Oral diseases, including dental caries and periodontitis, are among the most prevalent diseases worldwide and develop as a consequence of a microbial dysbiosis. Several bacterial strains are being tested as potential oral health-promoting organisms, but usually they are species isolated from niches other than the site where they must exert its probiotic action, typically from fecal samples. We hypothesize that oral inhabitants associated to health conditions will be more effective than traditional, gut-associated probiotic species in key aspects such as colonization of the oral site where disease takes place or the possession of oral health promoting functions, as well as more practical issues like safety and toxicity, and establishing proper doses for administration. As an example of these active colonizers, we describe the case of Streptococcus dentisani, a new streptococcal species isolated from dental plaque of caries-free individuals. We have detected it in 98% of dental plaque samples from healthy individuals and, as expected, it does not produce any toxic secondary metabolite and does not survive a simulated stomach digestion, preventing potential secondary effects. Besides, this species has a double probiotic action, as it inhibits the growth of major oral pathogens through the production of bacteriocins, and also buffers acidic pH (the primary cause of dental caries) through an arginolytic pathway. We propose the use of S. dentisani as a promising probiotic against tooth decay.

Staphylococcus aureus pathogenicity islands (SaPIs) have an intimate relationship with temperate staphylococcal phages. During phage growth, SaPIs are induced to replicate and are efficiently encapsidated into special small phage heads commensurate with their size. We have analyzed by amino acid sequencing and mass spectrometry the protein composition of the specific SaPI particles. This has enabled identification of major capsid and tail proteins and a putative portal protein. As expected, all these proteins were phage encoded. Additionally, these analyses suggested the existence of a protein required for the formation of functional phage but not SaPI particles. Mutational analysis demonstrated that the phage proteins identified were involved only in the formation and possibly the function of SaPI or phage particles, having no role in other SaPI or phage functions.

Most public health measures to contain the COVID-19 pandemic are based on preventing the pathogen spread, and the use of oral antiseptics has been proposed as a strategy to reduce transmission risk. The aim of this manuscript is to test the efficacy of mouthwashes to reduce salivary viral load in vivo. This is a multi-centre, blinded, parallel-group, placebo-controlled randomised clinical trial that tests the effect of four mouthwashes (cetylpyridinium chloride, chlorhexidine, povidone-iodine and hydrogen peroxide) in SARS-CoV-2 salivary load measured by qPCR at baseline and 30, 60 and 120 min after the mouthrinse. A fifth group of patients used distilled water mouthrinse as a control. Eighty-four participants were recruited and divided into 12–15 per group. There were no statistically significant changes in salivary viral load after the use of the different mouthwashes. Although oral antiseptics have shown virucidal effects in vitro, our data show that salivary viral load in COVID-19 patients was not affected by the tested treatments. This could reflect that those mouthwashes are not effective in vivo, or that viral particles are not infective but viral RNA is still detected by PCR. Viral infectivity studies after the use of mouthwashes are therefore required. (https://clinicaltrials.gov/ct2/show/NCT04707742; Identifier: NCT04707742)

SaPIbov2 is a member of the SaPI family of staphylococcal pathogenicity islands and is very closely related to SaPIbov1. Typically, certain temperate phages can induce excision and replication of one or more of these islands and can package them into special small phage-like particles commensurate with their genome sizes (referred to as the excision-replication-packaging [ERP] cycle). We have studied the phage-SaPI interaction in some depth using SaPIbov2, with special reference to the role of its integrase. We demonstrate here that SaPIbov2 can be induced to replicate by different staphylococcal phages. After replication, SaPIbov2 is efficiently encapsidated and transferred to recipient organisms, including different non-Staphylococcus aureus staphylococci, where it integrates at a SaPI-specific attachment site, att C , by means of a self-coded integrase (Int). Phages that cannot induce the SaPIbov2 ERP cycle can transfer the island by recA-dependent classical generalized transduction and can also transfer it by a novel mechanism that requires the expression of SaPIbov2 int in the recipient but not in the donor. It is suggested that this mechanism involves the encapsidation of standard transducing fragments containing the intact island followed by int-mediated excision, circularization, and integration in the recipient.

CD mothers' breast milk is characterized by a reduced abundance of immunoprotective compounds (TGF-β1 and sIgA) and bifidobacteria. The reduction in these components could theoretically diminish the protective effects of breast-feeding on the child's future risk of developing CD.

Real-time biofilm analysis provides a promising tool to evaluate antibiotic therapy in clinical biofilm-mediated infections.

The platelet fibrinogen receptor, integrin ␣ IIb ␤ 3 , is a noncovalent heterodimer of glycoproteins IIb and IIIa. This work was aimed at elucidating the role played by the carboxy-terminal extracellular, transmembrane, and cytoplasmic regions of the glycoprotein ␤ 3 in the formation of functional complexes with ␣ subunits. Progressive carboxy-terminal deletions of ␤ 3 revealed that surface exposure of ␣ IIb ␤ 3 or ␣ v ␤ 3 could not occur in the absence of the transmembrane domain of ␤ 3 . In con- IntroductionThe glycoprotein (GP) IIb-IIIa complex, integrin ␣ IIb ␤ 3 , is a calcium-dependent, noncovalent heterodimer formed by GPIIb and GPIIIa. This complex is found in the plasma membrane of megakaryocytes, platelets, and some tumor tissues 1-3 and functions as a receptor for fibrinogen and other adhesive proteins like the von Willebrand factor, fibronectin, or vitronectin. 4 The ␤ 3 subunit may also complex the GP ␣ v to form the vitronectin receptor (integrin ␣ v ␤ 3 ) that shares with ␣ IIb ␤ 3 the binding of fibrinogen although with different affinity. 5 The platelet ␣ IIb ␤ 3 complex is essential to maintain a normal hemostasis. Unlike other platelet receptors that are constitutively active, the ␣ IIb ␤ 3 is maintained in a low-affinity state for its ligands. Disruption of the vascular endothelium and exposure of platelets to the action of agonists and adhesive proteins from the subendothelial matrix induces a cellular activation. The activated cells interact with adhesive proteins from the extracellular matrix, 6,7 and the ␣ IIb ␤ 3 receptors are able to bind fibrinogen with high affinity (insideout signaling), resulting in platelet aggregation. 8 Conversely, ligand-bound ␣ IIb ␤ 3 propagates signals to the interior of the cell (outside-in signaling) leading to enhanced interaction with the cytoskeleton, clustering of receptors (increased ligand avidity), and formation of focal contacts rich in signaling complexes. 9,10 The agonist-induced increase in ligand affinity of ␣ IIb ␤ 3 is thought to be the result of conformational changes of the heterodimer [11][12][13] initiated by the interaction of the cytoplasmic tails of ␣ and ␤ 3 subunits with cytosolic proteins. Despite the pathophysiologic importance of the platelet ␣ IIb ␤ 3 receptor, the knowledge of the mechanisms controlling its state of activation is rather limited.Unlike previous reports, 14 recent work from our laboratory 15 showed that a truncated form of ␤ 3 lacking the transmembrane and cytosolic domains failed to associate with ␣ IIb . The present work was aimed at further investigating the role played by the carboxyterminal domain of ␤ 3 in the surface expression and function of ␤ 3 heterodimers. The results obtained in this study indicate that surface expression of ␣ IIb ␤ 3 could not occur in the absence of the transmembrane domain of ␤ 3 . The present study has also revealed that either deletion of the carboxy-terminal region of the ␤ 3 ectodomain or disruption of the 663-687 disulfide bridge confers constitutive activity to the ␤ 3 integr...

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