The inhibiting effect of the transcription factor p53 on dengue virus infection by activating the type I interferon

To investigate the role of the transcription factor p53 in the course of the dengue virus (DV) infection. The human hepatocellular carcinoma cell strain HepG2 with a low expression level of p53 was built by using the retroviral-mediated RNA interference technology, and was detected by Western blot. The wild group and the interference group were respectively infected by the type 2 DV. The viral titration was detected by the Vero plaque assay, the viral multiplication was detected by the immunofluorescence, the cell apoptosis after virus infection was detected by FCM and the level of IFN-β was analyzed by ELISA. Compared to the wild group, the expression level of p53 in the interference group decreased significantly, which indicated that the HepG2 cell strain with the low expression level of p53 was successfully built. 24h after DV infection, the virus titration in the interference group was 100 times higher than that in the wild group. The result of the immunofluorescence showed that, the amount of green fluorescent cells in the interference group was significant higher than that in the wild group. It was indicated that the DV infection was inhibited by p53. However, 24h after DV infection, there was no significant difference in the amount of apoptotic cells in both groups. And the amount of IFN-β in the wild group increased 6 times. The DV infection was inhibited by the transcription factor p53 by activating type I interferon pathway other than promoting the cell apoptosis.

[Inventory building of phages against extensively drug-resistant Acinetobacter baumannii isolated from wounds of patients with severe burn and related characteristic analysis]

OBJECTIVE

To build inventory of phages against extensively drug-resistant Acinetobacter Baumannii isolated from wounds of inpatients of burn ICU and analyze related characteristics.

METHODS

In 2014 and 2015, 131 strains of extensively drug-resistant Acinetobacter Baumannii were isolated from wounds of inpatients of burn ICU from one hospital in Chongqing. In 2015, 98 strains of extensively drug-resistant Acinetobacter Baumannii were isolated from wounds of inpatients of burn ICU from 6 hospitals in Guangdong province. Above-mentioned 229 strains were collected for conducting experiments as follows: (1) Multilocus sequence typing (MLST) of strains isolated from Chongqing and Guangdong province was analyzed. (2) Sewage co-culture method was applied for isolation of phages with above-mentioned strains and sewage from Chongqing and Guangdong province. Numbers of isolated phages and times of successful isolation and unsuccessful isolation were recorded. (3) The most prevalent subtypes of strains from Chongqing and Guangdong province in 2015 were collected, and their phages respectively underwent cross infection with all strains from Chongqing and those from Guangdong province. The lysis ability of phage was observed when phage underwent cross infection with the same subtype of strain or not the same, and the lytic ratio was calculated. (4) Fluid of phage in one type was randomly selected and equally divided into 3 parts, and its titer was determined by double dilution method. Then each part of phage fluid was subdivided into 3 small parts, which were cultured with LB fluid medium and respectively stored under the condition of -20 ℃, 4 ℃, and room temperature. After being stored for 1 month and 2 months, the titer of phage was determined for evaluating stability of phage. Data were processed with Fisher's exact test, chi-square test, and one-way analysis of variance.

RESULTS

(1) The major type of strains from Chongqing in 2014 was ST368 (45%, 31/69), and major types of strains from Chongqing in 2015 were ST75 (26%, 16/62) and ST195 (24%, 15/62), while that from Guangdong province in 2015 was ST977 (46%, 45/98). (2) For strains from Chongqing, isolation effect of phage with sewage of Chongqing (8 times of successful isolation with 9 strains of phages and 1 time of unsuccessful isolation) was better than that with sewage of Guangdong province (1 time of successful isolation with 1 strain of phage and 7 times of unsuccessful isolation). For strains from Guangdong province, isolation effect of phage with sewage of Guangdong province (8 times of successful isolation with 6 strains of phages) was better than that with sewage of Chongqing (7 times of unsuccessful isolation with no phage). These differences were statistically significant (P<0.05 or P<0.01). There was no obvious difference in isolation effect of phage between strains from Chongqing with sewage of Chongqing and strains from Guangdong province with sewage of Guangdong province (P>0.05). (3) The ratios of phages of ST75 and ST977 extensively drug-resistant Acinetobacter Baumannii strains lysing the strains with the same type were respectively 13/16 and 8/9, which were obviously higher than those lysing the strains with different type (respectively 11/115 and 3/53, with χ(2) values respectively 48.23 and 68.46, P values below 0.001). (4) Compared with that before storage, titer of phage under storage condition of -20 ℃, 4 ℃, and room temperature for 1 month decreased by approximately 1 order of magnitude, and that for 2 months decreased by approximately 2 orders of magnitude. After being stored for 1 month and 2 months, there were no statistically significant differences in titer of phage among 3 storage conditions (with F values respectively 1.29 and 1.07, P values above 0.05).

CONCLUSIONS

This study has successfully built an inventory covering 229 strains of phages of extensively drug-resistant Acinetobacter Baumannii. MLST of extensively drug-resistant Acinetobacter baumannii varies in different area and different time. Phage can be well isolated using sewage with the same source as that of strain. The lysis ability of phage is closely related to the MLST of strains. Inventory of phages should be built according to regional division. Moreover, phage cultured with LB fluid medium shows good stability without special requirements for storage conditions.

Dax1 and Nanog act in parallel to stabilize mouse embryonic stem cells and induced pluripotency

Nanog expression is heterogeneous and dynamic in embryonic stem cells (ESCs). However, the mechanism for stabilizing pluripotency during the transitions between Nanog(high) and Nanog(low) states is not well understood. Here we report that Dax1 acts in parallel with Nanog to regulate mouse ESC (mESCs) identity. Dax1 stable knockdown mESCs are predisposed towards differentiation but do not lose pluripotency, whereas Dax1 overexpression supports LIF-independent self-renewal. Although partially complementary, Dax1 and Nanog function independently and cannot replace one another. They are both required for full reprogramming to induce pluripotency. Importantly, Dax1 is indispensable for self-renewal of Nanog(low) mESCs. Moreover, we report that Dax1 prevents extra-embryonic endoderm (ExEn) commitment by directly repressing Gata6 transcription. Dax1 may also mediate inhibition of trophectoderm differentiation independent or as a downstream effector of Oct4. These findings establish a basal role of Dax1 in maintaining pluripotency during the state transition of mESCs and somatic cell reprogramming.

Knockdown of the inflammatory factor pentraxin-3 suppresses growth and invasion of lung adenocarcinoma through the AKT and NF-kappa B pathways

Pentraxin-3 (PTX3), a modulator of tumor-associated inflammation, is known to be positively correlated with tumor grade and severity of malignancies, but the function and molecular underlying mechanisms of PTX3 remain unclear. In the present study, the expression of PTX3 in human lung adenocarcinoma (LAC) was examined by immunohistochemical assay using a tissue microarray procedure. A loss-of-function experiment was performed to explore the effects of lentiviral vector-mediated PTX3 shRNA (Lv-shPTX3) on cell growth and invasive potential in LAC cell lines (A549 and LETPα-2), assessed by MTT and Transwell assays, respectively. We found that the expression of PTX3 protein was significantly increased in LAC tissues compared with that in adjacent non-cancerous tissues (ANCT) (60.42% vs. 29.17%, P=0.004), and positively correlated with lymphatic invasion of the tumor (P=0.006). Furthermore, knockdown of PTX3 suppressed tumor proliferation and invasion of LAC cells, followed by decreased expression of p-AKT, p-NF-kappa B, PCNA, and MMP-9. Taken together, our findings demonstrate that upregulation of PTX3 expression is correlated with tumor metastasis of LAC patients, and knockdown of PTX3 blocks the development of LAC through inhibition of the AKT and NF-kappa B pathways, suggesting that PTX3 may serve as a potential therapeutic target for the treatment of cancer.

Identification of in vivo induced protein antigens of Salmonella enterica serovar Typhi during human infection

During infectious disease episodes, pathogens express distinct subsets of virulence factors which allow them to adapt to different environments. Hence, genes that are expressed or upregulated in vivo are implicated in pathogenesis. We used in vivo induced antigen technology (IVIAT) to identify antigens which are expressed during infection with Salmonella enterica serovar Typhi. We identified 7 in vivo induced (IVI) antigens, which included BcfD (a fimbrial structural subunit), GrxC (a glutaredoxin 3), SapB (an ABC-type transport system), T3663 (an ABC-type uncharacterized transport system), T3816 (a putative rhodanese-related sulfurtransferase), T1497 (a probable TonB-dependent receptor) and T3689 (unknown function). Of the 7 identified antigens, 5 antigens had no cross-immunoreactivity in adsorbed control sera from healthy subjects. These 5 included BcfD, GrxC, SapB, T3663 and T3689. Antigens identified in this study are potential targets for drug and vaccine development and may be utilized as diagnostic agents.

[Study on expression of Streptococcus suis serotype 2 sly gene, purification and activity of its product]

OBJECTIVE

To clone and express Streptococcus suis serotype 2 (S. suis 2) sly gene for constructing an foundation on identification of S. suis 2 protective antigen.

METHODS

The sly gene was amplified from S. suis 2 clinical isolate strain 05ZYH33 genome DNA by PCR. The gene fragment was inserted into the expression vector pET-30b(+) to build pET30b-sly. When recombinant vector pET30b-sly was identified by restriction enzyme cutting and DNA sequencing as a correct one, subsequently it was transformed to E. coli Rosetta for expression under IPTG induction. The obtained fusion protein was purified by Ni-NTA affinity chromatography. The immunologic and hemolysis activity of the purified protein was proved through Western blot and hemolysis assay respectively.

RESULTS

The PCR product was around 1500 bp. The gene segment inserted into the recombinant vector was proven to be completely identical with the sly gene sequence in the total genome sequence of S. suis 2. The target protein expressed was up to 30% of the total somatic protein under IPTG induction. The protein purity reached above 80% after purification. The protein could be recognized by human serum infected with S. suis 2 and could dissolve swine erythrocytes with the Hemolytic titer as 256.

CONCLUSION

The expression vector pET30b-sly was successfully constructed. The target protein could be over-expressed in E. coli and possessed its biological activity after purification.

[Expression profile analysis of host HeLa cells invasived by Shigella flexneri 2a]

The changes of genes expression in HeLa cell during the invasion with Shigella species for 1h and 3h were analyzed by cDNA microarrays. The data showed that the expression levels of 752 genes were altered twice or greater as compared with the control 509 of them were up-regulated, and 306 were down-regulated. It was supposed that some signal pathways in HeLa cell were activated, then many genes were induced, and at last comprehensive cell responses were produced, so that HeLa cell could prevent against Shigella species infection. Two striking difference cDNA fragments TNFR 1B and ERBB2, which were up-regulated in the host epithelial cell during Shigella infection, analyzed expression by real time RT-PCR as determined by cDNA arrays. We suggested they play important roles in response to the invasive S. flexneri 2457T. Based on the results of gene expression alterations, the molecular pathogenic mechanism of Shigella species could be greatly and deeply understood, and the strategy for prevention against and treatment for shigellosis would be formed.

Electronic extension and identification of new HeLa cell ESTs differentially expressed after Shigella flexneri 2a infection

AIM: To investigate and test differential mRNA expression of new ESTs within HeLa epithelial cells following infection with Shigella flexneri 2457T.

METHODS: HeLa cells were incubated with S. flexneri 2a 2457T. A methylene blue assay was performed to examine the ratio of bacterial infection. Total RNA was extracted from HeLa cells and mRNA was isolated for use as probes. A cDNA microarray was assembled with about 3000 cDNA clones representing the same number of independent cDNA clusters, which were unknown-gene ESTs. Using 156 EST sequences obtained from cDNA microarray analysis as seed sequences, the Siclone software was applied for splicing, proofing, and extending EST sequences as long as possible. To validate the correctness of sequences after extension and to confirm the accuracy of the differential expression of genes from the microarray analysis, three new genes were selected and their transcription levels in HeLa cells were analyzed before and after Shigella infection using semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR).

RESULTS: Forty-five ESTs were determined as being differentially expressed, with ≥ 3-fold or ≤ 0.33-fold changes, and 25 of these were identified as known genes involved in several important intestinal functions. Interestingly, three strikingly different cDNA fragments from unknown ESTs, name NPCCKH12, ADBCSB0 and HTBAMG05, were cloned by RT-PCR, sequenced and their expression levels were confirmed by semi-quantitative RT-PCR. We confirmed that they were new human or pseudo genes.

CONCLUSION: Three new ESTs from HeLa cells, differentially expressed after S. flexneri 2a infection, were identified. This investigative strategy is useful for obtaining information to be applied as a basis for further study of the interactions between Shigella and epithelial cells.

Effect of PEG2000 on drug delivery characterization from solid lipid nanoparticles

The purpose of this work is to develop a PEG2000-modified solid lipid nanoparticles (SLN) intended to encapsulate a drug within their matrix and to study their characteristics. In the present report, drug-loaded SLN were prepared by a novel solvent diffusion method in an aqueous system. Monostearin and PEG2000 were used as carrier material and modifying agent, respectively. The model drug salbutamol sulphate was incorporated to study the characterization of entrapment efficiency, size, zeta potential (charge) and drug delivery characterization. In the test solution of pH 7.2 phosphate buffer, drug-release behavior from SLN suspension exhibited a biphasic pattern. With the monoastearin-based SLN, a distinctly prolonged release over a monitored period of 14 days was observed after a burst drug release in the first 8 hours. Over the monitored period of prolonged release, there was delayed release in the first 5 days with nearly 2.51% of the drug released each day, following which a slightly higher release rate (8.14% per day) appeared in the last 9 days. In contrast, the drug release rate from PEG2000-modified SLN was faster. Nevertheless, further work is required in order to optimize the release behavior of various entrapped drugs. These results also demonstrate that modification with PEG2000 can accelerate release of hydrophilic small molecule drugs from SLN.

Novel self-aggregates of chitosan oligosaccharide grafted stearic acid: preparation, characterization and protein association

A novel hydrophobically modified chitosan oligosaccharide (CSO) containing 5.4 stearic acid (SA) groups per 100 anhydroglucose units was synthesized by an 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC)-mediated coupling reaction. The purified copolymer was structurally characterized by IR spectroscopy. Characteristics of self-aggregates of the amphiphilic copolymers were studied by fluorescence spectroscopy and dynamic light scattering. The critical aggregation concentration (cac) value of the self-aggregates in aqueous solution was determined by measuring the fluorescence intensity of pyrene as a fluorescent probe. Mean diameter of self-aggregates in pH 7.0 PBS was 25.0 +/- 14.7 nm with a unimodal size distribution. The diameter, as well as the zeta potential of self-aggregates increased when the pH value of dispersion medium decreased. Bovine serum albumin (BSA) was further enveloped in the interface of different single self-aggregate and formed nanoparticles. The size of BSA-loaded stearic acid modified CSO nanoparticles depended on the pH values of the dispersed aqueous vehicle, and the size diminished when the pH values of the dispersed aqueous vehicle decreased, whilst, the BSA encapsulation efficiency enhanced. The nanoparticles were characterized by Transmission Electron Microscopy (TEM). BSA release from stearic acid modified CSO nanoparticles decreased when the pH values of the delivery media decreased, in the range from 7.2 to 5.8.

A novel preparation of solid lipid nanoparticles with cyclosporin A for prolonged drug release

Solid lipid nanoparticles were prepared by a novel solvent diffusion method in an aqueous system. The lipophilic model drug cyclosporin A was incorporated into SLN to study encapsulation efficiency, zeta potential (charge) and drug delivery. Stearylamine and cyclosporin A were dissolved in ethanol and acetone and the resultant organic solution was dropped into water at 60 degrees C. The drug-loaded SLN suspension quickly formed with an azury color. After burst drug release with 18% of the drug over the first 12 hours, a distinctly prolonged release over a monitored period of 16 days was observed, with nearly 4% of the drug being released each day. These results demonstrate the suitability of SLN produced with the proposed method as a prolonged release formulation for lipophilic drugs.

Preparation and characterization of solid lipid nanoparticles containing peptide

Solid lipid nanoparticles (SLN) are an alternative colloidal carrier system for controlled drug delivery. However, only a few have been studied regarding the incorporation of peptides into SLN, due to the hydrophilic peptide not easy to enter the lipophilic matrix of SLN. In the present report, peptide-loaded solid lipid nanoparticles were prepared by a novel solvent diffusion method in an aqueous system. The model peptide gonadorelin was incorporated to study the entrapment efficiency, size, zeta potential (charge) and drug delivery characterization. Gonadorelin and monostearin were dissolved in acetone and ethanol at 50 degrees C in water bath, the resultant organic solution was poured into an aqueous containing 1% polyvinyl alcohol (PVA) under mechanical agitation. The peptide-loaded solid lipid nanoparticles were quickly produced and separated by centrifugation. The average volume diameter of gonadorelin-loaded SLN is 421.7 nm and the zeta potential of SLN is -21.1 mV dispersed in distilled water. Up to 69.4% of gonadorelin can be incorporated. In vitro release of gonadorelin from SLN is slow. In the test solution of a 0.1N hydrochloric acid for 2h and then transferred in a pH 6.8 phosphate buffer (simulative gastrointestinal fluid), the drug-release behavior from SLN suspension exhibited a biphasic pattern. After burst drug-release at the first 6h at a percentage of 24.4% of loaded gonadorelin, a distinctly prolonged release over a monitored period of 12 days was observed and nearly 3.81% of drug was released in each day. In the test solution of a pH 6.8 phosphate buffer (simulative intestinal fluid), the drug-release rate from SLN was similar to that in the simulative gastrointestinal fluid. Further, a novel preparation method in the present research for peptide-loaded SLN was established. These results also demonstrate the principle suitability of SLN as a prolonged release formulation for hydrophilic peptide drugs.

Preparation of solid lipid nanoparticles with clobetasol propionate by a novel solvent diffusion method in aqueous system and physicochemical characterization

Solid lipid nanoparticles (SLN) are a colloidal carrier system for controlled drug delivery. Monostearin SLN were prepared by a novel solvent diffusion method in an acidic aqueous system in order to improve the recovery of the method. The lipophilic model drug clobetasol propionate was incorporated to study the recovery of nanoparticles, entrapment efficacy, zeta potential (charge) and drug delivery characterization. The drug and monostearin were dissolved in acetone and ethanol at 50 degrees C in water bath, the resultant organic solution was poured into an acidic aqueous (pH 1.10) containing 1% polyvinyl alcohol (PVA) under mechanical agitation at room temperature. The drug loaded SLN was quickly produced with an aggregation state and easily separated by centrifugation. The recovery of nanoparticles was markedly increased compared to using a usual aqueous (pH 5.73) containing the same concentration of PVA. After burst drug release at the first 3 h, a distinctly prolonged release over a monitored period of 4 days was observed and nearly 6% drug was released in each day. Further, a novel preparation method and the optimized separation parameters in the present research for SLN were established. These results also demonstrate the principle suitability of SLN as a prolonged release formulation for lipophilic drugs.

Multi-component reactive transport modeling of natural attenuation of an acid groundwater plume at a uranium mill tailings site

Natural attenuation of an acidic plume in the aquifer underneath a uranium mill tailings pond in Wyoming, USA was simulated using the multi-component reactive transport code PHREEQC. A one-dimensional model was constructed for the site and the model included advective-dispersive transport, aqueous speciation of 11 components, and precipitation-dissolution of six minerals. Transport simulation was performed for a reclamation scenario in which the source of acidic seepage will be terminated after 5 years and the plume will then be flushed by uncontaminated upgradient groundwater. Simulations show that successive pH buffer reactions with calcite, Al(OH)3(a), and Fe(OH)3(a) create distinct geochemical zones and most reactions occur at the boundaries of geochemical zones. The complex interplay of physical transport processes and chemical reactions produce multiple concentration waves. For SO4(2-) transport, the concentration waves are related to advection-dispersion, and gypsum precipitation and dissolution. Wave speeds from numerical simulations compare well to an analytical solution for wave propagation.

Cowpox virus genome encodes a second soluble homologue of cellular TNF receptors, distinct from CrmB, that binds TNF but not LT alpha

We show the cowpox genome (Brighton Red strain) contains a single copy gene, crmC, expressed at late times during viral infection, encoding a soluble, secreted protein whose sequence marks it as a new member of the TNF receptor family. The cysteine-rich protein contains 186 amino acids, the N-terminal 21 of which constitute a signal peptide, and two potential N-linked glycosylation sites. The approximately 25-kDa recombinant protein binds TNF specifically and completely inhibits TNF-mediated cytolysis. The strongest sequence homologues are the ligand-binding regions of the type II cellular TNF receptor (TNFRII) and CrmB, a distinct pox virus gene also encoding a soluble TNF binding protein. Unlike TNFRII and CrmB, CrmC does not bind lymphotoxin (LT alpha, TNF beta) and lacks the conserved (but nonhomologous) approximately 150-residue C-terminal domain of CrmB proteins. The presumed function of CrmC is viral inhibition of host-elicited TNF.

Cowpox virus contains two copies of an early gene encoding a soluble secreted form of the type II TNF receptor

The inverted terminal repeats of the DNA of cowpox virus (Brighton Red strain) contain the crmB gene, an additional member of a family of viral genes that modify cytokine responses to infection. The crmB gene is transcribed from an early promoter. The primary product is a 355-amino-acid protein containing a signal peptide sequence and three potential N-linked glycosylation sites. The mature gene product is a secreted soluble protein that has an apparent molecular mass of 48 kDa. TNF alpha and TNF beta bind to this protein in a competitive manner, consistent with the sequence of its N-terminal 176 amino acids, which closely resembles the ligand-binding domains of the type II (75-kDa) human TNF receptor. The sequence of the C-terminal 161 amino acids of the CrmB protein is unlike that of human TNF receptors, but overall, the CrmB protein is similar to the T2 proteins of the leporipoxviruses (48% identity) and the predicted product of the G4R/G2R open reading frame of variola virus (85% identity), suggesting that not only the TNF-binding domains but also the C-terminal regions contribute to the functions of these viral proteins. These results show that orthopoxiviruses such as cowpox virus encode secreted forms of TNF receptors that can contribute to the modification of TNF-mediated antiviral processes.

Transcription of the terminal loop region of vaccinia virus DNA is initiated from the telomere sequences directing DNA resolution

The telomeres of vaccinia virus DNA are transcribed at late times after infection. Analysis of cDNAs of RNA transcripts of the terminal loop region of the viral DNA shows that both inverted and complementary forms of the terminal loop region are transcribed. These late RNAs, which contain 5' poly(A) sequences, do not appear to encode any proteins. The transcriptional start sites for most of these RNAs are within the sequences that direct the resolution of concatemeric DNA replication intermediates (M. Merchlinsky and B. Moss, 1989, J. Virol. 63, 4354-4361). This suggests that the process of DNA resolution may involve transcription initiated from the telomere sequences required for resolution.