Laboratory-Based Prospective Surveillance for Community Outbreaks of Shigella spp. in Argentina

Background: To implement effective control measures, timely outbreak detection is essential. Shigella is the most common cause of bacterial diarrhea in Argentina. Highly resistant clones of Shigella have emerged, and outbreaks have been recognized in closed settings and in whole communities. We hereby report our experience with an evolving, integrated, laboratory-based, near real-time surveillance system operating in six contiguous provinces of Argentina during April 2009 to March 2012. Methodology To detect localized shigellosis outbreaks timely, we used the prospective space-time permutation scan statistic algorithm of SaTScan, embedded in WHONET software. Twenty three laboratories sent updated Shigella data on a weekly basis to the National Reference Laboratory. Cluster detection analysis was performed at several taxonomic levels: for all Shigella spp., for serotypes within species and for antimicrobial resistance phenotypes within species. Shigella isolates associated with statistically significant signals (clusters in time/space with recurrence interval ≥365 days) were subtyped by pulsed field gel electrophoresis (PFGE) using PulseNet protocols. Principal Findings In three years of active surveillance, our system detected 32 statistically significant events, 26 of them identified before hospital staff was aware of any unexpected increase in the number of Shigella isolates. Twenty-six signals were investigated by PFGE, which confirmed a close relationship among the isolates for 22 events (84.6%). Seven events were investigated epidemiologically, which revealed links among the patients. Seventeen events were found at the resistance profile level. The system detected events of public health importance: infrequent resistance profiles, long-lasting and/or re-emergent clusters and events important for their duration or size, which were reported to local public health authorities. Conclusions/Significance: The WHONET-SaTScan system may serve as a model for surveillance and can be applied to other pathogens, implemented by other networks, and scaled up to national and international levels for early detection and control of outbreaks

Antibodies to native myelin oligodendrocyte glycoprotein are serologic markers of early inflammation in multiple sclerosis

Myelin oligodendrocyte glycoprotein (MOG) is an integral membrane protein expressed in CNS oligodendrocytes and outermost myelin lamellae. Anti-MOG Abs cause myelin destruction (demyelination) in animal models of multiple sclerosis (MS); however, such pathogenic Abs have not yet been characterized in humans. Here, a method that specifically detects IgG binding to human MOG in its native, membrane-embedded conformation on MOG-transfected mammalian cells was used to evaluate the significance of these auto Abs. Compared with healthy controls, native MOG-specific IgGs were most frequently found in serum of clinically isolated syndromes (P < 0.001) and relapsing-remitting MS (P < 0.01), only marginally in secondary progressive MS (P < 0.05), and not at all in primary progressive MS. We demonstrate that epitopes exposed in this cell-based assay are different from those exposed on the refolded, extracellular domain of human recombinant MOG tested by solid-phase ELISA. In marmoset monkeys induced to develop MS-like CNS inflammatory demyelination, IgG reactivity against the native membrane-bound MOG is always detected before clinical onset of disease (P < 0.0001), unlike that against other myelin constituents. We conclude that (i) epitopes displayed on native, glycosylated MOG expressed in vivo are early targets for pathogenic Abs; (ii) these Abs, which are not detected in solid-phase assays, might be the ones to play a pathogenic role in early MS with predominant inflammatory activity; and (iii) the cell-based assay provides a practical serologic marker for early detection of CNS autoimmune demyelination including its preclinical stage at least in the primate MS model

Opposing Roles of Elk-1 and Its Brain-specific Isoform, Short Elk-1, in Nerve Growth Factor-induced PC12 Differentiation

International audienc

Mef2d is required for dermomyotome formation.

<p>(A) Embryos injected unilaterally with 400 pg of Mef2dF mRNA or 20 ng of moMef2d1 were fixed at stage 26 and submitted to staining with the specific muscle 12/101 antibody (red). (B) Expression of <i>Pax7</i> and <i>Pax3</i> mRNA at stage 17/18 (dorsal view or transverse sections at the trunk level). Co-staining of <i>Pax3</i> mRNA (purple) and differentiated muscle cells detected by 12/101 antibody (blue). Dotted lines indicate the position of the medial and lateral population of myogenic cells <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0052359#pone.0052359-Hinits1" target="_blank">[5]</a>. (C) Expression of <i>Pax3</i> mRNA on a transverse section at stage 22. (D) <i>Pax3</i> mRNA expression on lateral view (left) or on transverse section (right) at the tailbud stage after unilateral injection of Mef2dF or moMef2d1. Rescue experiments restored the phenotype of moMef2d1. Arrows indicate the sites of lateral ectopic expression of <i>Pax3</i>. (*) Injected side. Probes are in a framed box and indicated for each panel. Nc, notochord. For complete statistical data, see supporting information, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0052359#pone.0052359.s002" target="_blank">figure S2</a>.</p

Schematic representation of myotome and dermomyotome formation in <i>Xenopus</i>.

<p>(A) The most lateral <i>Meox2</i> expressing cells of the paraxial mesoderm give rise to the dermomyotome (De) whereas the lateral myogenic cells give rise to a dorsomedial (DoMe) and a ventrolateral (VeLa) cell population. The medial myogenic cells differentiate first and remain associated with the notochord <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0052359#pone.0052359-Hinits1" target="_blank">[5]</a>. Arrows design the movement of lateral paraxial mesoderm. Dotted arrows design the movement of invagination of neurectodermal cells. NT, neural tube. Nc, notochord. (B) Mef2d couples lateral myogenesis to dermomyotome formation: In lateral presomitic cells, Mef2d transactivates the <i>Myod</i> gene and in the most lateral presomitic cells Mef2d and Paraxis transactivates the <i>Meox2</i> gene.</p

Paraxis and Mef2d have a cooperative effect on dermomyotome formation.

<p>(A) Expression of <i>Paraxis</i> mRNA during neurulation. Costaining of <i>Mef2d</i> (blue) and <i>Paraxis</i> (purple) mRNA at stage 13 in comparison with <i>Mef2d</i> expression alone. Rounded brackets indicate the region of colocalization of <i>Paraxis</i> and <i>Mef2d</i>. Dorsal views. The anterior side of the embryos is on the left; st., stage. Vertical lines define the limit between anterior and trunk region. (B) Transverse sections of the costained embryos compared to <i>Mef2d</i> staining at stage 13 (upper panels). Expression of <i>Paraxis</i> and <i>Mef2d</i> at stage 17/18 (lower panels). Dotted lines indicate the position of the medial and lateral population of myogenic cells. (C) Expression of <i>Paraxis</i> mRNA on a transverse section at stage 23. (D) Western blot with anti-flag and anti-tubulin antibodies of late gastrula embryos injected bilaterally either with 300 pg of 5utrParaxis synthetic mRNA alone (lane1) or with oligomorpholinos: moControl (lane 2) or moParaxis1 (lane3). (E) Embryos injected unilaterally with 20 ng of moParaxis1 were submitted to <i>in situ</i> hybridization with <i>Pax3</i> antisense probe at the tailbud stage (lateral view or transverse section). A co-injection of ParaxisF’ mRNA (150 pg) with moParaxis1 was able to rescue the phenotype of moParaxis1 injected embryos (lateral view). (F) Unilateral injection of ParaxisGRF (150 pg) induced an increase of <i>Pax3</i> mRNA expression at the tailbud stage. Pax3 expression after co-injection of ParaxisF+Mef2dF or ParaxisGRF+Mef2dF. ParaxisGRF injection with moMef2d1 had no effect on <i>Pax3</i> expression. (*) Injected side. Probes are in a framed box and indicated for each panel. Nc, notochord. For complete statistical data, see supporting information, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0052359#pone.0052359.s002" target="_blank">figure S2</a>.</p

Sequence of oligomorpholinos.

<p>Sequence of oligomorpholinos.</p

<em>Mef2d</em> Acts Upstream of Muscle Identity Genes and Couples Lateral Myogenesis to Dermomyotome Formation in <em>Xenopus laevis</em>

<div><p><em>Xenopus</em> myotome is formed by a first medial and lateral myogenesis directly arising from the presomitic mesoderm followed by a second myogenic wave emanating from the dermomyotome. Here, by a series of gain and loss of function experiments, we showed that <em>Mef2d</em>, a member of the Mef2 family of MADS-box transcription factors, appeared as an upstream regulator of lateral myogenesis, and as an inducer of dermomyotome formation at the beginning of neurulation. In the lateral presomitic cells, we showed that <em>Mef2d</em> transactivates <em>Myod</em> expression which is necessary for lateral myogenesis. In the most lateral cells of the presomitic mesoderm, we showed that <em>Mef2d</em> and <em>Paraxis (Tcf15)</em>, a member of the Twist family of transcription factors, were co-localized and activate directly the expression of <em>Meox2</em>, which acts upstream of <em>Pax3</em> expression during dermomyotome formation. Cell tracing experiments confirm that the most lateral <em>Meox2</em> expressing cells of the presomitic mesoderm correspond to the dermomyotome progenitors since they give rise to the most dorsal cells of the somitic mesoderm. Thus, <em>Xenopus Mef2d</em> couples lateral myogenesis to dermomyotome formation before somite segmentation. These results together with our previous works reveal striking similarities between dermomyotome and tendon formation in <em>Xenopus</em>: both develop in association with myogenic cells and both involve a gene transactivation pathway where one member of the Mef2 family, <em>Mef2d</em> or <em>Mef2c</em>, cooperates with a bHLH protein of the Twist family, <em>Paraxis</em> or <em>Scx</em> (<em>Scleraxis</em>) respectively. We propose that these shared characteristics in <em>Xenopus laevis</em> reflect the existence of a vertebrate ancestral mechanism which has coupled the development of the myogenic cells to the formation of associated tissues during somite compartmentalization.</p> </div

Paraxis and Mef2d targets <i>Meox2</i> gene in the most lateral part of the presomitic mesoderm.

<p>(A) Embryos injected unilaterally with 20 ng of moParaxis1 or moMef2d1 were submitted to <i>in situ</i> hybridization with <i>Meox2</i> antisense probe at the neurula stage. Injection of either ParaxisF’ mRNA with moParaxis1 or Mef2dF with moMef2d1 was able to rescue the phenotype. (B) Unilateral injection of either ParaxisGRF or Mef2dGRF induced an increase of <i>Meox2</i> mRNA expression at the neurula stage after induction by dexamethasone (DXM) at stage 12.5. A cooperative effect was observed after co-injection of ParaxisGRF and Mef2dF. A treatment by cycloheximid (CHX) followed by induction by dexamethasone (DXM) at stage 12.5 indicated that <i>Meox2</i> is a direct target gene of Paraxis and Mef2d. (*) Injected side. Probes are in a framed box and indicated for each panel. (C) COS7 cells were transfected with p<i>meox2</i>-luc alone, or co-transfected with either Paraxis, Mef2d-V5/His or both and luciferase activity was determined 48 h after transfection. * P<0.01 (D) Protein extracts from COS7 cells transfected with Mef2d-V5/His alone or with either empty vector (Gal4) or Gal4-Paraxis construct were immunoprecipitated (IP) with Ni-NTA beads and subjected to Western blot (WB) using an anti-Gal4 antibody (upper panel). Input control experiments with anti-V5 (lower panel) or anti-Gal4 (mid panel) antibodies. For complete statistical data, see supporting information, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0052359#pone.0052359.s002" target="_blank">figure S2</a>.</p