鸡毒支原体SJ株的生物学特性及结构蛋白分析

对鸡毒支原体（MG）SJ株的生物学特性及结构蛋白进行分析，试验结果表明该菌株易于猪血清培养基中生长，并经5次传代后生长趋于稳定。与F株比较，SJ株对鸡胚气管环纤毛的损伤更为严重。SDS－PAGE图谱显示SJ，F和PG31之间的蛋白条带略有差异，暗示了结构蛋白的这些细微变化可能是MG致病的重要因素。     

用SDS—PAGE分析鸡毒霉形体广西分离株的结构蛋白

应用SDS－PAGE对鸡毒霉形体（Mycoplasma gallisepticum,MG)4个标准株和5个广西分离株的结构蛋白进行了比较分析。结果，在凝胶电泳图谱中10－100ku蛋白分子质量之间，F株缺少87ku蛋白带，Y3株在最靠近87ku蛋白带的上方和下方各缺少1条蛋白带，H2株和Y2株缺少64ku蛋白带，CH株缺少29ku蛋白带，97、75、43ku处的蛋白带为4个MG标准株和5个MG分离株所共有。表明9个MG供试菌株的结构蛋白都存在一定的差异，广西MG分离株的结构蛋白呈现多样性。     

鸡败血霉形体F株接种对商品产蛋鸡耐受热刺激的影响

鸡败血霉形体(MG)F 株在混合年龄商品产蛋鸡中的应用已获得认可。美国动物卫生协会的正式委员会同意在州政府有关部门控制下使用美国农业部批准商品生产的 MG 活苗。虽然 MG F 株能够产生气囊病变,但 Rodrigues 和 Kleven 研究认为在没有混合感染时,这种感染的严重程度低于野外强毒株。这些结果,加之生产商非正式报道1986年7～8月份。MG F 株免疫母鸡死亡率增加,表明 MG F株免疫可使鸡对热应激死亡有较大敏感性。确实,众多的禽病,以及随后因性能下降和死亡造成的损失都被认为与空气温度和/或湿度有关,也仅与热应激有关.本研究的目的是为了确定高传代 MG F 株免疫对于商品产蛋鸡热应激敏感性的影响。     

猪脾转移因子与鸡毒支原体F弱毒疫苗株联合接种对SPF鸡淋巴细胞比率影响的研究

为了解猪脾转移因子(TF)与鸡毒支原体(MG)F弱毒疫苗株联合接种对SPF鸡淋巴细胞比率的影响,以活菌数达109 ccu/mL的MG F株0.033 mL/羽与TF 0.02 mL/羽分侧点眼SPF鸡,设为A组;B组以MG F株0.033 mL/羽与生理盐水0.02 mL/羽分侧点眼;C组以生理盐水0.033 mL/羽与TF 0.02 mL/羽分侧点眼;D组以生理盐水0.033 mL/羽和0.02 mL/羽对应分侧点眼,作为对照组.点眼后第7 d采血测定淋巴细胞比率.结果显示,A组(63.9%)、B组(53.8%)和C组(54.6%)的淋巴细胞比率均值分别比D组(41.5%)提高了22.4%、12.3%和13.1%.结果表明,TF与MG F株单独使用均能提高SPF鸡的淋巴细胞比率,且TF与MG F株联合使用后淋巴细胞比率提高值高于单独使用.     

鸡毒支原体F弱毒疫苗株细胞免疫特性研究

为了解鸡毒支原体（Mycoplasma gallisepticum,MG）F弱毒疫苗株的细胞免疫特性,分别以活菌浓度为109（A组）、106（B组）ccu/mL的MG F株及生理盐水（C组）点眼接种SPF鸡,采用流式细胞技术及T淋巴细胞增殖试验对免疫前后淋巴细胞亚类Th/T、Tc/T、Th/Tc及刺激指数（SI）的动态变化规律进行研究。结果显示免疫后A、B组的Th/T、Tc/T、SI明显升高,其中Th/T于d5、d7,Tc/T、SI于d7、d14,A组显著高于B组（P〈0.05）。研究结果表明,免疫MG F株可较好的提高鸡的细胞免疫,且MG F株活菌浓度与接种鸡外周血Th/T、Tc/T、SI呈正相关。     

用SDS—PAGE进行鸡败血霉形体结构蛋白分析

利用SDS－PAGE方法对禽败血霉形体R，S6，F株和6株国内分离株进行了结构蛋白比较分析，电泳凝胶染色扫描结果显示，各株之间结构蛋白差异较大，R，S6株P64蛋白表达量较高，D9604株与其相似性较高，D9601，D9603和D9605与F株均有一条特异的75kDa条带，提示我国分离的MG强毒株可能存在着多样性。     

两株鸡败血支原体疫苗联合免疫为蛋鸡提供良好保护

近来，密西西比州立大学科学家研究了蛋鸡产蛋前期单独接种ts-11株鸡败血支原体（ts-11MG）疫苗或者与F株鸡败血支厚体（FMG）疫苗联合接种对商品蛋鸡消化器官、繁殖器官、血液特性的影响。试验鸡只的免疫接种方式采取以下4种处理：10周龄，假疫苗；10周龄，tS-11MG疫苗；10周龄，ts-11MG，22周龄，FMG；10周龄时，ts-11MG，45周龄时，FMG。结果显示，除了相对阴道长度，     

鸡毒支原体研究概况

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。     

鸡毒支原体增菌培养工艺及灭活油苗免疫效果

从满足鸡毒支原体生长繁殖对营养物质需求和提供高浓度繁殖生长空间两个方面着手,研究出鸡毒支原体增菌培养工艺。对MGS6株、R株增菌培养后,由于MG大量高浓度繁殖,使透明的培养液变得十分浑浊浓厚．颜色由近于黑色变成土黄色．静止数小时．瓶底产生一层乳白色MG菌体沉淀．菌数可达10^20FU／mL。10倍稀释制成油乳剂灭活苗免疫MG阳性鸡群．早期发病雏鸡免疫后15d左右临床症状消失．鸡群几乎不再发生鸡毒支原体病．并可控制减少鸡大肠杆菌病的发生．在鸡毒支原体培养及免疫方面取得突破性进展．     

鸡败血支原体mga0553编码基因的克隆与表达

设计1对引物对鸡败血支原体R株mga0553基因进行PCR扩增,并通过双酶切定向克隆到原核表达载体pET-32a（＋）,获得重组质粒pET-32a-mga0553。重组质粒经诱导表达并取表达产物进行分析,结果显示,mga0553基因获得了融合表达。Western—blotting证实,表达产物MGA_0553与MG阳性血清具有免疫反应性;生长抑制试验表明,鼠抗MGA0553血清对MG细胞的增殖具有抑制作用;间接免疫荧光染色检测结果显示：MG细胞呈现较强的绿色荧光。研究结果表明mga0553基因编码蛋白MGA_553是MG的一种膜相关蛋白。     

A quantitative study of single and mixed infection of the chicken trachea by Mycoplasma gallisepticum

The interaction between Mycoplasma gallisepticum (MG) and the tracheal mucosa of the young chicken was studied. The use of a selective plating method permitted differentiation between a pathogenic tylosin-resistant strain (227) and a less pathogenic tylosin-sensitive vaccine strain (F). Both MG strains adhered to the tracheal mucosa and colonized equally well. In mixed infection, the presence or absence of the second strain did not change the efficiency of colonization by either strain. When chickens were exposed to the vaccine strain 24 hr or 2 weeks before superinfection by the pathogen, there was no significant reduction in the efficiency of superinfection, despite the presence of 10(6) colony-forming units of MG strain F in the trachea. However, chickens had an increased ability to resist superinfection 5 weeks after exposure via the air sac. These results suggest that the biological mechanism underlying protection of F-strain-vaccinated chickens against adventitious infection by the homologous species does not involve competition for adherence sites or blockage by prior colonization.     

Identification of the antigenic components of the virulent Mycoplasma gallisepticum (R) in chickens: their role in differentiation from the vaccine strain (F)

The antibody response to different proteins of Mycoplasma gallisepticum (MG) was studied in chickens experimentally infected with virulent MG R strain. The chickens were challenged at 8 weeks of age by the intranasal route. Each cockerel received 1.3 X 10(6) colony-forming units (CFU). MG strains (R and F) were banded by Sodium Dodecyl Sulfate-Polyacrylamide Gel Electrophoresis (SDS-PAGE). The banding pattern was distinctively different between the two strains in the range of 92.5 to 200 kilodaltons (kD). Chicken sera collected at different times following challenge were analyzed by Western blot to determine the patterns of antibodies raised to specific MG proteins (R versus F strains). Early in infection (2 weeks postchallenge), antibodies to 60-kD and 75-kD polypeptides of MG R strain were produced. Subsequently (greater than or equal to 4 weeks postchallenge), antibodies recognized a larger number of MG antigens in both strains. The immunoblot patterns remained the same in the period 8-11 weeks postinfection in each of the two strains; however, the patterns were different when the two strains were compared. The early response recognized the 75-kD protein in the R strain while it recognized the 80-kD protein in the F strain. The late response recognized the 130-kD protein and the protein slightly heavier than 200 kD in the R strain. These two bands did not appear in the immunoblot performed against the F strain of MG. Electroeluted protein of MG R strain, namely adhesin (75 kD), showed a hemagglutination activity (HA) on chicken red blood cells. With the appearance of antibodies specific to the 60-kD and 75-kD polypeptides, there was a significant rise in hemagglutination-inhibition geometric mean titer of chicken sera.     

Experimental infection of ducks with Mycoplasma gallisepticum

Specific-pathogen-free ducks 24 and 180 days old were inoculated intranasally with the S6 strain of Mycoplasma gallisepticum (MG). No significant gross lesions were found in trachea, lung or air sacs at 7 or 28 days postinfection (PI). MG was recovered from the infraorbital sinus and trachea but not from the air sacs 7 and 28 days PI. A few ducks responded serologically by developing agglutinating antibody. MG multiplied in embryonated duck eggs but to lower titers than in embryonated chicken eggs.     

Evaluation of protection against Mycoplasma gallisepticum infection in chickens vaccinated with the F strain of M. gallisepticum

The effect of vaccination with the F strain of Mycoplasma gallisepticum (MG) on protection against challenge with a tylosin-resistant strain of MG was evaluated. White leghorn chickens vaccinated via eyedrop at 6 weeks of age were subsequently challenged with various dilutions of the tylosin-resistant MG strain, as were unvaccinated controls. Three days later, tracheal swabs were collected and cultured in medium with and without tylosin to distinguish between the vaccine and challenge strains. The mean infectious dose of the challenge strains was 3.8 log10 higher in the vaccinated group than in the controls, and the vaccinated group harbored fewer challenge organisms in the trachea. These findings suggest that the F strain of MG induces protection against infection with field strains of MG and that long-term vaccination with the F strain in multiple-age layer farms may result in replacement of field MG strains by the F strain.     

Comparison of a modified Edward-type medium and a modified SP4-type medium for primary isolation of Mycoplasma gallisepticum (MG) from chickens vaccinated with the F strain of MG

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.     

鸡毒支原体株间结构蛋白及其抗原性变异的比较研究

本研究以ＳＤＳ－ＰＡＧＥ及Ｗｅｓｔｅｒｎ Ｂｌｏｔ技术,应用鸡毒支原体国外强毒株Ｓ６、标准株ＰＧ３１,疫苗株Ｆ,北京分离 ＢＧ４４Ｔ、ＮＢ７２特异性多克隆抗血清对以上五株及疫苗株Ｖ、北京分离株Ｃ的结构及其抗原性进行了比较结果表明ＭＧ结构蛋白及其抗原性存在着株间的多样性和一定相似性,其中以Ｆ与Ｓ６、ＢＧ４４Ｔ与ＰＧ３１、ＮＢ７２与Ｃ更为接近,可能具有同源性。ＳＤＳ－ＰＡＧＥ显示出了ＭＧ株间结构蛋白微     

Identification of F strain Mycoplasma gallisepticum isolates by detection of an immunoreactive protein

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.     

鸡贫血病毒vp3基因克隆、序列分析和比较

克隆了从我国哈尔滨分离的一株鸡贫血病毒（CAV）的vp3基因，并对之进行了测序。该基因的开放读码枢由366bp组成，编码121个氨基酸，氨基酸组成具有已报道VP3的典型特点。本次克隆的基因与GenBank收录的CAV的vp3基因进行序列比较，同源性至少为98％。与国内报道的山东株SJ1的vp3基因有3个核苷酸的差异，表明国内的CAV毒株已经产生了一些分化。在EMBL中比较本次克隆的VP3蛋白一级结构，与之差异最大的是马来西亚分离株的VP3，有5个氨基酸残基不同，同源性为96％。同时收集EMBL中的CAV的VP3蛋白绘制进化树，我国哈尔滨分离的CAV毒株与CIA进化关系最近，而与Cux-1的2个衍生株QDWX1、QDWX3进化关系最远。这些结果进一步证明了CAV在遗传方面是较保守的病毒，来自哈尔滨的CAV不是CAV的一个独立分支。     

Use of mgc2-polymerase chain reaction-restriction fragment length polymorphism for rapid differentiation between field isolates and vaccine strains of Mycoplasma gallisepticum in Israel

Increasing use of Mycoplasma gallisepticum (MG) live vaccines has led to a need for a rapid test for differentiation of MG field strains from the live vaccine strains ts-11 and 6/85. We examined the differentiating potential of diagnostic polymerase chain reaction (PCR) primers targeted to the gene mgc2, encoding a cytadherence-related surface protein uniquely present in MG. The mgc2-PCR diagnostic primers are specific for MG in tests of all avian mycoplasmas or bacteria present in the chicken trachea and are sensitive enough to readily detect MG in tracheal swabs from field outbreaks. Differentiation of vaccine strain ts-11 was based on identification of restriction enzyme sites in the 300-base-pair (bp) mgc2-PCR amplicon present in ts-11 and missing in MG isolates from field outbreaks in Israel. Restriction sites for the enzymes HaeII and SfaN1 were identified in the amplified region in strain ts-11 and were not found in 28 field isolates of MG, comprising a representative cross section of all the MG isolates from the period 1997-2003. In practice, differential diagnosis of MG is achieved within 1 day of submission of tracheal swab samples by mgc2-PCR amplification and restriction of the amplicon with HaeII, giving a 270-bp fragment for ts-11 or no restriction for other MG strains tested. Application of the mgc2-PCR-restriction fragment length polymorphism (mgc2-PCR-RFLP) assay enabled differential diagnosis of both components of a mixture of ts-11 and non-ts-11 DNA, detecting the field strain in the presence of a large excess of ts-11. The test was successfully applied in vivo for monitoring vaccinates in a ts-11 vaccine trial. In principle, the test may also be used to identify the 6/85 vaccine strain, which yields a 237-bp product, readily differentiated from the approximately 300-bp PCR product of all other strains tested. Further testing of field isolates will be necessary to determine the applicability of this test in the United States and other countries.     

Influence of F strain Mycoplasma gallisepticum infection on response of commercial layers to heat exposure

Commercial layers were inoculated with F strain Mycoplasma gallisepticum (MG) and housed in either conventional chicken houses or the lower-stress environment of biological isolation units. At the end of 2 weeks, all treatment groups were placed in environmental chambers and subjected to 4 hr of heat stress (40 C with a dew point of 21 C). Rectal temperature, an indicator of response to high heat, was monitored. Rectal temperatures of F strain MG-inoculated hens housed in the conventional chicken house environment were significantly higher than those of uninoculated controls, whereas rectal temperatures of hens held in isolation units were comparable to those of their uninoculated controls.