Prokaryotic High-Level Expression System in Producing Adhesin Recombinant Protein E of Nontypeable Haemophilus influenzae

Background:

Adhesion protein E (PE) of Haemophilus influenzae is a 16 - 18 kDa protein with 160 amino acids which causes adhesion to epithelial cells and acts as a major factor in pathogenesis.

Objectives:

In this study, we performed cloning, expression and purification of PE as a candidate antigen for vaccine design upon further study.

Materials and Methods:

At first, the pe gene of NTHi ATCC 49766 strain (483 bp) was amplified by PCR. Then, to sequence the resulted amplicon, it was cloned into TA vector (pTZ57R/T). In the next step, the sequenced gene was sub-cloned in pBAD/gIII A vector and transformed into competent Escherichia coli TOP10. For overexpression, the recombinant bacteria were grown in broth medium containing arabinose and the recombinant protein was purified using metal affinity chromatography (Ni-nitrilotriacetic acid) (Ni-NTA agarose). Finally, the protein was detected using sodium dodecyl sulfate polyacrylamide gel electrophores (SDS-PAG) and confirmed by western blotting.

Results:

The cloned gene was confirmed by PCR, restriction digestion and sequencing. The sequenced gene was searched for homology in GenBank and 99% similarity was found to the already deposited genes in GenBank. Then we obtained PE using Ni-NTA agarose with up to 7 mg/mL concentration.

Conclusions:

The pe gene was successfully cloned and confirmed by sequencing. Finally, PE was obtained with high concentration. Due to high homology and similarity among the pe gene from NTHi ATCC 49766 and other NTHi strains in GenBank, we believe that the protein is a universal antigen to be used as a vaccine design candidate and further studies to evaluate its immunogenicity is underway.

Molecular Detection of Genomic Islands Associated With Class 1 and 2 Integron in Haemophilus influenzae Isolated in Iran

Background:

High levels of multidrug resistance are usually associated with mobile genetic elements that encode specific resistance genes. Integrons are important genetic elements involved in spreading antibiotic multi-resistance. In special cases, large exogenous segments in bacterial genomes form genomic islands, and one of the functions of these genomic islands is antibiotic resistance. Due to geographical heterogeneity in antibiotic resistance pattern, it is mandatory to determine resistance patterns that are region-specific rather than generalized.

Objectives:

The objective of this study was to detect class 1 and 2 integrons in clinical isolates of Haemophilus influenzae.

Patients and Methods:

Antibiogram tests were carried out for twenty clinical isolates collected from different patients admitted to the Milad hospital. The PCR reactions were performed using universal primers specified for Int1 and Int2 genes attributed to class 1 and 2 integrons. Also amplification of integrase genes related to genomic islands was investigated by designing specific primers.

Results:

Of the twenty isolates, all (100%) were resistant to clindamycin, chloramphenicol and tetracycline, 95% to amoxicillin, 50% to ceftriaxone, 45% to ciprofloxacin and 5% to azithromycin. Also, all isolates (100%) were sensitive to trimethoprim/sulfamethoxazole. Class 1 and 2 integrons were not detected in any of the isolates; however the integrase gene attributed to genomic islands was identified in twelve isolates.

Conclusions:

Antibiotic resistance gene cassettes may be carried on integron or other genetic elements. The purpose of this study was to detect integron or genomic islands involved in antibiotic resistance profile of the isolates of H. influenzae collected in this study.

Genotyping of Haemophilus influenzae type b strains and their incidence in the clinical samples isolated from Iranian patients

BACKGROUND AND OBJECTIVE

Haemophilus influenzae type b (Hib) is divided into two distinct genotypes, type I and type II, based on the structure of capsular polysaccharides. The capsulation locus of Haemophilus influenzae type b consists of three functionally distinct regions, designated regions 1 to 3. Region III contains hcsA and hcsB genes; however, notable sequence variation in this region can be used to recognize different Hib genotypes. The purpose of this study was to investigate the prevalence and genotype of the Hib strains isolated from patients with invasive disease in Iran.

MATERIALS AND METHODS

In the present study, 8 pairs of primers were used for identification and serotyping of encapsulated Haemophilus influenzae strains, as well as confirmation of species identification. Additionally, in order to identify the capsular genotypes of Haemophilus influenzae type b (type I and II), two additional primer pairs were used to amplify the hcsA gene.

RESULTS

Out of 50 isolates of H. influenzae, four were found to be type b. Interestingly, among these 4 Hib isolates, 2 strains belonged to the type-II category.

CONCLUSION

Our study shows that the prevalence of both Hib types I and II seems to be high in Iran.

Immunization with 3-oxododecanoyl-L-homoserine lactone-r-PcrV conjugate enhances survival of mice against lethal burn infections caused by Pseudomonas aeruginosa

Quorum Sensing and type III secretion system play an important role in the virulence of Pseudomonas (P.) aeruginosa in burn wound infections. We aimed to explore the feasibility of using 3-oxo-C₁₂-HSL-r-PcrV conjugate as a candidate vaccine against P. aeruginosa caused infections. 3-oxo-C₁₂-HSL-r-PcrV conjugate was prepared and used for immunization of mice (10 μg, subcutaneous, three times, at 2-week intervals). Mice were divided into five groups: I: PcrV; II: 3-oxo-C₁₂-HSL-r-PcrV (10 μg); III: 3-oxo-C₁₂-HSL-r-PcrV (20 μg); IV: 3-oxo-C₁₂-HSL; and V: PBS receiving groups. After each shot of immunization, total and isotype antibody responses against corresponding antigen were measured to determine the immunization efficacy. One month after the last immunization, all groups were burned and challenged subeschar with P. aeruginosa PAO1. Survival rate and bacterial quantity in the skin and internal organs (liver and spleen) were evaluated 25-hr after burn infection. Immunization with 3-oxo-C₁₂-HSL-r-PcrV significantly increased total IgG and specific subclass antibodies (IgG₁, IgG₂a, IgG₂b, and IgM) in the serum of the groups II and III compared to the control group (p<0.001). While all the control mice (PBS injected group) died within 2 days after bacterial challenge, 64% of the group I, 78% of group II, and 86% of group III, survived within 14 days after challenge. Interestingly, bacterial burden in the liver and spleen of 3-oxo-C₁₂-HSL-r-PcrV injected group (III) was significantly lower than the control group (p<0.001). The present study proposed two-component vaccine to inhibit Pseudomonas infections in burned mouse.

Nanosilver based anionic linear globular dendrimer with a special significant antiretroviral activity

HIV is commonly caused to a very complicated disease which has not any recognized vaccine, so designing and development of novel antiretroviral agents with specific application of nanomedicine is a globally interested research subject worldwide. In the current study, a novel structure of silver complexes with anionic linear globular dendrimer was synthesized, characterized and then assessed against HIV replication pathway in vitro as well. The results showed a very good yield of synthesis (up to 70%) for the nano-complex as well as a very potent significant (P < 0.05) antiretroviral activity with non-severe toxic effects in comparison with the Nevirapine as standard drug in positive control group. According to the present data, silver anionic linear globular dendrimers complex may have a promising future to inhibit replication of HIV viruse in clinical practice.

Preparation and In Vitro Evaluation of Antitumor Activity of TGFαL3-SEB as a Ligand-Targeted Superantigen

Tumor-targeted superantigens (TTSs) have been used to treat a variety of tumors in preclinical studies. The TTS utilizes the powerful T-cell activation strategy by means of staphylococcal enterotoxins (SEs) as superantigens (Sags) to target tumor cells. Monoclonal antibodies and tumor-related ligands have been used as targeting molecules of Sag. In this study, we assessed the antitumor potency of tumor-targeted superantigen (TTS) strategy to design and produce fusion protein as a new antitumor candidate. The third loop (L3) of transforming growth factor α (TGF-α) was genetically conjugated to staphylococcal enterotoxin type B (TGFαL3-SEB), and its in vitro antitumor activity against murine breast cancer cells (A431 cell line) was evaluated. We designed and prepared TGFαL3-SEB chimeric protein and evaluated superantigenic activity, binding property to cancer cells, overexpression of epidermal growth factor receptor (EGFR), and in vitro antitumor activities. Cloning of tgfαl3-seb was confirmed by colony-polymerase chain reaction, enzymatic digestion, and sequencing. The recombinant TGFαL3-SEB fusion protein with molecular weight of 31 kDa was expressed and confirmed by anti-His Western-blot analysis. The TGFαL3-SEB fusion protein attached to A431 cell line with proper affinity and induced dose-dependent cytotoxicity against EGFR-expressing cancer cells in vitro. The TGFαL3-SEB chimeric protein exhibited potent in vitro antitumor activity. Our findings indicated that TGFαL3-SEB may be a promising anticancer candidate in cancer immunotherapy, and further studies are required to explore its potential in vivo therapeutic applications.

Heterologous Expression of 3-O-Deacylase in Modulates the Endotoxicity of Lipopolysaccharide

The lipopolysaccharide (LPS) of <i>Acinetobacter baumannii</i> is a potent stimulator of proinflammatory cytokines, such as interleukin-6 (IL-6). The 3-O-deacylase (PagL)-modifying enzyme that removes the 3-O-linked acyl chain from the disaccharide backbone of lipid A provides the opportunity to develop a new therapeutic compound that could reduce detrimental inflammatory responses. The plasmid pMMB66EH-PagL obtained by recombinant DNA technology was electroporated into <i>A. baumannii</i> ATCC 19606. Compared with wild-type LPS, outer membrane vesicles and inactivated whole cells of engineered bacteria had a statistically significant decreased ability to produce IL-6. Structural analysis of lipid A by negative-ion matrix-assisted laser desorption/ionization time-of-flight mass spectrometry revealed that the profile of lipid A fractions under PagL expression was changed. Taken together, our data showed that recombinant penta-acylated lipid A had less immunoreactivity and that the tetra-acylated version of lipid A with TLR4 antagonist activity decreased the induction of IL-6 production in the murine macrophage cell line J774 A.1.

Synthesis and characterization of a novel chemically designed (Globo)3-DTPA-KLH antigen

In recent years, many experiments have been conducted for the production and evaluation of anticancer glycoconjugated vaccines in developed countries and many achievements have been accomplished with Globo H derivatives. In the current experiment, a new chemically designed triplicate version of (Globo H)₃–diethylenetriamine pentaacetic acid (DTPA)–KLH antigen was synthesized and characterized. Immunization with (Globo H)₃-DTPA-KLH, a hexasaccharide that is a member of a family of antigenic carbohydrates that are highly expressed in various types of cancers conjugated with DTPA and KLH protein, induced a high level of antibody titer along with an elevated level of IL-4 in mice. Treatment of tumors with the collected sera from immunized mice decreased the tumor size in nude mice as well. None of the immunized mice illustrated any sign of tumor growth after injection of MCF-7 cells compared to the control animals. These findings, based on the newly presented structure of the Globo H antigen, lend exciting and promising evidence for clinical advancement in the development of a therapeutic vaccine in the future.

In silico design, cloning and high level expression of L7/L12-TOmp31 fusion protein of Brucella antigens

Globally, Brucella melitensis and B. abortus are the most common cause of human brucellosis. The outer membrane protein 31 (Omp31) and L7/L12 are immunodominant and protective antigens conserved in human Brucella pathogens which are considered as potential vaccine candidates. We aimed to design the fusion protein from Brucella L7/L12 and truncated Omp31proteins, in silico, clone the fusion in pET28a vector, and express it in Escherichia coli host. Two possible fusion forms, L7/L12-TOmp31 and TOmp31-L7/L12 were subjected to in silico modeling and analysis. Analysis and validation of the fusion proteins with three dimensional (3D) models showed that both models are in the range of native proteins. However, L7/L12-Tomp31 structure was more valid than the TOmp31-L7/L12 model and subjected to in vitro production. The major histocompatibility complex (MHC II) epitope mapping using IEDB database indicated that the model contained good MHC II binders. The L7/L12-TOmp31 coding sequence was cloned in pET28a vector. The integrity of the construct was confirmed by polymerase chain reaction, restriction enzyme mapping, and sequencing. The fusion was successfully expressed in E. coli BL21 (DE3) by induction with isopropyl β-D-thiogalactopyranoside. The rL7/L12-TOmp31 was purified with Ni-NTA column. The yield of the purified rL7/L12-TOmp31 was estimated by Bradford method and found to be 40 mg/L of the culture. Western blotting with anti-His antibody revealed a specific reactivity with purified rL7/L12-TOmp31 produced in E. coli and showed the functional expression in the prokaryotic system. In this study, a new protein vaccine candidate against brucellosis was constructed with the help of bioinformatics tools and the construct was expressed in the bacterial host. Studies evaluating the immunogenicity and cross-protection of this fusion protein against B. melitensis and B. abortus are underway.

Preparation and Evaluation of a New Lipopolysaccharide-based Conjugate as a Vaccine Candidate for Brucellosis

Objectives

Development of an efficacious vaccine against brucellosis has been a challenge for scientists for many years. At present, there is no licensed vaccine against human brucellosis. To overcome this problem, currently, antigenic determinants of Brucella cell wall such as Lipopolysaccharide (LPS) are considered as potential candidates to develop subunit vaccines.

Methods

In this study, Brucella abortus LPS was used for conjugation to Neisseria meningitidis serogroup B outer membrane vesicle (OMV) as carrier protein using carbodiimide and adipic acid–mediated coupling and linking, respectively. Groups of eight BALB/c mice were injected subcutaneously with 10 μg LPS alone, combined LPS + OMV and conjugated LPS–OMV on 0 days, 14 days, 28 days and 42 days. Anti-LPS IgG was measured in serum.

Results

The yield of LPS to OMV in LPS–OMV conjugate was 46.55%, on the basis of carbohydrate content. The ratio for LPS to OMV was 4.07. The LPS–OMV conjugate was the most immunogenic compound that stimulated following the first injection with increased IgG titer of ∼5-fold and ∼1.3-fold higher than that produced against LPS and LPS in noncovalent complex to OMV (LPS + OMV), respectively. The highest anti-LPS IgG titer was detected 2 weeks after the third injection (Day 42) of LPS–OMV conjugate. The conjugated compound elicited higher titers of IgG than LPS + OMV, that showed a 100–120-fold rise of anti-LPS IgG in mice.

Conclusion

These results indicate that our conjugated LPS–OMV can be used as a brucellosis vaccine, but further investigation is required.

Diversity of β-lactamases produced by imipenem resistant, Pseudomonas aeruginosa isolates from the bloodstream

INTRODUCTION

The emergence of imipenem non-susceptible Pseudomonas aeruginosa isolates is a matter of great concern because these isolates can become resistant to all available antibiotics. This study conducted to characterize β-lactamase genes in imipenem resistant P. aeruginosa isolates from bloodstream.

METHODS

56 non-duplicate clinical isolates of P. aeruginosa were collected in Tehran hospitals. Antibacterial susceptibility was determined by disk diffusion and MIC methods. ESBL and MBL production was confirmed by combined disk. β-Lactamase classes A, B and D genes were identified by PCR.

RESULTS

Seventeen (30.3%) isolates were imipenem resistant for which 16 isolates simultaneously were resistant to all tested antibiotics. While among 39 imipenem susceptible isolates, only two isolates were resistant to all tested antibiotics. In imipenem resistant isolates, blaTEM, blaSHV and blaOXA-10 were found in 41.1% of isolates and blaVIM, blaIMP and blaPER were identified in 47%, 11.7% and 5.8% of isolates respectively, while in imipenem susceptible isolates, blaTEM, blaSHV and blaOXA-10 were determined in 2.5%, 7.6% and 33.3% of isolates, respectively. The imipenem resistant isolates had been recovered mostly (67.7%) from patients in the Burn hospital.

CONCLUSION

The result of this study indicated the emergence of multidrug resistant MBL and non-MBL producing P. aeruginosa, particularly in the Burn hospital and blaVIM was dominant β-lactamase genes in imipenem resistant isolates. The isolation of carrier patients may lead to prevent a further dissemination.

Physico-chemical analysis of drinking groundwater of around Tehran by seasonal variation

This study was a cross-sectional descriptive study and done in four seasons during April 2011 to March 2012.The objective of the present study was to examine Physico-chemical properties of groundwater around Tehran. The results are also compared with the guideline values of Iranian legislation. A total of 160 drinking water samples were collected from different drinking groundwater around the Tehran. Total Dissolved Solids (TDS), conductivity and pH, were measured by using standard methods and the concentration of ions Cl-, F-, NO3-, NO2-, Br-, SO4(2-), PO4(3-), Ca2+, K+, Na+ and NH4+ in groundwater was performed using Ion chromatography (Metrohm Company, USA) with standard method. This study showed that most of the parameters in groundwater were below the Iranian permissible limit except total dissolved solids (N = 2), conductivity (N = 2), nitrate as NO3- (N = 22), chloride (N = 3), sulphate (N = 2), fluoride (N = 3) and ammonia (N = 8). There were significant differences (p < 0.05) between physico-chemical parameters such as pH, nitrite (NO2-), sodium, potassium, sulphate, ammonia, bromide and phosphate in different seasons. These results are important, not only for the many people who drink groundwater but also for the health supervisory agencies such as Ministry of Health and Institute of Standards and Industrial of Iran (ISIRI) to have more effective control on groundwater.

Induction of Strong and Specific Humoral and T-helper 1 Cellular Responses by HBsAg Entrapped in the Methanobrevibacter smithii Archaeosomes

BACKGROUND

Application of adjuvants with microbial origins is a recently highlighted approach in the vaccinology trials. Archaeosomes are among these microbial compounds with both adjuvant and liposomal activities and features.

METHODS

In the present study, recombinant HBsAg encapsulated into Methanobrevibacter smithii (M. smithii) archaeosomes. Balb/c mice immunized with this compound and humoral and cytokine secretion pattern of immunized models analyzed.

RESULTS

Frequency of IFN-γ secreting cells in the HBsAg-containing archaeosomes group was significantly higher than HBsAg and HBsAg(+)C/IFA groups (p≤0.05). IgG2a titer in the sera of HBsAg-containing archaeosomes group was also significantly higher than this subclass titer in the other groups (p≤ 0.05).

CONCLUSION

Analysis of induced responses revealed the immunopotentiating characteristics of M. smithii archaeosomes in the induction of T-helper 1 responses according to the dominance of IgG2a subtype and IFN-γ secreting splenocytes of immunized mice.

Genotyping of human parechoviruses in Iranian young children with aseptic meningitis and sepsis-like illness

Human parechoviruses (HPeV) are classified into 14 genotypes. HPeV1 and HPeV2 are the most prevalent genotypes in young children, which have been associated with mild to severe diseases. This study was conducted to investigate the involvement of HPeVs in aseptic meningitis and sepsis-like illness in Iran. Viral RNA was extracted from 148 cerebrospinal fluid samples from children <8 years old with primary diagnosis of aseptic meningitis and/or sepsis-like illness. Specific HPeV, HEV real-time PCR and HPeV typing were done to identify the infection rate of these viruses. HPeV and HEV were detected in 64 (43.24 %), 31 (20.94 %) of 148 patients with 10 (6.75 %) coinfection. VP1/VP3 junction region was successfully sequenced from 12 of the HPeV-positive specimens, and all of them were identified as HPeV1. HPeV was more prevalent than HEV in both aseptic meningitis and sepsis-like illness, so further studies are needed to understand the disease burden of HPeV infections, and clinical manifestations especially in specific illnesses of possible viral etiology. Direct detection of these viruses leads to reduce hospitalization and use of antibiotic, which are often followed by other complications in neonates and young children.

Immunization of Mice by BCG Formulated HCV Core Protein Elicited Higher Th1-Oriented Responses Compared to Pluronic-F127 Copolymer

BACKGROUND

A supreme vaccine for Hepatitis C virus (HCV) infection should elicit strong Th1-oriented cellular responses. In the absence of a Th1-specific adjuvant, immunizations by protein antigens generally induce Th2-type and weak cellular responses.

OBJECTIVES

To evaluate the adjuvant effect of BCG in comparison with nonionic copolymer-Pluronic F127 (F127) as a classic adjuvant in the formulation of HCV core protein (HCVcp) as a candidate vaccine for induction of Th1 immune responses.

MATERIALS AND METHODS

Expression of N-terminally His-Tagged HCVcp (1-122) by pIVEX2.4a-core vector harboring the corresponding gene under the control of arabinose-inducible (araBAD) promoter was achieved in BL21-AI strain of E.coli and purified through application of nitrilotriacetic acid (Ni-NTA) chromatography. Mice were immunized subcutaneously (s.c.) in base of the tail with 100 μl of immunogen (F127+HCVcp or BCG+HCVcp; 5 μgHCVcp/mouse/dose) or control formulations (PBS, BCG, F127) at weeks 0, 3, 6. Total and subtypes of IgG, as well as cellular immune responses (Proliferation, In vivo CTL and IFN-γ/IL-4 ELISpot assays against a strong and dominant H2-d restricted, CD8+-epitopic peptide, core 39-48; RRGPRLGVRA of HCVcp) were compared in each group of immunized animals.

RESULTS

Expression and purification of core protein around the expected size (21 kDa) was confirmed by Western blotting. The HCVcp + BCG vaccinated mice showed significantly higher lymphocyte proliferation and IFN-γ production but lower levels of cell lysis (45% versus 62% in CTL assay) than the HCVcp+F127 immunized animals. "Besides, total anti-core IgG and IgG1 levels were significantly higher in HCVcp + F127 immunized mice as compared to HCVcp + BCG vaccinated animals, indicating relatively higher efficacy of F127 for the stimulation of humoral and Th2-oriented immune responses".

CONCLUSIONS

Results showed that HCVcp + BCG induced a moderate CTL and mixed Th1/Th2 immune responses with higher levels of cell proliferation and IFN-γ secretion, indicating that BCG may have a better outcome when formulated in HCVcp-based subunit vaccines.