Preparation of Bacterial Ghosts for E. coli JM109 Using “Sponge-like Reduced Protocol”

Prodigiosin-Functionalized Probiotic Ghosts as a Bioinspired Combination Against Colorectal Cancer Cells

Lactobacillus acidophilus ghosts (LAGs) with the unique safety of a probiotic, inherent tropism for colon cells, and multiple bioactivities offer promise as drug carriers for colon targeting. Our objective was to evaluate LAGs functionalized with prodigiosin (PG), apoptotic secondary bacterial metabolite, as a bioinspired formulation against colorectal cancer (CRC). LAGs were prepared by a chemical method and highly purified by density gradient centrifugation. LAGs were characterized by microscopic and staining techniques as relatively small-sized uniform vesicles (≈1.6 µm), nearly devoid of cytoplasmic and genetic materials and having a negatively charged intact envelope. PG was highly bound to LAGs envelope, generating a physiologically stable bioactive entity (PG-LAGs), as verified by multiple microscopic techniques and lack of PG release under physiological conditions. PG-LAGs were active against HCT116 CRC cells at both the cellular and molecular levels. Cell viability data highlighted the cytotoxicity of PG and LAGs and LAGs-induced enhancement of PG selectivity for HCT116 cells, anticipating dose reduction for PG and LAGs. Molecularly, expression of the apoptotic caspase 3 and P53 biomarkers in HCT116 intracellular proteins was significantly upregulated while that of the anti-apoptotic Bcl-2 (B-cell lymphoma 2) was downregulated by PG-LAGs relative to PG and 5-fluorouracil. PG-LAGs provide a novel bacteria-based combination for anticancer biomedicine.

New typhoid vaccine using sponge-like reduced protocol: development and evaluation

Purpose

Typhoid remains a major health problem, especially in the developing world. Furthermore, the emergence of multidrug-resistant and extensively drug-resistant strains of Salmonella typhi added a sense of urgency to develop more effective typhoid vaccines, one of which is bacterial ghosts (BGs), prepared by both genetic and chemical means. The chemical method includes incubation with numerous agents for a short time at their minimum inhibitory or minimum growth concentrations. This study included the preparation of BGs by a sponge-like reduced protocol (SLRP).

Materials and Methods

Critical concentrations of sodium dodecyl sulfate, NaOH, and H₂O₂ were used. Moreover, high-quality BGs were visualized by scanning electron microscope (SEM). Subculturing was used to confirm the absence of vital cells. Besides, the concentrations of the released DNA and protein were estimated spectrophotometrically. In addition, the integrity of cells was proved by visualizing Gram-stained cells using a light microscope. Furthermore, a comparison between the immunogenicity and safety of the prepared vaccine and the available whole-cell killed vaccine was established.

Results

Improved preparation of high-quality BGs of S. typhi, visualized by SEM, revealed punctured cells with intact outer shells. Moreover, the absence of vital cells was confirmed by subculturing. At the same time, the release of respective amounts of proteins and DNA is another evidence of BGs' production. Additionally, the challenge test provided evidence that the prepared BGs are immunogenic and have the same efficacy as the whole cell vaccine.

Conclusion

The SLRP provided a simple, economical, and feasible method for BGs preparation.

Bacterial Ghosts of Pseudomonas aeruginosa as a Promising Candidate Vaccine and Its Application in Diabetic Rats

Infections with Pseudomonas aeruginosa (PA) pose a major clinical threat worldwide especially to immunocompromised patients. As a novel vaccine network for many kinds of bacteria, bacterial ghosts (BGs) have recently been introduced. In the present research, using Sponge-Like Reduced Protocol, P. aeruginosa ghosts (PAGs) were prepared to maintain surface antigens and immunogenicity. This is the first study, to our knowledge, on the production of chemically induced well-structured bacterial ghosts for PA using concentrations of different chemicals. The research was carried out using diabetic rats who were orally immunized at two-week intervals with three doses of PAGs. Rats were subsequently challenged either by the oral route or by the model of ulcer infection with PA. In challenged rats, in addition to other immunological parameters, organ bioburden and wound healing were determined, respectively. Examination of the scanning and transmission electron microscope (EM) proved that PAGs with a proper three-dimensional structure were obtained. In contrast to control groups, oral PAGs promoted the generation of agglutinating antibodies, the development of IFN-γ, and the increase in phagocytic activity in vaccinated groups. Antibodies of the elicited PAGs were reactive to PA proteins and lipopolysaccharides. The defense against the PA challenge was observed in PAGs-immunized diabetic rats. The resulting PAGs in orally vaccinated diabetic rats were able to evoke unique humoral and cell-mediated immune responses and to defend them from the threat of skin wound infection. These results have positive implications for future studies on the PA vaccine.

Bacteria from Infectious Particles to Cell Based Anticancer Targeted Drug Delivery Systems

Bacterial ghosts (BGs) are empty cell envelopes of nonliving evacuated bacterial cells. They are free from their cytoplasmic contents; however, they sustain their cellular 3D morphology and antigenic structures, counting on bioadhesive properties. Lately, they have been tested as an advanced drug delivery system (DDS) for different materials like DNA, peptides, or drugs, either single components or combinations. Different studies have revealed that, BG DDS were paid the greatest attention in recent years. The current review explores the impact of BGs on the field of drug delivery and drug targeting. BGs have a varied area of applications, including vaccine and tumor therapy. Moreover, the use of BGs, their synthesis, their uniqueness as a delivery system and application principles in cancer are discussed. Furthermore, the safety issues of BGs and stability aspects of using ghost bacteria as delivery systems are discussed. Future perspective efforts that must be followed for this important system to continue to grow are important and promising.

Recent Approaches towards Control of Fungal Diseases in Plants: An Updated Review

Recent research demonstrates that the number of virulent phytopathogenic fungi continually grows, which leads to significant economic losses worldwide. Various procedures are currently available for the rapid detection and control of phytopathogenic fungi. Since 1940, chemical and synthetic fungicides were typically used to control phytopathogenic fungi. However, the substantial increase in development of fungal resistance to these fungicides in addition to negative effects caused by synthetic fungicides on the health of animals, human beings, and the environment results in the exploration of various new approaches and green strategies of fungal control by scientists from all over the world. In this review, the development of new approaches for controlling fungal diseases in plants is discussed. We argue that an effort should be made to bring these recent technologies to the farmer level.

The Development of a Phytopathogenic Fungi Control Trial: Aspergillus flavus and Aspergillus niger Infection in Jojoba Tissue Culture as a Model

After introducing the idea of using concentrations equal to or less than the minimum inhibition concentration (MIC) of some active chemical compounds for evacuating microbial cells, different types of microbes were evacuated. The original protocol was given the name sponge-like protocol and then was reduced and modified from a microorganism to another to prepare microbial ghosts for various applications such as immunological applications, drug delivery, and isolation of DNA and protein. Fungal pathogens that infect plants critically affect cost effectiveness, quality, and quantity of their production. They kill plant cells and/or cause plant stress. Plant fungal infections can originate from many sources such as infected soil, seeds, or crop debris causing diseases and quality losses around the world with billions of US dollars annually as costs of the associated productivity loss. This study focused on the application of the sponge-like protocol in protecting in vitro tissue cultures of plants against fungal pathogens. This can be useful for research purposes or may be developed to be introduced in field applications. Aspergillus flavus and Aspergillus niger infection in tissue culture of jojoba (Simmondsia chinensis (Link) Schn.) was used as a model to establish the employment of this protocol to control plant fungal diseases. The best conditions for A. flavus and A. niger ghosts production previously mapped by randomization experimental design (reduced Plackett–Burman experimental design) were used to prepare fungal ghosts. SDS, NaOH, NaHCO₃, and H₂O₂ were used in their MIC (+1 level) or minimum growth concentration (MGC, −1 level) according to the determined optimal experimental design. The release of both of DNA and protein from the fungal cells was evaluated spectrophotometrically at 260_nm and 280_nm, respectively, as an indicator for cell loss of their cytoplasm. Fungal ghost cells were also examined by transmission electron microscopy. After confirming the preparation of high-quality fungal ghost cells, the same conditions were mimicked to control plant fungal infection. Jojoba grown in tissue culture was sprayed with fungal cells (about 10³ CFU) as a control experiment or fungal cells followed by treatment with solution (a) represents the fungal ghost cells formation calculated critical concentration (FGCCC) of SDS, NaOH, and NaHCO₃ and then treatment with solution (b) represents H₂O₂ FGCCC. The plant was examined on day 0 (plant grown before any infection or infection followed by treatment), day 5 (plant at day 5 after infection or infection followed by treatment), and day 10 (plant at day 10 after infection or infection followed by treatment). We observed fungal growth in case of control experiments at days 5 and 10 on the tissue culture medium, as well as plant, and the absence of any fungal growth in case of plant treated with FGCCC even after day 10. We recommend using this FGCCC in the form of chemical spraying formulation to treat the plants aiming to control different plant fungal infections in in vitro tissue culture systems or applied in field.

Vision of bacterial ghosts as drug carriers mandates accepting the effect of cell membrane on drug loading

The use of bacterial ghosts (BGs) for drug delivery is an extremely fascinating perspective especially with the inherited efficient target-ability to specialized tissues. Trafficking of drug molecules across the outer membrane of Gram-negative bacteria are important to be understood for both loading (influx) and drug release (efflux). In this study, Escherichia coli (E. coli) BGs were prepared using modified protocol sponge-like reduced protocol (SLRP) which was used for loading of doxorubicin (DOX). First time in the literature, different possible factors affecting DOX loading from BGs were examined in this study. These factors including drug concentration, temperature, pH gradient, incubation time and tonicity, are proposed to effect on drug loading into E. coli BGs. Results of optimum effect from accompanied factors were found to be 10 mg/mL as DOX concentration at pH 6 with tonicity of 0.7% incubated overnight at 4 °C. After gather all factors, the amount of DOX loaded inside the BGs was recorded as 37.58%. The in vitro release studies of DOX loaded BGs over time showed a burst initial release rate of 26.75% at the first 12 h followed by a period of sustained release lasting for 16 days to give maximum release rate of 58.04%. Remarkably, DOX loaded in BG showed more apoptosis (55%) than control and DOX solution. Overall, the results indicated the presence of some important factors to be controlled when loading drugs into BGs. Also, data showed the future possibility of utilizing BGs to deliver DOX to colon cancer cells.

The development of ghost vaccines trials

INTRODUCTION

Bacterial ghosts are intact bacterial cell envelopes that are emptied of their content by gentle biological or chemical poring methods. Ghost techniques increase the safety of the killed vaccines, while maintaining their antigenicity due to mild preparation procedures. Moreover, ghost-platforms may express and/or carry several antigens or plasmid-DNA encoding for protein epitopes.

AREAS COVERED

In this review, the development in ghost-vaccine production over the last 30 years is classified and discussed. The different applications of ghost-vaccines, how they trigger the immune system, their advantages and limitations are displayed. The phage-mediated lysis, molecular manipulation of the lysis-genes, and the biotechnological production of ghosts are described. The trials are classified according to the pattern of lysis and to the type of bacteria. Further subdivision includes chronological ordered application of the ghost as alternative-killed vaccine, recombinant antigen platform, plasmid DNA carrier, adjuvants, and dendritic cell inducer. Particular trials for specific pathogens or from distinct research schools are gathered.

EXPERT OPINION

Ghosts are highly qualified to act as immune-presenting platforms that express and/or carry several recombinant and DNA vaccines, as well as, being efficient alternative-killed vaccines. The coming years will show more molecular advances to develop ghost-production and to express more antigens.

Bacterial Ghosts Carrying 5-Fluorouracil: A Novel Biological Carrier for Targeting Colorectal Cancer

Bacterial ghosts (BGs) are non-deformed bacterial cell envelopes that possess undamaged external configurations for precise attachment to different cells of the human body. The Escherichia coli BGs were successfully produced using a modified sponge-like reduced protocol and characterized by SEM. Four different concentrations of 5-fluorouracil (5-FU) were used to study the impact on the "ghosts" cell wall. 5-FU was then loaded into the BGs and the loading capacity (LC %) and entrapment efficiency (EE %) were determined and were found to be 38.3 ± 0.8 and 76.6 ± 0.8, respectively. The in vitro release studies were conducted in dialysis bags over a time period of 16 days and the accumulative 5-FU released (%) was calculated. Overall, 69.2% of the ghost-associated 5-FU was released from the BGs and release from the E. coli ghosts is governed by non-Fickian diffusion. The Caco-2 cell line was used to investigate the cytotoxicity of 5-FU-loaded BGs.

Interaction between bacterial cell membranes and nano-TiO2 revealed by two-dimensional FTIR correlation spectroscopy using bacterial ghost as a model cell envelope

The interaction between microorganisms and nanoparticles is a crucial step towards understanding the subsequent biological effect. In this study, the interaction between TiO₂ nanoparticles and bacterial cell membrane was investigated by Two-dimensional Correlation Fourier Transformation Infrared spectroscopy (2D-FTIR-COS) using bacterial ghosts (BGs), which are non-living bacterial cell envelopes devoid of cytoplasm. The synchronous map of 2D-FTIR-COS results indicated that the functionalities in proteins of BGs preferentially interacted with TiO₂ nanoparticles; whereas the interaction of TiO₂ nanoparticles with characteristic functionality in polysaccharides (COH) and phospholipids (PO) were very weak or insensitive. This conclusion was further corroborated by settling of TiO₂ nanoparticles in the presence of pure protein, polysaccharide and phospholipid represented by bovine serum albumin (BSA), alginate and phosphatidylethanolamine (PE). Additionally, the asynchronous map of 2D-FTIR-COS indicated a sequential order of functionalities bonded to TiO₂ nanoparticles with the order of: COO^- > aromatic CC stretching > NH, amide II > CO, ketone. These findings contribute to deeper understanding of the interaction between TiO₂ nanoparticles and bacterial cell membrane in aquatic systems.

Generation of a Novel Staphylococcus aureus Ghost Vaccine and Examination of Its Immunogenicity against Virulent Challenge in Rats

Staphylococcus aureus is a Gram-positive pathogen that causes a wide range of infections in humans and animals. Bacterial ghosts are nonliving, empty cell envelopes and are well represented as novel vaccine candidates. In this study, we examined the immunogenicity and protective efficacy of S. aureus ghosts (SAGs) against a virulent challenge in rats. Nonliving SAGs were generated by using the MIC of sodium hydroxide. The formation of a transmembrane lysis tunnel structure in SAGs was visualized by scanning electron microscopy. To investigate these SAGs as a vaccine candidate, rats were divided into four groups, A (nonimmunized control), B (orally immunized), C (subcutaneously immunized), and D (intravenously immunized). The IgG antibody responses were significantly stronger in the SAG-immunized groups than in the nonimmunized control group (P < 0.05). Moreover, a significant increase in the populations of CD4(+) and CD8(+) T cells was observed in all three immunized groups (P < 0.05). We also found that serum bactericidal antibodies were significantly elicited in the SAG-immunized groups (P < 0.05). Most importantly, the bacterial loads in the immunized groups were significantly lower than those in the nonimmunized control group (P < 0.01). These results suggest that immunization with SAGs induces immune responses and provides protection against a virulent S. aureus challenge.

Evaluation the surface antigen of the Salmonella typhimurium ATCC 14028 ghosts prepared by "SLRP"

Recently, bacterial ghosts (BGs) were prepared using a protocol based on critical chemical concentrations. It has been given the name "sponge like" (SL) protocol and used in its reduced form "sponge like reduced protocol" (SLRP). While specific antibody for Salmonella is available on the market under the commercial names (of some kits) such as Febrile Antigen Kit (N.S. BIO-TEC), we used the described Kit to investigate the validity of the SLRP. In this study, using SLRP we succeeded to prepare STGs with correct surface antigens could interact with their specific antibodies. Additionally the study has included oral vaccination with STGs with challenge test. The rats serums have been evaluated against both of the O and H antigens. The antigen-antibody interaction (agglutination) results of both the SLRP and the animal experiments prove that we have correct STGs able to immunize the rats against viable Salmonella. STGs could be used as vaccine and as adjuvant and in the antibodies and in the diagnostic kits production. This study is an additional step for the establishment of correct BGs for immunological purposes.