sequencing and compared with reference IBV strains published in GenBank.The results showed that the N gene from the IBV isolate consisted of 1 230 bp,coding 409 amino acids.The M gene from the IBV isolate consisted of 678 bp,coding 225 amino acids.The sequence analysis of N gene showed that it shared 87.2% to 93.3% nucleotide homologies and 90.0% to 94.4% deduced amino acid sequence homologies with IBV strains from GenBank.The M gene sequence analysis showed that it shared 83.6% to 91.0% nucleotide homologies and 82.7% to 92.9% deduced amino acid sequence homologies.The phylogenetic tree analysis showed that it was closely related to BJ and LX4 strains,and were clustered into one group;But with the distant relatives from other strains of IBV.These results suggested that the isolate was a new variant of IBV.     

Establishment and Preliminary Application of Nano-PCR and LAMP Methods for Bovine Parainfluenza Type-3 Virus

This study was aimed to establish Nano-PCR and LAMP which were new rapid type of molecular detection technologies of bovine parainfluenza type-3 virus (BPIV3).The comparative specificity and sensitivity of BPIV3 Nano-PCR and LAMP PCR were tested, and the assay was applied to detect 10 clinical samples. The specificity and sensitivity tests showed that Nano-PCR and LAMP were only sensitive to BPIV3,without cross reaction to other viruses, such as bovine respiratory syncytial virus,infectious bovine rhinotracheitis virus and bovine viral diarrhea virus. In the sensitivity test, Nano-PCR and LAMP showed 10 times sensitivity than that of the traditional PCR technology,with the minimum detection of 4.16×10² copies/μL. Clinical test results showed that the coincidence rate of Nano-PCR and LAMP could reach to 100%, and the positive detection rate was much higher than that of normal PCR.Therefore, the Nano-PCR and LAMP methods established in this study provided a faster, sensitive and reliable tool for the clinical diagnosis of BPIV3.     

Prokaryotic Expression of BPIV3 NP Protein and Its Immunoenhancing Effect on the BPIV3 Inactivated Vaccine

【Objective】 This study was aimed to verify whether the NP protein of Bovine parainfluenza virus type 3 (BPIV3) could enhance the immune effect of BPIV3 inactivated vaccine【Method】 The antigenicity of the protein encoded by NP gene was analyzed by bioinformatics softwares,and the antigenic region was screened.The truncated NP gene sequence of BPIV3 was amplified by PCR and connected to pET-32a(+) plasmid.Then the high-purity BPIV3 NP protein was obtained by E.coli prokaryotic expression system and Ni affinity chromatography.It was confirmed by Western blotting.BPIV3 was inactivated with 0.3% formaldehyde and mixed with Freund's adjuvant 1:1 to prepare inactivated vaccine.Eight New Zealand White rabbits were randomly divided into four groups with two rabbits in each group,including inactivated vaccine group,NP protein group,inactivated vaccine and NP protein mixed group and control group.Blood samples were collected before and every 7 days after immunization.The levels of specific antibodies and neutralizing antibodies in New Zealand White rabbits of the four groups were measured and compared by indirect ELISA and virus neutralization test.【Result】 DNAStar analysis showed that the average antigen index of amino acid region 193-368 of NP protein was 0.4-1.7,and the hydrophilic index was 0-1.5,which proved that this region had strong antigenicity and hydrophilicity.The NP gene was amplified by PCR and the recombinant expression vector was constructed.Gene sequencing showed that the recombinant expression vector was consistent with the expected results.The results of SDS-PAGE showed that NP protein was highly expressed with a molecular weight of 50 ku and expressed in the form of inclusion body.Western blotting showed that the expressed protein had strong reactivity.The results of ELISA showed that 28 days after immunization,the specific antibody titer of the control group was 0,and the specific antibody titers of inactivated vaccine group,NP protein group and inactivated vaccine and NP protein mixed group reached 1:2¹¹,1:2¹⁷ and 1:2¹⁸,respectively.The results of virus neutralization test showed that 28 days after immunization,the neutralizing antibody titer of the control group was 0,and the neutralizing antibody titers of inactivated vaccine group,NP protein group and inactivated vaccine and NP protein mixed group were 1:2^3.32,1:2^4.48 and 1:2^4.98,respectively.【Conclusion】 BPIV3 NP protein could enhance the immune effect of BPIV3 inactivated vaccine.Adding NP protein to the inactivated vaccine could be used as a new vaccination method of BPIV3 inactivated vaccine.     

牛副流感3型病毒Nano-PCR、LAMP方法的建立及初步应用

试验旨在建立牛副流感3型病毒（bovine parainfluenza type-3 virus,BPIV3）纳米PCR（Nano-PCR）与环介导等温扩增技术（loop-mediated isothermal amplification,LAMP）新型快速分子检测技术,对其进行特异性和敏感性对比试验,并对10份临床样品进行了检测。特异性与敏感性试验结果显示,建立的Nano-PCR和LAMP方法只对BPIV3特异,而对牛呼吸道合胞体病毒、牛传染性鼻气管炎病毒、牛病毒性腹泻病毒无交叉反应;建立的Nano-PCR和LAMP方法具有相同的敏感性,均是普通PCR的10倍,最低核酸检出量均为4.16×10²拷贝/μL。临床检测结果显示,建立的两种方法阳性符合率为100%,且阳性检出率均高于普通PCR。因此,本试验建立的Nano-PCR和LAMP方法为BPIV3的临床诊断提供了更快速、敏感、可靠的工具。     

1株牛病毒性腹泻病毒分离毒株的基因组特征

旨在从宁夏某奶牛群持续感染牛分离牛源牛病毒性腹泻病毒（BVDV）,并解析其基因组特征,为研究我国不同地区BVDV分离株遗传演化规律提供理论依据。利用BVDV抗原检测试剂盒检测宁夏回族自治区银川市某示范区的240头高产奶牛间隔两周的双份抗凝血,筛选持续感染牛,分离血液淋巴细胞制备裂解液接种牛肾细胞（MDBK）,分离鉴定获得BVDV株,克隆测序获得全基因组序列,比较分析其遗传演化关系。从该示范区高产奶牛筛选获得2头持续感染牛,分离获得1株非致细胞病变型BVDV,命名为NX2019/01。测序获得基因组全序列（12 107 nt）,其中ORF长11 703 nt,编码3 898个氨基酸。在基因组水平,NX2019/01株与我国SD-15、ZM-95、XC、LN-1等1m亚型分离株相似性较高（92.17%~93.84%）,但E^rns、E1以及E2基因存在较大差异。示范区同群牛急性感染BVDV时,毒株E2蛋白N端编码区核苷酸突变可导致第9位或第67位氨基酸变异。重组分析表明,NX2019/01株E2基因179—288位核苷酸区段以及ZM-95株E1基因168位—E2基因332位核苷酸区段存在相似的重组信号,可能由主要亲本SD-15株与次要亲本LN-1株重组形成,表明NX2019/01株、ZM-95株在演化进程中与SD-15株以及LN-1株或早期流行的高度相似毒株存在密切关联。本研究从持续感染高产奶牛分离获得了牛源BVDV-1m亚型毒株,在基因组水平厘清了BVDV-1m亚型毒株的进化关系,并首次发现同亚型BVDV毒株基因同源重组,为进一步研究BVDV在我国的演化规律奠定了基础。     

牛A群轮状病毒G10型XJ-2022株分离鉴定及基因型分析

【目的】 试验旨在对新疆某规模牛场患腹泻疾病的犊牛进行病原学鉴定及基因型分析。【方法】 采用抗原诊断试剂盒方法对在新疆某牛场随机采集的15份腹泻犊牛粪便样品进行检测,对抗原检测结果为阳性的样品进行反复冻融和过滤处理,然后将样品接种于Marc-145细胞进行病毒的分离和传代。对分离毒株进行间接免疫荧光试验（IFA）和负染电镜观察进一步确定病原。对分离株的VP6和VP7基因进行PCR扩增测序,并对其进行基因相似性比对和进化树分析。【结果】 抗原诊断试剂盒结果显示,3份粪便样品呈牛轮状病毒（Bovine rotavirus,BRV）抗原阳性。将阳性粪便样品分别接种于Marc-145细胞,仅有1份样品连续盲传至第9代出现明显的细胞病变效应（CPE）。IFA结果显示,接种该分离株的Marc-145细胞有亮绿色荧光,对照组未见荧光。电镜观察可见约65 nm的圆形病毒粒子,并命名为XJ-2022株。经PCR扩增获得VP6和VP7基因的目的条带,长度分别为1 356和342 bp。基因相似性比对和遗传进化分析表明,VP6基因与人源A群轮状病毒参考株DB2015-066（LC367318.1）相似性最高且遗传进化亲缘关系最近;VP7基因与牛源G10轮状病毒参考株XJX2（MN937506.1）相似性最高,遗传进化亲缘关系最近,确定该分离株为A群G10型轮状病毒。【结论】 试验成功分离到基因型为A群G10型BRV XJ-2022株,该毒株为新疆地区首次发现的多宿主来源的基因重配病毒。     

云南景洪帕利亚姆亚群达圭勒病毒的分离与鉴定

为了解牛感染帕利亚姆亚群达圭勒病毒（D’Aguilar virus,DAGV）情况,本研究应用BHK21细胞对2019年云南省景洪市采集的健康黄牛血液样品进行盲传病毒分离,对出现细胞病变的样品进行形态学、基因组带型和分子生物学鉴定,对分离到的病毒进行S2、S3、S7基因序列测定和比对分析。结果显示,有5个血液样品可致BHK21细胞病变,电镜观察到完整病毒颗粒呈球形,直径约50 nm;琼脂糖凝胶电泳结果发现5株新分离病毒基因组为10节段,呈现3-3-4的电泳带型特征,其带型特征与2014年在云南分离到的DAGV V106/YN/2014毒株相似;5株病毒S2、S3、S7基因核苷酸、氨基酸序列相似性均为100%,S3、S7片段核苷酸和氨基酸序列与中国本土分离的帕利亚姆亚群病毒（Palyamserogroup virus,PALV）毒株相似性最高;S2片段氨基酸与核苷酸序列与日本分离的DAGV相似性最高。S2、S3、S7基因遗传进化分析结果显示,5株新分离毒株间基因相似度为100%;5个毒株的S7与S3基因序列均与中国本土分离的已知部分PALV毒株在同一分支,亲缘关系较近,提示这5株毒株为PALV;5株毒株S2片段核苷酸序列与日本分离的部分DAGV毒株位于同一分支上,亲缘关系较近,进一步证实这5株毒株为PALV DAGV。本研究成功分离到5株DAGV毒株,并进行了基因片段遗传进化分析,为进一步开展DAGV流行病学研究提供基础。     

猪流行性腹泻病毒截短M基因克隆、生物信息学分析及其截短片段表达

【目的】 探索猪流行性腹泻病毒(Porcine epidemic diarrhea virus,PEDV)截短M蛋白的序列结构特征与原核表达情况。【方法】 根据已公布的PEDV M基因序列设计1对特异性引物,以从阳性病料提取的RNA为模板,通过RT-PCR扩增并克隆PEDV截短的M基因(rM),应用在线生物信息学软件预测rM蛋白的结构特征。将得到的截短的M基因克隆至原核表达载体pET-28a(+)中,构建原核表达质粒pET-28a-rM,将鉴定正确的pET-28a-rM转化大肠杆菌BL21(DE3)感受态细胞,成功构建重组菌株BL21(pET-28a-rM),并对重组菌株进行IPTG诱导表达,优化重组蛋白的表达条件,重组蛋白经亲和层析纯化后进行SDS-PAGE及Western blotting检测,同时应用重组蛋白制备兔抗rM多克隆抗体。【结果】 试验克隆得到大小为366 bp的截短的M基因,重组蛋白由121个氨基酸组成,预测蛋白分子质量大小约为12.8 ku。该蛋白的二级结构由无规则卷曲、延伸链、β-转角和α-螺旋组成,占比分别为48.76%、33.88%、9.09%和8.26%。该蛋白不含信号肽,但有跨膜区,包含21个磷酸化位点。SDS-PAGE结果显示,重组蛋白大小约为15 ku,以包涵体蛋白形式存在,在37 ℃、1 mmol/L IPTG诱导12 h时蛋白的表达量最高。Western blotting检测结果表明,重组蛋白与PEDV阳性血清具有较好的反应原性,纯化的重组蛋白免疫新西兰大白兔获得的高免血清效价高于1∶51 200。【结论】 本研究成功克隆PEDV 截短的M基因,对rM蛋白进行了生物信息学分析,获得了高纯度的rM蛋白,为猪流行性腹泻治疗及检测用生物制品的开发奠定了基础。     

牛副流感病毒3型3种基因型多重RT-PCR检测方法的建立

为建立检测牛副流感病毒3型（bovine parainfluenza virus type 3,BPIV3）3种基因型的多重RT-PCR方法,根据GenBank上发表的BPIV3 3种基因型病毒株的HN基因序列设计特异性引物,优化反应体系建立多重RT-PCR方法。结果显示,方法可同时扩增出BPIV3 A型150 bp、B型253 bp和C型342 bp的特异性片段,与牛传染性鼻气管炎病毒（IBRV）、牛呼吸道合胞体病毒（BRSV）、牛病毒性腹泻病毒（BVDV）、小反刍兽疫病毒（PPRV）、牛支原体、牛布鲁氏菌、羊布鲁氏菌、牛源多杀性巴氏杆菌A型和B型均无交叉反应,A、B、C基因型BPIV3最低阳性质粒检测量分别为0.89×10⁴、0.92×10⁴和1.53×10⁴拷贝/μL。本试验建立的多重RT-PCR检测方法操作方便、特异性强,应用于临床样本的检测,可快速检测BPIV3 3种基因型。     

贵州省猪流行性腹泻病毒ORF3、M基因克隆及序列分析

为了解贵州省猪流行性腹泻病毒(porcine epidemic diarrhea virus,PEDV)毒株ORF3及M基因的遗传变异情况,试验于2014年4月－2015年3月从贵州省5个地区采集105份腹泻仔猪的粪便,应用RT-PCR方法进行PEDV检测,从中选择8份PEDV阳性样本,扩增其ORF3及M基因,测序并进行序列比对分析.结果显示,从采集的105份粪便样本中可检出75份PEDV阳性样本,阳性率为71.43%;8株PEDV贵州株ORF3及M基因序列均无碱基缺失或插入;ORF3基因核苷酸及推导的氨基酸同源性在95.1%~100.0%与95.1%~99.6%之间,M基因核苷酸及推导的氨基酸同源性在98.4%~100.0%与98.7%~100.0%之间;氨基酸系统进化树分析结果显示,2014~2015年贵州流行株与近年来中国毒株、韩国毒株及泰国毒株亲缘关系较近,与疫苗株Attenuated DR13及CV777株亲缘关系较远.提示目前贵州省仔猪腹泻病原主要是PEDV,且为PEDV强毒株.     

Cloning and Sequence Analysis of ORF3 and M Gene of Porcine Epidemic Diarrhea Virus in Guizhou Province

To study the genetic variations of porcine epidemic diarrhea virus (PEDV) ORF3 and M gene in Guizhou province,we used RT-PCR method to detect PEDV in the dung what collected from diarheal porket in five regions of Guizhou province between April 2014 to March 2015,then selected eight positive samples,cloned and sequenced their ORF3 and M gene.The results showed that 75 samples were positive for PEDV,and the positive rate was 71.43%.The result of sequencing showed that ORF3 and M gene were intact;ORF3 gene shared from 95.1% to 100.0% nucleotide identity and 95.1% to 99.6% amino acid identity,and M gene shared from 98.4% to 100.0% nucleotide identity and 98.7% to 100.0% amino acid identity with eight PEDV Guizhou strains.Phylogenetic analysis revealed that Guizhou strains seem to be closely related to Chinese strains,Korean strains and Thai strains,and there were genetically different from the vaccine strains attenuated DR13 and CV777.The results suggested that in rencent years the mainly etiology of orket diarrhea was velogenic PEDV.     

牛副流感病毒3型核衣壳蛋白基因的真核表达

根据牛副流感病毒3型(BPIV-3)内蒙09株(NM09)全基因组序列(GenBank登录号:JQ063064)设计特异性引物,利用RT-PCR方法扩增出牛副流感病毒3型分离株的核衣壳蛋白(N)基因,通过NheI和NotI限制性内切酶位点亚克隆至真核表达载体pcDNA3.1/Zeo(+),获得真核重组质粒pcDNA3.1-N。采用Superfect转染试剂将重组质粒转染至BSR细胞中,转染后的BSR细胞经间接免疫荧光试验和RT-PCR方法检测,重组质粒pcDNA3.1-N在BSR细胞中能正确表达N蛋白。本研究结果为BPIV-3新型疫苗的研制奠定基础。     

山西一例牛病毒性腹泻病例病原分离鉴定及测序分析

为查找引起山西某牛场疑似牛病毒性腹泻病例的病因,对送检的9份牛鼻腔棉拭子样品,经处理后进行了多病原PCR或RT-PCR检测、病原分离、特征性细胞病变观察、效价测定、RT-PCR鉴定及基因测序分析。结果显示:从9份样品中检出6份BVDV核酸阳性,IBRV、BRSV、BPIV3、支原体均阴性,病料上清接种MDBK细胞进行培养,传至F5代发现MDBK细胞出现特征性病变,表现为细胞变亮、圆缩、拉网并逐渐形成空泡,效价为10-5.42TCID50/0.1mL,BVDV RT-PCR鉴定阳性,将其命名为BVDV-SX2020株,测序发现其5’UTR与BVDV Oregon C24V等参考毒株同属BVDV基因1a亚型。结果证实该起病例由BVDV-1a毒株感染引起。     

四川彭州猪流行性腹泻流行株全基因序列测定及其遗传变异分析

为了对四川省彭州某免疫过猪流行性腹泻病毒（PEDV）疫苗猪场猪感染的PEDV毒株基因组特征和遗传变异规律进行研究,本试验采用RT-PCR法筛选PEDV阳性样本,命名为SCXM株,对全基因组序列克隆测序获取全基因组序列,并对主要结构基因进行遗传变异分析和系统进化分析。结果显示,SCXM株的遗传变异主要集中在S基因,与71个毒株相比同源性为90.4%~99.2%,与猪场免疫疫苗株CV777相比同源性仅为93.8%。与国内常用疫苗毒株相比,在5个线性抗原表位（P1、S1P2、S1P3、SS5和SS6）和1个中和抗原表位（SID）均存在氨基酸位点突变。遗传进化分析表明,SCXM株属于G2b亚型PEDV,与湖北HBXY3株和越南毒株同在一个分支,表明这些地区流行毒株的演化过程存在相关性。另外对ORF3、M和N基因分析结果显示,SCXM与疫苗株相比均存在一定数量的氨基酸突变,但变异程度相对较小,且未引起抗原性预测值的变化。结果表明,PEDV SCXM株属新型变异毒株,其S基因发生较大程度的变异,S基因多个氨基酸突变和抗原性的变化可能是导致猪场疫苗免疫失败的原因之一。本研究丰富了PEDV基因学研究资料,探讨了SCXM株PEDV遗传变异和演化特征,为PEDV的分子演化研究奠定了基础。