Inhibition of Toxic Shock by Human Monoclonal Antibodies against Staphylococcal Enterotoxin B

BACKGROUND: Staphylococcus aureus is implicated in many opportunistic bacterial infections around the world. Rising antibiotic resistance and few alternative methods of treatment are just two looming problems associated with clinical management of S. aureus. Among numerous virulence factors produced by S. aureus, staphylococcal enterotoxin (SE) B is a secreted protein that binds T-cell receptor and major histocompatibility complex class II, potentially causing toxic shock mediated by pathological activation of T cells. Recombinant monoclonal antibodies that target SEB and block receptor interactions can be of therapeutic value. METHODOLOGY/PRINCIPAL FINDINGS: The inhibitory and biophysical properties of ten human monoclonal antibodies, isolated from a recombinant library by panning against SEB vaccine (STEBVax), were examined as bivalent Fabs and native full-length IgG (Mab). The best performing Fabs had binding affinities equal to polyclonal IgG, low nanomolar IC(50)s against SEB in cell culture assays, and protected mice from SEB-induced toxic shock. The orthologous staphylococcal proteins, SEC1 and SEC2, as well as streptococcal pyrogenic exotoxin C were recognized by several Fabs. Four Fabs against SEB, with the lowest IC(50)s, were converted into native full-length Mabs. Although SEB-binding kinetics were identical between each Fab and respective Mab, a 250-fold greater inhibition of SEB-induced T-cell activation was observed with two Mabs. CONCLUSIONS/SIGNIFICANCE: Results suggest that these human monoclonal antibodies possess high affinity, target specificity, and toxin neutralization qualities essential for any therapeutic agent

Acupuncture, or non-directive counselling versus usual care for the treatment of depression: a pilot study

<p>Abstract</p> <p>Background</p> <p>Depression is one of the most common reasons for consulting in primary care. Acupuncture is a popular complementary therapy choice for depression but its evidence base is poor with more robust high quality trials being required. More than half of depressed patients experience painful symptoms, with severe pain being associated with poor response to antidepressants. Acupuncture may have much to offer as an intervention for depression that also helps alleviate pain. Non-directive counselling is the most widely used psychological approach for depression in NHS settings, and provides a useful pragmatic comparison for acupuncture that would, according to our pre-trial qualitative research, be of high interest to doctors and patients.</p> <p>Methods and design</p> <p>The pilot study uses five arms and involves a pragmatic design. All patients will continue to receive usual care. Four groups of patients will be allocated to acupuncture, or non-directive counselling, in addition to usual GP care. The acupuncture and counselling arms will be further split into two groups to explore different treatment regimens. The primary outcome measure is the BDI II. Potentially eligible patients will be screened for depression using the PHQ-9, which is also a secondary outcome measure. Other secondary measures include the SF 36 bodily pain subscale, the CORE OM, the WBQ-12 and the EQ5D. Health economic data will be collected and measures of therapeutic engagement will be used to compare patient's views of therapists and GPs. The study will employ a fully randomised preference design with collection of data on patient preferences and prior expectations.</p> <p>Discussion</p> <p>This study has been implemented, and data are currently being analysed to inform the design of a full scale trial. Two practical operational issues that impacted on study implementation are discussed. Firstly, the challenge of recruiting depressed patients via GP consultation. Secondly, the problem of poor uptake and high attrition for counselling and acupuncture, which appeared to be associated with poor questionnaire return, and resulted in missing data. These problems may be relevant to other researchers working in the area of depression, or similar illnesses, where patients may lack motivation and energy to engage in research, or attend for treatment.</p> <p>Trial Registration</p> <p>Current Controlled Trials (ISRCTN 59267538)</p

A comparison of in vitro methods for assessing the potency of therapeutic antisera against the venom of the coral snake Micrurus nigrocinctus

Therapeutic antisera against Micrurus nigrocinctus venom were tested for protection against lethality, as well as for inhibition of the nicotinic acetylcholine receptor (AchR)-binding and neutralization of phospholipase A2 (PLA2) activities of the homologous venom. Protection against venom lethality did not correlate with inhibition of AchR-binding activity, whereas there was a significant correlation between antisera potency and inhibition of PLA2 activity (r = 0.82, n = 10, P < 0.02). Inhibition of PLA2 activity could be useful in assessing the protective efficacy of M. nigrocinctus antisera during antivenom production. Micrurus nigrocinctus nigrocinctus venom proteins were fractionated by cation-exchange chromatography on Mono S FPLC and fractions assayed for lethality, AchR-binding and PLA2 activities. Antisera were titrated by enzyme-linked immunoassay (ELISA) against a crude M. n. nigrocinctus venom, two FPLC lethal fractions containing AchR-binding activity, and two toxins purified from M. n. nigrocinctus venom. No correlation was found between protective efficacy and the ELISA titer against any of these antigens. Compared to other elapid venoms that contain few toxins as major components, M. n. nigrocinctus venom appears to be more complex and its lethal effect is likely to be due to the combined effect of several neurotoxins.Universidad de Costa Rica/[74l-93-301]/UCR/Costa RicaInternational Foundation for Science/[F/0883-4]/IFS/SueciaSwedish Agency for Research Cooperation with Developing Countries//SAREC/SueciaUCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias de la Salud::Instituto Clodomiro Picado (ICP

Identification of a Novel Calotropis procera Protein That Can Suppress Tumor Growth in Breast Cancer through the Suppression of NF-κB Pathway

10.1371/journal.pone.0048514PLoS ONE712

Bacillus anthracis Edema Toxin Inhibits Staphylococcus aureus Enterotoxin B Effects In Vitro: a Potential Protein Therapeutic?

Various in vitro effects of staphylococcal enterotoxin B (SEB) on human peripheral blood mononuclear cells were mitigated by Bacillus anthracis edema toxin. In particular, levels of some SEB-induced cytokines (tumor necrosis factor alpha, gamma interferon) and chemokines (monocyte chemoattractant protein 1, macrophage inflammatory protein 1 alpha [MIP-1α], MIP-1β) were significantly diminished or even nonexistent, depending upon the timing of edema toxin administration. Overall, these results suggest a novel use of B. anthracis edema toxin against a bacterial superantigen

Antibody-mediated neutralization and binding-reversal studies on α-neurotoxins from micrurus nigrocinctus nigrocinctus (coral snake) venom

An ELISA based, non-radioactive acetylcholine receptor (AchR) binding assay was used to detect the alpha-neurotoxins present in Micrurus nigrocinctus nigrocinctus venom. Sera from horses hyperimmunized against M. nigrocinctus venom contain antibodies which inhibit the binding of M. n. nigrocinctus alpha-neurotoxins to AchR and reverse the binding of toxins already complexed with the receptor. This result supports the importance of using antivenom therapeutically in M. n. nigrocinctus envenomations even after the onset of neurological symptoms. M. nigrocinctus antivenoms cross-reacted in an ELISA with several elapid alpha-neurotoxins and inhibited the binding of Bungarus multicinctus alpha-bungarotoxin and Naja naja oxiana neurotoxin II to AchR in vitro, suggesting the presence of short-chain and long-chain alpha-neurotoxins in M. nigrocinctus venom. In vivo neutralization experiments with M. nigrocinctus antivenom demonstrate that M. nigrocinctus venom contains short-chain alpha-neurotoxin(s) which share common neutralizing epitope(s) with Naja naja oxiana neurotoxin II.Swedish Agency for Research Cooperation with Developing Countries//SAREC/SueciaUniversidad de Costa Rica/[741-93-301]/UCR/Costa RicaUCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias de la Salud::Instituto Clodomiro Picado (ICP