Salmonella is recognized as one of the most common microbial pathogens worldwide. The bacterium contains the clustered regularly interspaced short palindromic repeats (CRISPR)-CRISPR-associated (Cas) systems, providing adaptive immunity against invading foreign nucleic acids. Previous studies suggested that certain bacteria employ the Cas proteins of CRISPR-Cas systems to target their own genes, which also alters the virulence during invasion of mammals. However, whether CRISPR-Cas systems in Salmonella have similar functions during bacterial invasion of host cells remains unknown. Here, we systematically analyzed the genes that are regulated by Cas3 in a type I-E CRISPR-Cas system and the virulence changes due to the deletion of cas3 in Salmonella enterica serovar Enteritidis. Compared to the cas3 gene wild-type (cas3 WT) Salmonella strain, cas3 deletion upregulated the lsrFGBE genes in lsr (luxS regulated) operon related to quorum sensing (QS) and downregulated biofilm-forming-related genes and Salmonella pathogenicity island 1 (SPI-1) genes related to the type three secretion system (T3SS). Consistently, the biofilm formation ability was downregulated in the cas3 deletion mutant (Δcas3). The bacterial invasive and intracellular capacity of Δcas3 to host cells was also reduced, thereby increasing the survival of infected host cells and live chickens. By the transcriptome-wide screen (RNA-Seq), we found that the cas3 gene impacts a series of genes related to QS, the flagellum, and SPI-1-T3SS system, thereby altering the virulence phenotypes. As QS SPI-1-T3SS and CRISPR-Cas systems are widely distributed in the bacteria kingdom, our findings extend our understanding of virulence regulation and pathogenicity in mammalian hosts for Salmonella and potentially other bacteria.

Severe fever with thrombocytopenia syndrome virus (SFTSV) is a novel phlebovirus that was identified to be the etiological pathogen of the emerging infectious disease, severe fever with thrombocytopenia syndrome (SFTS). SFTSV could be transmitted through tick bite. Transmission of SFTSV among humans has also been reported mainly through direct blood contact. In July 2014, a cluster of six suspected SFTS cases occurred in Shandong Province, China. In this cluster, both symptomatic and asymptomatic persons were included. By analyzing the clinical data and results of laboratory tests, and conducting the epidemiological interviews with the cases and their families, risk factors responsible for the transmission were evaluated. The findings suggested that SFTSV transmission among humans may cause asymptomatic infection via personal contact without blood exposure.

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BackgroundHepatocellular carcinoma (HCC) is a common malignant tumor with high fatality rate. Recent studies reported that up-regulation of long non-coding RNA antisense non-coding RNA in the INK4 locus (lncRNA ANRIL) was found in HCC tissues, and which could affect HCC cells biological processes. However, the potential molecular mechanism of ANRIL in HCC is still unclear. The study aimed to uncover the effect of ANRIL on HepG2 cells growth, migration and invasion.MethodsThe knockdown expression vectors of ANRIL were transfected into HepG2 cells, and qRT-PCR, CCK-8, flow cytometry, Transwell and western blot assays were performed to analyze the effect of ANRIL on cell proliferation, apoptosis, migration and invasion. The relative expression of miR-191 was then examined in ANRIL knockdown vector transfected cells. These experiments were repeated again for exploring the effect of miR-191 on HepG2 cells. NF-κB and Wnt/β-catenin signaling pathways were examined by using western blot assay.ResultsKnockdown of ANRIL inhibited proliferation, induced apoptosis, meanwhile suppressed migration and invasion of HepG2 cells. Additionally, the results showed that the expression level of miR-191 was down-regulated by ANRIL knockdown in HepG2 cells. Importantly, overexpression of miR-191 reversed the anti-tumor effect of ANRIL on cell proliferation, apoptosis, migration and invasion in HepG2 cells. Besides, we found that ANRIL knockdown inactivated NF-κB and Wnt/β-catenin pathways by regulating miR-191.ConclusionsThese data demonstrated that ANRIL knockdown suppressed proliferation, migration, invasion, and promoted apoptosis in HepG2 cells by down-regulating miR-191 and inactivating NF-κB and Wnt/β-catenin signaling pathways.

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