Zika virus (ZIKV) has been associated with serious health conditions, and an intense search to discover different ways to prevent and treat ZIKV infection is underway. Berberine and emodin possess several pharmacological properties and have been shown to be particularly effective against the entry and replication of several viruses. We show that emodin and berberine trigger a virucidal effect on ZIKV. When the virus was exposed to 160 µM of berberine, a reduction of 77.6% in the infectivity was observed; when emodin was used (40 µM), this reduction was approximately 83.3%. Dynamic light scattering data showed that both compounds significantly reduce the hydrodynamic radius of virus particle in solution. We report here that berberine and emodin, two natural compounds, have strong virucidal effect in Zika virus.

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BackgroundCorynebacterium pseudotuberculosis, a facultative intracellular bacterial pathogen, is the etiological agent of caseous lymphadenitis (CLA), an infectious disease that affects sheep and goats and it is responsible for significant economic losses. The disease is characterized mainly by bacteria-induced caseous necrosis in lymphatic glands. New vaccines are needed for reliable control and management of CLA. Thus, the putative virulence factors SpaC, SodC, NanH, and PknG from C. pseudotuberculosis FRC41 may represent new target proteins for vaccine development and pathogenicity studies.ResultsSpaC, PknG and NanH presented better vaccine potential than SodC after in silico analyses. A total of 136 B and T cell epitopes were predicted from the four putative virulence factors. A cluster analysis was performed to evaluate the redundancy degree among the sequences of the predicted epitopes; 57 clusters were formed, most of them (34) were single clusters. Two clusters from PknG and one from SpaC grouped epitopes for B and T-cell (MHC I and II). These epitopes can thus potentially stimulate a complete immune response (humoral and cellular) against C. pseudotuberculosis. Several other clusters, including two from NanH, grouped B-cell epitopes with either MHC I or II epitopes. The four target proteins were expressed in Escherichia coli. A purification protocol was developed for PknG expression.ConclusionsIn silico analyses show that the putative virulence factors SpaC, PknG and NanH present good potential for CLA vaccine development. Target proteins were successfully expressed in E. coli. A protocol for PknG purification is described.Electronic supplementary materialThe online version of this article (doi:10.1186/s12934-016-0479-6) contains supplementary material, which is available to authorized users.

Exfoliative toxins are serine proteases secreted by Staphylococcus aureus that are associated with toxin-mediated staphylococcal syndromes. To date, four different serotypes of exfoliative toxins have been identified and 3 of them (ETA, ETB, and ETD) are linked to human infection. Among these toxins, only the ETD structure remained unknown, limiting our understanding of the structural determinants for the functional differentiation between these toxins. We recently identified an ETD-like protein associated to S. aureus strains involved in mild mastitis in sheep. The crystal structure of this ETD-like protein was determined at 1.95 Å resolution and the structural analysis provide insights into the oligomerization, stability and specificity and enabled a comprehensive structural comparison with ETA and ETB. Despite the highly conserved molecular architecture, significant differences in the composition of the loops and in both the N- and C-terminal α-helices seem to define ETD-like specificity. Molecular dynamics simulations indicate that these regions defining ET specificity present different degrees of flexibility and may undergo conformational changes upon substrate recognition and binding. DLS and AUC experiments indicated that the ETD-like is monomeric in solution whereas it is present as a dimer in the asymmetric unit indicating that oligomerization is not related to functional differentiation among these toxins. Differential scanning calorimetry and circular dichroism assays demonstrated an endothermic transition centered at 52 °C, and an exothermic aggregation in temperatures up to 64 °C. All these together provide insights about the mode of action of a toxin often secreted in syndromes that are not associated with either ETA or ETB.

Summary Caseous lymphadenitis (CLA) is a small ruminant disease characterized by the development of granulomatous lesions in superficial and internal lymph nodes, as well as in some organs, and causes significant economic losses worldwide. The aetiological agent of CLA is the bacterium Corynebacterium pseudotuberculosis; however, the commercially available diagnostic tools present problems with regard to specificity, which can lead to false‐negative results. This study aimed to develop an indirect enzyme‐linked immunosorbent assay (ELISA) for the detection of specific immunoglobulins in goats and sheep using recombinant C. pseudotuberculosis PLD, CP40, PknG, DtxR and Grx proteins. For validation of the ELISAs, 130 goat serum samples and 160 sheep serum samples were used. The best ELISA for goats was developed using a combination of PLD and CP40 as antigens at a 1:1 ratio, which presented 96.9% sensitivity and 98.4% specificity. The most effective ELISA for sheep presented 91% sensitivity and 98.7% specificity when recombinant PLD alone was used as the antigen. These ELISAs can be used as highly accurate tools in epidemiological surveys and for the serodiagnosis of C. pseudotuberculosis infection in goats and sheep.