The Experts below are selected from a list of 27357 Experts worldwide ranked by ideXlab platform
Alexander A Khromykh - One of the best experts on this subject based on the ideXlab platform.
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a single amino acid substitution in the west nile Virus nonstructural protein ns2a disables its ability to inhibit alpha beta interferon induction and attenuates Virus Virulence in mice
Journal of Virology, 2006Co-Authors: Wen Jun Liu, Xiang Ju Wang, David C Clark, Mario Lobigs, Roy A Hall, Alexander A KhromykhAbstract:Alpha/beta interferons (IFN-α/β) are key mediators of the innate immune response against viral infection. The ability of Viruses to circumvent IFN-α/β responses plays a crucial role in determining the outcome of infection. In a previous study using subgenomic replicons of the Kunjin subtype of West Nile Virus (WNVKUN), we demonstrated that the nonstructural protein NS2A is a major inhibitor of IFN-β promoter-driven transcription and that a single amino acid substitution in NS2A (Ala30 to Pro [A30P]) dramatically reduced its inhibitory effect (W. J. Liu, H. B. Chen, X. J. Wang, H. Huang, and A. A. Khromykh, J. Virol. 78:12225-12235). Here we show that incorporation of the A30P mutation into the WNVKUN genome results in a mutant Virus which elicits more rapid induction and higher levels of synthesis of IFN-α/β in infected human A549 cells than that detected following wild-type WNVKUN infection. Consequently, replication of the WNVKUNNS2A/A30P mutant Virus in these cells known to be high producers of IFN-α/β was abortive. In contrast, both the mutant and the wild-type WNVKUN produced similar-size plaques and replicated with similar efficiency in BHK cells which are known to be deficient in IFN-α/β production. The mutant Virus was highly attenuated in neuroinvasiveness and also attenuated in neuroVirulence in 3-week-old mice. Surprisingly, the mutant Virus was also partially attenuated in IFN-α/βγ receptor knockout mice, suggesting that the A30P mutation may also play a role in more efficient activation of other antiviral pathways in addition to the IFN response. Immunization of wild-type mice with the mutant Virus resulted in induction of an antibody response of similar magnitude to that observed in mice immunized with wild-type WNVKUN and gave complete protection against challenge with a lethal dose of the highly virulent New York 99 strain of WNV. The results confirm and extend our previous original findings on the role of the flaviVirus NS2A protein in inhibition of a host antiviral response and demonstrate that the targeted disabling of a viral mechanism for evading the IFN response can be applied to the development of live attenuated flaviVirus vaccine candidates.
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a single amino acid substitution in the west nile Virus nonstructural protein ns2a disables its ability to inhibit alpha beta interferon induction and attenuates Virus Virulence in mice
Journal of Virology, 2006Co-Authors: Wen Jun Liu, Xiang Ju Wang, David C Clark, Mario Lobigs, Roy A Hall, Alexander A KhromykhAbstract:Alpha/beta interferons (IFN-alpha/beta) are key mediators of the innate immune response against viral infection. The ability of Viruses to circumvent IFN-alpha/beta responses plays a crucial role in determining the outcome of infection. In a previous study using subgenomic replicons of the Kunjin subtype of West Nile Virus (WNV(KUN)), we demonstrated that the nonstructural protein NS2A is a major inhibitor of IFN-beta promoter-driven transcription and that a single amino acid substitution in NS2A (Ala30 to Pro [A30P]) dramatically reduced its inhibitory effect (W. J. Liu, H. B. Chen, X. J. Wang, H. Huang, and A. A. Khromykh, J. Virol. 78:12225-12235). Here we show that incorporation of the A30P mutation into the WNV(KUN) genome results in a mutant Virus which elicits more rapid induction and higher levels of synthesis of IFN-alpha/beta in infected human A549 cells than that detected following wild-type WNV(KUN) infection. Consequently, replication of the WNV(KUN)NS2A/A30P mutant Virus in these cells known to be high producers of IFN-alpha/beta was abortive. In contrast, both the mutant and the wild-type WNV(KUN) produced similar-size plaques and replicated with similar efficiency in BHK cells which are known to be deficient in IFN-alpha/beta production. The mutant Virus was highly attenuated in neuroinvasiveness and also attenuated in neuroVirulence in 3-week-old mice. Surprisingly, the mutant Virus was also partially attenuated in IFN-alpha/betagamma receptor knockout mice, suggesting that the A30P mutation may also play a role in more efficient activation of other antiviral pathways in addition to the IFN response. Immunization of wild-type mice with the mutant Virus resulted in induction of an antibody response of similar magnitude to that observed in mice immunized with wild-type WNV(KUN) and gave complete protection against challenge with a lethal dose of the highly virulent New York 99 strain of WNV. The results confirm and extend our previous original findings on the role of the flaviVirus NS2A protein in inhibition of a host antiviral response and demonstrate that the targeted disabling of a viral mechanism for evading the IFN response can be applied to the development of live attenuated flaviVirus vaccine candidates.
Geoffrey L Smith - One of the best experts on this subject based on the ideXlab platform.
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a comparison of the effect of molluscum contagiosum Virus mc159 and mc160 proteins on vaccinia Virus Virulence in intranasal and intradermal infection routes
Journal of General Virology, 2018Co-Authors: Sunetra Biswas, Geoffrey L Smith, Brian M Ward, Joanna L ShislerAbstract:Molluscum contagiosum Virus (MCV) causes persistent, benign skin neoplasm in children and adults. MCV is refractive to growth in standard tissue culture and there is no relevant animal model of infection. Here we investigated whether another poxVirus (vaccinia Virus; VACV) could be used to examine MCV immunoevasion protein properties in vivo. The MCV MC159L or MC160L genes, which encode NF-κB antagonists, were inserted into an attenuated VACV lacking an NF-κB antagonist (vΔA49), creating vMC159 and vMC160. vMC160 slightly increased vΔA49 Virulence in the intranasal and intradermal routes of inoculation. vMC159 infection was less virulent than vΔA49 in both inoculation routes. vMC159-infected ear pinnae did not form lesions, but Virus replication still occurred. Thus, the lack of lesions was not due to abortive Virus replication. This system provides a new approach to examine MCV immunoevasion proteins within the context of a complete and complex immune system.
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increased attenuation but decreased immunogenicity by deletion of multiple vaccinia Virus immunomodulators
Vaccine, 2016Co-Authors: Rebecca P Sumner, Brian J Ferguson, Hongwei Ren, Geoffrey L SmithAbstract:Vaccinia Virus (VACV)-derived vectors are popular candidates for vaccination against diseases such as HIV-1, malaria and tuberculosis. However, their genomes encode a multitude of proteins with immunomodulatory functions, several of which reduce the immunogenicity of these vectors. Hitherto only limited studies have investigated whether the removal of these immunomodulatory genes in combination can increase vaccine efficacy further. To this end we constructed Viruses based on VACV strain Western Reserve (WR) lacking up to three intracellular innate immunomodulators (N1, C6 and K7). These genes were selected because the encoded proteins had known functions in innate immunity and the deletion of each gene individually had caused a decrease in Virus Virulence in the murine intranasal and intradermal models of infection and an increase in immunogenicity. Data presented here demonstrate that deletion of two, or three of these genes in combination attenuated the Virus further in an incremental manner. However, when vaccinated mice were challenged with VACV WR the double and triple gene deletion Viruses provided weaker protection against challenge. This was accompanied by inferior memory CD8+ T cell responses and lower neutralising antibody titres. This study indicates that, at least for the three genes studied in the context of VACV WR, the single gene deletion Viruses are the best vaccine vectors, and that increased attenuation induced by deletion of additional genes decreased immunogenicity. These data highlight the fine balance and complex relationship between viral attenuation and immunogenicity. Given that the proteins encoded by the genes examined in this study are known to affect specific aspects of innate immunity, the set of Viruses constructed here are interesting tools to probe the role of the innate immune response in influencing immune memory and vaccine efficacy.
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mapping the iκb kinase β ikkβ binding interface of the b14 protein a vaccinia Virus inhibitor of ikkβ mediated activation of nuclear factor κb
Journal of Biological Chemistry, 2011Co-Authors: Camilla T O Benfield, M W Bahar, D I Stuart, Jonathan M Grimes, Daniel S Mansur, Laura E Mccoy, Brian J Ferguson, Asa P Oldring, Stephen C Graham, Geoffrey L SmithAbstract:Abstract The IκB kinase (IKK) complex regulates activation of NF-κB, a critical transcription factor in mediating inflammatory and immune responses. Not surprisingly, therefore, many Viruses seek to inhibit NF-κB activation. The vaccinia Virus B14 protein contributes to Virus Virulence by binding to the IKKβ subunit of the IKK complex and preventing NF-κB activation in response to pro-inflammatory stimuli. Previous crystallographic studies showed that the B14 protein has a Bcl-2-like fold and forms homodimers in the crystal. However, multi-angle light scattering indicated that B14 is in monomer-dimer equilibrium in solution. This transient self-association suggested that the hydrophobic dimerization interface of B14 might also mediate its interaction with IKKβ, and this was investigated by introducing amino acid substitutions on the dimer interface. One mutant (Y35E) was entirely monomeric but still co-immunoprecipitated with IKKβ and blocked both NF-κB nuclear translocation and NF-κB-dependent gene expression. Therefore, B14 homodimerization is nonessential for binding and inhibition of IKKβ. In contrast, a second monomeric mutant (F130K) neither bound IKKβ nor inhibited NF-κB-dependent gene expression, demonstrating that this residue is required for the B14-IKKβ interaction. Thus, the dimerization and IKKβ-binding interfaces overlap and lie on a surface used for protein-protein interactions in many viral and cellular Bcl-2-like proteins.
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mapping the iκb kinase beta ikkβ binding interface of b14 a vaccinia Virus inhibitor of ikkβ mediated activation of nuclear factor kappa b
Journal of Biological Chemistry, 2011Co-Authors: Camilla T O Benfield, M W Bahar, D I Stuart, Jonathan M Grimes, Daniel S Mansur, Laura E Mccoy, Brian J Ferguson, Asa P Oldring, Stephen C Graham, Geoffrey L SmithAbstract:Abstract The IκB kinase (IKK) complex regulates activation of nuclear factor kappa B (NF-κB), a critical transcription factor in mediating inflammatory and immune responses. Not surprisingly, therefore, many Viruses seek to inhibit NF-κB activation. The vaccinia Virus (VACV) B14 protein contributes to Virus Virulence by binding to the IKKβ subunit of the IKK complex and preventing NF-κB activation in response to pro-inflammatory stimuli. Previous crystallographic studies showed that the B14 protein has a Bcl-2-like fold and forms homo-dimers in the crystal. However, multi-angle light scattering indicated that B14 is in monomer:dimer equilibrium in solution. This transient self-association suggested that the hydrophobic dimerisation interface of B14 might also mediate its interaction with IKKβ and this was investigated by introducing amino acid substitutions on the dimer interface. One mutant (Y35E) was entirely monomeric but still co-immunoprecipitated with IKKβ and blocked both NF-κB nuclear translocation and NF-κB-dependent gene expression. Therefore, B14 homo-dimerisation is non-essential for binding and inhibition of IKKβ. In contrast, a second monomeric mutant (F130K) neither bound IKKβ nor inhibited NF-κB-dependent gene expression, demonstrating that this residue is required for the B14-IKKβ interaction. Thus the dimerisation and IKKβ-binding interfaces overlap and lie on a surface used for protein:protein interactions in many viral and cellular Bcl-2-like proteins.
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inhibition of iκb kinase by vaccinia Virus Virulence factor b14
PLOS Pathogens, 2008Co-Authors: Ron A J Chen, Samantha Cooray, Grigory Ryzhakov, Felix Randow, Geoffrey L SmithAbstract:The IκB kinase (IKK) complex is a key regulator of signal transduction pathways leading to the induction of NF-κB-dependent gene expression and production of pro-inflammatory cytokines. It therefore represents a major target for the development of anti-inflammatory therapeutic drugs and may be targeted by pathogens seeking to diminish the host response to infection. Previously, the vaccinia Virus (VACV) strain Western Reserve B14 protein was characterised as an intracellular Virulence factor that alters the inflammatory response to infection by an unknown mechanism. Here we demonstrate that ectopic expression of B14 inhibited NF-κB activation in response to TNFα, IL-1β, poly(I:C), and PMA. In cells infected with VACV lacking gene B14R (vΔB14) there was a higher level of phosphorylated IκBα but a similar level of IκBα compared to cells infected with control Viruses expressing B14, suggesting B14 affects IKK activity. Direct evidence for this was obtained by showing that B14 co-purified and co-precipitated with the endogenous IKK complex from human and mouse cells and inhibited IKK complex enzymatic activity. Notably, the interaction between B14 and the IKK complex required IKKβ but not IKKα, suggesting the interaction occurs via IKKβ. B14 inhibited NF-κB activation induced by overexpression of IKKα, IKKβ, and a constitutively active mutant of IKKα, S176/180E, but did not inhibit a comparable mutant of IKKβ, S177/181E. This suggested that phosphorylation of these serine residues in the activation loop of IKKβ is targeted by B14, and this was confirmed using Ab specific for phospho-IKKβ.
Wen Jun Liu - One of the best experts on this subject based on the ideXlab platform.
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a single amino acid substitution in the west nile Virus nonstructural protein ns2a disables its ability to inhibit alpha beta interferon induction and attenuates Virus Virulence in mice
Journal of Virology, 2006Co-Authors: Wen Jun Liu, Xiang Ju Wang, David C Clark, Mario Lobigs, Roy A Hall, Alexander A KhromykhAbstract:Alpha/beta interferons (IFN-α/β) are key mediators of the innate immune response against viral infection. The ability of Viruses to circumvent IFN-α/β responses plays a crucial role in determining the outcome of infection. In a previous study using subgenomic replicons of the Kunjin subtype of West Nile Virus (WNVKUN), we demonstrated that the nonstructural protein NS2A is a major inhibitor of IFN-β promoter-driven transcription and that a single amino acid substitution in NS2A (Ala30 to Pro [A30P]) dramatically reduced its inhibitory effect (W. J. Liu, H. B. Chen, X. J. Wang, H. Huang, and A. A. Khromykh, J. Virol. 78:12225-12235). Here we show that incorporation of the A30P mutation into the WNVKUN genome results in a mutant Virus which elicits more rapid induction and higher levels of synthesis of IFN-α/β in infected human A549 cells than that detected following wild-type WNVKUN infection. Consequently, replication of the WNVKUNNS2A/A30P mutant Virus in these cells known to be high producers of IFN-α/β was abortive. In contrast, both the mutant and the wild-type WNVKUN produced similar-size plaques and replicated with similar efficiency in BHK cells which are known to be deficient in IFN-α/β production. The mutant Virus was highly attenuated in neuroinvasiveness and also attenuated in neuroVirulence in 3-week-old mice. Surprisingly, the mutant Virus was also partially attenuated in IFN-α/βγ receptor knockout mice, suggesting that the A30P mutation may also play a role in more efficient activation of other antiviral pathways in addition to the IFN response. Immunization of wild-type mice with the mutant Virus resulted in induction of an antibody response of similar magnitude to that observed in mice immunized with wild-type WNVKUN and gave complete protection against challenge with a lethal dose of the highly virulent New York 99 strain of WNV. The results confirm and extend our previous original findings on the role of the flaviVirus NS2A protein in inhibition of a host antiviral response and demonstrate that the targeted disabling of a viral mechanism for evading the IFN response can be applied to the development of live attenuated flaviVirus vaccine candidates.
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a single amino acid substitution in the west nile Virus nonstructural protein ns2a disables its ability to inhibit alpha beta interferon induction and attenuates Virus Virulence in mice
Journal of Virology, 2006Co-Authors: Wen Jun Liu, Xiang Ju Wang, David C Clark, Mario Lobigs, Roy A Hall, Alexander A KhromykhAbstract:Alpha/beta interferons (IFN-alpha/beta) are key mediators of the innate immune response against viral infection. The ability of Viruses to circumvent IFN-alpha/beta responses plays a crucial role in determining the outcome of infection. In a previous study using subgenomic replicons of the Kunjin subtype of West Nile Virus (WNV(KUN)), we demonstrated that the nonstructural protein NS2A is a major inhibitor of IFN-beta promoter-driven transcription and that a single amino acid substitution in NS2A (Ala30 to Pro [A30P]) dramatically reduced its inhibitory effect (W. J. Liu, H. B. Chen, X. J. Wang, H. Huang, and A. A. Khromykh, J. Virol. 78:12225-12235). Here we show that incorporation of the A30P mutation into the WNV(KUN) genome results in a mutant Virus which elicits more rapid induction and higher levels of synthesis of IFN-alpha/beta in infected human A549 cells than that detected following wild-type WNV(KUN) infection. Consequently, replication of the WNV(KUN)NS2A/A30P mutant Virus in these cells known to be high producers of IFN-alpha/beta was abortive. In contrast, both the mutant and the wild-type WNV(KUN) produced similar-size plaques and replicated with similar efficiency in BHK cells which are known to be deficient in IFN-alpha/beta production. The mutant Virus was highly attenuated in neuroinvasiveness and also attenuated in neuroVirulence in 3-week-old mice. Surprisingly, the mutant Virus was also partially attenuated in IFN-alpha/betagamma receptor knockout mice, suggesting that the A30P mutation may also play a role in more efficient activation of other antiviral pathways in addition to the IFN response. Immunization of wild-type mice with the mutant Virus resulted in induction of an antibody response of similar magnitude to that observed in mice immunized with wild-type WNV(KUN) and gave complete protection against challenge with a lethal dose of the highly virulent New York 99 strain of WNV. The results confirm and extend our previous original findings on the role of the flaviVirus NS2A protein in inhibition of a host antiviral response and demonstrate that the targeted disabling of a viral mechanism for evading the IFN response can be applied to the development of live attenuated flaviVirus vaccine candidates.
Roy A Hall - One of the best experts on this subject based on the ideXlab platform.
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a single amino acid substitution in the west nile Virus nonstructural protein ns2a disables its ability to inhibit alpha beta interferon induction and attenuates Virus Virulence in mice
Journal of Virology, 2006Co-Authors: Wen Jun Liu, Xiang Ju Wang, David C Clark, Mario Lobigs, Roy A Hall, Alexander A KhromykhAbstract:Alpha/beta interferons (IFN-α/β) are key mediators of the innate immune response against viral infection. The ability of Viruses to circumvent IFN-α/β responses plays a crucial role in determining the outcome of infection. In a previous study using subgenomic replicons of the Kunjin subtype of West Nile Virus (WNVKUN), we demonstrated that the nonstructural protein NS2A is a major inhibitor of IFN-β promoter-driven transcription and that a single amino acid substitution in NS2A (Ala30 to Pro [A30P]) dramatically reduced its inhibitory effect (W. J. Liu, H. B. Chen, X. J. Wang, H. Huang, and A. A. Khromykh, J. Virol. 78:12225-12235). Here we show that incorporation of the A30P mutation into the WNVKUN genome results in a mutant Virus which elicits more rapid induction and higher levels of synthesis of IFN-α/β in infected human A549 cells than that detected following wild-type WNVKUN infection. Consequently, replication of the WNVKUNNS2A/A30P mutant Virus in these cells known to be high producers of IFN-α/β was abortive. In contrast, both the mutant and the wild-type WNVKUN produced similar-size plaques and replicated with similar efficiency in BHK cells which are known to be deficient in IFN-α/β production. The mutant Virus was highly attenuated in neuroinvasiveness and also attenuated in neuroVirulence in 3-week-old mice. Surprisingly, the mutant Virus was also partially attenuated in IFN-α/βγ receptor knockout mice, suggesting that the A30P mutation may also play a role in more efficient activation of other antiviral pathways in addition to the IFN response. Immunization of wild-type mice with the mutant Virus resulted in induction of an antibody response of similar magnitude to that observed in mice immunized with wild-type WNVKUN and gave complete protection against challenge with a lethal dose of the highly virulent New York 99 strain of WNV. The results confirm and extend our previous original findings on the role of the flaviVirus NS2A protein in inhibition of a host antiviral response and demonstrate that the targeted disabling of a viral mechanism for evading the IFN response can be applied to the development of live attenuated flaviVirus vaccine candidates.
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a single amino acid substitution in the west nile Virus nonstructural protein ns2a disables its ability to inhibit alpha beta interferon induction and attenuates Virus Virulence in mice
Journal of Virology, 2006Co-Authors: Wen Jun Liu, Xiang Ju Wang, David C Clark, Mario Lobigs, Roy A Hall, Alexander A KhromykhAbstract:Alpha/beta interferons (IFN-alpha/beta) are key mediators of the innate immune response against viral infection. The ability of Viruses to circumvent IFN-alpha/beta responses plays a crucial role in determining the outcome of infection. In a previous study using subgenomic replicons of the Kunjin subtype of West Nile Virus (WNV(KUN)), we demonstrated that the nonstructural protein NS2A is a major inhibitor of IFN-beta promoter-driven transcription and that a single amino acid substitution in NS2A (Ala30 to Pro [A30P]) dramatically reduced its inhibitory effect (W. J. Liu, H. B. Chen, X. J. Wang, H. Huang, and A. A. Khromykh, J. Virol. 78:12225-12235). Here we show that incorporation of the A30P mutation into the WNV(KUN) genome results in a mutant Virus which elicits more rapid induction and higher levels of synthesis of IFN-alpha/beta in infected human A549 cells than that detected following wild-type WNV(KUN) infection. Consequently, replication of the WNV(KUN)NS2A/A30P mutant Virus in these cells known to be high producers of IFN-alpha/beta was abortive. In contrast, both the mutant and the wild-type WNV(KUN) produced similar-size plaques and replicated with similar efficiency in BHK cells which are known to be deficient in IFN-alpha/beta production. The mutant Virus was highly attenuated in neuroinvasiveness and also attenuated in neuroVirulence in 3-week-old mice. Surprisingly, the mutant Virus was also partially attenuated in IFN-alpha/betagamma receptor knockout mice, suggesting that the A30P mutation may also play a role in more efficient activation of other antiviral pathways in addition to the IFN response. Immunization of wild-type mice with the mutant Virus resulted in induction of an antibody response of similar magnitude to that observed in mice immunized with wild-type WNV(KUN) and gave complete protection against challenge with a lethal dose of the highly virulent New York 99 strain of WNV. The results confirm and extend our previous original findings on the role of the flaviVirus NS2A protein in inhibition of a host antiviral response and demonstrate that the targeted disabling of a viral mechanism for evading the IFN response can be applied to the development of live attenuated flaviVirus vaccine candidates.
Xiang Ju Wang - One of the best experts on this subject based on the ideXlab platform.
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a single amino acid substitution in the west nile Virus nonstructural protein ns2a disables its ability to inhibit alpha beta interferon induction and attenuates Virus Virulence in mice
Journal of Virology, 2006Co-Authors: Wen Jun Liu, Xiang Ju Wang, David C Clark, Mario Lobigs, Roy A Hall, Alexander A KhromykhAbstract:Alpha/beta interferons (IFN-α/β) are key mediators of the innate immune response against viral infection. The ability of Viruses to circumvent IFN-α/β responses plays a crucial role in determining the outcome of infection. In a previous study using subgenomic replicons of the Kunjin subtype of West Nile Virus (WNVKUN), we demonstrated that the nonstructural protein NS2A is a major inhibitor of IFN-β promoter-driven transcription and that a single amino acid substitution in NS2A (Ala30 to Pro [A30P]) dramatically reduced its inhibitory effect (W. J. Liu, H. B. Chen, X. J. Wang, H. Huang, and A. A. Khromykh, J. Virol. 78:12225-12235). Here we show that incorporation of the A30P mutation into the WNVKUN genome results in a mutant Virus which elicits more rapid induction and higher levels of synthesis of IFN-α/β in infected human A549 cells than that detected following wild-type WNVKUN infection. Consequently, replication of the WNVKUNNS2A/A30P mutant Virus in these cells known to be high producers of IFN-α/β was abortive. In contrast, both the mutant and the wild-type WNVKUN produced similar-size plaques and replicated with similar efficiency in BHK cells which are known to be deficient in IFN-α/β production. The mutant Virus was highly attenuated in neuroinvasiveness and also attenuated in neuroVirulence in 3-week-old mice. Surprisingly, the mutant Virus was also partially attenuated in IFN-α/βγ receptor knockout mice, suggesting that the A30P mutation may also play a role in more efficient activation of other antiviral pathways in addition to the IFN response. Immunization of wild-type mice with the mutant Virus resulted in induction of an antibody response of similar magnitude to that observed in mice immunized with wild-type WNVKUN and gave complete protection against challenge with a lethal dose of the highly virulent New York 99 strain of WNV. The results confirm and extend our previous original findings on the role of the flaviVirus NS2A protein in inhibition of a host antiviral response and demonstrate that the targeted disabling of a viral mechanism for evading the IFN response can be applied to the development of live attenuated flaviVirus vaccine candidates.
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a single amino acid substitution in the west nile Virus nonstructural protein ns2a disables its ability to inhibit alpha beta interferon induction and attenuates Virus Virulence in mice
Journal of Virology, 2006Co-Authors: Wen Jun Liu, Xiang Ju Wang, David C Clark, Mario Lobigs, Roy A Hall, Alexander A KhromykhAbstract:Alpha/beta interferons (IFN-alpha/beta) are key mediators of the innate immune response against viral infection. The ability of Viruses to circumvent IFN-alpha/beta responses plays a crucial role in determining the outcome of infection. In a previous study using subgenomic replicons of the Kunjin subtype of West Nile Virus (WNV(KUN)), we demonstrated that the nonstructural protein NS2A is a major inhibitor of IFN-beta promoter-driven transcription and that a single amino acid substitution in NS2A (Ala30 to Pro [A30P]) dramatically reduced its inhibitory effect (W. J. Liu, H. B. Chen, X. J. Wang, H. Huang, and A. A. Khromykh, J. Virol. 78:12225-12235). Here we show that incorporation of the A30P mutation into the WNV(KUN) genome results in a mutant Virus which elicits more rapid induction and higher levels of synthesis of IFN-alpha/beta in infected human A549 cells than that detected following wild-type WNV(KUN) infection. Consequently, replication of the WNV(KUN)NS2A/A30P mutant Virus in these cells known to be high producers of IFN-alpha/beta was abortive. In contrast, both the mutant and the wild-type WNV(KUN) produced similar-size plaques and replicated with similar efficiency in BHK cells which are known to be deficient in IFN-alpha/beta production. The mutant Virus was highly attenuated in neuroinvasiveness and also attenuated in neuroVirulence in 3-week-old mice. Surprisingly, the mutant Virus was also partially attenuated in IFN-alpha/betagamma receptor knockout mice, suggesting that the A30P mutation may also play a role in more efficient activation of other antiviral pathways in addition to the IFN response. Immunization of wild-type mice with the mutant Virus resulted in induction of an antibody response of similar magnitude to that observed in mice immunized with wild-type WNV(KUN) and gave complete protection against challenge with a lethal dose of the highly virulent New York 99 strain of WNV. The results confirm and extend our previous original findings on the role of the flaviVirus NS2A protein in inhibition of a host antiviral response and demonstrate that the targeted disabling of a viral mechanism for evading the IFN response can be applied to the development of live attenuated flaviVirus vaccine candidates.
