Construction and characterization of a full-length infectious clone of an emerging senecavirus A strain.

Senecavirus A (SVA) is an emerging virus that causes vesicular disease in pigs. Construction of a full-length SVA cDNA clone is crucial for understanding its replication and pathogenesis. Here, we successfully constructed a CMV-promoter-driven infectious cDNA clone of the SVA isolate SVA/GX/CH/2018, which we named rSVA GX01. Sequence comparison between the pSVA GX01 and the parental isolate (SVA/GX/CH/2018) revealed three single-nucleotide differences. Four-week-old piglets were experimentally infected with either the parental virus or the cloned virus. The results showed that the cloned rSVA GX01 displayed weak pathogenicity in 4-week-old pigs compared to the parental virus SVA CH-GX-01-2018. The infectious clone of SVA will serve as a valuable tool for studying the viral replication cycle and for functional analysis of the viral genome.

Emergence and Phylogenetic Analysis of a Getah Virus Isolated in Southern China.

Getah virus (GETV) has caused many outbreaks in animals in recent years. Monitoring of the virus and its related diseases is crucial to control the transmission of the virus. In the summer of 2018, we conducted routine tests on clinical samples from different pig farms in Guangxi province, South China, and isolated and characterized a GETV strain, named GX201808. Cytopathic effects were observed in BHK-21 cells inoculated with GX201808. The expression of E2 protein of GETV could be detected in virus-infected cells by indirect immunofluorescence assays. Electron microscopic analysis showed that the virus particles were spherical and ~70 nm in diameter with featured surface fibers. The multistep growth curves showed the virus propagated well in the BHK-21 cells. Molecular genetic analysis revealed that GX201808 belongs to Group 3, represented by Kochi-01-2005 isolated in Japan in 2005, and it clustered closely with the recently reported Chinese strains isolated from pigs, cattle, and foxes. A comparison of the identities of nucleotides and amino acids in the coding regions demonstrated that the GX201808 showed the highest amino acid identity (99.6%) with the HuN1 strain, a highly pathogenic isolate resulting in an outbreak of GETV infection in swine herds in Hunan province in 2017. In the present study, GETV was identified and isolated for the first time in Guangxi province of southern China, suggesting that future surveillance of this virus should be strengthened.

Emergence and phylogenetic analysis of a novel Seneca Valley virus strain in the Guangxi Province of China.

Senecavirus A (SVA), also known as Seneca Valley virus (SVV), is an emerging infectious pathogen which have been detected in swine herds from the Brazil, USA, Colombia, Thailand, Canada and some provinces in China, suggesting an increasing geographic distribution of this novel virus. Here, we isolated and characterized a SVV, designated SVA CH-GX-01-2018, thought to be responsible for typical vesicular lesions on the snouts and hooves of finishing pigs from a swine herds in Guangxi province, China, in August 2018. Phylogenetic analysis and sequence alignment indicated that this SVA CH-GX-01-2018 strain was closely related to the strains isolated in 2017 in Guangdong province, a neighboring province of Guangxi, South China, with 98.6% identity at the genome nucleotide level. Our findings characterized a novel SVV infection in pigs from South China and emphasize the importance of surveillance, reinforcing biosecurity measures and developing vaccines to prevent the spread of this viral pathogen.

MicroRNA-27a restrains the immune response to mycobacterium tuberculosis infection by targeting IRAK4, a promoter of the NF-κB pathway.

This study aimed to explore the influence of microRNA-27a on immune response to mycobacterium tuberculosis (Mtb) and the molecular mechanism. MiRNA-27a was screened one of the downregulated miRNAs in Mtb infected macrophages. The concentrations of IFN-γ, IL-ß, IL-6, and TNF-α in THP-1 macrophages after infection with Mtb and simultaneous transfection with miR-27a mimics or inhibitor were determined by ELISA. Colony-forming unit (CFU) assay was used to determine the survival situation of THP-1 infected with Mtb after transfection with miR-27a mimics or inhibitor. We used luciferase reporter assay and western blotting to study the relationship between miR-27a and IRAK4. MiR-27a was found differential expressed in Mtb infected macrophages, and the expressions of miR-27a in Mtb-infected THP-1 were remarkably downregulated with the increase of time and dose. Compared with the control, the levels of IFN-γ, IL-ß, IL-6, and TNF-α were enhanced after macrophages infected with Mtb, while further transfection of miR-27a mimics abolished the increase. IRAK4 was found the target gene of miR-27a and transfection of miR-27a mimics decreased the relative level of IRAK4. The concentration of IFN-γ, IL-ß, IL-6, and TNF-α in Mtb infected macrophages were reduced significantly after transfection of miR-27a mimics, while simultaneous transfection of pcDNA-IRAK4 abolished the decrease, which is the upstream molecular of NF-κB. In conclusion, miR-27a plays a key role in immune response to Mtb infection and intervening on miR-27a may be an effective way to treat TB.