A new proof-of-concept in bacterial reduction : antimicrobial action of violet-blue light (405 nm) in ex vivo stored plasma

Bacterial contamination of injectable stored biological fluids such as blood plasma and platelet concentrates preserved in plasma at room temperature is a major health-risk. Current pathogen-reduction technologies (PRT) rely on the use of chemicals and/or ultraviolet-light, which affects product quality and can be associated with adverse events in recipients. 405nm violet-blue light is antibacterial without the use of photosensitizers, and can be applied at levels safe for human exposure, making it of potential interest for decontamination of biological fluids such as plasma. As a pilot study to test whether 405nm light is capable of inactivating bacteria in biological fluids, rabbit and human plasma were seeded with bacteria and treated with a 405nm light emitting diode (LED) exposure system (patent pending). Inactivation was achieved in all tested samples, ranging from low volumes to pre-bagged plasma. 99.9% reduction of low density bacterial populations (≤103 CFUml-1), selected to represent typical ‘natural’ contamination levels, were achieved using doses of 144 Jcm-2. The penetrability of 405nm light, permitting decontamination of pre-bagged plasma, and the non-requirement for photosensitizing agents, provides a new proof-of-concept in bacterial reduction in biological fluids, especially injectable fluids relevant to transfusion medicine

New proof-of-concept in viral inactivation: virucidal efficacy of 405 nm light against feline calicivirus as a model for norovirus decontamination

The requirement for novel decontamination technologies for use in hospitals is ever present. One such system uses 405 nm visible light to inactivate microorganisms via ROS-generated oxidative damage. Although effective for bacterial and fungal inactivation, little is known about the virucidal effects of 405 nm light. Norovirus (NoV) gastroenteritis outbreaks often occur in the clinical setting, and this study was designed to investigate potential inactivation effects of 405 nm light on the NoV surrogate, feline calicivirus (FCV). FCV was exposed to 405 nm light whilst suspended in minimal and organically-rich media to establish the virucidal efficacy and the effect biologically-relevant material may play in viral susceptibility. Antiviral activity was successfully demonstrated with a 4 Log10 (99.99%) reduction in infectivity when suspended in minimal media evident after a dose of 2.8 kJ cm−2. FCV exposed in artificial faeces, artificial saliva, blood plasma and other organically rich media exhibited an equivalent level of inactivation using between 50–85% less dose of the light, indicating enhanced inactivation when the virus is present in organically-rich biologically-relevant media. Further research in this area could aid in the development of 405 nm light technology for effective NoV decontamination within the hospital environment

Non-ionizing 405nm light as a potential bactericidal technology for platelet safety : evaluation of in vitro bacterial inactivation and in vivo platelet recovery in severe combined immunodeficient mice

Bacterial contamination of ex vivo stored platelets is a cause of transfusion-transmitted infection. Violet-blue 405 nm light has recently demonstrated efficacy in reducing the bacterial burden in blood plasma, and its operational benefits such as non-ionizing nature, penetrability, and non-requirement for photosensitizing agents, provide a unique opportunity to develop this treatment for in situ treatment of ex vivo stored platelets as a tool for bacterial reduction. Sealed bags of platelet concentrates, seeded with low-level Staphylococcus aureus contamination, were 405 nm light-treated (3-10 mWcm-2) up to 8 hr. Antimicrobial efficacy and dose efficiency was evaluated by quantification of the post-treatment surviving bacterial contamination levels. Platelets treated with 10 mWcm-2 for 8 hr were further evaluated for survival and recovery in severe combined immunodeficient (SCID) mice. Significant inactivation of bacteria in platelet concentrates was achieved using all irradiance levels, with 99.6-100% inactivation achieved by 8 hr (P<0.05). Analysis of applied dose demonstrated that lower irradiance levels generally resulted in significant decontamination at lower doses: 180 Jcm-2/10 mWcm-2 (P=0.008) compared to 43.2 Jcm-2/3 mWcm-2 (P=0.002). Additionally, the recovery of light-treated platelets, compared to non-treated platelets, in the murine model showed no significant differences (P ≥ 0.05). This report paves the way for further comprehensive studies to test 405 nm light treatment as a bactericidal technology for stored platelet

Human platelet concentrates treated with microbicidal 405 nm light retain hemostasis activity

Chemical and UV light-based pathogen reduction technologies are currently in use for human platelet concentrates (PCs) to enhance safety from transfusion-transmitted infections. Relative to UV light, 405 nm violet-blue light in the visible spectrum is known to be less harmful. Hence, in this report for the first time, we have assessed the global hemostasis activity of PCs stored in plasma and the activities of six plasma coagulation factors (CFs) as a measure of in vitro hemostatic activity following exposure to the microbicidal 405 nm light. Apheresis PC samples collected from each screened human donor (n = 22) were used for testing of PCs and platelet poor plasma (PPP). Both PCs and PPPs were treated for 5 h with 405 nm light to achieve a previously established microbicidal light dose of 270 J/cm2. Activated partial thromboplastin time and prothrombin time-based potency assays using a coagulation analyzer and hemostatic capacity via Thromboelastography were analyzed. Thromboelastography analysis of the light-treated PCs and plasma present in the PCs showed little difference between the treated and untreated samples. Further, plasma present in the PCs during the light treatment demonstrated a better stability in potency assays for several coagulation factors compared to the plasma alone prepared from PCs first and subjected to the light treatment separately. Overall, PCs stored in plasma treated with 405 nm violet-blue light retain activity for hemostasis

Various NP-FL and deletion clones were made between the nNLS and cNLS regions

GFP is represented by chequered-box; NLS regions are indicated by darkly-shaded box; nuclear accumulation signal (NAS) is indicated by striped-box; rotavirus NSP6 is represented by an empty, unshaded box. Critical amino acid (R or M) at position 105 is indicated by larger font size and an asterisk. Cellular localization of each construct is indicated by N (nuclear), N>C (nuclear greater than cytoplasm), C>N (cytoplasm greater than nuclear), and C (cytoplasmic).<p><b>Copyright information:</b></p><p>Taken from "Application of bioinformatics-coupled experimental analysis reveals a new transport-competent nuclear localization signal in the nucleoprotein of Influenza A virus strain"</p><p>http://www.biomedcentral.com/1471-2121/9/22</p><p>BMC Cell Biology 2008;9():22-22.</p><p>Published online 28 Apr 2008</p><p>PMCID:PMC2386121.</p><p></p

Sequence generated from WS/33L in the present study is compared with 5 other WS/33 sequences represented as WS-A includes sequences EMBL:, EMBL: and EMBL: and WS-B includes sequences GenBank: and GenBank:

NP sequence of the 1918 pandemic flu strain [GenBank: ] is also included for comparison. Identical amino acids are represented by "-"; Phylogenetically important regions (PIR) are underlined; phylogenetically important positions (PIP) are indicated by an asterisk.<p><b>Copyright information:</b></p><p>Taken from "Application of bioinformatics-coupled experimental analysis reveals a new transport-competent nuclear localization signal in the nucleoprotein of Influenza A virus strain"</p><p>http://www.biomedcentral.com/1471-2121/9/22</p><p>BMC Cell Biology 2008;9():22-22.</p><p>Published online 28 Apr 2008</p><p>PMCID:PMC2386121.</p><p></p

All NP-GFP plasmid constructs and the empty vector C2-GFP (control) were transfected into COS-7L cells and cell lysates were analyzed to confirm expression of the fusion proteins

Molecular weight markers (in kDa) are indicated on the left. The caspase-cleaved N-terminal fragment of NP-L is indicated by an asterisk (*).<p><b>Copyright information:</b></p><p>Taken from "Application of bioinformatics-coupled experimental analysis reveals a new transport-competent nuclear localization signal in the nucleoprotein of Influenza A virus strain"</p><p>http://www.biomedcentral.com/1471-2121/9/22</p><p>BMC Cell Biology 2008;9():22-22.</p><p>Published online 28 Apr 2008</p><p>PMCID:PMC2386121.</p><p></p

A peptide derived from phage display library exhibits antibacterial activity against E. coli and Pseudomonas aeruginosa.

Emergence of drug resistant strains to currently available antibiotics has resulted in the quest for novel antimicrobial agents. Antimicrobial peptides (AMPs) are receiving attention as alternatives to antibiotics. In this study, we used phage-display random peptide library to identify peptides binding to the cell surface of E. coli. The peptide with sequence RLLFRKIRRLKR (EC5) bound to the cell surface of E. coli and exhibited certain features common to AMPs and was rich in Arginine and Lysine residues. Antimicrobial activity of the peptide was tested in vitro by growth inhibition assays and the bacterial membrane permeabilization assay. The peptide was highly active against gram-negative organisms and showed significant bactericidal activity against E. coli and P. aeruginosa resulting in a reduction of 5 log(10) CFU/ml. In homologous plasma and platelets, incubation of EC5 with the bacteria resulted in significant reduction of E. coli and P. aeruginosa, compared to the peptide-free controls. The peptide was non-hemolytic and non-cytotoxic when tested on eukaryotic cells in culture. EC5 was able to permeabilize the outer membrane of E. coli and P. aeruginosa causing rapid depolarization of cytoplasmic membrane resulting in killing of the cells at 5 minutes of exposure. The secondary structure of the peptide showed a α-helical conformation in the presence of aqueous environment. The bacterial lipid interaction with the peptide was also investigated using Molecular Dynamic Simulations. Thus this study demonstrates that peptides identified to bind to bacterial cell surface through phage-display screening may additionally aid in identifying and developing novel antimicrobial peptides