RESUMO
Argentine hemorrhagic fever, caused by Junín virus (JUNV), is the most common of the South American arenaviral hemorrhagic fevers. The disease has a case fatality rate of 15-30% in untreated patients. Although early intervention with immune plasma is effective, diminishing stocks and limited availability outside of Argentina underscores the need for new therapeutics. Ideally, these would be broadly active agents effective against all the pathogenic arenaviruses. The fusion inhibitor LHF-535 and the nucleoside analog favipiravir have shown promise in animal models of Lassa fever, a disease endemic in parts of Africa and the most prominent of the arenaviral hemorrhagic fevers. Against JUNV, a high dose of favipiravir is required to achieve protection in the gold-standard guinea pig infection model. Here, we demonstrate a synergistic effect by the coadministration of LHF-535 with a sub-optimal dose of favipiravir in guinea pigs challenged with JUNV. Administered individually, LHF-535 and sub-optimal favipiravir only delayed the onset of severe disease. However, combined dosing of the drugs afforded complete protection against lethal JUNV infection in guinea pigs. The benefits of the drug combination were also evident by the absence of viremia and infectious virus in tissues compared to guinea pigs treated with only the placebos. Thus, combined targeting of JUNV-endosomal membrane fusion and the viral polymerase with pan-arenaviral LHF-535 and favipiravir may expand their indication beyond Lassa fever, providing a significant barrier to drug resistance.
Assuntos
Amidas , Antivirais , Modelos Animais de Doenças , Vírus Junin , Pirazinas , Pirazinas/farmacologia , Pirazinas/administração & dosagem , Pirazinas/uso terapêutico , Animais , Cobaias , Amidas/farmacologia , Amidas/uso terapêutico , Amidas/administração & dosagem , Vírus Junin/efeitos dos fármacos , Antivirais/farmacologia , Antivirais/administração & dosagem , Antivirais/uso terapêutico , Febre Hemorrágica Americana/tratamento farmacológico , Febre Hemorrágica Americana/virologia , Quimioterapia Combinada , Feminino , Sinergismo Farmacológico , Infecções por Arenaviridae/tratamento farmacológicoRESUMO
INTRODUCTION: Mammarenaviruses are negative-sense bisegmented enveloped RNA viruses that are endemic in Africa, the Americas, and Europe. Several are highly virulent, causing acute human diseases associated with high case fatality rates, and are considered to be significant with respect to public health impact or bioterrorism threat. AREAS COVERED: This review summarizes the status quo of treatment development, starting with drugs that are in advanced stages of evaluation in early clinical trials, followed by promising candidate medical countermeasures emerging from bench analyses and investigational animal research. EXPERT OPINION: Specific therapeutic treatments for diseases caused by mammarenaviruses remain limited to the off-label use of ribavirin and transfusion of convalescent sera. Progress in identifying novel candidate medical countermeasures against mammarenavirus infection has been slow in part because of the biosafety and biosecurity requirements. However, novel methodologies and tools have enabled increasingly efficient high-throughput molecular screens of regulatory-agency-approved small-molecule drugs and led to the identification of several compounds that could be repurposed for the treatment of infection with several mammarenaviruses. Unfortunately, most of them have not yet been evaluated in vivo. The most promising treatment under development is a monoclonal antibody cocktail that is protective against multiple lineages of the Lassa virus in nonhuman primate disease models.
Assuntos
Antivirais , Infecções por Arenaviridae , Arenaviridae , Desenvolvimento de Medicamentos , Humanos , Animais , Antivirais/farmacologia , Infecções por Arenaviridae/tratamento farmacológico , Infecções por Arenaviridae/virologia , Arenaviridae/efeitos dos fármacos , Virulência , Desenho de FármacosRESUMO
During chronic viral infections, CD8 T cells rapidly lose antiviral and immune-stimulatory functions in a sustained program termed exhaustion. In addition to this loss of function, CD8 T cells with the highest affinity for viral antigen can be physically deleted. Consequently, treatments designed to restore function to exhausted cells and control chronic viral replication are limited from the onset by the decreased breadth of the antiviral T cell response. Yet, it remains unclear why certain populations of CD8 T cells are deleted while others are preserved in an exhausted state. We report that CD8 T cell deletion during chronic viral infection can be prevented by therapeutically lowering viral replication early after infection. The initial resistance to deletion enabled long-term maintenance of antiviral cytolytic activity of the otherwise deleted high-affinity CD8 T cells. In combination with decreased virus titers, CD4 T cell help and prolonged interactions with costimulatory molecules B7-1/B7-2 were required to prevent CD8 T cell deletion. Thus, therapeutic strategies to decrease early virus replication could enhance virus-specific CD8 T cell diversity and function during chronic infection.
Assuntos
Infecções por Arenaviridae/imunologia , Linfócitos T CD8-Positivos/imunologia , Vírus da Coriomeningite Linfocítica/imunologia , Infecção Persistente/imunologia , Imunidade Adaptativa , Animais , Antivirais/uso terapêutico , Infecções por Arenaviridae/tratamento farmacológico , Infecções por Arenaviridae/virologia , Antígeno B7-1/metabolismo , Antígeno B7-2/metabolismo , Linfócitos T CD4-Positivos/imunologia , Vírus da Coriomeningite Linfocítica/efeitos dos fármacos , Vírus da Coriomeningite Linfocítica/fisiologia , Camundongos , Camundongos Endogâmicos C57BL , Proteínas do Nucleocapsídeo/imunologia , Infecção Persistente/tratamento farmacológico , Infecção Persistente/virologia , Ribavirina/uso terapêutico , Carga Viral , Replicação Viral/efeitos dos fármacosRESUMO
Lujo virus (LUJV), a highly pathogenic arenavirus, was first identified in 2008 in Zambia. To aid the identification of effective therapeutics for LUJV, we developed a recombinant reporter virus system, confirming reporter LUJV comparability with wild-type virus and its utility in high-throughput antiviral screening assays. Using this system, we evaluated compounds with known and unknown efficacy against related arenaviruses, with the aim of identifying LUJV-specific and potential new pan-arenavirus antivirals. We identified six compounds demonstrating robust anti-LUJV activity, including several compounds with previously reported activity against other arenaviruses. These data provide critical evidence for developing broad-spectrum antivirals against high-consequence arenaviruses.
Assuntos
Antivirais/farmacologia , Arenavirus/efeitos dos fármacos , Lujo virus/efeitos dos fármacos , Animais , Infecções por Arenaviridae/tratamento farmacológico , Infecções por Arenaviridae/virologia , Arenavirus/fisiologia , Linhagem Celular Tumoral , Chlorocebus aethiops , Genoma Viral , Proteínas de Fluorescência Verde/genética , Humanos , Lujo virus/genética , Lujo virus/fisiologia , Testes de Sensibilidade Microbiana , Proteínas Recombinantes , Células Vero , Internalização do Vírus/efeitos dos fármacosRESUMO
Several arenaviruses, including Lassa and Lujo viruses in Africa and five New World arenavirus (NWA) species in the Americas, cause life-threatening viral hemorrhagic fevers. In the absence of licensed antiviral therapies, these viruses pose a significant public health risk. The envelope glycoprotein complex (GPC) mediates arenavirus entry through a pH-dependent fusion of the viral and host endosomal membranes. It thus is recognized as a viable target for small-molecule fusion inhibitors. Here, we report on the antiviral activity and pre-clinical development of the novel broad-spectrum arenavirus fusion inhibitors, ARN-75039 and ARN-75041. In Tacaribe virus (TCRV) pseudotyped and native virus assays, the ARN compounds were active in the low to sub-nanomolar range with selectivity indices exceeding 1000. Pharmacokinetic analysis of the orally administered compounds revealed an extended half-life in mice supporting once-daily dosing, and the compounds were well tolerated at the highest tested dose of 100 mg/kg. In a proof-of-concept prophylactic efficacy study, doses of 10 and 35 mg/kg of either compound dramatically improved survival outcome and potently inhibited TCRV replication in serum and various tissues. Additionally, in contrast to surviving mice that received ribavirin or placebo, animals treated with ARN-75039 or ARN-75041 were cured of TCRV infection. In a follow-up study with ARN-75039, impressive therapeutic efficacy was demonstrated under conditions where treatment was withheld until after the onset of disease. Taken together, the data strongly support the continued development of ARN-75039 as a candidate therapeutic for the treatment of severe arenaviral diseases.
Assuntos
Antivirais/farmacologia , Infecções por Arenaviridae/tratamento farmacológico , Arenavirus do Novo Mundo/efeitos dos fármacos , Fusão de Membrana/efeitos dos fármacos , Bibliotecas de Moléculas Pequenas/farmacologia , Administração Oral , Animais , Antivirais/farmacocinética , Chlorocebus aethiops , Masculino , Camundongos , Ribavirina/farmacologia , Bibliotecas de Moléculas Pequenas/farmacocinética , Células Vero , Proteínas do Envelope Viral/química , Proteínas do Envelope Viral/metabolismo , Internalização do Vírus/efeitos dos fármacosRESUMO
Neglected diseases caused by arenaviruses such as Lassa virus (LASV) and filoviruses like Ebola virus (EBOV) primarily afflict resource-limited countries, where antiviral drug development is often minimal. Previous studies have shown that many approved drugs developed for other clinical indications inhibit EBOV and LASV and that combinations of these drugs provide synergistic suppression of EBOV, often by blocking discrete steps in virus entry. We hypothesize that repurposing of combinations of orally administered approved drugs provides effective suppression of arenaviruses. In this report, we demonstrate that arbidol, an approved influenza antiviral previously shown to inhibit EBOV, LASV, and many other viruses, inhibits murine leukemia virus (MLV) reporter viruses pseudotyped with the fusion glycoproteins (GPs) of other arenaviruses (Junin virus [JUNV], lymphocytic choriomeningitis virus [LCMV], and Pichinde virus [PICV]). Arbidol and other approved drugs, including aripiprazole, amodiaquine, sertraline, and niclosamide, also inhibit infection of cells by infectious PICV, and arbidol, sertraline, and niclosamide inhibit infectious LASV. Combining arbidol with aripiprazole or sertraline results in the synergistic suppression of LASV and JUNV GP-bearing pseudoviruses. This proof-of-concept study shows that arenavirus infection in vitro can be synergistically inhibited by combinations of approved drugs. This approach may lead to a proactive strategy with which to prepare for and control known and new arenavirus outbreaks.
Assuntos
Antivirais/uso terapêutico , Infecções por Arenaviridae/tratamento farmacológico , Arenavirus/efeitos dos fármacos , Administração Oral , Animais , Infecções por Arenaviridae/virologia , Linhagem Celular , Chlorocebus aethiops , Sinergismo Farmacológico , Quimioterapia Combinada/métodos , Células HEK293 , Humanos , Camundongos , Estudo de Prova de Conceito , Células VeroRESUMO
Understanding the genetics of susceptibility to infectious agents is of great importance to our ability to combat disease. Here, we show that voltage-gated calcium channels (VGCCs) are critical for cellular binding and entry of the New World arenaviruses Junín and Tacaribe virus, suggesting that zoonosis via these receptors could occur. Moreover, we demonstrate that α1s haploinsufficiency renders cells and mice more resistant to infection by these viruses. In addition to being more resistant to infection, haploinsufficient cells and mice required a lower dosage of VGCC antagonists to block infection. These studies underscore the importance of genetic variation in susceptibility to both viruses and pharmaceutics.
Assuntos
Infecções por Arenaviridae/genética , Canais de Cálcio Tipo L/genética , Resistência à Doença/genética , Animais , Infecções por Arenaviridae/tratamento farmacológico , Arenavirus do Novo Mundo/fisiologia , Agonistas dos Canais de Cálcio/farmacologia , Agonistas dos Canais de Cálcio/uso terapêutico , Bloqueadores dos Canais de Cálcio/farmacologia , Bloqueadores dos Canais de Cálcio/uso terapêutico , Canais de Cálcio Tipo L/deficiência , Canais de Cálcio Tipo L/metabolismo , Células Cultivadas , Relação Dose-Resposta a Droga , Heterozigoto , Humanos , Camundongos , Camundongos Mutantes , Mutação , Ligação Viral/efeitos dos fármacos , Internalização do Vírus/efeitos dos fármacosRESUMO
INTRODUCTION: Arenavirus are unique category-A pathogens that are also classified as Orphan diseases. Very few options exist currently for treating Viral Hemorrhagic Fever (VHF) caused by viruses belonging to the Arenaviridae family [1]. The current review provides detailed patent landscape and a description of selected technologies developed for combating category-A Arenavirus. Currently, Arenavirus infections are epidemic [2] but could cause widespread pandemics due to ease of dissemination and lack of immunity against these viruses. AREAS COVERED: The key strings for selected Arenavirus VHF were run separately in MCPaIRS®, PatSeer, and Questel database. The search was limited to Title, Abstract and Claim fields; one member per patent family was considered for analysis. EXPERT OPINION: Synthetic molecules dominate the patent landscape, while natural products have not been extensively claimed for the treatment of Arenavirus infection. The broad-spectrum activity has been highly desired for Arenavirus treatment, but few reports have experimentally tested it. With each year, a constant increase in number of patents published is seen, while the maximum number of applications was filed in 2017. The research in VHF is driven by public funds; the maximum numbers of patents were filed by publicly funded organizations.
Assuntos
Antivirais/farmacologia , Infecções por Arenaviridae/tratamento farmacológico , Febres Hemorrágicas Virais/tratamento farmacológico , Animais , Infecções por Arenaviridae/virologia , Arenavirus/isolamento & purificação , Febres Hemorrágicas Virais/virologia , Humanos , Patentes como Assunto , Doenças Raras/tratamento farmacológico , Doenças Raras/virologiaRESUMO
The potent antiviral properties of 3-deazaneplanocin, 3-deaza-isoneplanocins (1) and recently discovered l-like carbocyclic nucleosides (2, 3 and 4) prompted us to pursue rationally conceived l-like 3-deazaneplanocin analogues. The synthesis of those analogues including l-like 3-deazaneplanocin (5), l-like 3-bromo-3-deazaneplanocin (6), and l-like 5'-fluoro-5'-deoxy-3-deazaneplanocin (7), was accomplished from a common intermediate, (-)-cyclopentenone (8). Antiviral analysis found 5 and 6 to display favorable activity against the Ebola virus, as expected for 3-deazaadenine carbocyclic nucleosides. Compound 5 also showed activity against arenaviruses, including Pinchinde and Tacaribe.
Assuntos
Adenosina/análogos & derivados , Antivirais/síntese química , Antivirais/farmacologia , Infecções por Arenaviridae/tratamento farmacológico , Arenaviridae/efeitos dos fármacos , Ebolavirus/efeitos dos fármacos , Doença pelo Vírus Ebola/tratamento farmacológico , Adenosina/química , Infecções por Arenaviridae/virologia , Doença pelo Vírus Ebola/virologia , Humanos , Estrutura MolecularRESUMO
Several mammarenaviruses, chiefly Lassa virus (LASV) in Western Africa and Junín virus (JUNV) in the Argentine Pampas, cause severe disease in humans and pose important public health problems in their endemic regions. Moreover, mounting evidence indicates that the worldwide-distributed mammarenavirus lymphocytic choriomeningitis virus (LCMV) is a neglected human pathogen of clinical significance. The lack of licensed mammarenavirus vaccines and partial efficacy of current anti-mammarenavirus therapy limited to an off-label use of the nucleoside analog ribavirin underscore an unmet need for novel therapeutics to combat human pathogenic mammarenavirus infections. This task can be facilitated by the implementation of "drug repurposing" strategies to reduce the time and resources required to advance identified antiviral drug candidates into the clinic. We screened a drug repurposing library of 11,968 compounds (Repurposing, Focused Rescue and Accelerated Medchem [ReFRAME]) and identified several potent inhibitors of LCMV multiplication that had also strong anti-viral activity against LASV and JUNV. Our findings indicate that enzymes of the rate-limiting steps of pyrimidine and purine biosynthesis, the pro-viral MCL1 apoptosis regulator, BCL2 family member protein and the mitochondrial electron transport complex III, play critical roles in the completion of the mammarenavirus life cycle, suggesting they represent potential druggable targets to counter human pathogenic mammarenavirus infections.
Assuntos
Antivirais/farmacologia , Arenaviridae/efeitos dos fármacos , Bases de Dados de Produtos Farmacêuticos , Avaliação Pré-Clínica de Medicamentos/métodos , Reposicionamento de Medicamentos/métodos , Células A549 , Animais , Apoptose , Arenaviridae/fisiologia , Infecções por Arenaviridae/tratamento farmacológico , Infecções por Arenaviridae/imunologia , Infecções por Arenaviridae/virologia , Chlorocebus aethiops , Relação Dose-Resposta a Droga , Complexo III da Cadeia de Transporte de Elétrons/metabolismo , Células HEK293 , Humanos , Interferons/genética , Vírus Junin/efeitos dos fármacos , Vírus Lassa/efeitos dos fármacos , Vírus da Coriomeningite Linfocítica/efeitos dos fármacos , Proteínas Proto-Oncogênicas c-bcl-2/metabolismo , Purinas/biossíntese , Pirimidinas/biossíntese , Células Vero , Replicação Viral/efeitos dos fármacosRESUMO
Some studies show eliminating senescent cells rejuvenate aged mice and attenuate deleterious effects of chemotherapy. Nevertheless, it remains unclear whether senescence affects immune cell function. We provide evidence that exposure of mice to ionizing radiation (IR) promotes the senescent-associated secretory phenotype (SASP) and expression of p16INK4a in splenic cell populations. We observe splenic T cells exhibit a reduced proliferative response when cultured with allogenic cells in vitro and following viral infection in vivo. Using p16-3MR mice that allow elimination of p16INK4a -positive cells with exposure to ganciclovir, we show that impaired T-cell proliferation is partially reversed, mechanistically dependent on p16INK4a expression and the SASP. Moreover, we found macrophages isolated from irradiated spleens to have a reduced phagocytosis activity in vitro, a defect also restored by the elimination of p16INK4a expression. Our results provide molecular insight on how senescence-inducing IR promotes loss of immune cell fitness, which suggest senolytic drugs may improve immune cell function in aged and patients undergoing cancer treatment.
Assuntos
Senescência Celular/efeitos da radiação , Radiação Ionizante , Baço/metabolismo , Baço/efeitos da radiação , Linfócitos T/imunologia , Linfócitos T/efeitos da radiação , Animais , Antivirais/uso terapêutico , Infecções por Arenaviridae/tratamento farmacológico , Infecções por Arenaviridae/imunologia , Infecções por Arenaviridae/virologia , Proliferação de Células/efeitos da radiação , Células Cultivadas , Senescência Celular/genética , Inibidor p16 de Quinase Dependente de Ciclina/genética , Inibidor p16 de Quinase Dependente de Ciclina/metabolismo , Ganciclovir/uso terapêutico , Vírus da Coriomeningite Linfocítica/imunologia , Macrófagos/metabolismo , Camundongos , Camundongos Transgênicos , Fenótipo , Rejuvenescimento/fisiologia , Baço/virologiaRESUMO
Lassa virus (LASV) causes Lassa hemorrhagic fever in humans and poses a significant threat to public health in West Africa. Current therapeutic treatments for Lassa fever are limited, making the development of novel countermeasures an urgent priority. In this study, we identified losmapimod, a p38 mitogen-activated protein kinase (MAPK) inhibitor, from 102 screened compounds as an inhibitor of LASV infection. Losmapimod exerted its inhibitory effect against LASV after p38 MAPK down-regulation, and, interestingly, had no effect on other arenaviruses capable of causing viral hemorrhagic fever. Mechanistic studies showed that losmapimod inhibited LASV entry by affecting the stable signal peptide (SSP)-GP2 subunit interface of the LASV glycoprotein, thereby blocking pH-dependent viral fusion. As an aryl heteroaryl bis-carboxyamide derivative, losmapimod represents a novel chemical scaffold with anti-LASV activity, and it provides a new lead structure for the future development of LASV fusion inhibitors.
Assuntos
Antivirais/farmacologia , Ciclopropanos/farmacologia , Vírus Lassa/efeitos dos fármacos , Piridinas/farmacologia , Internalização do Vírus/efeitos dos fármacos , Animais , Infecções por Arenaviridae/tratamento farmacológico , Arenavirus/efeitos dos fármacos , Linhagem Celular , Chlorocebus aethiops , Reposicionamento de Medicamentos , Inibidores Enzimáticos/farmacologia , Humanos , Febre Lassa/tratamento farmacológico , Febre Lassa/virologia , Células Vero , Proteínas Virais de Fusão/efeitos dos fármacos , Proteínas Quinases p38 Ativadas por Mitógeno/antagonistas & inibidores , Proteínas Quinases p38 Ativadas por Mitógeno/metabolismoRESUMO
Hemorrhagic fevers (HF) resulting from pathogenic arenaviral infections have traditionally been neglected as tropical diseases primarily affecting African and South American regions. There are currently no FDA-approved vaccines for arenaviruses, and treatments have been limited to supportive therapy and use of non-specific nucleoside analogs, such as Ribavirin. Outbreaks of arenaviral infections have been limited to certain geographic areas that are endemic but known cases of exportation of arenaviruses from endemic regions and socioeconomic challenges for local control of rodent reservoirs raise serious concerns about the potential for larger outbreaks in the future. This review synthesizes current knowledge about arenaviral evolution, ecology, transmission patterns, life cycle, modulation of host immunity, disease pathogenesis, as well as discusses recent development of preventative and therapeutic pursuits against this group of deadly viral pathogens.
Assuntos
Infecções por Arenaviridae , Arenavirus/imunologia , Surtos de Doenças , Febres Hemorrágicas Virais , Tolerância Imunológica , Ribavirina/uso terapêutico , África/epidemiologia , Infecções por Arenaviridae/tratamento farmacológico , Infecções por Arenaviridae/epidemiologia , Infecções por Arenaviridae/imunologia , Febres Hemorrágicas Virais/tratamento farmacológico , Febres Hemorrágicas Virais/epidemiologia , Febres Hemorrágicas Virais/imunologia , Humanos , América do Sul/epidemiologiaRESUMO
Arenaviruses are a large family of emerging enveloped negative-strand RNA viruses that include several causative agents of viral hemorrhagic fevers. For cell entry, human-pathogenic arenaviruses use different cellular receptors and endocytic pathways that converge at the level of acidified late endosomes, where the viral envelope glycoprotein mediates membrane fusion. Inhibitors of arenavirus entry hold promise for therapeutic antiviral intervention and the identification of "druggable" targets is of high priority. Using a recombinant vesicular stomatitis virus pseudotype platform, we identified the clotrimazole-derivative TRAM-34, a highly selective antagonist of the calcium-activated potassium channel KCa3.1, as a specific entry inhibitor for arenaviruses. TRAM-34 specifically blocked entry of most arenaviruses, including hemorrhagic fever viruses, but not Lassa virus and other enveloped viruses. Anti-arenaviral activity was likewise observed with the parental compound clotrimazole and the derivative senicapoc, whereas structurally unrelated KCa3.1 inhibitors showed no antiviral effect. Deletion of KCa3.1 by CRISPR/Cas9 technology did not affect the antiarenaviral effect of TRAM-34, indicating that the observed antiviral effect of clotrimazoles was independent of the known pharmacological target. The drug affected neither virus-cell attachment, nor endocytosis, suggesting an effect on later entry steps. Employing a quantitative cell-cell fusion assay that bypasses endocytosis, we demonstrate that TRAM-34 specifically inhibits arenavirus-mediated membrane fusion. In sum, we uncover a novel antiarenaviral action of clotrimazoles that currently undergo in vivo evaluation in the context of other human diseases. Their favorable in vivo toxicity profiles and stability opens the possibility to repurpose clotrimazole derivatives for therapeutic intervention against human-pathogenic arenaviruses.IMPORTANCE Emerging human-pathogenic arenaviruses are causative agents of severe hemorrhagic fevers with high mortality and represent serious public health problems. The current lack of a licensed vaccine and the limited treatment options makes the development of novel antiarenaviral therapeutics an urgent need. Using a recombinant pseudotype platform, we uncovered that clotrimazole drugs, in particular TRAM-34, specifically inhibit cell entry of a range of arenaviruses, including important emerging human pathogens, with the exception of Lassa virus. The antiviral effect was independent of the known pharmacological drug target and involved inhibition of the unusual membrane fusion mechanism of arenaviruses. TRAM-34 and its derivatives currently undergo evaluation against a number of human diseases and show favorable toxicity profiles and high stability in vivo Our study provides the basis for further evaluation of clotrimazole derivatives as antiviral drug candidates. Their advanced stage of drug development will facilitate repurposing for therapeutic intervention against human-pathogenic arenaviruses.
Assuntos
Antivirais/farmacologia , Arenavirus/efeitos dos fármacos , Clotrimazol/farmacologia , Fusão de Membrana/efeitos dos fármacos , Células A549 , Animais , Infecções por Arenaviridae/tratamento farmacológico , Linhagem Celular , Linhagem Celular Tumoral , Chlorocebus aethiops , Endocitose/efeitos dos fármacos , Células HEK293 , Células HeLa , Febres Hemorrágicas Virais/tratamento farmacológico , Febres Hemorrágicas Virais/virologia , Humanos , Canais de Potássio Ativados por Cálcio de Condutância Intermediária/metabolismo , Vírus Lassa/efeitos dos fármacos , Células Vero , Proteínas do Envelope Viral/metabolismo , Ligação Viral/efeitos dos fármacos , Internalização do Vírus/efeitos dos fármacosRESUMO
Regulatory T cells (Tregs) play a cardinal role in the immune system by suppressing detrimental autoimmune responses, but their role in acute, chronic infectious diseases and tumor microenvironment remains unclear. We recently demonstrated that IFN-α/ß receptor (IFNAR) signaling promotes Treg function in autoimmunity. Here we dissected the functional role of IFNAR-signaling in Tregs using Treg-specific IFNAR deficient (IFNARfl/flxFoxp3YFP-Cre) mice in acute LCMV Armstrong, chronic Clone-13 viral infection, and in tumor models. In both viral infection and tumor models, IFNARfl/flxFoxp3YFP-Cre mice Tregs expressed enhanced Treg associated activation antigens. LCMV-specific CD8+ T cells and tumor infiltrating lymphocytes from IFNARfl/flxFoxp3YFP-Cre mice produced less antiviral and antitumor IFN-γ and TNF-α. In chronic viral model, the numbers of antiviral effector and memory CD8+ T cells were decreased in IFNARfl/flxFoxp3YFP-Cre mice and the effector CD4+ and CD8+ T cells exhibited a phenotype compatible with enhanced exhaustion. IFNARfl/flxFoxp3YFP-Cre mice cleared Armstrong infection normally, but had higher viral titers in sera, kidneys and lungs during chronic infection, and higher tumor burden than the WT controls. The enhanced activated phenotype was evident through transcriptome analysis of IFNARfl/flxFoxp3YFP-Cre mice Tregs during infection demonstrated differential expression of a unique gene signature characterized by elevated levels of genes involved in suppression and decreased levels of genes mediating apoptosis. Thus, IFN signaling in Tregs is beneficial to host resulting in a more effective antiviral response and augmented antitumor immunity.
Assuntos
Infecções por Arenaviridae/imunologia , Neoplasias do Colo/imunologia , Interferon Tipo I/farmacologia , Coriomeningite Linfocítica/imunologia , Melanoma Experimental/imunologia , Linfócitos T Reguladores/imunologia , Microambiente Tumoral/imunologia , Animais , Antivirais/farmacologia , Infecções por Arenaviridae/tratamento farmacológico , Infecções por Arenaviridae/metabolismo , Infecções por Arenaviridae/virologia , Linfócitos T CD8-Positivos/efeitos dos fármacos , Linfócitos T CD8-Positivos/imunologia , Linfócitos T CD8-Positivos/metabolismo , Células Cultivadas , Neoplasias do Colo/tratamento farmacológico , Neoplasias do Colo/metabolismo , Neoplasias do Colo/virologia , Imunidade Inata/efeitos dos fármacos , Imunidade Inata/imunologia , Interferon gama/metabolismo , Coriomeningite Linfocítica/tratamento farmacológico , Coriomeningite Linfocítica/metabolismo , Coriomeningite Linfocítica/virologia , Vírus da Coriomeningite Linfocítica/efeitos dos fármacos , Melanoma Experimental/tratamento farmacológico , Melanoma Experimental/metabolismo , Melanoma Experimental/virologia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Receptor de Interferon alfa e beta/fisiologia , Transdução de Sinais/efeitos dos fármacos , Linfócitos T Reguladores/efeitos dos fármacos , Linfócitos T Reguladores/metabolismo , Linfócitos T Reguladores/virologia , Microambiente Tumoral/efeitos dos fármacosRESUMO
Several arenaviruses cause hemorrhagic fever (HF) disease in humans and represent important public health problems in their endemic regions. In addition, evidence indicates that the worldwide-distributed prototypic arenavirus lymphocytic choriomeningitis virus is a neglected human pathogen of clinical significance. There are no licensed arenavirus vaccines, and current antiarenavirus therapy is limited to an off-label use of ribavirin that is only partially effective. Therefore, there is an unmet need for novel therapeutics to combat human pathogenic arenaviruses, a task that will be facilitated by the identification of compounds with antiarenaviral activity that could serve as probes to identify arenavirus-host interactions suitable for targeting, as well as lead compounds to develop future antiarenaviral drugs. Screening of a combinatorial library of Krönhke pyridines identified compound KP-146 [(5-(5-(2,3-dihydrobenzo[ b][1,4] dioxin-6-yl)-4'-methoxy-[1,1'-biphenyl]-3-yl)thiophene-2-carboxamide] as having strong anti-lymphocytic choriomeningitis virus (LCMV) activity in cultured cells. KP-146 did not inhibit LCMV cell entry but rather interfered with the activity of the LCMV ribonucleoprotein (vRNP) responsible for directing virus RNA replication and gene transcription, as well as with the budding process mediated by the LCMV matrix Z protein. LCMV variants with increased resistance to KP-146 did not emerge after serial passages in the presence of KP-146. Our findings support the consideration of Kröhnke pyridine scaffold as a valuable source to identify compounds that could serve as tools to dissect arenavirus-host interactions, as well as lead candidate structures to develop antiarenaviral drugs.
Assuntos
Antivirais/farmacologia , Arenavirus/efeitos dos fármacos , Mineração de Dados , Descoberta de Drogas , Piridinas/farmacologia , Bibliotecas de Moléculas Pequenas , Animais , Antivirais/síntese química , Antivirais/química , Infecções por Arenaviridae/tratamento farmacológico , Infecções por Arenaviridae/virologia , Arenavirus/fisiologia , Linhagem Celular , Técnicas de Química Sintética , Chlorocebus aethiops , Relação Dose-Resposta a Droga , Desenho de Fármacos , Descoberta de Drogas/métodos , Avaliação Pré-Clínica de Medicamentos , Vírus da Coriomeningite Linfocítica/efeitos dos fármacos , Piridinas/síntese química , Piridinas/química , Células Vero , Replicação Viral/efeitos dos fármacosRESUMO
Arenavirus is a genetic term for viruses belonging to the family Arenaviridae and is presented from lymphocytic choriomeningitis virus (LCMV), which shows almost no pathogenicity to humans, to Lassa virus, Junin virus, Machupo virus, Chapare virus, Lujo virus, Sabia virus, and Guanarito virus, which shows high pathogenicity to humans. These viruses except for LCMV are risk group 4 pathogens specified by World Health Organization. Based on this designation, it is designated as Class I pathogens in Japan. Although there have been no reports excluding one imported case of the Lassa fever patient, it is not surprising whenever imported cases occur in our country. Considering the disease severity and mortality rate, it is an urgent matter to develop vaccines and therapeutic drugs in endemic areas, and maintenances of these are also important in countries other than endemic areas. However, basic research on highly pathogenic arenavirus infections and development of therapeutic drugs are not easily progressed, because handling in highly safe research facilities is indispensable. In this article, we will outline the current knowledge from the recent basic research on arenavirus to the development situation of antivirals against arenaviruses.
Assuntos
Antivirais , Infecções por Arenaviridae/tratamento farmacológico , Infecções por Arenaviridae/virologia , Arenavirus/classificação , Arenavirus/patogenicidade , Descoberta de Drogas , África Ocidental/epidemiologia , Infecções por Arenaviridae/epidemiologia , Infecções por Arenaviridae/prevenção & controle , Arenavirus/genética , Arenavirus/fisiologia , Surtos de Doenças , Descoberta de Drogas/tendências , Genoma Viral/genética , Humanos , Pesquisa/tendências , Transcrição Gênica , Vacinas Virais , VírionRESUMO
INTRODUCTION: Arenaviruses are enveloped negative stranded viruses endemic in Africa, Europe and the Americas. Several arenaviruses cause severe viral hemorrhagic fever with high mortality in humans and pose serious public health threats. So far, there are no FDA-approved vaccines and therapeutic options are restricted to the off-label use of ribavirin. The major human pathogenic arenaviruses are classified as Category A agents and require biosafety level (BSL)-4 containment. AREAS COVERED: Herein, the authors cover the recent progress in the development of BSL2 surrogate systems that recapitulate the entire or specific steps of the arenavirus life cycle and are serving as powerful platforms for drug discovery. Furthermore, they highlight the identification of selected novel drugs that target individual steps of arenavirus multiplication describing their discovery, their targets, and mode of action. EXPERT OPINION: The lack of effective drugs against arenaviruses is an unmatched challenge in current medical virology. Novel technologies have provided important insights into the basic biology of arenaviruses and the mechanisms underlying virus-host cell interaction. Significant progress of our understanding of how the virus invades the host cell paved the way to develop powerful novel screening platforms. Recent efforts have provided a range of promising drug candidates currently under evaluation for therapeutic intervention in vivo.
Assuntos
Antivirais/uso terapêutico , Infecções por Arenaviridae/tratamento farmacológico , Descoberta de Drogas/métodos , Animais , Antivirais/farmacologia , Infecções por Arenaviridae/epidemiologia , Infecções por Arenaviridae/virologia , Arenavirus/isolamento & purificação , Desenho de Fármacos , Humanos , Vacinas Virais/administração & dosagemRESUMO
The family Arenaviridae currently comprises over 20 viral species, each of them associated with a main rodent species as the natural reservoir and in one case possibly phyllostomid bats. Moreover, recent findings have documented a divergent group of arenaviruses in captive alethinophidian snakes. Human infections occur through mucosal exposure to aerosols or by direct contact of abraded skin with infectious materials. Arenaviruses merit interest both as highly tractable experimental model systems to study acute and persistent infections and as clinically important human pathogens including Lassa (LASV) and Junin (JUNV) viruses, the causative agents of Lassa and Argentine hemorrhagic fevers (AHFs), respectively, for which there are no FDA-licensed vaccines, and current therapy is limited to an off-label use of ribavirin (Rib) that has significant limitations. Arenaviruses are enveloped viruses with a bi-segmented negative strand (NS) RNA genome. Each genome segment, L (ca 7.3 kb) and S (ca 3.5 kb), uses an ambisense coding strategy to direct the synthesis of two polypeptides in opposite orientation, separated by a noncoding intergenic region (IGR). The S genomic RNA encodes the virus nucleoprotein (NP) and the precursor (GPC) of the virus surface glycoprotein that mediates virus receptor recognition and cell entry via endocytosis. The L genome RNA encodes the viral RNA-dependent RNA polymerase (RdRp, or L polymerase) and the small (ca 11 kDa) RING finger protein Z that has functions of a bona fide matrix protein including directing virus budding. Arenaviruses were thought to be relatively stable genetically with intra- and interspecies amino acid sequence identities of 90-95 % and 44-63 %, respectively. However, recent evidence has documented extensive arenavirus genetic variability in the field. Moreover, dramatic phenotypic differences have been documented among closely related LCMV isolates. These data provide strong evidence of viral quasispecies involvement in arenavirus adaptability and pathogenesis. Here, we will review several aspects of the molecular biology of arenaviruses, phylogeny and evolution, and quasispecies dynamics of arenavirus populations for a better understanding of arenavirus pathogenesis, as well as for the development of novel antiviral strategies to combat arenavirus infections.
Assuntos
Infecções por Arenaviridae/virologia , Arenavirus/genética , Evolução Molecular , Animais , Antivirais/farmacologia , Infecções por Arenaviridae/tratamento farmacológico , Arenavirus/classificação , Arenavirus/efeitos dos fármacos , Arenavirus/fisiologia , Variação Genética , Genoma Viral , Humanos , Filogenia , Replicação ViralRESUMO
BACKGROUND: In 2008 a nosocomial outbreak of five cases of viral hemorrhagic fever due to a novel arenavirus, Lujo virus, occurred in Johannesburg, South Africa. Lujo virus is only the second pathogenic arenavirus, after Lassa virus, to be recognized in Africa and the first in over 40 years. Because of the remote, resource-poor, and often politically unstable regions where Lassa fever and other viral hemorrhagic fevers typically occur, there have been few opportunities to undertake in-depth study of their clinical manifestations, transmission dynamics, pathogenesis, or response to treatment options typically available in industrialized countries. METHODS AND FINDINGS: We describe the clinical features of five cases of Lujo hemorrhagic fever and summarize their clinical management, as well as providing additional epidemiologic detail regarding the 2008 outbreak. Illness typically began with the abrupt onset of fever, malaise, headache, and myalgias followed successively by sore throat, chest pain, gastrointestinal symptoms, rash, minor hemorrhage, subconjunctival injection, and neck and facial swelling over the first week of illness. No major hemorrhage was noted. Neurological signs were sometimes seen in the late stages. Shock and multi-organ system failure, often with evidence of disseminated intravascular coagulopathy, ensued in the second week, with death in four of the five cases. Distinctive treatment components of the one surviving patient included rapid commencement of the antiviral drug ribavirin and administration of HMG-CoA reductase inhibitors (statins), N-acetylcysteine, and recombinant factor VIIa. CONCLUSIONS: Lujo virus causes a clinical syndrome remarkably similar to Lassa fever. Considering the high case-fatality and significant logistical impediments to controlled treatment efficacy trials for viral hemorrhagic fever, it is both logical and ethical to explore the use of the various compounds used in the treatment of the surviving case reported here in future outbreaks. Clinical observations should be systematically recorded to facilitate objective evaluation of treatment efficacy. Due to the risk of secondary transmission, viral hemorrhagic fever precautions should be implemented for all cases of Lujo virus infection, with specialized precautions to protect against aerosols when performing enhanced-risk procedures such as endotracheal intubation.