Publications by authors named "Akhalesh K Shakya"

9 Publications

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The Differentiation of Human Cytomegalovirus Infected-Monocytes Is Required for Viral Replication.

Front Cell Infect Microbiol 2020 31;10:368. Epub 2020 Jul 31.

Department of Microbiology and Immunology, Center for Molecular and Tumor Virology, Louisiana State University Health Sciences Center-Shreveport, Shreveport, LA, United States.

Viral dissemination is a key mechanism responsible for persistence and disease following human cytomegalovirus (HCMV) infection. Monocytes play a pivotal role in viral dissemination to organ tissue during primary infection and following reactivation from latency. For example, during primary infection, infected monocytes migrate into tissues and differentiate into macrophages, which then become a source of viral replication. In addition, because differentiated macrophages can survive for months to years, they provide a potential persistent infection source in various organ systems. We broadly note that there are three phases to infection and differentiation of HCMV-infected monocytes: (1) Virus enters and traffics to the nucleus through a virus receptor ligand engagement event that activates a unique signalsome that initiates the monocyte-to-macrophage differentiation process. (2) Following initial infection, HCMV undergoes a "quiescence-like state" in monocytes lasting for several weeks and promotes monocyte differentiation into macrophages. While, the initial event is triggered by the receptor-ligand engagement, the long-term cellular activation is maintained by chronic viral-mediated signaling events. (3) Once HCMV infected monocytes differentiate into macrophages, the expression of immediate early viral (IE) genes is detectable, followed by viral replication and long term infectious viral particles release. Herein, we review the detailed mechanisms of each phase during infection and differentiation into macrophages and discuss the biological significance of the differentiation of monocytes in the pathogenesis of HCMV.
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http://dx.doi.org/10.3389/fcimb.2020.00368DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7411144PMC
July 2020

Correction for Shakya et al., "Interferon Gamma Inhibits Varicella-Zoster Virus Replication in a Cell Line-Dependent Manner".

J Virol 2020 Mar 17;94(7). Epub 2020 Mar 17.

Department of Microbiology and Immunology, Louisiana State University Health Sciences Center, Shreveport, Louisiana, USA

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http://dx.doi.org/10.1128/JVI.02138-19DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7081888PMC
March 2020

Intranasal treatment with CpG-B oligodeoxynucleotides protects CBA mice from lethal equine herpesvirus 1 challenge by an innate immune response.

Antiviral Res 2019 09 25;169:104546. Epub 2019 Jun 25.

Department of Microbiology and Immunology, Center for Molecular and Tumor Virology, Louisiana State University Health Sciences Center, Shreveport, LA, 71130-3932, USA.

Equine herpesvirus 1 (EHV-1) is the causative agent of a number of equine disease manifestations, including severe disease of the central nervous system, respiratory infections, and abortion storms. Our results showed that intranasal treatment with CpG-B oligodeoxynucleotides (ODN 1826) protected CBA mice from pathogenic EHV-1 RacL11 challenge. The IFN-γ gene and seven interferon-stimulated genes (ISGs) were upregulated 39.4- to 260.3-fold at 8 h postchallenge in the lungs of RacL11-challenged mice that had been treated with CpG-B ODN. Interestingly, IFN-γ gene expression was upregulated by 26-fold upon RacL11 challenge in CpG-B ODN-treated mice lungs as compared to that of CpG-A ODN (ODN 1585)-treated mice lungs; however, the seven ISGs were upregulated by 2.4-5.0-fold, suggesting that IFN-γ is a major factor in the protection of CBA mice from the lethal challenge. Pre-treatment with IFN-γ significantly reduced EHV-1 yield in murine alveolar macrophage MH-S cells, but not in mouse lung epithelial MLE12 cells. These results suggest that CpG-B ODN may be used as a prophylactic agent in horses and provide a basis for more effective treatment of EHV-1 infection.
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http://dx.doi.org/10.1016/j.antiviral.2019.104546DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6699901PMC
September 2019

Interferon Gamma Inhibits Varicella-Zoster Virus Replication in a Cell Line-Dependent Manner.

J Virol 2019 06 29;93(12). Epub 2019 May 29.

Department of Microbiology and Immunology, Louisiana State University Health Sciences Center, Shreveport, Louisiana, USA

The major immediate early 62 (IE62) protein of varicella-zoster virus (VZV) is delivered to newly infected cell nuclei, where it initiates VZV replication by transactivating viral immediate early (IE), early (E), and late (L) genes. Interferon gamma (IFN-γ) is a potent cytokine produced following primary VZV infection. Furthermore, VZV reactivation correlates with a decline in IFN-γ-producing immune cells. Our results showed that treatment with 20 ng/ml of IFN-γ completely reduced intracellular VZV yield in A549 lung epithelial cells, MRC-5 lung fibroblasts, and ARPE-19 retinal epithelial cells at 4 days post-VZV infection. However, IFN-γ reduced virus yield only 2-fold in MeWo melanoma cells compared to that of untreated cells. IFN-β significantly inhibited VZV replication in both ARPE-19 and MeWo cells. In luciferase assays with VZV open reading frame 61 (ORF61) promoter reporter plasmid, IFN-γ abrogated the transactivation activity of IE62 by 95%, 97%, and 89% in A549, ARPE-19, and MRC-5 cells, respectively. However, IFN-γ abrogated IE62's transactivation activity by 16% in MeWo cells, indicating that IFN-γ inhibits VZV replication as well as IE62-mediated transactivation in a cell line-dependent manner. The expression of VZV IE62 and ORF63 suppressed by IFN-γ was restored by JAK1 inhibitor treatment, indicating that the inhibition of VZV replication is mediated by JAK/STAT1 signaling. In the presence of IFN-γ, knockdown of interferon response factor 1 (IRF1) increased VZV replication. Ectopic expression of IRF1 reduced VZV yields 4,000-fold in MRC-5 and ARPE-19 cells but 3-fold in MeWo cells. These results suggest that IFN-γ blocks VZV replication by inhibiting IE62 function in a cell line-dependent manner. Our results showed that IFN-γ significantly inhibited VZV replication in a cell line-dependent manner. IFN-γ inhibited VZV gene expression after the immediate early stage of infection and abrogated IE62-mediated transactivation. These results suggest that IFN-γ blocks VZV replication by inhibiting IE62 function in a cell line-dependent manner. Understanding the mechanisms by which IFN-γ plays a role in VZV gene programming may be important in determining the tissue restriction of VZV.
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http://dx.doi.org/10.1128/JVI.00257-19DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6613748PMC
June 2019

Comparative Genomic Sequencing and Pathogenic Properties of Equine Herpesvirus 1 KyA and RacL11.

Front Vet Sci 2017 11;4:211. Epub 2017 Dec 11.

Department of Microbiology and Immunology, Center for Molecular and Tumor Virology, Louisiana State University Health Sciences Center, Shreveport, LA, United States.

Equine herpesvirus 1 (EHV-1) is a major pathogen affecting equines worldwide. The virus causes respiratory disease, abortion, and, in some cases, neurological disease. EHV-1 Kentucky A (KyA) is attenuated in the mouse and equine, whereas wild-type pathogenic strain RacL11 induces severe inflammatory infiltration of the lung, causing infected mice to succumb. The complete DNA sequencing of the KyA genome revealed that genes UL17 (ORF17), US6 (ORF73; gI), US7 (ORF74; gE), and US8 (ORF75; 10 K) are deleted as compared to the RacL11 and Ab4 genomes. In-frame deletions in the US1 (ORF68), US4 (ORF71; gp2), and UL63 (ORF63; EICP0) genes and point mutations in 14 different open reading frames (ORFs) were detected in the KyA genome. Interestingly, UL1 (ORF1) and UL2 (ORF2) were deleted in both KyA and RacL11. Our previous studies showed that EHV-1 glycoproteins gI, gE, and full-length gp2 contribute to the pathogenesis of the RacL11 strain. The confirmation of these gene deletions in KyA suggests their contribution to the attenuation of this virus. The growth kinetics results revealed that KyA replicates to high titers in cell culture as compared to RacL11 and Ab4, indicating that the above genomic deletions and mutations in KyA do not have an inhibitory effect on KyA replication in cells of mouse, rabbit, equine, or human origin. Studies of EHV-1 pathogenesis in CBA mice showed that KyA is attenuated whereas mice infected with RacL11 succumbed by 3-6 days post-infection, which is consistent with our previous results.
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http://dx.doi.org/10.3389/fvets.2017.00211DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5732242PMC
December 2017

Immunization with Attenuated Equine Herpesvirus 1 Strain KyA Induces Innate Immune Responses That Protect Mice from Lethal Challenge.

J Virol 2016 09 26;90(18):8090-104. Epub 2016 Aug 26.

Department of Microbiology and Immunology and Center for Molecular and Tumor Virology, Louisiana State University Health Sciences Center, Shreveport, Louisiana, USA.

Unlabelled: Equine herpesvirus 1 (EHV-1) is a major pathogen affecting equines worldwide. The virus causes respiratory disease, abortion, and, in some cases, neurological disease. EHV-1 strain KyA is attenuated in the mouse and equine, whereas wild-type strain RacL11 induces severe inflammation of the lung, causing infected mice to succumb at 4 to 6 days postinfection. Our previous results showed that KyA immunization protected CBA mice from pathogenic RacL11 challenge at 2 and 4 weeks postimmunization and that KyA infection elicited protective humoral and cell-mediated immune responses. To investigate the protective mechanisms of innate immune responses to KyA, KyA-immunized mice were challenged with RacL11 at various times postvaccination. KyA immunization protected mice from RacL11 challenge at 1 to 7 days postimmunization. Immunized mice lost less than 10% of their body weight and rapidly regained weight. Virus titers in the lungs of KyA-immunized mice were 1,000-fold lower at 2 days post-RacL11 challenge than virus titers in the lungs of nonimmunized mice, indicating accelerated virus clearance. Affymetrix microarray analysis revealed that gamma interferon (IFN-γ) and 16 antiviral interferon-stimulated genes (ISGs) were upregulated 3.1- to 48.2-fold at 8 h postchallenge in the lungs of RacL11-challenged mice that had been immunized with KyA. Murine IFN-γ inhibited EHV-1 infection of murine alveolar macrophages and protected mice against lethal EHV-1 challenge, suggesting that IFN-γ expression is important in mediating the protection elicited by KyA immunization. These results suggest that EHV-1 KyA may be used as a live attenuated EHV-1 vaccine as well as a prophylactic agent in horses.

Importance: Viral infection of cells initiates a signal cascade of events that ultimately attempts to limit viral replication and prevent infection through the expression of host antiviral proteins. In this study, we show that EHV-1 KyA immunization effectively protected CBA mice from pathogenic RacL11 challenge at 1 to 7 days postvaccination and increased the expression of IFN-γ and 16 antiviral interferon-stimulated genes (ISGs). The administration of IFN-γ blocked EHV-1 replication in murine alveolar macrophages and mouse lungs and protected mice from lethal challenge. To our knowledge, this is the first report of an attenuated EHV-1 vaccine that protects the animal at 1 to 7 days postimmunization by innate immune responses. Our findings suggested that IFN-γ serves as a novel prophylactic agent and may offer new strategies for the development of anti-EHV-1 agents in the equine.
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http://dx.doi.org/10.1128/JVI.00986-16DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5008086PMC
September 2016

Full trans-activation mediated by the immediate-early protein of equine herpesvirus 1 requires a consensus TATA box, but not its cognate binding sequence.

Virus Res 2016 Jan 2;211:222-32. Epub 2015 Nov 2.

Department of Microbiology and Immunology, and Center for Molecular and Tumor Virology, Louisiana State University Health Sciences Center, Shreveport, LA 71130-3932, United States.

The immediate-early protein (IEP) of equine herpesvirus 1 (EHV-1) has extensive homology to the IEP of alphaherpesviruses and possesses domains essential for trans-activation, including an acidic trans-activation domain (TAD) and binding domains for DNA, TFIIB, and TBP. Our data showed that the IEP directly interacted with transcription factor TFIIA, which is known to stabilize the binding of TBP and TFIID to the TATA box of core promoters. When the TATA box of the EICP0 promoter was mutated to a nonfunctional TATA box, IEP-mediated trans-activation was reduced from 22-fold to 7-fold. The IEP trans-activated the viral promoters in a TATA motif-dependent manner. Our previous data showed that the IEP is able to repress its own promoter when the IEP-binding sequence (IEBS) is located within 26-bp from the TATA box. When the IEBS was located at 100 bp upstream of the TATA box, IEP-mediated trans-activation was very similar to that of the minimal IE(nt -89 to +73) promoter lacking the IEBS. As the distance from the IEBS to the TATA box decreased, IEP-mediated trans-activation progressively decreased, indicating that the IEBS located within 100 bp from the TATA box sequence functions as a distance-dependent repressive element. These results indicated that IEP-mediated full trans-activation requires a consensus TATA box of core promoters, but not its binding to the cognate sequence (IEBS).
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http://dx.doi.org/10.1016/j.virusres.2015.10.026DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4692279PMC
January 2016

Functional Characterization of the Serine-Rich Tract of Varicella-Zoster Virus IE62.

J Virol 2016 01 4;90(2):959-71. Epub 2015 Nov 4.

Department of Microbiology and Immunology, and Center for Molecular and Tumor Virology, Louisiana State University Health Sciences Center, Shreveport, Louisiana, USA.

Unlabelled: The immediate early 62 protein (IE62) of varicella-zoster virus (VZV), a major viral trans-activator, initiates the virus life cycle and is a key component of pathogenesis. The IE62 possesses several domains essential for trans-activation, including an acidic trans-activation domain (TAD), a serine-rich tract (SRT), and binding domains for USF, TFIIB, and TATA box binding protein (TBP). Transient-transfection assays showed that the VZV IE62 lacking the SRT trans-activated the early VZV ORF61 promoter at only 16% of the level of the full-length IE62. When the SRT of IE62 was replaced with the SRT of equine herpesvirus 1 (EHV-1) IEP, its trans-activation activity was completely restored. Herpes simplex virus 1 (HSV-1) ICP4 that lacks a TAD very weakly (1.5-fold) trans-activated the ORF61 promoter. An IE62 TAD-ICP4 chimeric protein exhibited trans-activation ability (10.2-fold), indicating that the IE62 TAD functions with the SRT of HSV-1 ICP4 to trans-activate viral promoters. When the serine and acidic residues of the SRT were replaced with Ala, Leu, and Gly, trans-activation activities of the modified IE62 proteins IE62-SRTΔSe and IE62-SRTΔAc were reduced to 46% and 29% of wild-type activity, respectively. Bimolecular complementation assays showed that the TAD of IE62, EHV-1 IEP, and HSV-1 VP16 interacted with Mediator 25 in human melanoma MeWo cells. The SRT of IE62 interacted with the nucleolar-ribosomal protein EAP, which resulted in the formation of globular structures within the nucleus. These results suggest that the SRT plays an important role in VZV viral gene expression and replication.

Importance: The immediate early 62 protein (IE62) of varicella-zoster virus (VZV) is a major viral trans-activator and is essential for viral growth. Our data show that the serine-rich tract (SRT) of VZV IE62, which is well conserved within the alphaherpesviruses, is needed for trans-activation mediated by the acidic trans-activation domain (TAD). The TADs of IE62, EHV-1 IEP, and HSV-1 VP16 interacted with cellular Mediator 25 in bimolecular complementation assays. The interaction of the IE62 SRT with nucleolar-ribosomal protein EAP resulted in the formation of globular structures within the nucleus. Understanding the mechanisms by which the TAD and SRT of IE62 contribute to the function of this essential regulatory protein is important in understanding the gene program of this human pathogen.
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http://dx.doi.org/10.1128/JVI.02096-15DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4702665PMC
January 2016

Non-polio enteroviruses in acute flaccid paralysis children of India: vital assessment before polio eradication.

J Paediatr Child Health 2009 Jul-Aug;45(7-8):409-13. Epub 2009 Jul 20.

Department of Microbiology, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow-226014, India.

Aim: This study is an overview of non-polio enterovirus (NPEV) circulating in North India studied from the perspective of poliomyelitis eradication. Wild polio cases declined because of intensive oral polio vaccine immunization. As we approach global eradication of poliovirus (PV), NPEV causing acute flaccid paralysis (AFP) are equal cause of concern.

Methods: A total of 46 653 AFP samples (World Health Organization) and apparently 1000 healthy contacts living in the same geographical area were studied (2004-2007). Serological identification of NPEV was done using RIVM-specific pools (The Netherlands). Untyped (UT)-NPEVs were sequenced directly from reverse transcription-polymerase chain reaction using pan-enterovirus (Pan-EV) primer (CDC, Atlanta, GA) targeting highly conserved 5'un-translated regions of the enterovirus.

Results: In this study, 12 513 NPEVs were isolated from the collected stool samples. Seroneutralization had identified 67% of NPEV isolates, whereas 32.6% remained as UT- NPEV. Of the typed NPEVs, Coxsackie-B accounted for 32.3%; followed by echoviruses-11, 12, 13, 7 between 8 and 28%. In sequencing few UT-NPEVs, some were identified also as echovirus-30, 11 and 18 which were probably present in mixtures as they remained UT-NPEV in ENT. Newly classified human enterovirus virus-86 (HEV) (EU079026), HEV-97(EU071767) and HEV-B isolate (EU071768) were isolated in AFP samples.

Conclusions: This study provided definitive information about circulation, prevalence and new emerging NPEV in the polio-endemic region of India, hence they should be considered in AFP surveillance. This would help in adopting and planning new strategies in post-PV eradication era in the country. This is the right time to prepare for the future tasks while we head towards a polio-free region.
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http://dx.doi.org/10.1111/j.1440-1754.2009.01529.xDOI Listing
December 2009