scholarly journals Modulation of p53 Cellular Function and Cell Death by African Swine Fever Virus

2004 ◽  
Vol 78 (13) ◽  
pp. 7165-7174 ◽  
Author(s):  
Aitor G. Granja ◽  
María L. Nogal ◽  
Carolina Hurtado ◽  
José Salas ◽  
María L. Salas ◽  
...  
Keyword(s):  
Caspase 3 ◽  
African Swine Fever Virus ◽  
African Swine Fever ◽  
Fever Virus ◽  
Tumor Suppressor P53 ◽  
Infected Cells ◽  
Cellular Dna ◽  
P53 Inactivation ◽  
Infectious Cycle ◽  
Active Caspase

ABSTRACT Modulation of the activity of tumor suppressor p53 is a key event in the replication of many viruses. We have studied the function of p53 in African swine fever virus (ASFV) infection by determining the expression and activity of this transcription factor in infected cells. p53 levels are increased at early times of infection and are maintained throughout the infectious cycle. The protein is transcriptionally active, stabilized by phosphorylation, and localized in the nucleus. p53 induces the expression of p21 and Mdm2. Strikingly, these two proteins are located at the cytoplasmic virus factories. The retention of Mdm2 at the factory may represent a viral mechanism to prevent p53 inactivation by the protein. The expression of apoptotic proteins, such as Bax or active caspase-3, is also increased following ASFV infection, although the increase in caspase-3 does not appear to be, at least exclusively, p53 dependent. Bax probably plays a role in the induction of apoptosis in the infected cells, as suggested by the release of cytochrome c from the mitochondria. The significance of p21 induction and localization is discussed in relation to the shutoff of cellular DNA synthesis that is observed in ASFV-infected cells.

scholarly journals African Swine Fever Virus IAP Homologue Inhibits Caspase Activation and Promotes Cell Survival in Mammalian Cells

2001 ◽  
Vol 75 (6) ◽  
pp. 2535-2543 ◽  
Author(s):  
Marı́a L. Nogal ◽  
Gonzalo González de Buitrago ◽  
Clara Rodrı́guez ◽  
Beatriz Cubelos ◽  
Angel L. Carrascosa ◽  
...  
Keyword(s):  
Cell Death ◽  
Caspase 3 ◽  
African Swine Fever Virus ◽  
African Swine Fever ◽  
Vero Cells ◽  
Proteolytic Processing ◽  
Fever Virus ◽  
Caspase Activation ◽  
Apoptosis Protein ◽  
Infected Cells

ABSTRACT African swine fever virus (ASFV) A224L is a member of the inhibitor of apoptosis protein (IAP) family. We have investigated the antiapoptotic function of the viral IAP both in stably transfected cells and in ASFV-infected cells. A224L was able to substantially inhibit caspase activity and cell death induced by treatment with tumor necrosis factor alpha and cycloheximide or staurosporine when overexpressed in Vero cells by gene transfection. We have also observed that ASFV infection induces caspase activation and apoptosis in Vero cells. Furthermore, using a deletion mutant of ASFV lacking the A224L gene, we have shown that the viral IAP modulates the proteolytic processing of the effector cell death protease caspase-3 and the apoptosis which are induced in the infected cells. Our findings indicate that A224L interacts with the proteolytic fragment of caspase-3 and inhibits the activity of this protease during ASFV infection. These observations could indicate a conserved mechanism of action for ASFV IAP and other IAP family members to suppress apoptosis.

scholarly journals African Swine Fever Virus pB119L Protein Is a Flavin Adenine Dinucleotide-Linked Sulfhydryl Oxidase

2006 ◽  
Vol 80 (7) ◽  
pp. 3157-3166 ◽  
Author(s):  
Irene Rodríguez ◽  
Modesto Redrejo-Rodríguez ◽  
Javier M. Rodríguez ◽  
Alí Alejo ◽  
José Salas ◽  
...  
Keyword(s):  
Disulfide Bonds ◽  
Flavin Adenine Dinucleotide ◽  
Virus Assembly ◽  
Nonstructural Protein ◽  
African Swine Fever Virus ◽  
African Swine Fever ◽  
Fever Virus ◽  
Structural Protein ◽  
Sulfhydryl Oxidase ◽  
Infected Cells

ABSTRACT Protein pB119L of African swine fever virus belongs to the Erv1p/Alrp family of sulfhydryl oxidases and has been described as a late nonstructural protein required for correct virus assembly. To further our knowledge of the function of protein pB119L during the virus life cycle, we have investigated whether this protein possesses sulfhydryl oxidase activity, using a purified recombinant protein. We show that the purified protein contains bound flavin adenine dinucleotide and is capable of catalyzing the formation of disulfide bonds both in a protein substrate and in the small molecule dithiothreitol, the catalytic activity being comparable to that of the Erv1p protein. Furthermore, protein pB119L contains the cysteines of its active-site motif CXXC, predominantly in an oxidized state, and forms noncovalently bound dimers in infected cells. We also show in coimmunoprecipitation experiments that protein pB119L interacts with the viral protein pA151R, which contains a CXXC motif similar to that present in thioredoxins. Protein pA151R, in turn, was found to interact with the viral structural protein pE248R, which contains disulfide bridges and belongs to a class of myristoylated proteins related to vaccinia virus L1R, one of the substrates of the redox pathway encoded by this virus. These results suggest the existence in African swine fever virus of a system for the formation of disulfide bonds constituted at least by proteins pB119L and pA151R and identify protein pE248R as a possible final substrate of this pathway.

scholarly journals African Swine Fever Virus IAP-Like Protein Induces the Activation of Nuclear Factor Kappa B

2002 ◽  
Vol 76 (8) ◽  
pp. 3936-3942 ◽  
Author(s):  
Clara I. Rodríguez ◽  
María L. Nogal ◽  
Angel L. Carrascosa ◽  
María L. Salas ◽  
Manuel Fresno ◽  
...  
Keyword(s):  
Caspase 3 ◽  
African Swine Fever Virus ◽  
Tumor Necrosis Factor Receptor ◽  
African Swine Fever ◽  
Fever Virus ◽  
Dominant Negative ◽  
Jurkat Cells ◽  
Dominant Negative Mutant ◽  
Iκb Kinase ◽  
Necrosis Factor

ABSTRACT African swine fever virus (ASFV) encodes a homologue of the inhibitor of apoptosis (IAP) that promotes cell survival by controlling the activity of caspase-3. Here we show that ASFV IAP is also able to activate the transcription factor NF-κB. Thus, transient transfection of the viral IAP increases the activity of an NF-κB reporter gene in a dose-responsive manner in Jurkat cells. Similarly, stably transfected cells expressing ASFV IAP have elevated basal levels of c-rel, an NF-κB-dependent gene. NF-κB complexes in the nucleus were increased in A224L-expressing cells compared with control cells upon stimulation with phorbol myristate acetate (PMA) plus ionomycin. This resulted in greater NF-κB-dependent promoter activity in ASFV IAP-expressing than in control cells, both in basal conditions and after PMA plus ionophore stimulation. The elevated NF-κB activity seems to be the consequence of higher IκB kinase (IKK) basal activity in these cells. The NF-κB-inducing activity of ASFV IAP was abrogated by an IKK-2 dominant negative mutant and enhanced by expression of tumor necrosis factor receptor-associated factor 2.

scholarly journals African swine fever virus A238L inhibitor of NF-κB and of calcineurin phosphatase is imported actively into the nucleus and exported by a CRM1-mediated pathway

2007 ◽  
Vol 88 (2) ◽  
pp. 411-419 ◽  
Author(s):  
Rhiannon N. Silk ◽  
Gavin C. Bowick ◽  
Charles C. Abrams ◽  
Linda K. Dixon
Keyword(s):  
Molecular Mass ◽  
Nuclear Import ◽  
Nuclear Export ◽  
African Swine Fever Virus ◽  
African Swine Fever ◽  
Fever Virus ◽  
Infected Cells ◽  
Calcineurin Phosphatase

This study examined nuclear and cytoplasmic shuttling of the African swine fever virus (ASFV) A238L protein, which is an inhibitor of NF-κB and of calcineurin phosphatase. The results showed that the protein was present in both the nucleus and the cytoplasm in ASFV-infected cells and that the higher molecular mass 32 kDa form of the A238L protein was the predominant nuclear form, which accumulated later in infection. In contrast, both the 28 and 32 kDa forms of the A238L protein were present in the cytoplasm. The A238L protein was actively imported into the nucleus and exported by a CRM1-mediated pathway, although a pool of the protein remained in the cytoplasm and did not enter the nucleus. By using a recombinant ASFV from which the A238L gene had been deleted, it was shown that expression of A238L did not inhibit nuclear import of the NF-κB p50 or p65 subunit and did not inhibit nuclear export of p65 by a CRM1-mediated pathway. The results were consistent with a model in which A238L functions within both the nucleus and the cytoplasm.

scholarly journals Macrophage Transcriptional Responses following In Vitro Infection with a Highly Virulent African Swine Fever Virus Isolate

2006 ◽  
Vol 80 (21) ◽  
pp. 10514-10521 ◽  
Author(s):  
Fuquan Zhang ◽  
Paul Hopwood ◽  
Charles C. Abrams ◽  
Alison Downing ◽  
Frazer Murray ◽  
...  
Keyword(s):  
Proinflammatory Cytokines ◽  
Time Course ◽  
African Swine Fever Virus ◽  
Expression Profiles ◽  
African Swine Fever ◽  
Fever Virus ◽  
Surface Proteins ◽  
Transcriptional Responses ◽  
Expression Levels ◽  
Infected Cells

ABSTRACT We used a porcine microarray containing 2,880 cDNAs to investigate the response of macrophages to infection by a virulent African swine fever virus (ASFV) isolate, Malawi LIL20/1. One hundred twenty-five targets were found to be significantly altered at either or both 4 h and 16 h postinfection compared with targets after mock infection. These targets were assigned into three groups according to their temporal expression profiles. Eighty-six targets showed increased expression levels at 4 h postinfection but returned to expression levels similar to those in mock-infected cells at 16 h postinfection. These encoded several proinflammatory cytokines and chemokines, surface proteins, and proteins involved in cell signaling and trafficking pathways. Thirty-four targets showed increased expression levels at 16 h postinfection compared to levels at 4 h postinfection and in mock-infected cells. One host gene showed increased expression levels at both 4 and 16 h postinfection compared to levels in mock-infected cells. The microarray results were validated for 12 selected genes by quantitative real-time PCR. Levels of protein expression and secretion were measured for two proinflammatory cytokines, interleukin 1β and tumor necrosis factor alpha, during a time course of infection with either the virulent Malawi LIL20/1 isolate or the OUR T88/3 nonpathogenic isolate. The results revealed differences between these two ASFV isolates in the amounts of these cytokines secreted from infected cells.

African swine fever virus-induced proteins on the plasma membranes of infected cells

Virology ◽  
1989 ◽  
Vol 168 (2) ◽  
pp. 406-408 ◽  
Author(s):  
C. Alcaraz ◽  
B. Pasamontes ◽  
F. Ruiz Gonzalvo ◽  
J.M. Escribano
Keyword(s):  
Plasma Membranes ◽  
African Swine Fever Virus ◽  
African Swine Fever ◽  
Fever Virus ◽  
Infected Cells ◽  
Induced Proteins
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