Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 2.475
Filtrar
1.
Arch Virol ; 165(11): 2561-2587, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32876795

RESUMO

Orf virus (ORFV) infects sheep and goat tissues, resulting in severe proliferative lesions. To analyze cellular protein expression in ORFV-infected goat skin fibroblast (GSF) cells, we used two-dimensional liquid chromatography-tandem mass spectrometry coupled with isobaric tags for relative and absolute quantification (iTRAQ). The proteomics approach was used along with quantitative reverse transcription polymerase chain reaction (RT-qPCR) to detect differentially expressed proteins in ORFV-infected GSF cells and mock-infected GSF cells. A total of 282 differentially expressed proteins were identified. It was found that 222 host proteins were upregulated and 60 were downregulated following viral infection. We confirmed that these proteins were differentially expressed and found that heat shock 70-kDa protein 1B (HSPA1B) was differentially expressed and localized in the cytoplasm. It was also noted that HSPA1B caused inhibition of viral proliferation, in the middle and late stages of viral infection. The differentially expressed proteins were associated with the biological processes of viral binding, cell structure, signal transduction, cell adhesion, and cell proliferation.


Assuntos
Fibroblastos/metabolismo , Proteínas de Choque Térmico HSP70/fisiologia , Vírus do Orf/fisiologia , Proteoma/genética , Replicação Viral , Animais , Células Cultivadas , Cromatografia Líquida , Fibroblastos/virologia , Cabras , Interações Hospedeiro-Patógeno , Vírus do Orf/genética , Proteômica , Espectrometria de Massas em Tandem
2.
Proc Natl Acad Sci U S A ; 117(36): 22113-22121, 2020 09 08.
Artigo em Inglês | MEDLINE | ID: mdl-32843346

RESUMO

RNA polymerase (Pol) III has a noncanonical role of viral DNA sensing in the innate immune system. This polymerase transcribes viral genomes to produce RNAs that lead to induction of type I interferons (IFNs). However, the genetic and functional links of Pol III to innate immunity in humans remain largely unknown. Here, we describe a rare homozygous mutation (D40H) in the POLR3E gene, coding for a protein subunit of Pol III, in a child with recurrent and systemic viral infections and Langerhans cell histiocytosis. Fibroblasts derived from the patient exhibit impaired induction of type I IFN and increased susceptibility to human cytomegalovirus (HCMV) infection. Cultured cell lines infected with HCMV show induction of POLR3E expression. However, induction is not restricted to DNA virus, as sindbis virus, an RNA virus, enhances the expression of this protein. Likewise, foreign nonviral DNA elevates the steady-state level of POLR3E and elicits promoter-dependent and -independent transcription by Pol III. Remarkably, the molecular mechanism underlying the D40H mutation of POLR3E involves the assembly of defective initiation complexes of Pol III. Our study links mutated POLR3E and Pol III to an innate immune deficiency state in humans.


Assuntos
Citomegalovirus/fisiologia , Fibroblastos/imunologia , Fibroblastos/virologia , RNA Polimerase III/metabolismo , Animais , Chlorocebus aethiops , Citomegalovirus/imunologia , Células Dendríticas , Regulação Enzimológica da Expressão Gênica , Humanos , Mutação , RNA Polimerase III/genética , Células Vero
3.
J Virol ; 94(18)2020 08 31.
Artigo em Inglês | MEDLINE | ID: mdl-32641474

RESUMO

Human cytomegalovirus (HCMV) is a ubiquitous pathogen that can cause severe clinical disease in allograft recipients and infants infected in utero Virus-neutralizing antibodies defined in vitro have been proposed to confer protection against HCMV infection, and the virion envelope glycoprotein B (gB) serves as a major target of neutralizing antibodies. The viral fusion protein gB is nonfusogenic on its own and requires glycoproteins H (gH) and L (gL) for membrane fusion, which is in contrast to requirements of related class III fusion proteins, including vesicular stomatitis virus glycoprotein G (VSV-G) or baculovirus gp64. To explore requirements for gB's fusion activity, we generated a set of chimeras composed of gB and VSV-G or gp64, respectively. These gB chimeras were intrinsically fusion active and led to the formation of multinucleated cell syncytia when expressed in the absence of other viral proteins. Utilizing a panel of virus-neutralizing gB-specific monoclonal antibodies (MAbs), we could demonstrate that syncytium formation of the fusogenic gB/VSV-G chimera can be significantly inhibited by only a subset of neutralizing MAbs which target antigenic domain 5 (AD-5) of gB. This observation argues for differential modes of action of neutralizing anti-gB MAbs and suggests that blocking the membrane fusion function of gB could be one mechanism of antibody-mediated virus neutralization. In addition, our data have important implications for the further understanding of the conformation of gB that promotes membrane fusion as well as the identification of structures in AD-5 that could be targeted by antibodies to block this early step in HCMV infection.IMPORTANCE HCMV is a major global health concern, and antiviral chemotherapy remains problematic due to toxicity of available compounds and the emergence of drug-resistant viruses. Thus, an HCMV vaccine represents a priority for both governmental and pharmaceutical research programs. A major obstacle for the development of a vaccine is a lack of knowledge of the nature and specificities of protective immune responses that should be induced by such a vaccine. Glycoprotein B of HCMV is an important target for neutralizing antibodies and, hence, is often included as a component of intervention strategies. By generation of fusion-active gB chimeras, we were able to identify target structures of neutralizing antibodies that potently block gB-induced membrane fusion. This experimental system provides an approach to screen for antibodies that interfere with gB's fusogenic activity. In summary, our data will likely contribute to both rational vaccine design and the development of antibody-based therapies against HCMV.


Assuntos
Anticorpos Neutralizantes/farmacologia , Citomegalovirus/genética , Proteínas Mutantes Quiméricas/genética , Proteínas do Envelope Viral/genética , Animais , Anticorpos Monoclonais/metabolismo , Anticorpos Monoclonais/farmacologia , Anticorpos Neutralizantes/metabolismo , Anticorpos Antivirais/metabolismo , Anticorpos Antivirais/farmacologia , Sítios de Ligação , Fusão Celular , Linhagem Celular , Citomegalovirus/efeitos dos fármacos , Citomegalovirus/metabolismo , Células Epiteliais/efeitos dos fármacos , Células Epiteliais/metabolismo , Células Epiteliais/virologia , Fibroblastos/efeitos dos fármacos , Fibroblastos/metabolismo , Fibroblastos/virologia , Expressão Gênica , Células Gigantes/efeitos dos fármacos , Células Gigantes/metabolismo , Células Gigantes/ultraestrutura , Células Gigantes/virologia , Células HEK293 , Humanos , Camundongos , Proteínas Mutantes Quiméricas/química , Proteínas Mutantes Quiméricas/metabolismo , Cultura Primária de Células , Ligação Proteica , Conformação Proteica em alfa-Hélice , Conformação Proteica em Folha beta , Domínios e Motivos de Interação entre Proteínas , Células Estromais/efeitos dos fármacos , Células Estromais/metabolismo , Células Estromais/virologia , Vesiculovirus/genética , Vesiculovirus/metabolismo , Proteínas do Envelope Viral/metabolismo
4.
J Virol ; 94(18)2020 08 31.
Artigo em Inglês | MEDLINE | ID: mdl-32641483

RESUMO

The Kaposi's sarcoma-associated herpesvirus (KSHV)-encoded open reading frame 50 (ORF50) protein is the key transactivator responsible for the latent-to-lytic switch. Here, we investigated the transcriptional activation of the ORF56 gene (encoding a primase protein) by ORF50 and successfully identified an ORF50-responsive element located in the promoter region between positions -97 and -44 (designated 56p-RE). This 56p-RE element contains a noncanonical RBP-Jκ-binding sequence and a nonconsensus Sp1/Sp3-binding sequence. Electrophoretic mobility shift assays revealed that RBP-Jκ, Sp3, and ORF50 could form stable complexes on the 56p-RE element. Importantly, transient-reporter analysis showed that Sp3, but not RBP-Jκ or Sp1, acts in synergy with ORF50 to activate the 56p-RE-containing reporter construct, and the synergy mainly depends on the Sp1/Sp3-binding region of the 56p-RE element. Sequence similarity searches revealed that the promoters for ORF21 (thymidine kinase), ORF60 (ribonucleotide reductase, small subunit), and cellular interleukin-10 (IL-10) contain a sequence motif similar to the Sp1/Sp3-binding region of the 56p-RE element, and we found that these promoters could also be synergistically activated by ORF50 and Sp3 via the conserved motifs. Noteworthily, the conversion of the Sp1/Sp3-binding sequence of the 56p-RE element into a consensus high-affinity Sp-binding sequence completely lost the synergistic response to ORF50 and Sp3. Moreover, transcriptional synergy could not be detected through other ORF50-responsive elements from the viral PAN, K12, ORF57, and K6 promoters. Collectively, the results of our study demonstrate that ORF50 and Sp3 can act in synergy on the transcription of specific gene promoters, and we find a novel conserved cis-acting motif in these promoters essential for transcriptional synergy.IMPORTANCE Despite the critical role of ORF50 in the KSHV latent-to-lytic switch, the molecular mechanism by which ORF50 activates its downstream target genes, especially those that encode the viral DNA replication enzymes, is not yet fully understood. Here, we find that ORF50 can cooperate with Sp3 to synergistically activate promoters of the viral ORF56 (primase), ORF21 (thymidine kinase), and ORF60 (ribonucleotide reductase) genes via similar Sp1/Sp3-binding motifs. Additionally, the same synergistic effect can be seen on the promoter of the cellular IL-10 gene. Overall, our data reveal an important role for Sp3 in ORF50-mediated transactivation, and we propose a new subclass of ORF50-responsive elements in viral and cellular promoters.


Assuntos
Herpesvirus Humano 8/genética , Proteínas Imediatamente Precoces/genética , Regiões Promotoras Genéticas , Fator de Transcrição Sp1/genética , Fator de Transcrição Sp3/genética , Transativadores/genética , Transcrição Genética , Animais , Sítios de Ligação , Linhagem Celular , Linhagem Celular Tumoral , Células Clonais , Fibroblastos/virologia , Regulação da Expressão Gênica , Células HEK293 , Herpesvirus Humano 8/metabolismo , Interações Hospedeiro-Patógeno/genética , Humanos , Proteínas Imediatamente Precoces/metabolismo , Proteína de Ligação a Sequências Sinal de Recombinação J de Imunoglobina/genética , Proteína de Ligação a Sequências Sinal de Recombinação J de Imunoglobina/metabolismo , Interleucina-10/genética , Interleucina-10/metabolismo , Linfócitos/virologia , Camundongos , Ligação Proteica , Elementos de Resposta , Transdução de Sinais , Fator de Transcrição Sp1/metabolismo , Fator de Transcrição Sp3/metabolismo , Transativadores/metabolismo , Proteínas Virais/genética , Proteínas Virais/metabolismo , Proteínas Virais Reguladoras e Acessórias/genética , Proteínas Virais Reguladoras e Acessórias/metabolismo
5.
J Virol ; 94(18)2020 08 31.
Artigo em Inglês | MEDLINE | ID: mdl-32641484

RESUMO

Human adenoviruses (HAdV) are ubiquitous within the human population and comprise a significant burden of respiratory illnesses worldwide. Pediatric and immunocompromised individuals are at particular risk for developing severe disease; however, no approved antiviral therapies specific to HAdV exist. Ivermectin is an FDA-approved broad-spectrum antiparasitic drug that also exhibits antiviral properties against a diverse range of viruses. Its proposed function is inhibiting the classical protein nuclear import pathway mediated by importin-α (Imp-α) and -ß1 (Imp-ß1). Many viruses, including HAdV, rely on this host pathway for transport of viral proteins across the nuclear envelope. In this study, we show that ivermectin inhibits HAdV-C5 early gene transcription, early and late protein expression, genome replication, and production of infectious viral progeny. Similarly, ivermectin inhibits genome replication of HAdV-B3, a clinically important pathogen responsible for numerous recent outbreaks. Mechanistically, we show that ivermectin disrupts binding of the viral E1A protein to Imp-α without affecting the interaction between Imp-α and Imp-ß1. Our results further extend ivermectin's broad antiviral activity and provide a mechanistic underpinning for its mode of action as an inhibitor of cellular Imp-α/ß1-mediated nuclear import.IMPORTANCE Human adenoviruses (HAdVs) represent a ubiquitous and clinically important pathogen without an effective antiviral treatment. HAdV infections typically cause mild symptoms; however, individuals such as children, those with underlying conditions, and those with compromised immune systems can develop severe disseminated disease. Our results demonstrate that ivermectin, an FDA-approved antiparasitic agent, is effective at inhibiting replication of several HAdV types in vitro This is in agreement with the growing body of literature suggesting ivermectin has broad antiviral activity. This study expands our mechanistic knowledge of ivermectin by showing that ivermectin targets the ability of importin-α (Imp-α) to recognize nuclear localization sequences, without effecting the Imp-α/ß1 interaction. These data also exemplify the applicability of targeting host factors upon which viruses rely as a viable antiviral strategy.


Assuntos
Transporte Ativo do Núcleo Celular/efeitos dos fármacos , Adenovírus Humanos/efeitos dos fármacos , Antiparasitários/farmacologia , Ivermectina/farmacologia , Replicação Viral/efeitos dos fármacos , alfa Carioferinas/genética , beta Carioferinas/genética , Células A549 , Transporte Ativo do Núcleo Celular/genética , Adenovírus Humanos/genética , Adenovírus Humanos/metabolismo , Adenovírus Humanos/patogenicidade , Linhagem Celular Tumoral , Núcleo Celular/efeitos dos fármacos , Núcleo Celular/metabolismo , Núcleo Celular/virologia , Citosol/efeitos dos fármacos , Citosol/metabolismo , Citosol/virologia , Fibroblastos/efeitos dos fármacos , Fibroblastos/virologia , Regulação da Expressão Gênica , Células HEK293 , Interações Hospedeiro-Patógeno/efeitos dos fármacos , Interações Hospedeiro-Patógeno/genética , Humanos , Transdução de Sinais , Proteínas Virais/antagonistas & inibidores , Proteínas Virais/genética , Proteínas Virais/metabolismo , alfa Carioferinas/antagonistas & inibidores , alfa Carioferinas/metabolismo , beta Carioferinas/metabolismo
6.
J Virol ; 94(18)2020 08 31.
Artigo em Inglês | MEDLINE | ID: mdl-32669329

RESUMO

Herpesviruses exist in nature within each host animal. Ten herpesviruses have been isolated from bats and their biological properties reported. A novel bat alphaherpesvirus, which we propose to name "Pteropus lylei-associated alphaherpesvirus (PLAHV)," was isolated from urine of the fruit bat Pteropus lylei in Vietnam and characterized. The entire genome sequence was determined to be 144,008 bp in length and predicted to include 72 genes. PLAHV was assigned to genus Simplexvirus with other bat alphaherpesviruses isolated from pteropodid bats in Southeast Asia and Africa. The replication capacity of PLAHV in several cells was evaluated in comparison with that of herpes simplex virus 1 (HSV-1). PLAHV replicated better in the bat-originated cell line and less in human embryonic lung fibroblasts than HSV-1 did. PLAHV was serologically related to another bat alphaherpesvirus, Pteropodid alphaherpesvirus 1 (PtAHV1), isolated from a Pteropus hypomelanus-related bat captured in Indonesia, but not with HSV-1. PLAHV caused lethal infection in mice. PLAHV was as susceptible to acyclovir as HSV-1 was. Characterization of this new member of bat alphaherpesviruses, PLAHV, expands the knowledge on bat-associated alphaherpesvirology.IMPORTANCE A novel bat alphaherpesvirus, Pteropus lylei-associated alphaherpesvirus (PLAHV), was isolated from urine of the fruit bat Pteropus lylei in Vietnam. The whole-genome sequence was determined and was predicted to include 72 open reading frames in the 144,008-bp genome. PLAHV is circulating in a species of fruit bats, Pteropus lylei, in Asia. This study expands the knowledge on bat-associated alphaherpesvirology.


Assuntos
Alphaherpesvirinae/genética , Quirópteros/virologia , Genoma Viral , Infecções por Herpesviridae/veterinária , Proteínas Virais/genética , Aciclovir/farmacologia , Alphaherpesvirinae/classificação , Alphaherpesvirinae/efeitos dos fármacos , Alphaherpesvirinae/patogenicidade , Animais , Antivirais/farmacologia , Células COS , Linhagem Celular , Chlorocebus aethiops , Fibroblastos/virologia , Expressão Gênica , Tamanho do Genoma , Células HeLa , Infecções por Herpesviridae/tratamento farmacológico , Infecções por Herpesviridae/epidemiologia , Infecções por Herpesviridae/mortalidade , Herpesvirus Humano 1/classificação , Herpesvirus Humano 1/genética , Herpesvirus Humano 1/crescimento & desenvolvimento , Herpesvirus Humano 1/patogenicidade , Humanos , Camundongos , Filogenia , Análise de Sobrevida , Células Vero , Vietnã/epidemiologia , Proteínas Virais/metabolismo , Replicação Viral
7.
J Virol ; 94(17)2020 08 17.
Artigo em Inglês | MEDLINE | ID: mdl-32581105

RESUMO

Human Cytomegalovirus (HCMV) is a ubiquitous pathogen that has coevolved with its host and, in doing so, is highly efficient in undermining antiviral responses that limit successful infections. As a result, HCMV infections are highly problematic in individuals with weakened or underdeveloped immune systems, including transplant recipients and newborns. Understanding how HCMV controls the microenvironment of an infected cell so as to favor productive replication is of critical importance. To this end, we took an unbiased proteomics approach to identify the highly reversible, stress-induced, posttranslational modification (PTM) protein S-nitrosylation on viral proteins to determine the biological impact on viral replication. We identified protein S-nitrosylation of 13 viral proteins during infection of highly permissive fibroblasts. One of these proteins, pp71, is critical for efficient viral replication, as it undermines host antiviral responses, including stimulator of interferon genes (STING) activation. By exploiting site-directed mutagenesis of the specific amino acids we identified in pp71 as protein S-nitrosylated, we found this pp71 PTM diminishes its ability to undermine antiviral responses induced by the STING pathway. Our results suggest a model in which protein S-nitrosylation may function as a host response to viral infection that limits viral spread.IMPORTANCE In order for a pathogen to establish a successful infection, it must undermine the host cell responses inhibitory to the pathogen. As such, herpesviruses encode multiple viral proteins that antagonize each host antiviral response, thereby allowing for efficient viral replication. Human Cytomegalovirus encodes several factors that limit host countermeasures to infection, including pp71. Herein, we identified a previously unreported posttranslational modification of pp71, protein S-nitrosylation. Using site-directed mutagenesis, we mutated the specific sites of this modification thereby blocking this pp71 posttranslational modification. In contexts where pp71 is not protein S-nitrosylated, host antiviral response was inhibited. The net result of this posttranslational modification is to render a viral protein with diminished abilities to block host responses to infection. This novel work supports a model in which protein S-nitrosylation may be an additional mechanism in which a cell inhibits a pathogen during the course of infection.


Assuntos
Antivirais/farmacologia , Citomegalovirus/efeitos dos fármacos , Proteína S/metabolismo , Proteínas Virais/metabolismo , Linhagem Celular , Fibroblastos/virologia , Regulação Viral da Expressão Gênica , Humanos , Proteínas de Membrana/genética , Mutagênese Sítio-Dirigida , Proteínas Virais/efeitos dos fármacos , Proteínas Virais/genética , Replicação Viral
8.
PLoS Pathog ; 16(6): e1008647, 2020 06.
Artigo em Inglês | MEDLINE | ID: mdl-32559251

RESUMO

A trimeric glycoprotein complex on the surface of human cytomegalovirus (HCMV) binds to platelet-derived growth factor (PDGF) receptor α (PDGFRα) to mediate host cell recognition and fusion of the viral and cellular membranes. Soluble PDGFRα potently neutralizes HCMV in tissue culture, and its potential use as an antiviral therapeutic has the benefit that any escape mutants will likely be attenuated. However, PDGFRα binds multiple PDGF ligands in the human body as part of developmental programs in embryogenesis and continuing through adulthood. Any therapies with soluble receptor therefore come with serious efficacy and safety concerns, especially for the treatment of congenital HCMV. Soluble virus receptors that are orthogonal to human biology might resolve these concerns. This engineering problem is solved by deep mutational scanning on the D2-D3 domains of PDGFRα to identify variants that maintain interactions with the HCMV glycoprotein trimer in the presence of competing PDGF ligands. Competition by PDGFs is conformation-dependent, whereas HCMV trimer binding is independent of proper D2-D3 conformation, and many mutations at the receptor-PDGF interface are suitable for functionally separating trimer from PDGF interactions. Purified soluble PDGFRα carrying a targeted mutation succeeded in displaying wild type affinity for HCMV trimer with a simultaneous loss of PDGF binding, and neutralizes trimer-only and trimer/pentamer-expressing HCMV strains infecting fibroblasts or epithelial cells. Overall, this work makes important progress in the realization of soluble HCMV receptors for clinical application.


Assuntos
Infecções por Citomegalovirus , Citomegalovirus , Estrutura Quaternária de Proteína , Receptores Virais , Linhagem Celular , Citomegalovirus/química , Citomegalovirus/genética , Citomegalovirus/metabolismo , Infecções por Citomegalovirus/genética , Infecções por Citomegalovirus/metabolismo , Células Epiteliais/metabolismo , Células Epiteliais/patologia , Células Epiteliais/virologia , Fibroblastos/metabolismo , Fibroblastos/patologia , Fibroblastos/virologia , Humanos , Mutação , Domínios Proteicos , Receptor alfa de Fator de Crescimento Derivado de Plaquetas/química , Receptor alfa de Fator de Crescimento Derivado de Plaquetas/genética , Receptor alfa de Fator de Crescimento Derivado de Plaquetas/metabolismo , Receptores Virais/química , Receptores Virais/genética , Receptores Virais/metabolismo
9.
Arch Virol ; 165(8): 1827-1835, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32507978

RESUMO

Human cytomegalovirus (HCMV) infection causes high morbidity and mortality among immunocompromised patients and can remain in a latent state in host cells. Expression of the immediate-early (IE) genes sustains HCMV replication and reactivation. As a novel genome-editing tool, the clustered regularly interspaced short palindromic repeat (CRISPR)/CRISPR-associated protein 9 (Cas9) system has been extensively utilized to modify and edit genomic DNA. In the present study, the CRISPR/Cas9 system was used to target the IE region of the HCMV genome via specific single-guide RNAs (sgRNAs). Infection with CRISPR/Cas9/sgRNA lentiviral constructs significantly reduced viral gene expression and virion production in HFF primary fibroblasts and inhibited viral DNA production and reactivation in the THP-1 monocytic cell line. Thus, the CRISPR/Cas9/sgRNA system can accurately and efficiently target HCMV replication and reactivation and represents a novel therapeutic strategy against latent HCMV infection.


Assuntos
Sistemas CRISPR-Cas/genética , Repetições Palindrômicas Curtas Agrupadas e Regularmente Espaçadas/genética , Citomegalovirus/genética , Endonucleases/genética , Genes Virais/genética , Replicação Viral/genética , Linhagem Celular , Infecções por Citomegalovirus/virologia , DNA Viral/genética , Fibroblastos/virologia , Edição de Genes/métodos , Expressão Gênica/genética , Células HEK293 , Humanos , RNA Guia/genética , Células THP-1
10.
J Virol ; 94(14)2020 07 01.
Artigo em Inglês | MEDLINE | ID: mdl-32350071

RESUMO

Human cytomegalovirus (HCMV) envelope glycoprotein complexes, gH/gL/gO trimer and gH/gL/UL128-131 pentamer, are important for cell-free HCMV entry. While soluble NRP2-Fc (sNRP2-Fc) interferes with epithelial/endothelial cell entry through UL128, soluble platelet-derived growth factor receptor α-Fc (sPDGFRα-Fc) interacts with gO, thereby inhibiting infection of all cell types. Since gO is the most variable subunit, we investigated the influence of gO polymorphism on the inhibitory capacities of sPDGFRα-Fc and sNRP2-Fc. Accordingly, gO genotype 1c (GT1c) sequence was fully or partially replaced by gO GT2b, GT3, and GT5 sequences in the bacterial artificial chromosome (BAC) TB40-BAC4-luc background (where luc is luciferase). All mutants were tested for fibroblast and epithelial cell infectivity, for virion content of gB, gH, and gO, and for infection inhibition by sPDGFRα-Fc and sNRP2-Fc. Full-length and partial gO GT swapping may increase epithelial-to-fibroblast ratios due to subtle alterations in fibroblast and/or epithelial infectivity but without substantial changes in gB and gH levels in mutant virions. All gO GT mutants except recombinant gO GT1c/3 displayed a nearly complete inhibition at 1.25 µg/ml sPDGFRα-Fc on epithelial cells (98% versus 91%), and all experienced complete inhibition on fibroblasts (≥99%). While gO GT replacement did not influence sNRP2-Fc inhibition at 1.25 µg/ml on epithelial cells (97% to 99%), it rendered recombinant mutant GT1c/3 moderately accessible to fibroblast inhibition (40%). In contrast to the steep sPDGFRα-Fc inhibition curves (slope of >1.0), sNRP2-Fc dose-response curves on epithelial cells displayed slopes of ∼1.0, suggesting functional differences between these entry inhibitors. Our findings demonstrate that artificially generated gO recombinants rather than the major gO genotypic forms may affect the inhibitory capacities of sPDGFRα and sNRP2 in a cell type-dependent manner.IMPORTANCE Human cytomegalovirus (HCMV) is known for its broad cell tropism, as reflected by the different organs and tissues affected by HCMV infection. Hence, inhibition of HCMV entry into distinct cell types could be considered a promising therapeutic option to limit cell-free HCMV infection. Soluble forms of cellular entry receptor PDGFRα rather than those of entry receptor neuropilin-2 inhibit infection of multiple cell types. sPDGFRα specifically interacts with gO of the trimeric gH/gL/gO envelope glycoprotein complex. HCMV strains may differ with respect to the amounts of trimer in virions and the highly polymorphic gO sequence. In this study, we show that the major gO genotypes of HCMV that are also found in vivo are similarly well inhibited by sPDGFRα. Novel gO genotypic forms potentially emerging through recombination, however, may evade sPDGFRα inhibition on epithelial cells. These findings provide useful additional information for the future development of anti-HCMV therapeutic compounds based on sPDGFRα.


Assuntos
Citomegalovirus , Fibroblastos/metabolismo , Glicoproteínas de Membrana , Neuropilina-2 , Polimorfismo Genético , Multimerização Proteica , Proteínas do Envelope Viral , Internalização do Vírus , Citomegalovirus/química , Citomegalovirus/genética , Citomegalovirus/metabolismo , Fibroblastos/patologia , Fibroblastos/virologia , Humanos , Glicoproteínas de Membrana/química , Glicoproteínas de Membrana/genética , Glicoproteínas de Membrana/metabolismo , Neuropilina-2/química , Neuropilina-2/genética , Neuropilina-2/metabolismo , Proteínas Recombinantes de Fusão/química , Proteínas Recombinantes de Fusão/genética , Proteínas Recombinantes de Fusão/metabolismo , Solubilidade , Proteínas do Envelope Viral/química , Proteínas do Envelope Viral/genética , Proteínas do Envelope Viral/metabolismo
11.
Sci Rep ; 10(1): 7257, 2020 04 29.
Artigo em Inglês | MEDLINE | ID: mdl-32350357

RESUMO

Coronaviruses that cause severe acute respiratory syndrome (SARS) and Middle East respiratory syndrome (MERS) are speculated to have originated in bats. The mechanisms by which these viruses are maintained in individuals or populations of reservoir bats remain an enigma. Mathematical models have predicted long-term persistent infection with low levels of periodic shedding as a likely route for virus maintenance and spillover from bats. In this study, we tested the hypothesis that bat cells and MERS coronavirus (CoV) can co-exist in vitro. To test our hypothesis, we established a long-term coronavirus infection model of bat cells that are persistently infected with MERS-CoV. We infected cells from Eptesicus fuscus with MERS-CoV and maintained them in culture for at least 126 days. We characterized the persistently infected cells by detecting virus particles, protein and transcripts. Basal levels of type I interferon in the long-term infected bat cells were higher, relative to uninfected cells, and disrupting the interferon response in persistently infected bat cells increased virus replication. By sequencing the whole genome of MERS-CoV from persistently infected bat cells, we identified that bat cells repeatedly selected for viral variants that contained mutations in the viral open reading frame 5 (ORF5) protein. Furthermore, bat cells that were persistently infected with ΔORF5 MERS-CoV were resistant to superinfection by wildtype virus, likely due to reduced levels of the virus receptor, dipeptidyl peptidase 4 (DPP4) and higher basal levels of interferon in these cells. In summary, our study provides evidence for a model of coronavirus persistence in bats, along with the establishment of a unique persistently infected cell culture model to study MERS-CoV-bat interactions.


Assuntos
Quirópteros/virologia , Infecções por Coronavirus/virologia , Fibroblastos/virologia , Insetívoros/virologia , Coronavírus da Síndrome Respiratória do Oriente Médio/genética , Fases de Leitura Aberta/genética , Mutação Puntual , Animais , Quirópteros/anatomia & histologia , Chlorocebus aethiops , Dipeptidil Peptidase 4/metabolismo , Fibroblastos/metabolismo , Genoma Viral/genética , Humanos , Insetívoros/anatomia & histologia , Fator Regulador 3 de Interferon/genética , Fator Regulador 3 de Interferon/metabolismo , Interferon Tipo I/metabolismo , Rim/citologia , Proteínas Quinases Ativadas por Mitógeno/genética , Proteínas Quinases Ativadas por Mitógeno/metabolismo , Proteínas do Nucleocapsídeo/genética , Receptores Virais/metabolismo , Transfecção , Células Vero , Replicação Viral/genética , Sequenciamento Completo do Genoma
12.
Vet Microbiol ; 243: 108620, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32273006

RESUMO

Infectious bursal disease virus (IBDV), the etiological agent of infectious bursal disease (IBD), is a variable RNA virus of Avibirnavirus. Some artificially attenuated vaccine strains of IBDV can adapt to cell culture of chicken embryo fibroblast (CEF) cell or its immortalized cell line DF1 in vitro while wild-type IBDV cannot. In this study, for the first time, a naturally occurring cell-adapted classic strain (genogroup 1) of IBDV named IBD17JL01 was identified in China. Animal experiments showed that IBD17JL01 could severely damage the central immune organ of infected chickens. Sequence analysis of the full-length genome revealed the peculiar molecular characteristics of IBD17JL01 with a few amino acid substitutions that might be involved in cell-tropism, antigenicity, and virulence of IBDV. Identification of this novel strain is beneficial to our understanding of the complexity of the epidemiology of IBDV. And the expansion of viral cell-tropism might increase the potential risk of the reassortment of different IBDVs including the live vaccines.


Assuntos
Infecções por Birnaviridae/veterinária , Galinhas/virologia , Genoma Viral , Vírus da Doença Infecciosa da Bursa/genética , Vírus da Doença Infecciosa da Bursa/isolamento & purificação , Tropismo Viral , Adaptação Biológica , Substituição de Aminoácidos , Animais , Técnicas de Cultura de Células , Linhagem Celular , China , Fibroblastos/virologia , Genótipo , Filogenia , Doenças das Aves Domésticas/virologia , Virulência
13.
J Virol ; 94(12)2020 06 01.
Artigo em Inglês | MEDLINE | ID: mdl-32238587

RESUMO

Cyclic GMP-AMP synthase (cGAS) senses double-stranded DNA and synthesizes the second messenger cyclic GMP-AMP (cGAMP), which binds to mediator of IRF3 activation (MITA) and initiates MITA-mediated signaling, leading to induction of type I interferons (IFNs) and other antiviral effectors. Human cytomegalovirus (HCMV), a widespread and opportunistic pathogen, antagonizes the host antiviral immune response to establish latent infection. Here, we identified HCMV tegument protein UL94 as an inhibitor of the cGAS-MITA-mediated antiviral response. Ectopic expression of UL94 impaired cytosolic double-stranded DNA (dsDNA)- and DNA virus-triggered induction of type I IFNs and enhanced viral replication. Conversely, UL94 deficiency potentiated HCMV-induced transcription of type I IFNs and downstream antiviral effectors and impaired viral replication. UL94 interacted with MITA, disrupted the dimerization and translocation of MITA, and impaired the recruitment of TBK1 to the MITA signalsome. These results suggest that UL94 plays an important role in the immune evasion of HCMV.IMPORTANCE Human cytomegalovirus (HCMV), a large double-stranded DNA (dsDNA) virus, encodes more than 200 viral proteins. HCMV infection causes irreversible abnormalities of the central nervous system in newborns and severe syndromes in organ transplantation patients or AIDS patients. It has been demonstrated that HCMV has evolved multiple immune evasion strategies to establish latent infection. Previous studies pay more attention to the mechanism by which HCMV evades immune response in the early phase of infection. In this study, we identified UL94 as a negative regulator of the innate immune response, which functions in the late phase of HCMV infection.


Assuntos
Proteínas do Capsídeo/imunologia , Citomegalovirus/imunologia , Genoma Viral , Evasão da Resposta Imune , Proteínas de Membrana/imunologia , Proteínas Serina-Treonina Quinases/imunologia , RNA Interferente Pequeno/genética , Proteínas do Capsídeo/genética , Núcleo Celular/imunologia , Núcleo Celular/virologia , GMP Cíclico/imunologia , GMP Cíclico/metabolismo , Citomegalovirus/genética , Citomegalovirus/crescimento & desenvolvimento , Citosol/imunologia , Citosol/virologia , DNA/imunologia , DNA/metabolismo , Fibroblastos/imunologia , Fibroblastos/virologia , Regulação da Expressão Gênica , Células HEK293 , Humanos , Imunidade Inata , Fator Regulador 3 de Interferon/genética , Fator Regulador 3 de Interferon/imunologia , Proteínas de Membrana/genética , Cultura Primária de Células , Ligação Proteica , Multimerização Proteica , Transporte Proteico , Proteínas Serina-Treonina Quinases/genética , RNA Interferente Pequeno/imunologia , Transdução de Sinais , Sequenciamento Completo do Exoma
14.
J Virol ; 94(12)2020 06 01.
Artigo em Inglês | MEDLINE | ID: mdl-32238588

RESUMO

Tetherin/BST-2 is an antiviral protein that blocks the release of enveloped viral particles by linking them to the membrane of producing cells. At first, BST-2 genes were described only in humans and other mammals. Recent work identified BST-2 orthologs in nonmammalian vertebrates, including birds. Here, we identify the BST-2 sequence in domestic chicken (Gallus gallus) for the first time and demonstrate its activity against avian sarcoma and leukosis virus (ASLV). We generated a BST-2 knockout in chicken cells and showed that BST-2 is a major determinant of an interferon-induced block of ASLV release. Ectopic expression of chicken BST-2 blocks the release of ASLV in chicken cells and of human immunodeficiency virus type 1 (HIV-1) in human cells. Using metabolic labeling and pulse-chase analysis of HIV-1 Gag proteins, we verified that chicken BST-2 blocks the virus at the release stage. Furthermore, we describe BST-2 orthologs in multiple avian species from 12 avian orders. Previously, some of these species were reported to lack BST-2, highlighting the difficulty of identifying sequences of this extremely variable gene. We analyzed BST-2 genes in the avian orders Galliformes and Passeriformes and showed that they evolve under positive selection. This indicates that avian BST-2 is involved in host-virus evolutionary arms races and suggests that BST-2 antagonists exist in some avian viruses. In summary, we show that chicken BST-2 has the potential to act as a restriction factor against ASLV. Characterizing the interaction of avian BST-2 with avian viruses is important in understanding innate antiviral defenses in birds.IMPORTANCE Birds are important hosts of viruses that have the potential to cause zoonotic infections in humans. However, only a few antiviral genes (called viral restriction factors) have been described in birds, mostly because birds lack counterparts of highly studied mammalian restriction factors. Tetherin/BST-2 is a restriction factor, originally described in humans, that blocks the release of newly formed virus particles from infected cells. Recent work identified BST-2 in nonmammalian vertebrate species, including birds. Here, we report the BST-2 sequence in domestic chicken and describe its antiviral activity against a prototypical avian retrovirus, avian sarcoma and leukosis virus (ASLV). We also identify BST-2 genes in multiple avian species and show that they evolve rapidly in birds, which is an important indication of their relevance for antiviral defense. Analysis of avian BST-2 genes will shed light on defense mechanisms against avian viral pathogens.


Assuntos
Proteínas Aviárias/imunologia , Vírus do Sarcoma Aviário/imunologia , Antígeno 2 do Estroma da Médula Óssea/imunologia , Evolução Molecular , Galliformes/imunologia , Sarcoma Aviário/imunologia , Sequência de Aminoácidos , Animais , Proteínas Aviárias/genética , Vírus do Sarcoma Aviário/genética , Vírus do Sarcoma Aviário/patogenicidade , Antígeno 2 do Estroma da Médula Óssea/genética , Linhagem Celular , Fibroblastos/imunologia , Fibroblastos/virologia , Galliformes/genética , Galliformes/virologia , Regulação da Expressão Gênica , Células HEK293 , HIV-1/genética , HIV-1/imunologia , Interações Hospedeiro-Patógeno/genética , Interações Hospedeiro-Patógeno/imunologia , Humanos , Passeriformes/genética , Passeriformes/imunologia , Passeriformes/virologia , Sarcoma Aviário/genética , Sarcoma Aviário/virologia , Seleção Genética , Alinhamento de Sequência , Homologia de Sequência de Aminoácidos , Transdução de Sinais , Liberação de Vírus , Replicação Viral , Produtos do Gene gag do Vírus da Imunodeficiência Humana/genética , Produtos do Gene gag do Vírus da Imunodeficiência Humana/imunologia
15.
PLoS Pathog ; 16(3): e1008387, 2020 03.
Artigo em Inglês | MEDLINE | ID: mdl-32126128

RESUMO

Mediator of IRF3 activation (MITA, also named as STING/ERIS/MPYS/TMEM173), is essential to DNA virus- or cytosolic DNA-triggered innate immune responses. In this study, we demonstrated the negative regulatory role of RING-finger protein (RNF) 90 in innate immune responses targeting MITA. RNF90 promoted K48-linked ubiquitination of MITA and its proteasome-dependent degradation. Overexpression of RNF90 inhibited HSV-1- or cytosolic DNA-induced immune responses whereas RNF90 knockdown had the opposite effects. Moreover, RNF90-deficient bone marrow-derived dendritic cells (BMDCs), bone marrow-derived macrophages (BMMs) and mouse embryonic fibroblasts (MEFs) exhibited increased DNA virus- or cytosolic DNA-triggered signaling and RNF90 deficiency protected mice from DNA virus infection. Taken together, our findings suggested a novel function of RNF90 in innate immunity.


Assuntos
Herpesvirus Humano 1/imunologia , Imunidade Inata , Proteínas de Membrana/imunologia , Proteólise , Proteínas com Motivo Tripartido/imunologia , Ubiquitina-Proteína Ligases/imunologia , Ubiquitinação/imunologia , Animais , Células da Medula Óssea/imunologia , Células da Medula Óssea/virologia , Células Dendríticas/imunologia , Células Dendríticas/virologia , Fibroblastos/imunologia , Fibroblastos/virologia , Herpesvirus Humano 1/genética , Macrófagos/imunologia , Macrófagos/virologia , Proteínas de Membrana/genética , Camundongos , Camundongos Knockout , Proteínas com Motivo Tripartido/genética , Ubiquitina-Proteína Ligases/genética , Ubiquitinação/genética
16.
Vet Microbiol ; 242: 108589, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-32122593

RESUMO

The CRISPR/CRISPR-associated protein 9 (Cas9) system is a powerful gene-editing tool originally discovered as an integral mediator of bacterial adaptive immunity. Recently, this technology has been explored for its potential utility in providing new and unique treatments for viral infection. Marek's disease virus (MDV) and avian leukosis virus subgroup J (ALV-J), major immunosuppressive viruses, cause significant economic losses to the chicken industry. Here, we evaluated the efficacy of using MDV as a CRISPR/Cas9-delivery system to directly target and disrupt the reverse-transcribed products of the ALV-J RNA genome during its infection cycle in vitro and in vivo. We first screened multiple potential guide RNA (gRNA) target sites in the ALV-J genome and identified several optimized targets capable of effectively disrupting the latently integrated viral genome and providing efficient defense against new infection by ALV-J in cells. The optimal single-gRNAs and Cas9-expression cassettes were inserted into the genome of an MDV vaccine strain. The results indicated that engineered MDV stably expressing ALV-J-targeting CRISPR/Cas9 efficiently resisted ALV-J challenge in host cells. These findings demonstrated the CRISPR/Cas9 system as an effective treatment strategy against ALV-J infection. Furthermore, the results highlighted the potential of MDV as an effective delivery system for CRISPR/Cas9 in chickens.


Assuntos
Leucose Aviária/prevenção & controle , Sistemas CRISPR-Cas , Herpesvirus Galináceo 2/genética , Vacinas contra Doença de Marek/genética , Doenças das Aves Domésticas/prevenção & controle , Animais , Leucose Aviária/virologia , Vírus da Leucose Aviária/genética , Vírus da Leucose Aviária/patogenicidade , Galinhas/virologia , Fibroblastos/virologia , Edição de Genes/métodos , Vetores Genéticos , Genoma Viral , Doenças das Aves Domésticas/virologia , RNA Guia/genética , RNA Viral/genética , Organismos Livres de Patógenos Específicos , Integração Viral
17.
Vet Microbiol ; 242: 108610, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-32122614

RESUMO

Reticuloendotheliosis virus (REV) infection of multiple avian species can lead to a number of diseases such as runting syndrome, immunosuppression and oncogenesis, causing major economic losses. MicroRNAs play important roles in post-transcriptional regulation, effectively inhibiting protein synthesis, and participating in many biological processes in cells, including proliferation, differentiation, apoptosis, lipometabolism, virus infection and replication, and tumorigenesis. Based on our previous high-throughput sequencing results, we explore the regulatory mechanisms of microRNA-155(miR-155) in chicken embryo fibroblasts (CEFs) in response to REV infection. Our results revealed expression of miR-155 in CEFs after REV infection upregulated in a time- and dose-dependent manner, indicating miR-155 plays a role in REV infection in CEFs indeed. After transfected with miR-155-mimic and miR-155-inhibitor, we found overexpression of miR-155 targeted caspase-6 and FOXO3a to inhibit apoptosis and accelerate cell cycle, thus improving viability of REV-infected CEFs. This result also verified the protective role of miR-155 in the viability of CEFs in the presence of REV. Knockdown of miR-155 also supported these above conclusions. Our findings uncover a new mechanism of REV pathogenesis in CEFs, and also provide a theoretical basis for uncovering new effective treatment and prevention methods for RE based on miR-155.


Assuntos
Fibroblastos/virologia , Regulação da Expressão Gênica , Interações entre Hospedeiro e Microrganismos/genética , MicroRNAs/genética , Vírus da Reticuloendoteliose/fisiologia , Infecções por Retroviridae/veterinária , Animais , Apoptose , Caspase 6/genética , Embrião de Galinha/virologia , Técnicas de Silenciamento de Genes , Sequenciamento de Nucleotídeos em Larga Escala , Infecções por Retroviridae/genética , Regulação para Cima
18.
J Med Chem ; 63(8): 3896-3907, 2020 04 23.
Artigo em Inglês | MEDLINE | ID: mdl-32191456

RESUMO

The critical consequences of human cytomegalovirus (HCMV) infection in the transplant population and in congenitally infected infants, the limited treatment options for HCMV, and the rise of resistant mutants toward existing therapies has fueled the search for new anti-HCMV agents. A pp28-luciferase recombinant HCMV was used as a reporter system for high-throughput screening of HCMV inhibitors. Approximately 400 000 compounds from existing libraries were screened. Subsequent validation assays using resynthesized compounds, several virus strains, and detailed virology assays resulted in the identification of five structurally unique and selective HCMV inhibitors, active at sub to low micromolar concentrations. Further characterization revealed that each compound inhibited a specific stage of HCMV replication. One compound was also active against herpes simplex virus (HSV1 and HSV2), and another compound was active against Epstein-Barr virus (EBV). Drug combination studies revealed that all five compounds were additive with ganciclovir or letermovir. Future studies will focus on optimization of these new anti-HCMV compounds along with mechanistic studies.


Assuntos
Antivirais/química , Antivirais/farmacologia , Citomegalovirus/efeitos dos fármacos , Descoberta de Drogas/métodos , Animais , Antivirais/uso terapêutico , Células Cultivadas , Citomegalovirus/fisiologia , Infecções por Citomegalovirus/tratamento farmacológico , Infecções por Citomegalovirus/fisiopatologia , Relação Dose-Resposta a Droga , Fibroblastos/efeitos dos fármacos , Fibroblastos/fisiologia , Fibroblastos/virologia , Humanos , Masculino , Camundongos
19.
J Virol ; 94(8)2020 03 31.
Artigo em Inglês | MEDLINE | ID: mdl-31996433

RESUMO

Human cytomegalovirus (HCMV) glycoproteins H and L (gH/gL) can be bound by either gO or the UL128 to UL131 proteins (referred to here as UL128-131) to form complexes that facilitate entry and spread, and the complexes formed are important targets of neutralizing antibodies. Strains of HCMV vary considerably in the levels of gH/gL/gO and gH/gL/UL128-131, and this can impact infectivity and cell tropism. In this study, we investigated how natural interstrain variation in the amino acid sequence of gO influences the biology of HCMV. Heterologous gO recombinants were constructed in which 6 of the 8 alleles or genotypes (GT) of gO were analyzed in the backgrounds of strains TR and Merlin (ME). The levels of gH/gL complexes were not affected, but there were impacts on entry, spread, and neutralization by anti-gH antibodies. AD169 (AD) gO (GT1a) [referred to here as ADgO(GT1a)] drastically reduced cell-free infectivity of both strains on fibroblasts and epithelial cells. PHgO(GT2a) increased cell-free infectivity of TR in both cell types, but spread in fibroblasts was impaired. In contrast, spread of ME in both cell types was enhanced by Towne (TN) gO (GT4), despite similar cell-free infectivity. TR expressing TNgO(GT4) was resistant to neutralization by anti-gH antibodies AP86 and 14-4b, whereas ADgO(GT1a) conferred resistance to 14-4b but enhanced neutralization by AP86. Conversely, ME expressing ADgO(GT1a) was more resistant to 14-4b. These results suggest that (i) there are mechanistically distinct roles for gH/gL/gO in cell-free and cell-to-cell spread, (ii) gO isoforms can differentially shield the virus from neutralizing antibodies, and (iii) effects of gO polymorphisms are epistatically dependent on other variable loci.IMPORTANCE Advances in HCMV population genetics have greatly outpaced understanding of the links between genetic diversity and phenotypic variation. Moreover, recombination between genotypes may shuffle variable loci into various combinations with unknown outcomes. UL74(gO) is an important determinant of HCMV infectivity and one of the most diverse loci in the viral genome. By analyzing interstrain heterologous UL74(gO) recombinants, we showed that gO diversity can have dramatic impacts on cell-free and cell-to-cell spread as well as on antibody neutralization and that the manifestation of these impacts can be subject to epistatic influences of the global genetic background. These results highlight the potential limitations of laboratory studies of HCMV biology that use single, isolated genotypes or strains.


Assuntos
Anticorpos Neutralizantes/imunologia , Citomegalovirus/genética , Epitopos/imunologia , Glicoproteínas de Membrana/genética , Glicoproteínas de Membrana/imunologia , Polimorfismo Genético , Proteínas do Envelope Viral/genética , Proteínas do Envelope Viral/imunologia , Sequência de Aminoácidos , Linhagem Celular , Citomegalovirus/imunologia , Células Epiteliais/virologia , Fibroblastos/virologia , Humanos , Proteínas Recombinantes , Proteínas Virais
20.
J Virol ; 94(7)2020 03 17.
Artigo em Inglês | MEDLINE | ID: mdl-31915281

RESUMO

Human cytomegalovirus (HCMV) is a ubiquitous pathogen that encodes many proteins to modulate the host immune response. Extensive efforts have led to the elucidation of multiple strategies employed by HCMV to effectively block NK cell targeting of virus-infected cells and the major histocompatibility complex (MHC) class I-primed CD8+ T cell response. However, viral regulation of the MHC class II-mediated CD4+ T cell response is understudied in endogenous MHC class II-expressing cells, largely because the popular cell culture systems utilized for studying HCMV do not endogenously express MHC class II. Of the many cell types infected by HCMV in the host, myeloid cells, such as monocytes, are of particular importance due to their role in latency and subsequent dissemination throughout the host. We investigated the impact of HCMV infection on MHC class II in Kasumi-3 cells, a myeloid-progenitor cell line that endogenously expresses the MHC class II gene, HLA-DR. We observed a significant reduction in the expression of surface and total HLA-DR at 72 h postinfection (hpi) and 120 hpi in infected cells. The decrease in HLA-DR expression was independent of the expression of previously described viral genes that regulate the MHC class II complex or the unique short (US) region of HCMV, a region expressing many immunomodulatory genes. The altered surface level of HLA-DR was not a result of increased endocytosis and degradation but was a result of a reduction in HLA-DR transcripts due to a decrease in the expression of the class II transactivator (CIITA).IMPORTANCE Human cytomegalovirus (HCMV) is an opportunistic herpesvirus that is asymptomatic for healthy individuals but that can lead to severe pathology in patients with congenital infections and immunosuppressed patients. Thus, it is important to understand the modulation of the immune response by HCMV, which is understudied in the context of endogenous MHC class II regulation. Using Kasumi-3 cells as a myeloid progenitor cell model endogenously expressing MHC class II (HLA-DR), this study shows that HCMV decreases the expression of HLA-DR in infected cells by reducing the transcription of HLA-DR transcripts early during infection independently of the expression of previously implicated genes. This is an important finding, as it highlights a mechanism of immune evasion utilized by HCMV to decrease the expression of MHC class II in a relevant cell system that endogenously expresses the MHC class II complex.


Assuntos
Infecções por Citomegalovirus/imunologia , Antígenos HLA-DR/genética , Células Progenitoras Mieloides/imunologia , Proteínas Nucleares/genética , Transativadores/genética , Ativação Transcricional , Apresentação do Antígeno , Linfócitos T CD4-Positivos/citologia , Linfócitos T CD8-Positivos/citologia , Linhagem Celular , Citomegalovirus , Endocitose , Fibroblastos/imunologia , Fibroblastos/virologia , Regulação da Expressão Gênica , Humanos , Células Progenitoras Mieloides/virologia
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA