A winged-helix protein from Sulfolobus turreted icosahedral virus points toward stabilizing disulfide bonds in the intracellular proteins of a hyperthermophilic virus

Sulfolobus turreted icosahedral virus (STIV) was the first non-tailed icosahedral virus to be isolated from an archaeal host. Like other archaeal viruses, its 37 open reading frames generally lack sequence similarity to genes with known function. The roles of the gene products in this and other archaeal viruses are thus largely unknown. However, a protein's three-dimensional structure may provide functional and evolutionary insight in cases of minimal sequence similarity. In this vein, the structure of STIV F93 reveals a homodimer with strong similarity to the winged-helix family of DNA-binding proteins. Importantly, an interchain disulfide bond is found at the dimer interface, prompting analysis of the cysteine distribution in the putative intracellular proteins of the viral proteome. The analysis suggests that intracellular disulfide bonds are common in cellular STIV proteins, where they enhance the thermostability of the viral proteome.     

武汉市6起食物中毒副溶血弧菌分子特征研究

目的：了解武汉地区6起食物中毒病原菌副溶血弧菌分子特征。方法：对6起食物中毒共16株分离株进行药敏分析,运用PCR技术进行耐热性溶血毒素基因（tdh）和耐热性溶血毒素相关溶血素基因（trh）检测,并进行肠道细菌重复基因间共同序列PCR（ER IC-PCR）分析。结果：16株副溶血弧菌对第三代头孢和喹诺酮类较敏感,tdh阳性,trh阴性,ER IC-PCR结果显示每起食物中毒菌株亲缘关系非常紧密,有3起属于同一个群,另外2起属于一个群。结论：武汉地区流行的主要副溶血弧菌分子特征为tdh阳性,trh阴性,ER IC-PCR技术是分析副溶血弧菌引起食物中毒菌株非常有效的工具。     

环境样品中病原性副溶血性弧菌高效检出法

〔目的〕为了提高环境样品中病原性副溶血性弧菌的检出率。〔方法〕采用PCR法、免疫磁珠法和神奈川现象培养基三者结合使用。〔结果〕分别从一份海水和一份海泥中检出了产生TDH ,神奈川现象阳性的副溶血性弧菌 ,血清型为O3 :K6。该血清型与同期发生的副溶血性弧菌食物中毒患者检出率最高的副溶血性弧菌血清型相同。经SfiⅠ ,NotⅠ限制性内切酶处理后 ,脉冲场凝胶电泳比较 ,一份海水与一名患者分离菌株、一份海泥与两名患者分离菌株的条带相同 ,表明为同一克隆派生而来。同时也说明食物中毒的发生与污染了TDH阳性O3:K6副溶血性弧菌的海水有关。〔结论〕该方法解决了用一般细菌培养分离方法很难从引起食物中毒的环境样品中检出病原性副溶血性弧菌的困扰 ,也为研究TDH阳性副溶血性弧菌在环境中的分布及由其引起的食物中毒的预防提供了重要依据。     

A novel buffer system, AnyDirect, can improve polymerase chain reaction from whole blood without DNA isolation

BACKGROUND: Polymerase chain reaction (PCR) using DNA from blood samples is a valuable tool in the field of medical diagnostics. However, DNA isolation from blood is a laborious and sample-consuming step, and hampers the automation of PCR for large-scale studies. Attempts to perform PCR from blood without DNA isolation have been difficult to achieve, since numerous endogenous and exogenous blood constituents may inhibit PCR. METHODS: We used a novel buffer system, 'AnyDirect', that conserves the enzymatic activity of DNA polymerases for effective use in direct PCR from whole blood under various conditions. RESULTS: Using AnyDirect, DNA amplification was achieved from whole blood with a variety of thermostable DNA polymerases. Amplification occurred regardless of target size (up to 1.7 kb), presence of various known PCR inhibitors, and high target GC content. Importantly, low copy number DNA targets were effectively amplified from whole blood. CONCLUSIONS: AnyDirect buffer allows direct PCR from whole blood and may facilitate detection of genetic diseases or infections by eliminating the time and effort for DNA extraction. The use of AnyDirect could facilitate the development of high-throughput PCR for large-scale diagnostic screening or investigation of various medical conditions.     

Molecular cloning and characterization of a new and highly thermostable esterase from Geobacillus sp. JM6

A new lipolytic enzyme gene was cloned from a thermophile Geobacillus sp. JM6. The gene contained 750 bp and encoded a 249‐amino acid protein. The recombinant enzyme was expressed and purified from Escherichia coli BL21 (DE3) with a molecular mass of 33.6 kDa. Enzyme assays using p‐nitrophenyl esters with different acyl chain lengths as the substrates confirmed its esterase activity, yielding the highest activity with p‐nitrophenyl butyrate. When p‐nitrophenyl butyrate was used as a substrate, the optimum reaction temperature and pH for the enzyme were 60 °C and pH 7.5, respectively. Geobacillus sp. JM6 esterase showed excellent thermostability with 68% residual activity after incubation at 100 °C for 18 h. A theoretical structural model of strain JM6 esterase was developed with a monoacylglycerol lipase from Bacillus sp. H‐257 as a template. The predicted core structure exhibits an α/β hydrolase fold, and a putative catalytic triad (Ser97, Asp196, and His226) was identified. Inhibition assays with PMSF indicated that serine residue is involved in the catalytic activity of strain JM6 esterase. The recombinant esterase showed a relatively good tolerance to the detected detergents and denaturants, such as SDS, Chaps, Tween 20, Tween 80, Triton X‐100, sodium deoxycholate, urea, and guanidine hydrochloride.

     

双重PCR检测副溶血性弧菌的tlh和tdh基因方法建立与初步应用

目的 建立同时检测副溶血性弧菌的tlh和tdh基因的双重聚合酶链式反应(PCR)法. 方法 根据副溶血性弧菌的tlh、tdh基因序列设计引物,进行PCR扩增及电泳检测.同时优化反应体系,测定稳定性、重复性、特异性及灵敏度. 结果 本实验设计的引物能特异性地扩增副溶血性弧菌的450、269 bp的片段,而对其它种类的菌物无特异性扩增,结果表明该方法特异性好,双重PCR检测灵敏度为100 cfu/ml.并进行了肛门拭子样品的检测. 结论 初步建立能在8h内快速、灵敏、特异地检出副溶血性弧菌毒力菌株的双重PCR技术.     

检测副溶血弧菌TDH斑点免疫胶体金渗滤法的研究

目的:制备特异性检测副溶血弧菌TDH的斑点免疫胶体金渗滤测试盒(Dot immunogold filtration assay,DIG-FA)。方法:T6D4和T9H4两株抗体分别标记于金颗粒和点样于硝酸纤维素膜,通过双抗体夹心法来开发斑点免疫胶体金渗滤测试盒,并对测试盒的特异性、重复性、稳定性做了分析。结果:研制的斑点免疫胶体金渗滤测试盒能够特异性检测副溶血弧菌TDH,其最低检测限达到250 ng/ml TDH,该测试盒在4℃恒温条件下保存12周后仍表现出准确和稳定的检测结果。结论:成功制备了检测副溶血弧菌TDH的斑点免疫胶体金渗滤测试盒,对现场快速检测TDH提供了可靠的测试工具。     

Can thermostable vaccines help address cold-chain challenges? Results from stakeholder interviews in six low- and middle-income countries

IntroductionThis study captures the perspectives of stakeholders at multiple levels of the vaccine supply chain regarding their assessment of challenges with storing vaccines within recommended temperature ranges and their perceptions on the benefits of having vaccines with improved stability, including the potential short-term storage and transport of vaccines in a controlled-temperature chain.MethodsSemi-structured interviews were undertaken with 158 immunization stakeholders in six countries. Interviewees included national decision-makers and advisors involved in vaccine purchasing decisions, national Expanded Programme on Immunization managers, and health and logistics personnel at national, subnational, and health facility levels.ResultsChallenges with both heat and freeze-exposure of vaccines were recognized in all countries, with heat-exposure being a greater concern. Conditions leading to freeze-exposure including ice build-up due to poor refrigerator performance and improper icepack conditioning were reported by 53% and 28% of participants, respectively. Respondents were interested in vaccine products with improved heat/freeze-stability characteristics. The majority of those involved in vaccine purchasing indicated they would be willing to pay a US$0.05 premium per dose for a freeze-stable pentavalent vaccine (68%) or a heat-stable rotavirus vaccine (59%), although most (53%) preferred not to pay the premium for a heat-stable pentavalent vaccine if the increased stability required changing from a liquid to a lyophilized product. Most respondents (73%) were also interested in vaccines labeled for short-term use in a controlled-temperature chain. The majority (115/158) recognized the flexibility this would provide during outreach or should cold-chain breaks occur. Respondents were also aware that possible confusion might arise and additional training would be required if handling conditions were changed for some, but not all vaccines.ConclusionParticipating immunization stakeholders recognized the benefits of vaccine products with improved stability characteristics and of labeling vaccines for controlled-temperature chain use as a means to help address cold-chain issues in their immunization programs.     

杭州地区2000-2002年副溶血弧菌的分子分型研究

目的了解杭州地区2000-2002年副溶血弧菌临床和环境分离菌株的分子流行病学特征.方法对172株2000年和2002年从临床食物中毒患者和散发腹泻病例以及外环境（小水产品）中分离的副溶血弧菌菌株进行血清分型.对40株临床来源O3：K6型菌株及环境来源O3：KUT（K抗原未分型）型菌株,应用PCR技术进行耐热直接溶血素基因（tdh）和耐热直接溶血素相关基因（trh）的检测,并进行核糖体基因分型（ribotyping）、随机扩增多态性DNA分析（RAPD）、肠道细菌重复基因间共同序列PCR（ERIC-PCR）等.结果在调查的13起副溶血弧菌引起的食物中毒中,tdh阳性、trh阴性的O3：K6血清型引起的有11起（84.6%）;tdh阳性、trh阴性的O4：K8菌引起有2起（15.4%）.在散发腹泻病例中,tdh阳性、trh阴性的O3：K6、O4：K8和O1：KUT菌株分别占26.5%（9/34）、17.6%（6/34）和38.2%（13/34）,未能分型的占17.6%（6/34）.在水产品中分离的菌株中,37株分属7种O血清型,其中未见有O3：K6和O4：K8血清型;另外有9株未能分型;其中除1株O1：KUT菌株trh阳性外,其余tdh和trh均为阴性.绝大部分食物中毒患者和散发腹泻病例分离的O3：K6菌株在ribotyping、ERIC-PCR及RAPD三种指纹上均属于一种密切相关的克隆群,而环境分离的O3：KUT菌株与临床分离的O3：K6菌株间,在三者指纹上均有明显差异.结论临床来源和小水产品来源的副溶血弧菌菌株间血清型分布有显著差别;一群关系密切、tdh阳性、trh阴性的O3：K6血清型菌株在杭州地区呈优势流行.