Re-emergence of Crimean-Congo hemorrhagic fever virus in Central Africa

Background

Crimean-Congo hemorrhagic fever (CCHF) is a severe tick-borne disease well recognized through Europe and Asia where diagnostic tests and medical surveillance are available. However, it is largely neglected in Africa, especially in the tropical rainforest of Central Africa where only sporadic human cases have been reported and date back to more than 30 years. We describe here an isolated human case that occurred in the Democratic Republic of the Congo in 2008 and performed phylogenetic analysis to investigate whether it resulted from a regional re-emergence or from the introduction of a novel virus in the area.

Methods and Findings

Near complete segment S and partial segment M sequences were characterized. Bayesian phylogenetic analysis and datation were performed to investigate the relationship between this new strain and viral strains from Africa, Europe and Asia. The new strain is phylogenetically close to the previously described regional genotype (II) that appears to be specific to Central Africa. Phylogenetic discrepancy between segment S and M suggested genetic exchange among local sublineages, which was dated back to 130–590 years before present.

Conclusions

The phylogenetic analyses presented here suggest ongoing CCHF virus circulation in Central Africa for a long time despite the absence of reported human cases. Many infections have most probably been overlooked, due to the weakness of healthcare structures and the absence of available diagnostic procedure. However, despite the lack of accurate ecological data, the sporadic reporting of human cases could also be partly associated with a specific sylvatic cycle in Central Africa where deforestation may raise the risks of re-emergence. For these reasons, together with the high risk of nosocomial transmission, public health authorities'' attention should be drawn to this etiological agent.     

Stain-Free total protein staining is a superior loading control to β-actin for Western blots

Semi-quantification of proteins using Western blots typically involves normalization against housekeeping genes such as β-actin. More recently, Ponceau S and Coomassie blue staining have both been shown to be suitable alternatives to housekeeping genes as loading controls. Stain-Free total protein staining offers the advantage of no staining or destaining steps. Evaluation of the use of Stain-Free staining as an alternative to β-actin or the protein stain Ponceau S showed that Stain-Free staining was superior to β-actin and as good as or better than Ponceau S staining as a loading control for Western blots.     

Telencephalic neural precursor cells show transient competence to interpret the dopaminergic niche of the embryonic midbrain

Neural Precursor Cells (NPCs) generate complex stereotypic arrays of neuronal subtypes in the brain. This process involves the integration of patterning cues that progressively restrict the fate of specific NPCs. Yet the capacity of NPCs to interpret foreign microenvironments during development remains poorly defined. The aim of this work was to test the competence of mouse telencephalic NPCs to respond to the dopaminergic niche of the mesencephalon. Telencephalic NPCs isolated from midgestation mouse embryos (E10.5) and transplanted to age-matched mesencephalic explants efficiently differentiated into neurons but were largely unable to produce midbrain dopaminergic (mDA) neurons. Instead, E10.5 telencephalic NPCs behaved as restricted gabaergic progenitors that maintained ectopic expression of Foxg1 and Pax6. In contrast, E8.5 telencephalic NPCs were able to differentiate into Lmx1a⁺/Foxa2⁺/TH⁺ neurons in the dopaminergic niche of the mesencephalic explants. In addition, these early telencephalic NPCs showed region-dependent expression of Nkx6.1, Nkx2.2 and site-specific differentiation into gabaergic neurons within the mesencephalic tissue. Significant dopaminergic differentiation of E8.5 telencephalic NPCs was not observed after transplantation to E12.5 mesencephalic explants, suggesting that inductive signals in the dopaminergic niche rapidly decay after midgestation. Moreover, we employed transplantation of embryonic stem cells-derived precursors to demonstrate that extinction of inductive signals within the telencephalon lags behind the commitment of residing NPCs. Our data indicate that the plasticity to interpret multiple instructive niches is an early and ephemeral feature of the telencephalic neural lineage.     

Landscape factors modulating patterns of salmonid distribution during summer in north Patagonian rivers

Understanding how ecosystem processes influencing fish distribution operate across spatial scales is important to understand biological invasions. Salmonids, originally from the Northern Hemisphere, have been repeatedly introduced throughout the world, making them an ideal group to test hypotheses about factors driving invasions. We assessed the influence of environmental variables at the watershed scale on the abundance and structure of salmonid assemblages in the breeding streams of the Upper Limay river basin, Rio Negro, Argentina. We combined field captures with digital map data and geographic information systems to examine landscape-level patterns of salmonid abundance in 35 representative sub-basins of the environmental gradient. We employed a hierarchical cluster analysis and classification and regression tree models to relate the abundance of salmonids and types of species assemblages with environmental characteristics at watershed level. We found stream localization, precipitation regime, altitude and air temperature to be important predictors of the abundance and assemblage structure of salmonids. Total catches showed an increasing gradient of catch-per-unit-effort from west to east and from north to south, with Oncorhynchus mykiss being the most abundant species. O. mykiss relative abundance was westward skewed, where smaller catchments with steeper and shaded valleys are drained by less productive streams with more irregular hydrological regimes, like those found in this species' North American native range. In contrast, the abundance of Salmo trutta abundance was eastward skewed, where larger, sunnier and more gently sloped catchments result in more productive streams with stable hydrological regimes, like those found in that species' European native range. Thus, differential salmonid abundance could result from the interplay between the evolutionary fingerprint left by each species' native environment (especially flow and temperature regimes) and the availability of those conditions in new environments to which they have been translocated. By furthering our understanding of how landscape conditioned invasion success, these findings can help guide the management of economically important introduced fish.     

Use of selective capture of transcribed sequences to identify genes preferentially expressed by Streptococcus suis upon interaction with porcine brain microvascular endothelial cells

By using the selective capture of transcribed sequences (SCOTS) approach, we identified 28 genes preferentially expressed by the major swine pathogen and zoonotic agent Streptococcus suis upon interaction with porcine brain microvascular endothelial cells. Several of these genes may be considered new S. suis candidate virulence factors. Results from this study demonstrate the suitability of SCOTS for the elucidation of gene expression in streptococcal species and may contribute to a better understanding of the pathogenesis of S. suis infections.     

Use of Selective Capture of Transcribed Sequences To Identify Genes Preferentially Expressed by Streptococcus suis upon Interaction with Porcine Brain Microvascular Endothelial Cells

By using the selective capture of transcribed sequences (SCOTS) approach, we identified 28 genes preferentially expressed by the major swine pathogen and zoonotic agent Streptococcus suis upon interaction with porcine brain microvascular endothelial cells. Several of these genes may be considered new S. suis candidate virulence factors. Results from this study demonstrate the suitability of SCOTS for the elucidation of gene expression in streptococcal species and may contribute to a better understanding of the pathogenesis of S. suis infections.