Preliminary investigation of human serum albumin-Vß inhibition on toxic shock syndrome induced by staphylococcus enterotoxin B in vitro and in vivo.

Staphylococcus enterotoxin B (SEB) is a superantigen that can induce massive activation of T cells with specific Vß and inflammatory cytokine cascades, which mediate shock. To date, no SEB vaccine has been developed for preventing toxic shock syndrome (TSS). Here, we evaluated the therapeutic effect of a fusion protein human serum albumin-Vß (HSA-Vß) on TSS induced by SEB. Compared with Vß, the preparation of HSA-Vß was much easier to handle owing to its solubility. Affinity testing showed that HSA-Vß had high affinity for SEB. In vitro results showed that HSA-Vß could effectively inhibit interferon (IFN)-γ and tumor necrosis factor (TNF)-α secretion by human peripheral blood mononuclear cells. Moreover, in vivo, HSA-Vß reduced IFN-γ and TNF-α levels in the serum and protected mice from SEB lethal challenge when administered simultaneously with SEB or 30 min after SEB. In summary, we simplified the preparation of Vß by fusion with HSA, creating the HSA-Vß protein, which effectively inhibited cytokine production and protected mice from lethal challenge with SEB. These data indicated that HSA-Vß may represent a novel therapeutic strategy for the treatment of SEB-induced TSS.

Inactivation of Ricin Toxin by Nanosecond Pulsed Electric Fields Including Evidences from Cell and Animal Toxicity.

Ricin is one of the most toxic and easily produced plant protein toxin extracted from the castor oil plant, and it has been classified as a chemical warfare agent. Here, nanosecond pulsed electric fields (nsPEFs) at 30 kV/cm (pulse durations: 10 ns, 100 ns, and 300 ns) were applied to inactivating ricin up to 4.2 µg/mL. To investigate the efficacy, cells and mice were tested against the ricin treated by the nsPEFs via direct intraperitoneal injection and inhalation exposure. Results showed that nsPEFs treatments can effectively reduce the toxicity of the ricin. Without the nsPEFs treatment, 100% of mice were killed upon the 4 µg ricin injection on the first day, however 40% of the mice survived the ricin treated by the nsPEFs. Compared to injection, inhalation exposure even with higher ricin dose required longer time to observe mice fatality. Pathological observations revealed damages to heart, lung, kidney, and stomach after the ricin exposure, more pronounced for lung and kidney including severe bleeding. Sodium dodecyl sulfate polyacrylamide gel electrophoresis(SDS-PAGE) and circular dichroism (CD) analyses revealed that although the primary structure of ricin was not altered, its secondary structures (beta-sheet and beta-turn) underwent transition upon the nsPEFs treatment.

Interaction of fibrinogen and muramidase-released protein promotes the development of Streptococcus suis meningitis.

Muramidase-released protein (MRP) is as an important virulence marker of Streptococcus suis (S. suis) serotype 2. Our previous works have shown that MRP can bind human fibrinogen (hFg); however, the function of this interaction in S. suis meningitis is not known. In this study, we found that the deletion of mrp significantly impairs the hFg-mediated adherence and traversal ability of S. suis across human cerebral microvascular endothelial cells (hCMEC/D3). Measurement of the permeability to Lucifer yellow in vitro and Evans blue extravasation in vivo show that the MRP-hFg interaction significantly increases the permeability of the blood-brain barrier (BBB). In the mouse meningitis model, wild type S. suis caused higher bacterial loads in the brain and more severe histopathological signs of meningitis than the mrp mutant at day 3 post-infection. Western blot analysis and immunofluorescence observations reveal that the MRP-hFg interaction can destroy the cell adherens junction protein p120-catenin of hCMEC/D3. These results indicate that the MRP-hFg interaction is important in the development of S. suis meningitis.

Induction of ROS generation and NF-κB activation in MARC-145 cells by a novel porcine reproductive and respiratory syndrome virus in Southwest of China isolate.

BACKGROUND: Porcine reproductive and respiratory syndrome virus (PRRSV) is the cause of an economically important swine disease that has devastated the swine industry since the late 1980s. The aim of the present study was to investigate the interaction between reactive oxygen species (ROS) and NF-κB by PRRSV infection. RESULTS: We isolated the local strain of PRRSV from southwest China, designated YN-2011, then sequenced and analyzed the genome. YN-2011 was then used to evaluate the interaction of ROS and NF-κB. In PRRSV infected MARC-145 cells, there was a time-dependent increase in ROS and Maleic Dialdehyde (MDA). Accordingly, NF-κB activation was also increased as PRRSV infection progressed. Degradation of IκB mRNA was detected late in PRRSV infection, and overexpression of the dominant negative form of IκBα significantly suppressed NF-κB induced by PRRSV. CONCLUSIONS: The results indicate that the generation of ROS is involved in PRRSV replication and this progression is associated with the alteration in NF-κB activity induced by ROS. These results should extend our better understanding the interaction between PRRSV and host MARC-145 cells.

Complete genome sequence of a novel natural recombinant porcine reproductive and respiratory syndrome virus isolated from a pig farm in yunnan province, southwest china.

YN-2011 is a highly pathogenic North American porcine reproductive and respiratory syndrome virus (PRRSV). Unlike previously described PRRSVs, which contained a 30-amino-acid deletion in NS2, YN-2011 had no amino acid deletions or insertions but had several new mutations in NS2. Here, we announce the complete genome sequence of YN-2011.