Response of Pseudomonas tolaasii,the causal agent of mushroom brown blotch disease to the volatile compounds produced by endofungal bacteria

Volatile organic compounds (VOCs) produced by bacteria have significant potential to control phytopathogens. In this study, the VOCs produced by endofungal bacteria Pseudomonas sp. Bi1, Bacillus sp. De3, Pantoea sp. Ma3 and Pseudomonas sp. De1 isolated from wild growing mushrooms were evaluated in vitro for their antagonistic activity against Pseudomonas tolaasii Pt18, the causal agent of mushroom brown blotch disease. The gas chromatography–mass spectrometry (GC–MS) analysis revealed that strains Pseudomonas sp. Bi1, Pseudomonas sp. De1, Bacillus sp. De3 and Pantoea sp. Ma3 produced eight, sixteen, nine, and twelve VOCs, respectively. All antagonistic endofungal bacteria produced VOCs which significantly reduced brown blotch symptoms on mushroom caps and inhibited the growth of P. tolaasii Pt18 at the varying levels. Scanning electron microscopy revealed severe morphological changes in cells of P. tolaasii Pt18 following exposure to the VOCs of Pseudomonas sp. Bi1 and De1. Furthermore, The VOCs produced by endofungal bacteria significantly reduced swarming, swimming, twitching, chemotaxis motility and biofilm formation by P. tolaasii Pt18 cells, which are essential contributors to pathogenicity. This is to first report about the inhibition effects of VOCs produced by antagonistic bacteria on virulence traits of P. tolaasii. Our findings provide new insights regarding the potential of antibacterial VOCs as a safe fumigant to control mushroom brown blotch disease.

     

Development of Novel Prime-Boost Strategies Based on a Tri-Gene Fusion Recombinant L. tarentolae Vaccine against Experimental Murine Visceral Leishmaniasis

Visceral leishmaniasis (VL) is a vector-borne disease affecting humans and domestic animals that constitutes a serious public health problem in many countries. Although many antigens have been examined so far as protein- or DNA-based vaccines, none of them conferred complete long-term protection. The use of the lizard non-pathogenic to humans Leishmania (L.) tarentolae species as a live vaccine vector to deliver specific Leishmania antigens is a recent approach that needs to be explored further. In this study, we evaluated the effectiveness of live vaccination in protecting BALB/c mice against L. infantum infection using prime-boost regimens, namely Live/Live and DNA/Live. As a live vaccine, we used recombinant L. tarentolae expressing the L. donovani A2 antigen along with cysteine proteinases (CPA and CPB without its unusual C-terminal extension (CPB^-CTE)) as a tri-fusion gene. For DNA priming, the tri-fusion gene was encoded in pcDNA formulated with cationic solid lipid nanoparticles (cSLN) acting as an adjuvant. At different time points post-challenge, parasite burden and histopathological changes as well as humoral and cellular immune responses were assessed. Our results showed that immunization with both prime-boost A2-CPA-CPB^-CTE-recombinant L. tarentolae protects BALB/c mice against L. infantum challenge. This protective immunity is associated with a Th1-type immune response due to high levels of IFN-γ production prior and after challenge and with lower levels of IL-10 production after challenge, leading to a significantly higher IFN-γ/IL-10 ratio compared to the control groups. Moreover, this immunization elicited high IgG1 and IgG2a humoral immune responses. Protection in mice was also correlated with a high nitric oxide production and low parasite burden. Altogether, these results indicate the promise of the A2-CPA-CPB^-CTE-recombinant L. tarentolae as a safe live vaccine candidate against VL.     

An electrochemical biosensor for 3-hydroxybutyrate detection based on screen-printed electrode modified by coenzyme functionalized carbon nanotubes

3-Hydroxybutyrate, one of the main blood ketone bodies, has been considered as a critical indicator for diagnosis of diabetic ketoacidosis. Biosensors designed for detection of 3-hydroxybutyrate with advantages of precision, easiness and speedy performance have attracted increasing attention. This study attempted to develop a 3-hydroxybutyrate dehydrogenase-based biosensor in which single-walled carbon nanotubes (SWCNT) was used in order to immobilize the cofactor, NAD⁺, on the surface of screen-printed electrode. The formation of NAD⁺–SWCNT conjugates was assessed by electrochemistry and electron microscopy. Cyclic voltammetry was used to analyze the performance of this biosensor electrochemically. The considerable shelf life and reliability of the proposed biosensor to analyze real sample was confirmed by this method. The reduction in the over potential of electrochemical oxidation of NADH to ?0.15 V can be mentioned as a prominent feature of this biosensor. This biosensor can detect 3-hydroxybutyrate in the linear range of 0.01–0.1 mM with the low detection limit of 0.009 mM. Simultaneous application of screen-printed electrode and SWCNT has made the biosensor distinguished which can open new prospects for detection of other clinically significant metabolites.     

Efficient growth inhibition of EGFR over-expressing tumor cells by an anti-EGFR nanobody

Epidermal growth factor receptor (EGFR) is deemed to be one of the main molecular targets for diagnosis and treatment of cancer. It has been identified that EGFR involves in pathogenesis of some forms of human cancers. Monoclonal antibodies targeting EGFR could control the tumor cell growth, proliferation, and apoptosis by suppressing the signal transduction pathways. Nanobodies can be regarded as the smallest intact antigen binding fragments, derived from heavy chain-only antibodies existing in camelids. Here, we describe the identification of an EGFR-specific nanobody, referred to as OA-cb6, obtained from immunized camel with a cell line expressing high levels of EGFR. Utilizing flow cytometry (FACS) and blotting methods, we demonstrated that OA-cb6 nanobody binds specifically to EGFR expressing on the surface of A431 cells. In addition, OA-cb6 nanobody potently causes the inhibition of EGFR over expression, cell growth and proliferation. The antibody fragments can probably be regarded as worthwhile binding block for further rational design of anti-cancer therapy.     

Determination of HSV-1 UL5 and UL29 gene copy numbers in an HSV complementing Vero cell line

The genetic stability of transgenes is a critical characteristic used to assess constructed cell lines used for vaccine production. The evaluation of gene copy numbers by a qPCR method, is one of the most common approaches used to assess the consistency of transgenes in a constructed cell line. The cell line AV529-19 is a Vero-based cell line specifically engineered to express the HSV-1 UL5 and UL29 open reading frames. AV529-19 is used to support the replication of a defective HSV-2 viral candidate vaccine called HSV529. To assess the genetic stability of the UL5 and UL29 transgenes in AV529-19 cells, a digital PCR-based approach was developed. During characterization of the test method, the specificity, accuracy, and intermediate precision of the assay was investigated based on regulatory guidelines. The developed assay was used to monitor the stability of the transgenes in the manufactured AV529-19 cell lines by comparison of transgene copy numbers in the master cell bank (MCB) with their copy numbers in the extended cell bank (ECB). Results showed that the UL29 and UL5 transgenes are stable in that there are one and three copies of the UL29 and UL5 genes, respectively, per cell in both the AV529-19 MCB and ECB.     

Investigating the Structural Stability of RADA16-I Peptide Conjugated to Gold Nanoparticles

International Journal of Peptide Research and Therapeutics - RADA 16-I is an amphiphilic peptide which can form macroscopic scaffolds through self-assembly and has found many applications in tissue...     

Modulation of Apoptosis and Oxidative Stress with Nesfatin-1 in Doxorubicin Induced Cardiotoxicity in Male Rat

International Journal of Peptide Research and Therapeutics - Fibroblast growth factor 21 (FGF21) is a metabolic regulator with a wide range of biological functions. Although previous studies have...     

Toll-like receptors signaling network in pre-eclampsia: An updated review

Toll-like receptors (TLRs) are innate immune cells receptors. They are expressed on leukocytes, epithelial cells, and more particularly on placental immune cells and chorion trophoblast. Upregulation of innate immune response occurs during normal pregnancy, but its excessive activity is involved in the pathology of pregnancy complications including pregnancy-induced hypertension and pre-eclampsia (PE). The recent studies about the overmuch inflammatory responses and aberrant placentation are associated with increased expression of TLRs in PE patients. This review has tried to focus on the relationship between some activities of TLRs and the risk of preeclampsia development.