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Total 20 results found since Jan 2013.

Cytorhabdovirus phosphoprotein shows RNA silencing suppressor activity in plants, but not in insect cells.
Abstract RNA silencing in plants and insects provides an antiviral defense and as a countermeasure most viruses encode RNA silencing suppressors (RSS). For the family Rhabdoviridae, no detailed functional RSS studies have been reported in plant hosts and insect vectors. In agroinfiltrated Nicotiana benthamiana leaves we show for the first time for a cytorhabdovirus, lettuce necrotic yellows virus (LNYV), that one of the nucleocapsid core proteins, phosphoprotein (P) has relatively weak local RSS activity and delays systemic silencing of a GFP reporter. Analysis of GFP small RNAs indicated that the P protein did no...
Source: Virology - January 12, 2015 Category: Virology Authors: Mann KS, Johnson KN, Dietzgen RG Tags: Virology Source Type: research

Mungbean yellow mosaic Indian virus encoded AC2 protein suppresses RNA silencing by inhibiting Arabidopsis RDR6 and AGO1 activities.
Abstract RNA silencing refers to a conserved RNA-directed gene regulatory mechanism in a wide range of eukaryotes. It plays an important role in many processes including growth, development, genome stability, and antiviral defense in the plants. Geminivirus encoded AC2 is identified as an RNA silencing suppressor protein, however, the mechanism of action has not been characterized. In this paper, we elucidate another mechanism of AC2-mediated suppression activity of Mungbean Yellow Mosaic India Virus (MYMIV). The AC2 protein, unlike many other suppressors, does not bind to siRNA or dsRNA species and its suppressio...
Source: Virology - September 30, 2015 Category: Virology Authors: Kumar V, Mishra SK, Rahman J, Taneja J, Sundaresan G, Mishra NS, Mukherjee SK Tags: Virology Source Type: research

The modulation of hepatitis C virus 1a replication by PKR is dependent on NF-kB mediated interferon beta response in Huh7.5.1 cells.
Abstract Protein kinase R (PKR), a sensor of double-stranded RNA, plays an important role in the host response to viral infection. Hepatitis C genotype 2a virus (HCV2a) has been shown to induce PKR activation to suppress the translation of antiviral interferon stimulated genes (ISGs), suggesting that PKR inhibitor can be beneficial for treating chronically HCV-infected patients in conjunction with interferon alpha and ribavirin. However, in this study, we found that PKR inhibition using siRNA PKR, shRNA PKR or PKR inhibitor enhanced HCV 1a replication and rendered Huh7.5.1 cells more susceptible to HCV1a infection...
Source: Virology - February 8, 2013 Category: Virology Authors: Zhang L, Alter HJ, Wang H, Jia S, Wang E, Marincola FM, Shih JW, Wang RY Tags: Virology Source Type: research

hnRNP A2/B1 interacts with influenza A viral protein NS1 and inhibits virus replication potentially through suppressing NS1 RNA/protein levels and NS1 mRNA nuclear export.
In this study, we identified heterogeneous nuclear ribonucleoprotein A2/B1 (hnRNP A2/B1) as an interacting partner of NS1 proteins by a proteomic method. Knockdown of hnRNP A2/B1 by small interfering RNA (siRNA) resulted in higher levels of NS vRNA, NS1 mRNA, and NS1 protein in the virus-infected cells. In addition, we demonstrated that hnRNP A2/B1 proteins are associated with NS1 and NS2 mRNAs and that knockdown of hnRNP A2/B1 promotes transport of NS1 mRNA from the nucleus to the cytoplasm in the infected cells. Lastly, we showed that knockdown of hnRNP A2/B1 leads to enhanced virus replication. Our results suggest that ...
Source: Virology - January 18, 2014 Category: Virology Authors: Wang Y, Zhou J, Du Y Tags: Virology Source Type: research

The nucleolar phosphoprotein B23 targets Newcastle disease virus matrix protein to the nucleoli and facilitates viral replication.
In this study, a nucleolar phosphoprotein B23 was identified to interact with Newcastle disease virus (NDV) matrix (M) protein. We found that NDV M protein accumulated in the nucleolus by binding B23 early in infection, but resulted in the redistribution of B23 from the nucleoli to the nucleoplasm later in infection. In vitro binding studies utilizing deletion mutants indicated that amino acids 30-60 of M and amino acids 188-245 of B23 were required for binding. Furthermore, knockdown of B23 by siRNA or overexpression of B23 or M-binding B23-derived polypeptides remarkably reduced cytopathic effect and inhibited NDV replic...
Source: Virology - March 1, 2014 Category: Virology Authors: Duan Z, Chen J, Xu H, Zhu J, Li Q, He L, Liu H, Hu S, Liu X Tags: Virology Source Type: research

Tetherin restricts HSV-2 release and is counteracted by multiple viral glycoproteins.
Abstract Tetherin has been defined as a restriction factor of HIV-1 and several other enveloped viruses. However, the significance of tetherin in viral infection remains to be further addressed. Here, we investigated whether tetherin plays a role in HSV-2 infection. Our study revealed that overexpression of tetherin restricted the release of HSV-2 into the extracellular medium, while knockdown of tetherin by siRNA enhanced its release. We further demonstrated that HSV-2 infection and viral glycoproteins gB, gD, gH and gL but not gM significantly downregulated the endogenous expression of tetherin. Additional study...
Source: Virology - November 26, 2014 Category: Virology Authors: Liu Y, Luo S, He S, Zhang M, Wang P, Li C, Huang W, Hu B, Griffin GE, Shattock RJ, Hu Q Tags: Virology Source Type: research

Flavivirus sfRNA suppresses antiviral RNA interference in cultured cells and mosquitoes and directly interacts with the RNAi machinery.
In this study, we demonstrate that two flaviviruses, Dengue virus and Kunjin virus, significantly repress siRNA-mediated RNAi in infected human cells as well as during infection of the mosquito vector Culex quinquefasciatus. Arthropod-borne flaviviruses generate a small structured non-coding RNA from the viral 3' UTR referred to as sfRNA. Analysis of infections with a mutant Kunjin virus that is unable to generate appreciable amounts of the major sfRNA species indicated that RNAi suppression was associated with the generation of the non-coding sfRNA. Co-immunoprecipitation of sfRNA with RNAi mediators Dicer and Ago2 sugges...
Source: Virology - August 28, 2015 Category: Virology Authors: Moon SL, Dodd BJ, Brackney DE, Wilusz CJ, Ebel GD, Wilusz J Tags: Virology Source Type: research

DC-SIGN as an attachment factor mediates Japanese encephalitis virus infection of human dendritic cells via interaction with a single high-mannose residue of viral E glycoprotein.
Abstract The skin-resident dendritic cells (DCs) are thought to be the first defender to encounter incoming viruses and likely play a role in Japanese encephalitis virus (JEV) early infection. In the current study, following the demonstration of JEV productive infection in DCs, we revealed that the interaction between JEV envelope glycoprotein (E glycoprotein) and DC-SIGN was important for such infection as evidenced by antibody neutralization and siRNA knockdown experiments. Moreover, the high-mannose N-linked glycan at N154 of E glycoprotein was shown to be crucial for JEV binding to DC-SIGN and subsequent inter...
Source: Virology - November 26, 2015 Category: Virology Authors: Wang P, Hu K, Luo S, Zhang M, Deng X, Li C, Jin W, Hu B, He S, Li M, Du T, Xiao G, Zhang B, Liu Y, Hu Q Tags: Virology Source Type: research

Caveolin- and clathrin-independent entry of BKPyV into primary human proximal tubule epithelial cells.
Abstract BK polyomavirus (BKPyV) is a human pathogen that causes polyomavirus-associated nephropathy and hemorrhagic cystitis in transplant patients. Gangliosides and caveolin proteins have previously been reported to be required for BKPyV infection in animal cell models. Recent studies from our lab and others, however, have indicated that the identity of the cells used for infection studies can greatly influence the behavior of the virus. We therefore wished to re-examine BKPyV entry in a physiologically relevant primary cell culture model, human renal proximal tubule epithelial cells. Using siRNA knockdowns, we ...
Source: Virology - February 19, 2016 Category: Virology Authors: Zhao L, Marciano AT, Rivet CR, Imperiale MJ Tags: Virology Source Type: research

Hemagglutinin of influenza A virus binds specifically to cell surface nucleolin and plays a role in virus internalization.
Abstract The hemagglutinin (HA) protein of influenza A virus initiates cell entry by binding to sialic acids on target cells. In the current study, we demonstrated that in addition to sialic acids, influenza A/Puerto Rico/8/34 H1N1 (PR8) virus HA specifically binds to cell surface nucleolin (NCL). The interaction between HA and NCL was initially revealed with virus overlay protein binding assay (VOPBA) and subsequently verified with co-immunoprecipitation. Importantly, inhibiting cell surface NCL with NCL antibody, blocking PR8 viruses with purified NCL protein, or depleting endogenous NCL with siRNA all substanti...
Source: Virology - April 12, 2016 Category: Virology Authors: Chan CM, Chu H, Zhang AJ, Leung LH, Sze KH, Kao RY, Chik KK, To KK, Chan JF, Chen H, Jin DY, Liu L, Yuen KY Tags: Virology Source Type: research

The down-regulation of casein kinase 1 alpha as a host defense response against infectious bursal disease virus infection.
In conclusion, down-regulation of CK1α during IBDV infection as a host defense response increased abundance of IFNAR1, which in turn enhanced an inhibitory effect on IBDV replication. PMID: 28988058 [PubMed - as supplied by publisher]
Source: Virology - October 4, 2017 Category: Virology Authors: Zhang L, Li H, Chen Y, Gao X, Lu Z, Gao L, Wang Y, Gao Y, Gao H, Liu C, Cui H, Zhang Y, Pan Q, Qi X, Wang X Tags: Virology Source Type: research

Small RNA-based interactions between rice and the viruses which cause the tungro disease.
Abstract Rice tungro disease is caused by a complex of two viruses, Rice tungro bacilliform virus (RTBV) and Rice tungro spherical virus (RTSV). To examine the RNAi-based defence response in rice during tungro disease, we characterized the virus-derived small RNAs and miRNAs by Deep Sequencing. We found that, while 21 nt/22 nt (nucleotide) siRNAs are predominantly produced in a continuous, overlapping and asymmetrical manner from RTBV, siRNA accumulation from RTSV were negligible. Additionally, 54 previously known miRNAs from rice, predicted to be regulating genes involved in plant defence, hormone signaling and d...
Source: Virology - August 3, 2018 Category: Virology Authors: Zarreen F, Kumar G, Johnson AMA, Dasgupta I Tags: Virology Source Type: research

GADD34 attenuates HIV-1 replication by viral 5'-UTR TAR RNA-mediated translational inhibition.
Abstract Role of GADD34, a protein that is induced following cellular stress, in HIV-1 replication was investigated. GADD34 was induced during the late phase of HIV-1 infection. siRNA-knockdown of GADD34 stimulated whereas overexpression of GADD34 inhibited HIV-1 replication. GADD34 N-terminal ER-binding-helix amino acid region 1-192 alone was found to be sufficient for the inhibition of HIV-1 replication whereas protein-phosphatase -1-binding domain and eIF-2α-phosphatase activity of GADD34 were not crucial for anti-HIV-1 activity. GADD34 did not alter the HIV-1 RNA levels but reduced the viral protein expressio...
Source: Virology - November 14, 2019 Category: Virology Authors: Ishaq M, Marshall H, Natarajan V Tags: Virology Source Type: research

Thymidylate synthase is essential for efficient HIV-1 replication in macrophages
Virology. 2021 Jun 14;561:47-57. doi: 10.1016/j.virol.2021.05.002. Online ahead of print.ABSTRACTThymidylate synthase (TS) is a key enzyme in nucleotide biosynthesis. A study performed by our group on human monocyte-derived macrophages (MDMs) infected with HIV-1 showed that many enzymes related to the folate cycle pathway, such as TS, are upregulated in productively infected cells. Here, we suggest that TS is essential for an effective HIV-1 infection in MDMs. Indeed, a TS specific small interfering RNA (siRNA) as well as the TS specific inhibitor Raltitrexed (RTX) caused a reduction in productively infected cells. Quantit...
Source: Virology - June 19, 2021 Category: Virology Authors: Vincent Desrosiers Corinne Barat Yann Breton Michel Ouellet Michel J Tremblay Source Type: research