ABSTRACT
Acinetobacter baumannii [A. baumannii] is a major hospital pathogen with a high capacity to resist most common anti-microbial agents. A. baumannii is the etiologic agent for various illnesses including pneumonia, meningitis, and bloodstream infections. Biofilm associated proteins [Bap] are specific cell surface proteins essential for the formation of biofilm and play a main role in its pathogenicity. Previously, we have studied various regions of this protein. Considering different criteria, some regions were introduced as conserved and immunogenic. The immunogenicity of one of those regions pertaining to amino acids 706-1076 previously examined has shown that its expression triggers high antibody levels when injected to mice thereby protecting the animals against the bacterium. The present study examines region 4 of the Bap protein in order to validate the previous bioinformatics studies and its immunogenicity. In order to obtain immunity against this pathogen, a 1620 bp gene from Bap was amplified and cloned in pET32a. This region from Bap was cloned, expressed and verified by monoclonal antibodies. BALB/c mice were immunized by subcutaneous injection of the pure recombinant protein. Mice immune response was determined by ELISA. High titer of raised antibodies implied that the recombinant protein was a strong antigen and immunogen. The results indicate that this protein can be a suitable choice for developing a new recombinant vaccine against A. baumannii
ABSTRACT
Acinetobacter baumannii [A. baumannii] is a Gram-negative, non-motile aerobic bacterium which is known as a nosocomial pathogen that is often resistant to a broad range of antibiotics. The pathogen is a serious agent of mortality and morbidity in hospitals, particularly among immunocompromised patients. Treatment and control of its infections is complicated owing to its high antibiotic resistance, survival in various environmental conditions and utilization of wide range of nutrient sources. Early detection of the pathogen in established infections is pivotal for infection control. Culture and biochemical tests are current methods for detection of the bacterium, which take approximately 2-5 days. Hence, a new, rapid, specific and affordable diagnostic test is needed. Development of such test depends on a suitable biomarker that lacks crossreactivity with other bacteria. This study intends to unveil a 34.4 kDa outer membrane protein [OMP] introduced by Islam et al. in A. baumannii ATCC19606. We harnessed various bioinformatic servers to screen the entire proteome of this bacterium. Properties critical to the screening included molecular weight, localization, topology, homology, antigenicity and allergenicity of proteins. Three proteins were found as suitable candidate molecular weights as well as localization points of view. BLAST searches, antigen probability predictions and other analyses led to the selection of one protein as the best specific antigen of A. baumannii. The in silico analyses unveiled the best candidate protein vide accession number ZP_05827218.1
ABSTRACT
Acinetobacter baumannii [A. baumannii] has a good potential to colonize on various surfaces. As a virulence factor, adhesion to surfaces is the first step in colonization. The Two-Partner Secretion System [TPS] proteins are key factors for bacterial attachment. The purpose of this study is to identify and study the role of this family of proteins in adhesion of A. baumannii to human epithelial cells. Gene homologues that encoded the TPS were analyzed by bioinformatics tools and the primers were designed accordingly. The constructs synthesized in the pET22b vector were transferred to BL21[DE3]. The transformed cells were named FhaB1 and FhaB2. The protein expression on the cell membrane was studied in addition to bacterial adhesion and biofilm formation by recombinant strains, A. baumannii and E.coli BL21[DE3]. Bioinformatic studies showed the bacterial potential of producing two exoproteins [FhaB1 and FhaB2]. Expression of the recombinant proteins on the outer membrane was confirmed by Western Blot Analysis and whole cell ELISA. The results revealed an association between the recombinant cells and bacterial adhesion and biofilm formation. FhaB1, FhaB2 and A. baumannii exhibited enhanced adherence to human lung epithelial cells compared to E.coli BL21[DE3] TPS in A.baumannii is of adherence and colonization factors and is one of the bacterial virulence factors
ABSTRACT
Despite toxic effects of some essential oils, their use is not under control. With a view to increasing trend of utilisation of herbal products, some biological aspects of Thymus daenensis are repoted here for the first time. Antimicrobial properties using disk diffusion and dilution tests, nitric oxide radical scavenging by Marcocci et al method and cytotoxic properties employing dimethylthiazolyl diphenyltetrazolium bromide reduction test were carried out with Thymus daenensis and commercial Thyme essential oils and their main chemical compound, thymol. The microbial sensitivity to the oils were in Candida albicans>E. coli>S. aureus>P. aeruginosa order. The minimum inhibitory and microbicidal concentrations were in the range of 0.04-10mg/ml. Nitric oxide radical scavenging was dose dependent with an IC50 of 5, 75, 863 micro g, and total phenolics of 644.07 +/- 6.79, 16.94 +/- 2.55, 10.33 +/- 2.31 micro g Gallic acid equivalent per mg sample and total flavonoid content of 73.51 +/- 1.34, 0.56 +/- 0.02, 0.21 +/- 0.09 mg Catechin equivalent per gram T. daenensis oil, commercial thyme oil and thymol respectively. The concentrations from T. daenensis oil, commercial thyme oil and thymol required to exert 50% fatal effect [IC50] on healthy human normal lymphocytes and Hela cells were 1455, 12.10, 2867 and 4.95, 3.61, 1730 micro g respectively. T. daenensis with its good antimicrobial property can prevent formation of toxic reactive oxygen species and as a good antioxidant, it can directly scavenge NO and O2-. With a view to cancerous cells killing properties of the oils at their lowest concentrations without fatal effect on normal healthy cells, feasibility of their application in combating cancerous cells may be promising
ABSTRACT
Profound consumption of medicinal plants products worldwide and public misconception of the products safety puts the urgent need forward as to evaluation of their safe and harmful aspects. In the present study the Lavandula angustifolia essential oil was studied with a view to the foregoing criteria. The antimicrobial, antioxidative, hematologic and cytotoxic properties of Lavandula angustifolia essential oil were studied. The bacterial strains sensitive to Lavandula angustifolia oil were in the following order: S. aureus>E. coli>K. pneumonia>Streptococcus faecalis>P. aeruginosa. Antioxidative property of the oil was carried out using beta carotene bleaching test and the results were compared with the standard synthetic antioxidants. Lipid peroxidation inhibitions were lower than the synthetic antioxidant BHT and BHA. The oil concentration required for 50% [IC50] free radical scavenging of DPPH was 56 micro g/ml with total phenol contents of 85.43 micro g GAE/mg for L. angustifolia oil. Ferricreducing antioxidant power [FRAP] in the blood sera of the rats gavaged with a daily dose of 100 micro l oil increased by 167.57%. Adverse therapeutic effects were noted as a result of feeding the rats with the essential oil. The volatile oil displayed cytotoxic effects on the human tumor cell line [HeLa cells] and peripheral blood cells with the IC50 of 26 and 21 micro g/ml respectively. The mutagenic and antimutagenic properties of various concentrations of Lavandula angustifolia oil on TA98 and TA100 strains Salmonella typhimurium in the presence and absence of S9 fraction were determined. The results show that the Lavandula oil used in the present study may not be consumed without dose determination