Lactococcus lactis Expressing Type I Interferon From Atlantic Salmon Enhances the Innate Antiviral Immune Response In Vivo and In Vitro.

In salmon farming, viruses are responsible for outbreaks that produce significant economic losses for which there is a lack of control tools other than vaccines. Type I interferon has been successfully used for treating some chronic viral infections in humans. However, its application in salmonids depends on the proper design of a vehicle that allows its massive administration, ideally orally. In mammals, administration of recombinant probiotics capable of expressing cytokines has shown local and systemic therapeutic effects. In this work, we evaluate the use of Lactococcus lactis as a type I Interferon expression system in Atlantic salmon, and we analyze its ability to stimulate the antiviral immune response against IPNV, in vivo and in vitro. The interferon expressed in L. lactis, even though it was located mainly in the bacterial cytoplasm, was functional, stimulating Mx and PKR expression in CHSE-214 cells, and reducing the IPNV viral load in SHK-1 cells. In vivo, the oral administration of this L. lactis producer of Interferon I increases Mx and PKR expression, mainly in the spleen, and to a lesser extent, in the head kidney. The oral administration of this strain also reduces the IPNV viral load in Atlantic salmon specimens challenged with this pathogen. Our results show that oral administration of L. lactis producing Interferon I induces systemic effects in Atlantic salmon, allowing to stimulate the antiviral immune response. This probiotic could have effects against a wide variety of viruses that infect Atlantic salmon and also be effective in other salmonids due to the high identity among their type I interferons.

New Copper(I) Complex with a Coumarin as Ligand with Antibacterial Activity against Flavobacterium psychrophilum.

A new copper (I) complex, [Cu(NN1)2](ClO4), was synthesized, where NN1 was a imine ligand 6-((quinolin-2-ylmethylene)amino)-2H-chromen-2-one obtained by a derivatization of natural compound coumarin. The structural characterization in solution was done by NMR techniques, UV-Vis and cyclic voltammetry. The potential antibacterial effect of [Cu(NN1)2](ClO4), was assessed for F. psychrophilum isolated 10094. F. psychrophilum is a Gram-negative bacterium which causes diseases such as bacterial cold-water disease and rainbow trout fry syndrome, causing large economic losses in the freshwater salmonid aquaculture industry. This complex show to have antibacterial activity against F. psychrophilum 10094 at non-cytotoxic concentration in cell line derived from trout (F. psychrophilum 10094 IC50 16.0 ± 0.9; RT-GUT IC50 53.0 ± 3.1 µg/mL).

Antibacterial activity of cuticular components from heliotropium species, against staphylococcus aureus and salmonella tiphymurium / Actividad antibacteriana de componentes cuticulares de especies de heliotropium frente a staphylococcus aureus y salmonella tiphymurium

In this communication the antibacterial activity of filifolinol (1), naringenin (2) 3-O-methylgalangin (3) and pinocembrin (4) isolated from the resinous exudates of Heliotropium filifolium and H. sinuatum, were evaluated by flow cytometry against Staphylococcus aureus and Salmonella tiphymurium. The results showed that filifolinol (1) and naringenin (2) were inactive in the range of concentrations used (10 to 1000 ug/mL). On the other hand, pinocembrin (4) produced a decrease in cell surface at 500 ug/mL and the total disappearance of both bacterial populations at 1000 ug/mL. Also, 3-O-methylgalangin (3) showed the total disappearance at 1000 ug/mL of both bacterial populations and a decrease at 200 μg/mL for S. typhimurium and at 500 μg/mL for S. aureus.

En esta comunicación, la actividad antibacteriana de filifolinol (1), naringenina (2), 3-O-methylgalangina (3) y pinocembrina (4) aislados de los exudados resinosos de Heliotropium filifolium y H. sinuatum, fueron evaluados por citometría de flujo frente a Staphylococcus aureus y Salmonella tiphymurium. Los resultados mostraron que filifolinol (1) y naringenina (2) fueron inactivos en el intervalo de concentraciones usadas (10 a 1000 μg / mL). Por otro lado, pinocembrina (4) produce una disminución de la superficie de las células a 500 ug/mL y la desaparición total de ambas poblaciones bacterianas a 1.000 ug/mL. También, 3-O-metilgalangina (3) mostró la desaparición total a 1.000 ug / mL tanto de ambas poblaciones de bacterias y una disminución a 200 ug/mL para S. typhimurium y en 500 μg/mL para S. aureus.

Evaluation of the bactericidal activity of secondary metabolites isolated from Heliotropium genus against Piscirickettsia salmonis / Evaluación de la actividad bactericida de metabolitos secundarios aislados desde especies del género Heliotropiumcontra Piscirickettsia salmonis

The intracellular bacteria Piscirickettsia salmonis is the most prevalent pathogen in the Chilean salmon industry, responsible for 50 percent of losses in recent years. So far, there are no effective treatments to control infections by this pathogen due to the emergence of antibiotics resistance. Therefore, it is extremely important to conduct research to find successful antibacterial therapies. In this paper, we evaluated the in vitro bactericidal activity of flavonoids and aromatic geranyl derivatives isolated from the resinous exudate of species Heliotropium filifolium, H. sinuatum y H. huascoense. The results showed that the compounds Filifolinone, Naringenine and 3-O- methylgalangine cause different percentage of mortality of bacteria and therefore they are good candidates to continue its evaluation in vitro and in vivo.

La bacteria intracelular Piscirickettsia salmonis es el patógeno de mayor incidencia en la industria salmonera chilena siendo responsable de un 50 por ciento de las pérdidas en los últimos años. Hasta ahora no hay tratamientos efectivos para este patógeno que permitan controlar las infecciones provocadas por él debido a la aparición de resistencia a antibióticos. Por lo tanto, resulta de gran importancia investigar para encontrar terapias antibacterianas efectivas. En este trabajo nosotros evaluamos la actividad bactericida in vitro de flavonoides y derivados aromáticos geranilados aislados desde el exudado resinoso de las especies vegetales Heliotropium filifolium, H. sinuatum y H. huascoense. Los resultados mostraron que los compuestos Filifolinona, Naringenina y 3-O-metilgalangina provocan diferentes porcentajes de mortalidad de la bacteria y, por lo tanto, son candidatos para seguir siendo evaluados tanto in vitro como in vivo.

Characterization of the arginine decarboxylase gene (ORF HP0422, speA) involved in acid tolerance in Helicobacter pylori.

BACKGROUND: Helicobacter pylori is a motile microaerophilic bacterium that colonizes the human stomach. H. pylori infection triggers gastric diseases, such as gastritis, peptic ulcer and gastric cancer. Stomach represents a barrier for microorganism colonization, particularly because of its high hydrochloric acid concentration. The main mechanism developed by H. pylori to maintain intracellular pH homeostasis in this environment is the urease activity. However, urease negative strains can be also isolated from clinical samples, suggesting that H. pylori presents other components involved in acid resistance. OBJECTIVE: Here, we present some evidence that the arginine decarboxylase gene (speA) in H. pylori could be involved in an acid adaptation mechanism similar to the one in Enterobacteriaceae, which is dependent on the presence of arginine. METHODS: Indeed, speA mRNA and protein expression are acutely induced by acid stress. RESULTS: Moreover, we showed that H. pylori uses arginine in an acid response mechanism required for its growth in acid conditions. CONCLUSION: Altogether, these results provide novel information regarding the H. pylori physiology and acid response mechanism.

tlpA gene expression is required for arginine and bicarbonate chemotaxis in Helicobacter pylori.

About half of the human population is infected with Helicobacter pylori, a bacterium causing gastritis, peptic ulcer and progression to gastric cancer. Chemotaxis and flagellar motility are required for colonization and persistence of H. pylori in the gastric mucus layer. It is not completely clear which chemical gradients are used by H. pylori to maintain its position. TlpA, a chemotaxis receptor for arginine/ bicarbonate, has been identified. This study aimed to find out whether tlpA gene expression is required for the chemotactic response to arginine/bicarbonate. Wild-type motile H. pylori ATCC 700392 and H. pylori ATCC 43504, a strain having an interrupted tlpA gene, were used. Also, a tlpA-knockout mutant of H. pylori 700392 (H. pylori 700-tlpA::cat) was produced by homologous recombination. Expression of tlpA was assessed by a Reverse Transcriptase-Polymerase Chain Reaction (RT-PCR) assay. Chemotaxis was measured as a Relative Chemotaxis Response (RCR) by a modified capillary assay. H. pylori 700392 presented chemotaxis to arginine and sodium bicarbonate. H. pylori 700-tlpA::cat showed neither tlpA gene expression nor chemotaxis towards arginine and bicarbonate. Besides confirming that TlpA is a chemotactic receptor for arginine/bicarbonate in H. pylori, this study showed that tlpA gene expression is required for arginine/bicarbonate chemotaxis.

tlpA gene expression is required for arginine and bicarbonate chemotaxis in Helicobacter pylori

About half of the human population is infected with Helicobacter pylori, a bacterium causing gastritis, peptic ulcer and progression to gastric cancer. Chemotaxis and flagellar motility are required for colonization and persistence of H. pylori in the gastric mucus layer. It is not completely clear which chemical gradients are used by H. pylori to maintain its position. TlpA, a chemotaxis receptor for arginine/ bicarbonate, has been identified. This study aimed to find out whether tlpA gene expression is required for the chemotactic response to arginine/bicarbonate. Wild-type motile H. pylori ATCC 700392 and H. pylori ATCC 43504, a strain having an interrupted tlpA gene, were used. Also, a tlpA-knockout mutant of H. pylori 700392 (H. pylori 700-tlpA::cat) was produced by homologous recombination. Expression of tlpA was assessed by a Reverse Transcriptase-Polymerase Chain Reaction (RT-PCR) assay. Chemotaxis was measured as a Relative Chemotaxis Response (RCR) by a modified capillary assay. H. pylori 700392 presented chemotaxis to arginine and sodium bicarbonate. H. pylori 700-tlpA::cat showed neither tlpA gene expression nor chemotaxis towards arginine and bicarbonate. Besides confirming that TlpA is a chemotactic receptor for arginine/bicarbonate in H. pylori, this study showed that tlpA gene expression is required for arginine/bicarbonate chemotaxis.