共查询到19条相似文献，搜索用时 765 毫秒
1.
pMGA多基因家族主要编码一类黏附素/血凝素蛋白,存在于鸡败血支原体的细胞表面,其主要功能是促进支原体黏附到宿主细胞上.近年来的相关研究发现,编码pMGA的基因数量从32～70不等,主要在转录水平上通过(GAA)n基序的数量改变引发pMGA基因的选择性转录,造成pMGA蛋白的抗原发生变异,从而干扰宿主正常免疫功能的发挥,使支原体对宿主产生严重的免疫逃逸.其中,(GAA)n基序已被证实在pMGA基因表达调控中起重要作用.这一三联体重复基序数目的多少直接影响到pMGA基因的ON/OFF转录.本文通过对鸡败血支原体pMGA多基因家族分子生物学研究进展进行浅要综述,以提出pMGA基因可能的转录调控机制.这对研究鸡败血支原体的分子致病机理及其免疫逃逸机制大有裨益. 相似文献
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旨在进一步探究鸡毒支原体（MG）感染SPF雏鸡后气管基因组转录水平的变化,筛选出MG感染后参与气管黏膜炎性损伤的差异表达基因和调控通路。使用MG-HY株菌液按0.2 mL·羽-1经点眼滴鼻感染SPF雏鸡,感染后收集气管组织利用RNA-Seq技术进行测序分析。转录组分析结果显示,在MG感染期间RNA-seq共筛选出3 112个显著（P<0.01）差异表达基因（DEGs）,其中,1 646个上调基因,1 466个下调基因。GO功能分析显示,差异基因主要涉及生物调节、刺激的反应、多细胞生物过程、细胞成分组织或生物发生等生物过程。KEGG-Pathway分析发现差异基因参与黏膜免疫信号传导通路,例如：细胞因子-细胞因子受体相互作用,细胞黏附分子（CAMs）,细胞外基质（ECM）受体相互作用、紧密连接、PPAR信号通路和MAPK信号通路等,表明这些基因参与了MG诱导的雏鸡气管炎症反应和损伤。使用qRT-PCR验证与黏膜免疫相关的13个差异表达的基因,其结果与转录组分析一致。本研究为进一步阐明MG感染导致宿主气管黏膜上皮损伤和黏膜免疫机制提供了基础。 相似文献
3.
microRNAs(miRNAs)是一种短的单链非编码小分子RNAs，无论是在正常发育还是疾病的发生发展过程中，都能够与靶mRNA结合，参与到基因的转录后调控过程，并在其中发挥重要的调节作用。近年来随着miRNAs研究的深入，越来越多的证据表明，病原感染后会引起宿主miRNAs表达水平发生变化，这些差异表达的miRNAs能够积极地参与到疾病的发生发展过程中，并通过调控靶基因的表达参与免疫功能、自噬、炎症反应、代谢等多种生物学过程来抑制或促进疾病的发展。此外，宿主miRNAs作为一种参与转录后调节的小分子RNAs，在病原感染过程中，鸡miRNAs除了可以靶向自身的基因来调控鸡先天免疫信号，也可以靶向病原的基因从而影响病原的吸附、入侵、增殖等过程。作者主要介绍了miRNAs的生物合成、功能以及鸡miRNAs在部分病毒、细菌、寄生虫等病原侵袭过程与致病过程中的调控作用及其机制，简述了不同病原感染后鸡miRNAs的调控策略，以期从miRNAs的角度为鸡病的诊断、治疗和防控提供一定的参考。 相似文献
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鸡毒霉形体HS株pMGA多基因族的研究 总被引：2，自引：1，他引：1
鸡毒霉形体（Mycoplasma gallisekpticum,GM)基因组中存在着编码细胞表面血凝粘附素蛋白（protein of Mycoplasma gallisepticum adhesin,pMGA)相关基因组的多基因族。为筛选出含有完整的pMGA基因片段，并估算出鸡毒霉形体HS株基因组中pMGA多基因族的基因数，本试验以pUC18为载体，用EcoR I限制性内切酶构建了鸡毒霉形体HS株的基因组文库。根据pMGA基因引导序列的保守区和pMGA基因间隔区的序列，人工合成了2个寡核苷酸探针（探针I、探针Ⅱ），经标记后，双筛选所建的基因文库，从600个转化子中共得到的38个含有pMGA基因的阳性克隆子，选其中1个7．5kb的片段（17号阳性克隆子，W17），用4种限制性内切酶（EcoR I,Hind Ⅲ，Pst I,Bgl Ⅱ）酶切消化，绘制了该片段的物理图谱。该片段酶切产物经电泳、转膜后与探针I和探针Ⅱ杂交，发现2个探针杂交图谱基本相同，根据杂交带及放射信号的强度值，估测出该片段含有4个pMGA基因，以这个片段所含的pMGA基因数为标准，估算出鸡毒霉形体HS株含有39个pMGA基因。 相似文献
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牛支原体致病机制研究进展 总被引：1，自引：0，他引：1
《动物医学进展》2015,(7)
牛支原体是引起牛呼吸系统疾病的主要病原之一,给养牛业造成了严重的经济损失。论文对近期国内外关于其致病机制的研究进展进行梳理,以期为牛支原体肺炎的防控提供参考。对牛支原体致病机制的研究可为研制有效的疫苗和新型绿色药物及其他防控途径提供理论依据,进而在临床上有效控制牛支原体引发的疾病。论文涉及三方面内容:一是牛支原体黏附蛋白的黏附作用;二是牛支原体在黏附基础上其代谢产物对宿主细胞的损伤和相关蛋白介导的宿主细胞凋亡;三是免疫学致病机制,包括黏附蛋白的免疫原性及免疫逃避机制、宿主的免疫应答及炎症损伤和宿主的抗炎反应及免疫抑制机制。 相似文献
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用限制性核酸内切酶对鸡毒霉形体(MG)HS株基因文库中经初步估测可能含有的4个鸡毒霉形体粘附蛋白(protein of Mycoplasma gallisepticum adhesin,pMAG)基因的MgW17重组质粒进行了不同组合的酶消化，根据消化片段的大小及酶切位点绘制了7．5kb外源片段的物理图谱；然后根据所得的物理图谱，选用PstI和EcoRI将MgWl7外源片段酶解成1．3、2．0、4．2kb3个部分，将它们分别亚克隆到SK^( )质粒上，得到了3个亚克隆于SGpl00、SGp200、SGp300。使用核酸外切酶Ⅲ缺失法构建缺失子系列，经序列分析后得到MgWl7外源片段的全部序列。序列全长7434bp，中间含有2个完整的pMGA基因和另2个不完整的pMGA基因的首部和尾部，分别将它们顺次命名为H—pMGAl．1、H—pMGAl．2、H—pMGAl．3和H—pMGAl．4。2个完整的pMGA基因的阅读框长度分别为1967bp(1．2)和2039bp(1．3)；H—pMGAl．1首部不完整的阅读框的长度为720bp，尾部不完整的H—pMGAl．4的长度为1752bp。将H—pMGA基因与已报道的MG．S6株、F株的pMGA基因进行了比较，探讨了pMGA基因在不同MG菌株中的相似性、基因启动子结构的差异、间隔区内GAA重复序列对转录调控的影响等。 相似文献
9.
重视支原体病的控制 提高养鸡生产水平 总被引：2，自引：0，他引：2
重视支原体病的控制提高养鸡生产水平傅先强（北京市种禽公司１０２２０９）禽的支原体病是由鸡败血支原体（ＭＧ）、滑膜支原体（ＭＳ）和火鸡支原体（ＭＭ）引起的。鸡败血支原体主要感染鸡、火鸡，也感染其他禽类，引起呼吸道疾病，在鸡群中长期流行，导致母鸡产蛋下降... 相似文献
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鸡毒支原体(MG)是对养禽业危害很大的支原体,主要导致禽类慢性呼吸道疾病(CRD),以禽的结膜炎、产蛋率及饲料转换率下降、屠宰率下降等为主要特征。MG可通过垂直和水平传播方式在鸡群中传播,每年给全球家禽产业带来巨大经济损失。随着对MG细胞表面抗原黏附素蛋白(pMGA)和PvpA、GapA的结构与功能研究的深入,K株、TG5株等MG疫苗研究也取得较大进展。由于抗生素的滥用,MG基因中也发生耐药突变,产生了QRDRs等抗药结构,导致MG在耐药性上也出现新的特点。论文主要对国内外MG的疫苗开发、耐药情况和检测技术等进行综述,旨在对家禽MG的综合防控提供借鉴。 相似文献
12.
应用多重套式PCR检测鸡毒支原体和鸡滑液囊支原体 总被引：2，自引：0，他引：2
根据已发表的鸡毒和鸡滑液支原体血凝素基因序列pMGA和vlhA各设计两对引物,建立鉴别诊断两种支原体的多重套式PCR方法,对其进行温度条件、Ⅱ步模板浓度优化及特异性、敏感性实验。该方法在两步PCR后能特异性地扩增出MG(408 bp)和MS(688 bp)两个目的片段。应用于临床样品检测,与支原体分离、SPA检测比较结果PCR灵敏度高于病原分离。 相似文献
13.
Noormohammadi AH Browning GF Cowling PJ O'Rourke D Whithear KG Markham PF 《Avian diseases》2002,46(2):405-411
Mycoplasma gallisepticum is a poultry pathogen that causes respiratory disease and loss of egg production worldwide. A live attenuated vaccine, ts-11, has been used for control of M. gallisepticum in several countries. The rapid serum agglutination test is usually used as an indicator of flock response to vaccination; however, in some flocks, the detected response may be weak or absent. With the use of specific monoclonal antibodies against M. gallisepticum strain S6 pMGA in immunoaffinity purification, the major membrane antigen of ts-11 was purified. An indirect enzyme-linked immunosorbent assay (ELISA) was developed with the purified antigen, and its potential for detection of antibodies induced after ts-11 vaccination was compared with an indirect ELISA with M. gallisepticum strain S6 pMGA. In the presence of high levels of ts-11-induced antibodies, both antigens detected similar numbers of positive sera. However, when lower levels of antibodies were present, ts-11 pMGA showed a higher sensitivity than S6 pMGA. Further examination of ts-11 pMGA with Mycoplasma synoviae-infected chicken sera revealed that ts-11 pMGA is specific for M. gallisepticum antibodies. With a panel of sera from ts-11-vaccinated or non-ts-11-vaccinated field chickens, the ts-11 pMGA ELISA was found to be more sensitive than the commercial rapid serum agglutination test in detecting antibodies to ts-11 vaccine. The results from this study suggest that the major membrane antigen of M. gallisepticum may have slightly different antigenic profiles in different strains, thereby necessitating the use of autologous antigens in serodiagnostic assays to increase sensitivity of the tests for mycoplasma antibodies. Thus, the low level of antibody response after ts-11 vaccination is, at least partially, due to the low ability of the current diagnostic antigens to bind ts-11 antibodies. 相似文献
14.
The S-layer protein CTC surface-display system of Bacillus thuringiensis (Bt) was used to test the possibility of displaying the protein of Mycoplasma gallisepticum (MG) agglutinin (pMGA) on the Bt cell surface. By fusing part of pmga1.2 (pmga1.2p) with the surface-anchoring motif of ctc, two recombinant plasmids, pCTC-PMGA1.2P and pCSPMGA1.2P, were constructed. They harboured the fusion genes ctc-pmga1.2p and csa-ctc-pmga1.2p (csa represents csaAB operon, important in anchoring the S-layer protein on the cell surface), respectively. Two recombinant Bt strains were constructed by electro-transferring recombinant plasmids to a Bt plasmid-free derivative strain BMB171. Strains obtained were BCCG (bearing pCTC-PMGA1.2P and the csaAB operon-carrying plasmid pMIL-CSA) and CG (pCSPMGA1.2P). The vegetative cells of both strains were used as antigens for haemagglutination (HA) and haemagglutination inhibition (HI) assays. HA and HI assays showed that recombinant PMGA1.2P proteins were not only displayed on the cell surface of BCCG and CG, but also specific to MG-positive serum. After oral immunization of chickens with spores, both BCCG and CG elicited a humoral response to PMGA1.2P and exhibited immunogenicity, as indicated by serum plate agglutination (SPA) assays. This study suggests the possibility of generating heat-stable and oral vaccines against infectious diseases of fowl with Bt surface-display system. 相似文献
15.
We have previously identified species-specific DNA fragments, referred to as MS2/28 and Mm14, of Mycoplasma synoviae and Mycoplasma meleagridis, respectively. In the present study, we extended our analysis of the MS2/28 fragment that was found to encode a species-specific antigenic site, and we demonstrated the specificity of the Mycoplasma gallisepticum hemagglutinin protein encoded by pMGA1.2 (a member of the vlhA gene family). Then, we combined the Escherichia coli-expressed products of MS2/28, Mm14, and pMGA1.2, to develop a recombinant antigen-based enzyme-linked immunosorbent assay (recELISA), for the simultaneous and specific detection of antibodies to the three aforementioned major avian mycoplasma species. For comparative purposes, a novel in-house crude antigen capture ELISA (capELISA) was developed in parallel. In the latter protocol, the microtiter wells were enriched in species-specific antigens by capturing sonicated crude antigens on coated rabbit polyclonal antibodies that had been extensively adsorbed with the whole antigen of the heterologous species. With regard to rapid serum agglutination, both ELISA tests were highly specific, and they showed a significant correlation when field sera from naturally infected birds were tested. recELISA proved to be highly specific because absorbance values, with the heterologous species, were significantly lower (P < 0.001) than those obtained with capELISA. Given its cost-effectiveness and simplicity, the recombinant antigen-based ELISA seems to represent a valid tool for the specific screening of the three major avian mycoplasma species. recELISA will be particularly useful with regard to trade control because a large number of samples from various fields could be rapidly processed. 相似文献
16.
The efficacy of two media, an Edward-type medium (EPJ) and a modified SP4-type medium (SP4-PS), were compared for primary isolation of Mycoplasma gallisepticum (MG) from commercial layer chickens (n = 58) vaccinated with the live F strain of MG. Three groups of chickens that differed in the interval after vaccinal exposure to the F strain (32, 41, and 102 weeks) were studied at necropsy. Mycoplasma isolation was attempted from the trachea, sinus, and cloaca using lavage and swab techniques but was successful only from the trachea and sinus. MG was isolated from 39 (8.4%) of 463 culture attempts from 58 tracheal inocula and 58 sinus inocula. Isolation of MG was successful more frequently using EPJ medium than SP4-PS medium, and isolation occurred more often from the sinus than from the trachea. Of the 58 chickens studied, 19 (33%) were shown by culture to be infected with MG. Isolation was successful only from 32- and 41-week post-vaccination exposure groups. However, all chickens studied were serologically positive for MG antibody by rapid-plate agglutination and hemagglutination-inhibition assays. 相似文献
17.
Commercial laying hens were examined microbiologically at necropsy 31 or 42 weeks after aerosol vaccination with the F strain of Mycoplasma gallisepticum (MG). Mycoplasma isolates were studied in Western blots probed with polyclonal antiserum raised in rabbits to F strain immunogen. The persistence of the vaccine strain was demonstrated by detection of a 75-kilodalton immunoreactive protein, which was present in all MG isolates and thought to be a unique marker of the F strain. Use of PCA-F to probe Western blots allowed simultaneous identification of non-MG isolates, non-F strains of MG, and the F strain of MG. 相似文献
18.
In this study, the technical performance of culture, two commercially available polymerase chain reaction (PCR) tests, rapid plate agglutination (RPA) test, hemagglutination inhibition (HI) test, and eight commercially available enzyme-linked immunosorbent assays (ELISAs) were compared for the detection of avian mycoplasma infections from 3 days postinfection (d.p.i.) through 35 d.p.i. The tests were carried out on samples from specified pathogen-free layers that were infected at 66 wk of age with recent Mycoplasma synoviae (MS) and Mycoplasma gallisepticum (MG) field strains, MS and MG ATCC strains, and Mycoplasma imitans (MIM), respectively. Results showed a high percentage of positive samples in the homologous infected groups and a high percentage of negative samples (100%) in the uninfected and heterologous infected groups during 35 d.p.i. of both culture and PCR tests. For the group infected with the MG 15302 ATCC strain, serology was more sensitive than bacteriology. All MG and MS tests, with the exception of MG ELISA kit D showed a lower percentage of positive samples during 35 d.p.i. for the detection of the MG and MS ATCC strain infection compared with that of the field strains. Also, the number of cross-reactions (false positives) in the serologic tests was lower after infection with an ATCC strain than after an infection with the MG or MS field strain. Contradictory to other studies, the ELISAs and the RPA test using undiluted serum showed a relatively high number of false-positive results. The MG ELISAs (except ELISA kit D) showed more false-positive results (up to 37%) in the MIM-infected group than in the MS-infected groups. This was not unexpected, as MIM and MG have a close antigenic relationship. The results of the serologic tests in this study showed that a certain level of false-positive results can be expected in about any serologic test. Although the level of false-positive results varied between several serologic tests, this study showed that it is not advisable to rely completely on one test (system) only. 相似文献
19.
Two groups of Mycoplasma gallisepticum (MG) isolates (n = 24) from Jordan were analyzed by molecular methods and compared with other Middle Eastern isolates, related international isolates, and reference strains. The first group (n = 19) was isolated from July 2004 to January 2005 (isolation period A), and the newer group (n = 5) from June 2007 to April 2008 (isolation period B). The groups of isolates are from chicken flocks from northern Jordan, but are not from the same farms. None of the flocks were vaccinated for MG. Random amplified polymorphic DNA analysis, targeted sequencing of the partial MG cytadhesin 2 (mgc2), and the MG 16S-23S rRNA intergenic spacer region (IGSR) divided the Jordanian isolates into two groups. All of the 19 isolates from time period A, in addition to two isolates from time period B, were indistinguishable from the F strain. Three of five isolates from time period B were characterized as wild types and were indistinguishable from each other. The wild-type field strain was readily distinguished from the F strain. It was 91% and 96.4% similar to the F strain based on Clustal-W alignments of sequences of mgc2 and IGSR, respectively. Sequence similarity of mgc2 gene of the Jordan wild-type strain to isolates from Israel and Egypt ranged from 96.5% to 100%, whereas for IGSR it was 99.4%-100%. We theorize that the F-strain live MG vaccine, commonly used in Jordan prior to 2007, was transmitted to nonvaccinated poultry in the region and was a predominant genotype during time period A. 相似文献