Structure of a carotenoid gene cluster from Pantoea sp. strain C1B1YArunkumar K.R.
Structure of a carotenoid gene
cluster from Pantoea sp. strain C1B1Y and characterization of β-carotene hydroxylase (crtZ) gene
by functional complementation in Escherichia coli.
Guide to Molecular Cloning - Download the GuideQIAGEN
Molecular cloning can be sometimes tricky with significant challenges involved. Overcome the challenges with the essential knowledge and tips for successful cloning.
NativeFolderTM is a bacterial culture medium specially formulated to promote the folding and the expression of soluble recombinant proteins in E. coli. NativeFolderTM contains proprietary compounds that prevent protein aggregation and misfolding during protein expression. Don’t waste your time experimenting with the renaturation of inclusion bodies. Use NativeFolderTM and express your correctly folded target protein in the soluble fraction. Simply add water to the provided mix, autoclave and filter sterilize. Recombinant proteins of up to 110 kDa were successfully expressed as soluble fractions using NativeFolderTM.
Structure of a carotenoid gene cluster from Pantoea sp. strain C1B1YArunkumar K.R.
Structure of a carotenoid gene
cluster from Pantoea sp. strain C1B1Y and characterization of β-carotene hydroxylase (crtZ) gene
by functional complementation in Escherichia coli.
Guide to Molecular Cloning - Download the GuideQIAGEN
Molecular cloning can be sometimes tricky with significant challenges involved. Overcome the challenges with the essential knowledge and tips for successful cloning.
NativeFolderTM is a bacterial culture medium specially formulated to promote the folding and the expression of soluble recombinant proteins in E. coli. NativeFolderTM contains proprietary compounds that prevent protein aggregation and misfolding during protein expression. Don’t waste your time experimenting with the renaturation of inclusion bodies. Use NativeFolderTM and express your correctly folded target protein in the soluble fraction. Simply add water to the provided mix, autoclave and filter sterilize. Recombinant proteins of up to 110 kDa were successfully expressed as soluble fractions using NativeFolderTM.
olymerase chain reaction (PCR) is a method widely used in molecular biology to make several copies of a specific DNA segment. Using PCR, copies of DNA sequences are exponentially amplified to generate thousands to millions of more copies of that particular DNA segment.
olymerase chain reaction (PCR) is a method widely used in molecular biology to make several copies of a specific DNA segment. Using PCR, copies of DNA sequences are exponentially amplified to generate thousands to millions of more copies of that particular DNA segment.
Austin Virology and Retrovirology is an international scholarly peer reviewed Open Access journal, aims to promote the research in the field of Virology.
Austin Virology and Retrovirology is a comprehensive Open Access peer reviewed scientific Journal that covers multidisciplinary fields. We provide limitless access towards accessing our literature hub with colossal range of articles. The journal aims to publish high quality varied article types such as Research, Review, Case Reports, Short Communications, Perspectives (Editorials), Clinical Images
Austin Virology and Retrovirology supports the scientific modernization and enrichment in virology research community by magnifying access to peer reviewed scientific literary works. Austin also brings universally peer reviewed member journals under one roof thereby promoting knowledge sharing, collaborative and promotion of multidisciplinary science.
a) Describe two ways the researcher could minimise experimenter bias i.docxbickerstaffinell
a) Describe two ways the researcher could minimise experimenter bias in this study.
b) Describe a way the researchers could minimise sample bias in this study. (distinct from your answers in part a)
Nuclear import of SARS-CoV-2 nucleocapsid (N) protein is not inhibited by overmectin B.A. Loney* and M.A. Larkey* *Bundoora Institute for Applied Medical Research. Introduction The causative agent of the current COVID-19 pandemic, SARS-CoV-2, is a single stranded positive sense RNA virus that is closely related to severe acute respiratory syndrome coronavirus (SARS-CoV). It has been previously shown that SARS-CoV-2 nucleocapsid (N) is present in the cytoplasm but can also actively localize to the nucleolus where it can interact with host proteins and also bind to viral RNA. It has also been previously shown that nuclear import of similar nucleocapsid proteins (including the HIV-1 nucleocapsid protein, NC) from other RNA viruses can be inhibited by the drug overmectin resulting in decreased viral replication efficiency. There are multiple nuclear import pathways mediated by different receptors. The two most common nuclear import pathways are mediated by the importin / heterodimer or by the importin homodimer. Overmectin has previously been demonstrated to inhibit nuclear import by disrupting the importin / pathway. In this study SARS-CoV-2 nucleocapsid (N) was transfected into Hela cells and the effectiveness of overmectin at inhibiting its nuclear import was determined. Methods Expression of N protein in the absence of other viral proteins. To investigate the nuclear import of SARS-CoV-2 N protein three constructs were created. 1. pEGFP-NCov2. The N gene (from SARS-CoV-2, isolate BJ04) was cloned into the eukaryotic expression vector pEGFP-C1 (Promega) such that expression of the N gene was under the control of a cytomegalovirus (CMV) polymerase Il promoter to express an N protein fusion with the C-terminal of EGFP. 2. pEGFP. The pEGFP-C1 expression vector alone. 3. EEGFP-TRF1. A positive control for nuclear import. The human TRF1 gene was cloned into the eukaryotic expression vector pEGFP-C1 to express an N protein fusion with the C-terminal of EGFP. TRF1 nuclear localisation has shown to be mediated by the importin homodimer. Hela cells were cultured in 12 separate culture plates at a density of 1 0 5 cells per 9.6 cm 2 plate with each plate containing 2 coverslips. Cells were cultured using Cell Biologics' Culture Complete Growth Medium with 5\% foetal calf serum at 3 7 C and 5% CO 2 . Cells were transfected with 2 g of either pEGFPNCov2 (plates 1,4,7 and 10), pEGFP (plates 2, 5, 8 and 11) or pEGFP-TRF1 (3, 6, 9 and 12) and 50 g of Lipofectamine (GibcoBRL). 12 hours post-transfection, even numbered plates were treated with 5 M overmectin in DMSO and odd numbered plates were left untreated. After 24 hours coverslips were removed, and the cells fixed. DAPI was added to visualise the nuclei and the localisation of GFP determined by fluorescent mic.
Rice is the principal food crop for more than half of the
world's population. Rice, as a staple food, supports more
than three billion people and comprises 50%–80% of their
daily calorie intake [1]. Adverse environmental factors
such as excessive cold, heat, drought, and salinity stresses
result in a considerable yield loss of crop plants all over
the world. Plant adaptations to environmental stresses
depend on the activation of cascades of molecularnetworks involved in signal transduction, stress perception,
and expressions of stress‐related genes. These
abiotic stresses elicit complex cellular responses in the
plant system, resulting in the production of excessive
reactive oxygen species (ROS) such as hydrogen peroxide
(H2O2), hydroxyperoxyl (HO2·), superoxide (O2
−), and
singlet oxygen (1O2) radicals. To protect themselves from
adverse conditions, plants have evolved a number of
cellular defense mechanisms including antioxidants such
as ascorbate, glutathione, and tocopherols as well as
ROS‐detoxifying enzymes such as superoxide dismutases
(SODs), peroxidases, and catalases (CATs) [2,3].
Securing your Kubernetes cluster_ a step-by-step guide to success !KatiaHIMEUR1
Today, after several years of existence, an extremely active community and an ultra-dynamic ecosystem, Kubernetes has established itself as the de facto standard in container orchestration. Thanks to a wide range of managed services, it has never been so easy to set up a ready-to-use Kubernetes cluster.
However, this ease of use means that the subject of security in Kubernetes is often left for later, or even neglected. This exposes companies to significant risks.
In this talk, I'll show you step-by-step how to secure your Kubernetes cluster for greater peace of mind and reliability.
The Art of the Pitch: WordPress Relationships and SalesLaura Byrne
Clients don’t know what they don’t know. What web solutions are right for them? How does WordPress come into the picture? How do you make sure you understand scope and timeline? What do you do if sometime changes?
All these questions and more will be explored as we talk about matching clients’ needs with what your agency offers without pulling teeth or pulling your hair out. Practical tips, and strategies for successful relationship building that leads to closing the deal.
DevOps and Testing slides at DASA ConnectKari Kakkonen
My and Rik Marselis slides at 30.5.2024 DASA Connect conference. We discuss about what is testing, then what is agile testing and finally what is Testing in DevOps. Finally we had lovely workshop with the participants trying to find out different ways to think about quality and testing in different parts of the DevOps infinity loop.
In his public lecture, Christian Timmerer provides insights into the fascinating history of video streaming, starting from its humble beginnings before YouTube to the groundbreaking technologies that now dominate platforms like Netflix and ORF ON. Timmerer also presents provocative contributions of his own that have significantly influenced the industry. He concludes by looking at future challenges and invites the audience to join in a discussion.
GridMate - End to end testing is a critical piece to ensure quality and avoid...ThomasParaiso2
End to end testing is a critical piece to ensure quality and avoid regressions. In this session, we share our journey building an E2E testing pipeline for GridMate components (LWC and Aura) using Cypress, JSForce, FakerJS…
Removing Uninteresting Bytes in Software FuzzingAftab Hussain
Imagine a world where software fuzzing, the process of mutating bytes in test seeds to uncover hidden and erroneous program behaviors, becomes faster and more effective. A lot depends on the initial seeds, which can significantly dictate the trajectory of a fuzzing campaign, particularly in terms of how long it takes to uncover interesting behaviour in your code. We introduce DIAR, a technique designed to speedup fuzzing campaigns by pinpointing and eliminating those uninteresting bytes in the seeds. Picture this: instead of wasting valuable resources on meaningless mutations in large, bloated seeds, DIAR removes the unnecessary bytes, streamlining the entire process.
In this work, we equipped AFL, a popular fuzzer, with DIAR and examined two critical Linux libraries -- Libxml's xmllint, a tool for parsing xml documents, and Binutil's readelf, an essential debugging and security analysis command-line tool used to display detailed information about ELF (Executable and Linkable Format). Our preliminary results show that AFL+DIAR does not only discover new paths more quickly but also achieves higher coverage overall. This work thus showcases how starting with lean and optimized seeds can lead to faster, more comprehensive fuzzing campaigns -- and DIAR helps you find such seeds.
- These are slides of the talk given at IEEE International Conference on Software Testing Verification and Validation Workshop, ICSTW 2022.
Encryption in Microsoft 365 - ExpertsLive Netherlands 2024Albert Hoitingh
In this session I delve into the encryption technology used in Microsoft 365 and Microsoft Purview. Including the concepts of Customer Key and Double Key Encryption.
UiPath Test Automation using UiPath Test Suite series, part 5DianaGray10
Welcome to UiPath Test Automation using UiPath Test Suite series part 5. In this session, we will cover CI/CD with devops.
Topics covered:
CI/CD with in UiPath
End-to-end overview of CI/CD pipeline with Azure devops
Speaker:
Lyndsey Byblow, Test Suite Sales Engineer @ UiPath, Inc.
Why You Should Replace Windows 11 with Nitrux Linux 3.5.0 for enhanced perfor...SOFTTECHHUB
The choice of an operating system plays a pivotal role in shaping our computing experience. For decades, Microsoft's Windows has dominated the market, offering a familiar and widely adopted platform for personal and professional use. However, as technological advancements continue to push the boundaries of innovation, alternative operating systems have emerged, challenging the status quo and offering users a fresh perspective on computing.
One such alternative that has garnered significant attention and acclaim is Nitrux Linux 3.5.0, a sleek, powerful, and user-friendly Linux distribution that promises to redefine the way we interact with our devices. With its focus on performance, security, and customization, Nitrux Linux presents a compelling case for those seeking to break free from the constraints of proprietary software and embrace the freedom and flexibility of open-source computing.
Alt. GDG Cloud Southlake #33: Boule & Rebala: Effective AppSec in SDLC using ...James Anderson
Effective Application Security in Software Delivery lifecycle using Deployment Firewall and DBOM
The modern software delivery process (or the CI/CD process) includes many tools, distributed teams, open-source code, and cloud platforms. Constant focus on speed to release software to market, along with the traditional slow and manual security checks has caused gaps in continuous security as an important piece in the software supply chain. Today organizations feel more susceptible to external and internal cyber threats due to the vast attack surface in their applications supply chain and the lack of end-to-end governance and risk management.
The software team must secure its software delivery process to avoid vulnerability and security breaches. This needs to be achieved with existing tool chains and without extensive rework of the delivery processes. This talk will present strategies and techniques for providing visibility into the true risk of the existing vulnerabilities, preventing the introduction of security issues in the software, resolving vulnerabilities in production environments quickly, and capturing the deployment bill of materials (DBOM).
Speakers:
Bob Boule
Robert Boule is a technology enthusiast with PASSION for technology and making things work along with a knack for helping others understand how things work. He comes with around 20 years of solution engineering experience in application security, software continuous delivery, and SaaS platforms. He is known for his dynamic presentations in CI/CD and application security integrated in software delivery lifecycle.
Gopinath Rebala
Gopinath Rebala is the CTO of OpsMx, where he has overall responsibility for the machine learning and data processing architectures for Secure Software Delivery. Gopi also has a strong connection with our customers, leading design and architecture for strategic implementations. Gopi is a frequent speaker and well-known leader in continuous delivery and integrating security into software delivery.
LF Energy Webinar: Electrical Grid Modelling and Simulation Through PowSyBl -...DanBrown980551
Do you want to learn how to model and simulate an electrical network from scratch in under an hour?
Then welcome to this PowSyBl workshop, hosted by Rte, the French Transmission System Operator (TSO)!
During the webinar, you will discover the PowSyBl ecosystem as well as handle and study an electrical network through an interactive Python notebook.
PowSyBl is an open source project hosted by LF Energy, which offers a comprehensive set of features for electrical grid modelling and simulation. Among other advanced features, PowSyBl provides:
- A fully editable and extendable library for grid component modelling;
- Visualization tools to display your network;
- Grid simulation tools, such as power flows, security analyses (with or without remedial actions) and sensitivity analyses;
The framework is mostly written in Java, with a Python binding so that Python developers can access PowSyBl functionalities as well.
What you will learn during the webinar:
- For beginners: discover PowSyBl's functionalities through a quick general presentation and the notebook, without needing any expert coding skills;
- For advanced developers: master the skills to efficiently apply PowSyBl functionalities to your real-world scenarios.
Sudheer Mechineni, Head of Application Frameworks, Standard Chartered Bank
Discover how Standard Chartered Bank harnessed the power of Neo4j to transform complex data access challenges into a dynamic, scalable graph database solution. This keynote will cover their journey from initial adoption to deploying a fully automated, enterprise-grade causal cluster, highlighting key strategies for modelling organisational changes and ensuring robust disaster recovery. Learn how these innovations have not only enhanced Standard Chartered Bank’s data infrastructure but also positioned them as pioneers in the banking sector’s adoption of graph technology.
Epistemic Interaction - tuning interfaces to provide information for AI supportAlan Dix
Paper presented at SYNERGY workshop at AVI 2024, Genoa, Italy. 3rd June 2024
https://alandix.com/academic/papers/synergy2024-epistemic/
As machine learning integrates deeper into human-computer interactions, the concept of epistemic interaction emerges, aiming to refine these interactions to enhance system adaptability. This approach encourages minor, intentional adjustments in user behaviour to enrich the data available for system learning. This paper introduces epistemic interaction within the context of human-system communication, illustrating how deliberate interaction design can improve system understanding and adaptation. Through concrete examples, we demonstrate the potential of epistemic interaction to significantly advance human-computer interaction by leveraging intuitive human communication strategies to inform system design and functionality, offering a novel pathway for enriching user-system engagements.
Smart TV Buyer Insights Survey 2024 by 91mobiles.pdf91mobiles
91mobiles recently conducted a Smart TV Buyer Insights Survey in which we asked over 3,000 respondents about the TV they own, aspects they look at on a new TV, and their TV buying preferences.
2. DPV and have suffered considerable economic losses in expression vector pET-32a(+) were purchased from Invitrogen.
the commercial duck industry due to high mortality, de- Yeast extract and tryptone for bacterial medium preparation were
obtained from Promega. Fetal bovine serum (FBS), antibiotics,
creased egg production of ducks and the different lethal- and isopropyl--D -thiogalactopyranoside (IPTG) were bought
ity in wild waterfowl [1–9]. In China, the virulence of from Novagen. Restriction enzymes, DNA ligase, Ex Taq DNA
DPV has recently increased in geese but declined in ducks polymerase, DNA molecular weight markers, and protein mo-
[10]. Presently, however, the molecular characteristics of lecular weight markers were obtained from TaKaRa; other re-
DPV remain largely unknown. agents were offered by the Avian Diseases Research Center of the
Sichuan Agricultural University. All reagents were of the highest
DPV is composed of a linear, double-stranded DNA purity that was commercially available. Purification of His-tagged
genome with 64.3% guanine-plus-cytosine content, protein was performed on a Ni2+-NTA resin (Qiagen). Here, E. coli
which is higher than any other reported avian herpesvi- strain DH5␣ was used as the cloning host for the UL35 gene en-
rus in the subfamily Alphaherpesvirinae [11]. Although coding VP26 because of its very high transformation efficiency.
DPV was previously grouped in the subfamily Alphaher- For the expression of His6-tagged VP26, the E. coli strain BL21
(DE3) was used. This strain has the advantage of being deficient
pesvirinae [12, 13], it was classified as an unassigned vi- in both the lon and ompT proteases and harbors the T7 bacterio-
rus in the Herpesviridae family according to the Eighth phage RNA polymerase gene, which permits the specific expres-
International Committee on Taxonomy of Viruses [14]. sion of heterologous genes driven by the T7 promoter [19–21].
At present, studies on the genomic organization and nu-
cleotide sequence of DPV lag behind other members of Preparation of DPV DNA
DPV was propagated in primary duck embryo fibroblasts that
the Herpesviridae family because most of the previous were grown in Dulbecco’s MEM (D-MEM; Gibco-BRL) supple-
studies have focused on the epidemiology and prevention mented with 10% FBS at 37 ° . For virus infection, D-MEM supple-
of this disease. To the best of our knowledge, neither the mented with 2–3% FBS was used. Viral particles were harvested
molecular structure of the genome nor the restriction en- when the cytopathic effect reached 75%. Cell lysates containing
zyme map of DPV DNA has been published up to now DPV were subjected to three freeze-thaw cycles and were then
stored at –70 ° until use. The presence of DPV was confirmed by
[4]. To date, the majority of reported DPV sequences are both electron microscopy and polymerase chain reaction (PCR),
limited to single open reading frames (ORFs) in the as described previously [15, 22].
unique long (UL) region, which includes UL6 [4, 15], To isolate the nuclear DPV DNA, 5–10 ml DPV-containing cell
UL25, UL26, UL26.5, UL27, UL28, UL29, and UL30 [16, lysate was centrifuged at 5,000 rpm for 10 min at 4 ° . The superna-
17]. However, no reports have been published concerning tant was decanted, and the cell pellet was resuspended in 2–5 ml
NET (0.1 M NaCl, 1.0 mM EDTA, pH 8.0, and 10 mM Tris, pH 8.0).
the DPV UL35 gene. Therefore, very little is known about The cell suspension was centrifuged at 5,000 rpm for 10 min at 4 ° .
the DPV UL35 gene or its encoding protein, VP26. Then, the supernatant was discarded and the pellet was redissolved
Recently, a DPV CHv-strain genomic library was con- in 750 l NET, 7.5 l proteinase K (10 mg stock), and 50 l of 15%
structed successfully for the first time [18] and the UL35 sarcosyl. The sample was incubated at 37 ° to promote proteinase
gene was discovered in our laboratory. In an effort to elu- K activity. The cell lysate was then centrifuged at 12,000 rpm for
30 min at 4 ° . The nuclear DNA-containing supernatant was trans-
cidate the function of VP26, we constructed a recombi- ferred to a fresh tube and submitted to RNase treatment at 37 ° for
nant expression plasmid that drives expression of the 1 or 2 h. DNA was extracted first with one volume of phenol (750
DPV VP26 fused to His6. This plasmid was used to trans- l), then with phenol/choloroform/isoamyl alcohol (25:24:1), and
form Escherichia coli BL21 (DE3) cells, which were sub- finally with chloroform. DNA was precipitated with two volumes
sequently induced to express the recombinant protein of prechilled absolute ethanol and stored at –20 ° for future use.
(His6-tagged VP26). His6-tagged VP26 was purified to Primer Design and PCR Amplification of the DPV UL35 Gene
near homogeneity using single-step immobilized metal The full-length DPV UL35 gene (GenBank accession No.
affinity chromatography (IMAC) on a nickel-nitrilotri- EF643558) is composed of 354 base pairs and contains a complete
acetic acid (Ni2+-NTA) affinity resin. The purified pro- theoretical ORF for a 117-residue UL35-like protein. The primers
tein was then used as an antigen for the production of for the PCR-based amplification of this ORF were designed using
the biological software Oligo6.0 and Primer5.0 and were synthe-
polyclonal antibody specific for His6-tagged VP26. sized by TaKaRa, with an expected amplified fragment of 354 bp.
The upstream primer 5GGATCCATGTCTAATTCTGGAG-
GTTCA anneals with the first 21 nucleotides of the UL35 se-
Materials and Methods quence and introduces an upstream BamHI restriction site (un-
derlined). The downstream primer 5AAGCTTTTATCGCT-
Virus, Strains, Plasmids, Enzymes, and Other Materials GATCGTCTGG is complementary to the final 18 nucleotides of
The DPV CHv strain is a high-virulence field strain of DPV the UL35 sequence and introduces a HindIII restriction site (un-
that was isolated and preserved in the authors’ laboratory. E. coli derlined). These restriction sites were included to facilitate the
strain DH5␣, E. coli BL21 (DE3), cloning vector pMD18-T, and subsequent cloning procedure.
142 Intervirology 2009;52:141–151 Cai /Cheng /Wang /Zhao /Zhu /Luo /Liu /
Chen
3. The UL35 gene was amplified by PCR from the genome of the Expression of the Recombinant Protein
DPV CHv strain, using DNA, which was purified as described For recombinant protein expression, E. coli strain BL21 (DE3)
above, as the template. PCR was performed in a 25-l reaction cells were transformed with the plasmid pET-32a(+)/UL35 and se-
volume, as described previously [22]. PCR amplifications were lected on LB solid medium containing ampicillin (100 g/ml). The
carried out using the following reaction cycles in a commercial transformants were inoculated into 5 ml of culture medium in test
PCR system (2700; GeneAmp): initial denaturation at 95 ° for tubes and allowed to grow overnight at 37 ° with constant agitation
5 min followed by 32 consecutive cycles of denaturation at 94 ° for (200 rpm). These cultures were used to inoculate 100 ml LB con-
50 s, annealing for 40 s at 56 ° , and extension at 72 ° for 40 s, and taining ampicillin (100 g/ml) and were submitted to vigorous
then a final extension at 72 ° for 10 min, using Ex Taq DNA poly- shaking in a fermenter. When the cultures initially reached loga-
merase. The amplified product (354 bp) was analyzed by electro- rithmic phase (at OD600 of 0.5–0.6), expression of the recombinant
phoresis on a 2% (w/v) agarose gel stained with 0.5 l/ml ethid- fusion protein, His6-tagged VP26, was induced by the addition of
ium bromide. After the PCR-amplified product had been vali- IPTG (final concentration 1.0 mM) with further growth at 37 ° for
dated as the intended product, it was purified using a PCR gel 4 h. After induction, the cells were harvested by centrifugation at
purification kit (Qiagen) according to the manufacturer’s instruc- 6,000 rpm for 10 min at 4 ° and lysed in 5! SDS-PAGE loading
tions. The purified PCR product was then submitted to ligation buffer (0.313 M Tris-HCl, pH 6.8, 50% glycerol, 10% SDS, and
into a pMD18-T vector. 0.05% bromophenol blue, with 100 mM DTT). Then, the cell ly-
sates were boiled for 15 min, centrifuged at 12,000 rpm for 10 min,
Construction of Cloning Plasmid pMD18-T/UL35 submitted to 12% SDS-PAGE, and then analyzed by Coomassie
The purified PCR product was digested with BamHI and brilliant blue R-250 staining. Briefly, the gel was stained with Coo-
HindIII restriction enzymes, purified and ligated into the corre- massie brilliant blue R-250 overnight and destained in 6% acetic
spondingly digested cloning vector pMD18-T at 16 ° overnight us- acid until a clear background was reached to assess the expression
ing T4 DNA ligase to generate a recombinant cloning plasmid level of the recombinant fusion protein by densitometric scanning
named pMD18-T/UL35 (fig. 1), using standard cloning methods using Bandscan4.5 software [25]. The uninduced control culture
[23]. Competent E. coli DH5␣ cells were transformed with the li- and the vector control culture were analyzed in parallel.
gation mixture by the heat shock method and used for propaga- To increase the production of the recombinant protein, cul-
tion of the cloning plasmid. The transformants were cultured at ture conditions for expression were optimized in terms of differ-
37 ° on Luria-Bertani (LB) solid medium (1.0% sodium chloride, ent temperatures (30, 34, and 37 ° ), concentrations of IPTG (0, 0.2,
1.0% tryptone, 0.5% yeast extract, and 1.5% agar) for 16 h and in 0.4. 0.6, 0.8, 1.0, 1.2, 1.5, and 2.0 mM), and durations of induction
LB liquid medium (as above but without agar) at 37 ° for 12 h, (0, 1, 2, 3, 4, 5, 6, and 7 h, and overnight). Protein expression was
supplemented with 100 g/ml ampicillin when plasmid mainte- assessed by SDS-PAGE, as described above.
nance was required. After mini-scale isolation of plasmid DNA For the initial experiments, which were designed to determine
using the modified alkaline lysis method [24], the presence of the the solubility of the recombinant protein, log phase cultures were
appropriate insert in the obtained plasmid was verified by PCR induced with 1 mM IPTG for 5 h at 34 ° , and approximately 4 g of
and restriction analysis. One clone was then selected and sent to wet weight cells from 1 liter of culture were harvested by centrif-
TaKaRa for sequencing. ugation at 6,000 rpm for 10 min. The cells were left overnight at
–20 ° and were then suspended in 20 ml lysis buffer of 20 mM Tris-
Construction of the pET-32a(+)/UL35 Expression Plasmid HCl buffer (pH 8.0) containing 100 m M NaCl, 1.0 mM phenyl-
After its sequence had been confirmed, pMD18-T/UL35 was methyl sulfonylfluoride (PMSF), and 1.0 mg/ml lysozyme. The
digested with BamHI and HindIII restriction enzymes and sub- suspension was incubated for 30 min at 4 ° with stirring and was
mitted to electrophoresis through a 1% agarose gel, then the DNA then pulse sonicated on ice (30 s working and 30 s resting on ice,
band corresponding to the digested insert (ORF) was cut and pu- Vibrocell VCX600 sonicator, 600 W max; Sonics and Materials)
rified from the agarose gel and directionally ligated into the pre- until the sample was clear. Sonication was performed to release
viously BamHI-/HindIII-digested and dephosphorylated expres- intracellular proteins. The resulting cell lysate was centrifuged at
sion vector pET-32a(+), downstream of the T7 Lac promoter and 12,000 rpm for 30 min. The clear supernatant (soluble fraction)
His6 tag and upstream of the T7 terminator, to construct the re- was collected and the remaining pellets (insoluble fraction),
combinant prokaryotic expression vector pET-32a(+)/UL35 using which contained the inclusion bodies, were dissolved in deion-
T4 DNA ligase (fig. 2). Cloning at the BamHI site in pET-32a(+) ized water and stored at –20 ° until use. Soluble and insoluble frac-
results in a His6 fusion to the N-terminus of the cloned gene. This tions were then analyzed in parallel by 12% SDS-PAGE.
fusion tag permits purification of the produced protein by metal
chelate chromatography on a nitrilotriacetic acid agarose matrix Purification of the Recombinant Protein
charged with nickel ions. The ligation mixture was transformed The pellets of the insoluble fraction (crude extract) were resus-
into competent E. coli DH5␣ cells. Positive clones with a gene in- pended in extraction buffer (0.5 M NaCl, 2 M urea, 1 mM DTT, 2%
sert in the plasmid were first evaluated by PCR and then recon- Triton X-100, and 20 mM Tris-HCl, pH 7.9), sonicated for 30 s at
firmed by restriction digestion and DNA sequencing. Each iden- 4 ° , and centrifuged at 15,000 rpm for 30 min. The pellets were
tified positive colony was grown in LB medium containing ampi- washed twice with washing buffer (0.5 M NaCl, 2 M urea, 20 mM
cillin (100 g/ml). The plasmid pET-32a(+)/UL35 was isolated Tris-HCl, pH 7.9), resuspended in regeneration buffer (0.5 M
from the bacterial cells and used to transform the competent E. NaCl, 6 M urea, 20 mM Tris-HCl, pH 7.9) and incubated at room
coli strain BL21 (DE3) cells for the purpose of recombinant pro- temperature (25 ° ) for 30 min. The incubated mixture was then
tein expression. centrifuged at 15,000 rpm for 10 min, and the resultant superna-
tant was submitted to further purification.
His6-Tagged UL35 Protein of Duck Intervirology 2009;52:141–151 143
Plague Virus
4. Color version available online
XmaI HincII
SmaI AccI Sse8387I
lacZ EcoRI SacI KpnI BamHI XbaI EcoRV SalI PstI SphI HindIII
5..
’ . GAGCGGATAACAATTTCACACAGGAAACAGCTATGACCAT GATTACGAATTCGA GCTCGG TACCC GG G GATTCTCTAGAGATATCGTCG ACCTG CAGGC ATGCAA GCTT
GGCACTG GCC GTCGTTTTACAACGTCGTGACTG GGA AAACCCT GGCG. . ’
.3
DPV CHv strain DNA
lacZ UL35 gene
PCR
UL35 gene
pMD18-T vector
Ampr HindIII BamHI
(2,692 bp)
ori
Ligation
XmaI
SmaI
lacZ EcoRI SacI KpnI BamHI HindIII
UL35 gene
5..
’ . GAGCGGATAACAATTTCACACAG GAAA CAGCTATG ACCATGATTACG AATTCGA GCTC GGTACCC GG G GATTC AA GCTT
GGCACTG GCC GTCGTTTTACAACGTCGTGACTG GGA AAACCCT GGCG. . ’
.3
lacZ
pMD18-T/UL35
Ampr
(3,016 bp)
ori
Fig. 1. Schematic diagram of the UL35 ORF cloned into the pMD18-T cloning vector.
The recombinant His-tagged VP26 was purified from the su- PMSF, and 10 mM imidazole). The chromatography flow rate,
pernatant obtained above by IMAC on Ni2+-NTA affinity resin which was driven by gravity, was 0.5 ml/min. The supernatant
following the manufacturer’s instructions with modifications. A (crude extract) was loaded onto the Ni 2+-NTA agarose resin col-
glass column (20 ml capacity) was packed with Ni 2+-NTA resin umn preequilibrated with IMAC buffer. The column was washed
matrix. The column was equilibrated with 4 bed volumes of successively with 3 bed volumes of IMAC buffer and 5 bed vol-
IMAC buffer (20 mM Tris-HCl, pH 8.0, 500 mM NaCl, 0.5 mM umes of IMAC buffer containing 20 m M imidazole. The protein
144 Intervirology 2009;52:141–151 Cai /Cheng /Wang /Zhao /Zhu /Luo /Liu /
Chen
5. Color version available online
AvaI
XhoI
EagI
NotI UL35 gene
HindIII
SalI
SacI
Bpu1102I EcoRI
BamHI
EcoRV HindIII BamHI
NcoI
BglII
KpnI
NspV
MscI
fl origin
trxA
UL35 gene
Ap HindIII
pET-32a(+)
BamHI
(5,900 bp)
lacl fl origin
trxA
ori
Ap
pET-32a(+)/UL35
(6,235 bp)
lacl
ori
a
T7 promoter lac operator XbaI rbs
TAATACGACTCACTATAGGGGAATTGTGAGCGGATAACAATTCCCCTCTAGAAATAATTTTGTTTAACTTTAAGAAGGAGA
Trx-Tag MscI His-Tag
T A T A C A T A T G A G C . . . 3 1 5 b p. . . C T G G C C G G T T C T G G T T C T G G C C A T A T G C A C C A T C A T C A T C A T C A T T C T T C T G G T C T G G T G C C A C G C G G T T C T
MetSer...105aa... LeuAlaGlySerGlySerGlyHisMetHisHisHisHisHisHisSerSerGlyLeuValProArgGlySer
S-Tag NspV BglII KpnI Thrombin
GGTATGAAAGAAACCGCTGCTGCTAAATTCGAACGCCAGCACATGGACAGCCCAGATCTGGGTACCGACGACGACGACAAG
GlyMetLysGluThrAlaAlaAlaLysPheGluArgGlnHisMetAspSerPro AspLeuGlyThrAspAspAspAspLys
EagI AvaI Enterokinase
NcoI EcoRV BamHI HindIII NotI XhoI His-Tag
UL35 gene
G C C A TGGCTGATATCGGATCC AAGCTTGCGGCCGCACTCGAGCACCACCACCACCACCACTGAGATCCGGCTGCTAA
Al aMet AlaA spIl eGly Ser leAlaCysGlyArgThrArgAlaProProProProProLeuArgSerGlyCysEnd
Bpu1102I T7 terminator
CAAAGCCCGAAAGGAAGCTGAGTTGGCTGCTGCCACCGCTGAGCAATAACTAGCATAACCCCTTGGGGCCTCTAAACGGGTCTTGAGGGGTTTTTTG
b LysProGluArgLysLeuSerIrpLeuLeuProProLeuSerAsnAsnEnd
Fig. 2. Construction of the recombinant expression plasmid pET-32a(+)/UL35. a Schematic diagram of the UL35
ORF cloned into the pET-32a(+) expression plasmid. b Detailed structural features of the constructed recom-
binant expression plasmid pET-32a(+)/UL35. The recombinant protein consisted of Trx, His tag, thrombin
cleavage site, S tag, and enterokinase cleavage site.
His6-Tagged UL35 Protein of Duck Intervirology 2009;52:141–151 145
Plague Virus
6. combinant protein and incomplete Freund’s adjuvant at a 1-week
interval. Subsequently, each rabbit was intravenously immunized
M1 1 2 3 M2 with 100 g of the purified recombinant protein. Two weeks after
the last injection, the rabbit with the best reactivity toward His6-
bp 15,000 tagged VP26 was sacrificed, and the antiserum was harvested
10,000 from the arteriae carotis and stored at –80 ° until further use.
7,500
5,000
2,500 Purification of the Antiserum
2,000 First, the rabbit IgG fraction was precipitated from the har-
vested rabbit polyclonal antiserum by ammonium sulfate precip-
1,000 1,000 itation. Then, by using a DEAE-Sepharose column (Bio-Rad), the
IgG fraction was purified by ion exchange column chromatogra-
750 phy following the manufacturer’s instructions. The purified IgG
fraction was analyzed by 12% SDS-PAGE.
500
250
Western Blot Analysis
250 To characterize the antigenicity of the recombinant fusion
protein, His6-tagged VP26, Western blot analysis was performed
100 according to a standard procedure [27] using the purified rabbit
anti-His6-tagged VP26 IgG. After the proteins had been sepa-
rated by 12% SDS-PAGE, the gel was immersed in transfer buffer
(0.24% Tris-HCl, 1.153% glycine, and 15% methanol, pH 8.8) and
electrophoretically transferred onto nitrocellulose membrane
Fig. 3. Characterization of the recombinant plasmid pMD18-T/ (Bio-Rad) preequilibrated in transfer buffer using a Mini Trans
UL35 by restriction digestion and PCR-based amplification. Blot electrophoretic transfer cell (Bio-Rad) at 80 V for 1.5 h. The
M1 = DNA marker of 2,000 bp; 1 = pMD18-T/UL35 digested with membrane was incubated in blocking buffer (5% BSA in PBS buff-
BamHI and HindIII; 2 = pMD18-T/UL35 digested with BamHI; er) for 1 h at 37 ° or overnight at 4 ° . After three washes (10 min
3 = product amplified from pMD18-T/UL35 (ORF 354 bp); M2 = each) with 1! PBS buffer, the membrane was incubated with rab-
DNA marker of 15,000 bp. bit anti-His6-tagged VP26 IgG at a dilution of 1:100 with 1% BSA
in PBS overnight at 4 ° . The membrane was then washed three
times with 1! PBS containing 0.1% Tween-20 (PBST), and was
further incubated with horseradish peroxidase-labeled goat anti-
rabbit IgG (Boster) at a dilution of 1:5,000 for 1 h at 37 ° . The mem-
impurities devoid of histidine tails were removed from the aga- brane was then washed three times with PBST and three times
rose resin at a flow rate of 2.0 ml/min at 4 ° . The fusion protein with PBS and developed with diaminobenzidine substrate buffer.
was eluted with IMAC buffer containing 8 M urea and 100 mM Color development was terminated by thorough washing in dis-
imidazole at a flow rate of 1.0 ml/min at 4 ° . Five-milliliter frac- tilled water.
tions were collected and analyzed by SDS-PAGE to identify the
fusion protein and to assess the level of homogeneity. The protein
concentration was estimated by the method of Bradford using bo-
vine serum albumin (BSA) as the standard (0–12 g) [26]. Frac- Results and Discussion
tions that contained the purified His6-tagged VP26, which was
in a denatured state, were pooled and dialyzed against PBS buffer Gene Amplification, Cloning, and Sequencing
(10 mM Na 2HPO4, 1.8 mM KH2PO4, pH 7.4, 140 mM NaCl, and On the basis of the constructed DPV CHv-strain ge-
2.7 mM KCl) containing 1 mM PMSF with progressively lower
concentrations of urea (4, 2, and 0 M) for a total time of 72 h. The nomic library [18], primers were designed to amplify the
purified recombinant protein was stored at 4 ° for use within 1 UL35 gene using DPV DNA as a template. BamHI and
week or at –70 ° for use after a longer time. HindIII sites were designed in the primers to facilitate
subsequent cloning. The PCR product (354 bp; data not
Production of Polyclonal Antibody against the Recombinant shown) was digested with BamHI and HindIII restriction
Protein
The purified recombinant protein was used for raising anti- enzymes and the ORF was inserted into the vector
body in New Zealand white rabbits. Blood (1.5 ml) was collected pMD18-T between the BamHI and HindIII sites to con-
prior to immunization by bleeding the rabbits from the marginal struct the cloning vector pMD18-T/UL35. Then, the re-
vein of the ear. This serum served as a negative control. After- combinant plasmid was confirmed by DNA sequencing
wards, the rabbits were then intradermally injected with a mix- and restriction digestion (fig. 3). The sequencing result
ture of 500 g of purified recombinant protein mixed with an
equal volume of Freund’s complete adjuvant (Promega) on the showed that there were no nucleotide errors in the syn-
back and proximal limbs (100 l/site). After 2 weeks, the rabbits thetic UL35 gene fragment (data not shown).
were twice boosted intramuscularly with 500 g of purified re-
146 Intervirology 2009;52:141–151 Cai /Cheng /Wang /Zhao /Zhu /Luo /Liu /
Chen
7. M1 1 2 3 4 5 M2 M 1 2 3 4 5 6 7 8 9
kDa
bp 116
15,000 66.2
10,000
7,500
5,000 45.0
2,000 2,500
35.0
1,000 1,000 25.0
750
500 18.4
14.4
250 250
100
a
4
Fig. 4. Characterization of the recombinant plasmid pET-32a(+)/
UL35 by restriction digestion and PCR-based amplification.
M 1 2 3 4 5 6 7 8 9
M1 = DNA marker of 2,000 bp; 1 = pET-32a(+); 2 = pET-32a(+) kDa
digested with BamHI and HindIII; 3 = pET-32a(+)/UL35 digested 116
66.2
with BamHI; 4 = pET-32a(+)/UL35 digested with BamHI and
HindIII; 5 = product amplified from pET-32a(+)/UL35; M2 = 45.0
DNA marker of 15,000 bp.
35.0
Fig. 5. Expression analysis and optimization of the expression
conditions of the His6-tagged VP26 fusion protein. a Coomassie-
stained SDS-PAGE gel (12%) analysis for the expression and opti- 25.0
mization of the temperature for His6-tagged VP26 fusion protein. 18.4
M = Protein molecular weight marker; 1 = total protein from 14.4
E. coli BL21/pET-32a(+) before induction; 2 = total protein from
E. coli BL21/pET-32a(+) after induction; 3 = total protein from
b
E. coli BL21/pET-32a(+)/UL35 before induction; 4, 6 and 8 = sol-
uble fractions of total protein from E. coli BL21/pET-32a(+)/UL35
after induction at 30, 34, and 37 ° , respectively; 5, 7 and 9 = in-
soluble fractions (inclusion bodies) of total protein from E. coli
BL21/pET-32a(+)/UL35 after induction at 30, 34 and 37 ° , respec- M 1 2 3 4 5 6 7 8 9
tively. b SDS-PAGE analysis for optimization of the concentration kDa
of IPTG for His6-tagged VP26 fusion protein expression. M =
protein molecular weight marker; 1–9 = total protein from E. coli 116
BL21/pET-32a(+)/UL35 after induction with the following con-
centrations of IPTG: 0, 0.2, 0.4. 0.6, 0.8, 1.0, 1.2, 1.5, and 2.0 m M, 66.2
respectively, at 34 ° . c SDS-PAGE analysis for optimization of the
duration of induction for His6-tagged VP26 fusion protein ex- 45.0
pression. M = protein molecular weight marker; 1–9 = total pro-
tein from E. coli BL21/pET-32a(+)/UL35 after induction with 35.0
IPTG (1.0 mM) for 0, 1, 2, 3, 4, 5, 6, and 7 h and overnight, respec-
tively, at 34 ° . Since an equal amount of sample was loaded into
each lane, it is possible to compare the expression levels among 25.0
lanes. The highest level of expression was observed for 5 h after
c
induction at 34 ° with 1 m M IPTG. Arrows indicate the position
of the fusion protein. 5
Construction of the Expression Plasmid E. coli [28]. The UL35 gene fragment, which was obtained
The prokaryotic expression vector pET-32a(+), which by digestion of pMD18-T/UL35 with BamHI and HindIII,
features a high stringency T7 lac promoter, His6 tag, and was directionally inserted downstream of the His6-tag
T7 terminator, has been recognized as one of the most sequence in the pET-32a(+) plasmid to construct the ex-
powerful tools for producing recombinant proteins in pression plasmid pET-32a(+)/UL35. The initial transfor-
His6-Tagged UL35 Protein of Duck Intervirology 2009;52:141–151 147
Plague Virus
8. was not detected in the negative control E. coli BL21 (DE3)
1 2 3 4 5 M 6 7 cells (fig. 5a, lane 3) nor was it found without induction
kDa of E. coli BL21 (DE3) cells transformed with the pET-
32a(+) vector (fig. 5a, lane 1). Analysis of the densitome-
116
try scan of the 12% SDS-PAGE gel showed that the IPTG-
induced band constituted approximately 24% of the total
66.2
proteins in the induced cell extract (data not shown).
The relative distribution of the expressed recombinant
45.0
protein in the soluble and insoluble fractions of the su-
pernatant and the pellet (see Materials and Methods) of
35.0
the cell lysate was examined after sonication. The recom-
binant protein was predominantly expressed in the in-
soluble fraction, in the form of inclusion bodies (fig. 5a,
25.0
lanes 5, 7 and 9), indicating that little or no soluble pro-
18.4 teins are formed. We then tried to optimize the expres-
sion conditions as described in Materials and Methods by
utilization of different durations of induction, concentra-
Fig. 6. Purification and Western blot analysis of the purified re- tions of IPTG and induction temperatures. The optimal
combinant His6-tagged VP26 fusion protein. M = Protein mo- induction of His6-tagged VP26 protein expression was
lecular weight marker; 1 = total protein from E. coli BL21/pET-
32a(+) before induction; 2 = total protein from E. coli BL21/pET- obtained by growth in the presence of 1.0 mM IPTG
32a(+) after induction; 3 = total protein from E. coli BL21/pET- (fig. 5b, lane 6) for 5 h (fig. 5c, lane 6) at 34 ° (fig. 5a, lane 7).
32a(+)/UL35 before induction; 4 = total protein from E. coli BL21/
pET-32a(+)/UL35 after IPTG induction (1.0 mM) at 34 ° for 5 h; Purification of the Recombinant Protein
5 = purified recombinant His6-tagged VP26 fusion protein using Generally, high-level expression of recombinant pro-
a single chromatographic step of IMAC on Ni2+-NTA agarose;
6 = rabbit anti-His6-tagged VP26 IgG reacted with His6-tagged teins in E. coli often results in the formation of insoluble
VP26; 7 = negative control serum reacted with His6-tagged and inactive aggregate known as inclusion bodies [29,
VP26. 30]. They develop as a result of misfolding or partial fold-
ing of polypeptides with exposed hydrophobic patches
and the consequent intermolecular interactions [31].
Therefore, purified inclusion bodies must be resolubi-
mation was carried out with competent E. coli DH5␣ cells lized by strong denaturants, such as 6 M guanidine hy-
for the purpose of screening. The positive colonies were drochloride or 8 M urea, which promote the disruption of
identified by PCR and restriction digestion (fig. 4). After intermolecular interactions and complete unfolding of
confirmation, a positive clone was submitted to DNA se- the protein [32, 33]. The denaturation solution is removed
quencing and the result confirmed that the UL35 gene by dilution or a buffer exchange step [34, 35], which per-
was in frame with the N-terminal His6 tag within the mits renaturation of the proteins.
pET-32a(+) multiple cloning sites (data not shown). Histidine tags have become common fusion partners
for recombinant proteins to facilitate purification using
Expression of the Recombinant Protein IMAC. For purification of the recombinant His6-tagged
After sequence confirmation, the recombinant plas- VP26 fusion protein from the insoluble fraction, the dis-
mid pET-32a(+)/UL35 was introduced into the expres- solved protein (inclusion bodies) was used as starting ma-
sion host E. coli BL21(DE3). A positive transformant was terial and subjected to His tag purification using a single
used for the subsequent induction. Initially, the induc- chromatographic step of IMAC on Ni2+-NTA agarose, as
tion of His6-tagged VP26 expression was carried out at described. After elution with IMAC buffer containing
37 ° for 4 h by the addition of 1.0 mM IPTG. A distinct 8 M urea and dialysis against PBS containing progressive-
band of approximately 33 kDa of molecular weight, cor- ly lower concentrations of urea (4, 2, and 0 M), a clear
responding to the expected size of the His6-tagged VP26 band corresponding to a molecular mass of about 33 kDa
fusion protein (fig. 5a, lane 9), was observed. This result was seen on the SDS-PAGE gel following Coomassie blue
confirmed that the ORF was properly expressed in the staining (fig. 6, lane 5). This procedure allowed to harvest
transformed E. coli BL21 (DE3) cells. Expressed protein ϳ620 mg of nearly homogeneous protein (98%, accord-
148 Intervirology 2009;52:141–151 Cai /Cheng /Wang /Zhao /Zhu /Luo /Liu /
Chen
9. Table 1. Purification of the recombinant His-tagged VP26 from 4 g of wet weight E. coli cells
Purification step Volume Total proteina His-tagged Protein concen- Purity Purification Cumulative
ml mg VP26, mg trationb, g/ml % factor, fold yield, %
Crude extractc 10 54.75 13.14 1,314 24 1 100
IMACd 3 1.90 1.86 620 98 4 14
a Total protein was isolated from 1 liter of culture medium after induction with 1.0 m M IPTG at 34° for 5 h.
b
Protein concentration indicates the concentration of His-tagged VP26. Protein concentrations were estimated by the Bradford
method using BSA as standard.
c The pellets containing the insoluble fraction (crude extract) obtained from 1 liter of culture medium after centrifugation and
sonication.
d
The purified recombinant His-tagged VP26 using IMAC on Ni2+-NTA affinity resin.
ing to gel densitometry analysis) per liter of culture me-
dium (1 liter bacterial cell culture produced about 4 g of M 1 2
wet weight cells in our study). The purification is sum- kDa
marized in table 1. 116
Purification of the Antiserum and Antigenicity
66.2
Analysis of the Recombinant Protein
After 4 injections had been given to 6 New Zealand Heavy
white rabbits, the serum containing anti-His6-tagged chain
VP26 polyclonal antibody with the stronger specificity 45.0
was collected. The rabbit anti-His6-tagged VP26 IgG, 35.0
with 55 and 22 kDa of the heavy and light chains, was
firstly precipitated by ammonium sulfate precipitation
(fig. 7, lane 1) and then purified by ion exchange column
25.0 Light
chromatography (fig. 7, lane 2). Western blot analysis chain
showed that the purified His6-tagged VP26 was recog-
nized by the rabbit anti-His6-tagged VP26 IgG and
showed a specific signal at 33 kDa, which is the expected
size of the fusion protein (fig. 6, lane 6). Importantly, no Fig. 7. SDS-PAGE analysis of the purified rabbit anti-His6-tagged
positive signal was observed when using the negative VP26 IgG. M = Protein molecular weight marker; 1 = rabbit anti-
control serum (fig. 6, lane 7), indicating that the recom- His6-tagged VP26 IgG obtained by ammonium sulfate precipita-
tion; 2 = rabbit anti-His6-tagged VP26 IgG obtained by ion ex-
binant protein induced an immunological response and change column chromatography.
that the antiserum had a high level of specificity. Based
upon these results, this antiserum was deemed suitable to
characterize the structure, molecular mechanism, and
functional involvement of the VP26 protein in the DPV
life cycle. replication in the nervous system. Furthermore, the ab-
Previous studies of the herpes simplex virus (HSV) sence of this protein will result in a 100-fold reduced yield
UL35 protein of the subfamily Alphaherpesvirinae have of infectious virus in the trigeminal ganglion [36–38].
documented that the UL35 gene acts as the real late gene This protein is located at the exterior of the icosahedral
␥2, which encodes a small nucleocapsid protein that is capsid, which indicates that VP26 may serve as a core that
located on the hexon of the nucleocapsid. This protein connects the capsid with the external tegument and en-
interacts with the viral DNA of the nucleocapsid. It is velope in the late stage of viral assembly [37]. The sites of
nonessential for the formation of the viral capsid and vi- this protein that are exposed on the outside of the capsid
ral propagation in cell culture, but it is essential for viral also reveal that VP26 is in a favorable position to couple
His6-Tagged UL35 Protein of Duck Intervirology 2009;52:141–151 149
Plague Virus
10. the capsid and its functional ligand, such as tegument expressed and purified from E. coli. Western blot analy-
[39]. Similarly, research on the homolog of VP26 suggests ses suggest that the polyclonal antibody raised against the
that the smallest capsid protein, which is located at the recombinant protein reacted with the purified recombi-
most exterior region of the capsid, may play an important nant protein, indicating that this specific antibody may
role in the tegumention and/or uncoating of the virion in serve as a good tool for future studies of VP26, e.g. anal-
the course of infection and in the regulation of the inter- yses of subcellular localization, and may permit elucida-
action between the capsid and tegument as well as cyto- tion of the structure, molecular mechanism, and func-
skeletal proteins [40]. Recent studies have also revealed tional involvement of VP26 in the DPV life cycle.
that VP26 of HSV-1 associates with ribosomes and may
regulate the host cell translation [41]. Based upon the im-
portant role played by HSV VP26 during HSV infection, Acknowledgments
we suggest that VP26 of DPV may play a similar role in
the course of DPV infection. Importantly, the exact roles The research was supported by grants from the National Nat-
ural Science Foundation of China (30771598), Changjiang Schol-
of DPV VP26 remain undefined. ars and Innovative Research Team of the University (PCSIRT-
0848), the earmarked fund for the Modern Agroindustrial Tech-
nology Research System (2009-2013), the New Century Excellent
Conclusion Talents Program of the University (NCET-06-0818), the Scien-
tific and Technological Innovation Major Project Funds of the
University (706050), the Cultivation Fund of the Key Scientific
In conclusion, the UL35 gene that encodes VP26 was and Technical Innovation Project, the Department of Education
amplified by PCR from the genome of the DPV CHv of the Sichuan Province (07ZZ028), and the Sichuan Province Ba-
strain. It was cloned, and the recombinant protein was sic Research Program (07JY029-016/17).
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