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Introduction. Dengue is a viral infection that may be asymptomatic or include severe manifestations. This study aims to describe the characteristics of a pediatric population during the epidemic outbreak in 2023. Population and methods. This cross-sectional study included patients with probable or confirmed dengue fever who were seen from March 13, 2023, to May 19, 2023, in a pediatric hospital in the Autonomous City of Buenos Aires. Results. A total of 112 patients were included. The median age was 12 years; 58% were male. Seventy-six percent of them came from the City of Buenos Aires. Twenty-five percent had cohabitants with symptoms compatible with a suspected case. The most frequent clinical manifestations were fever, headache, retro-ocular pain, myalgia, and arthralgia. The most frequent laboratory alterations were leukopenia (65%) and elevated transaminases (60%). Twenty-one percent (24/112) presented alarm signs and required hospitalization. Leukopenia, plateletopenia, and elevated transaminases were associated with the presence of alarm signs. RT-PCR was detected in fifty-three patients; serotype 2 was the most frequent. Twenty-one patients had positive NS1 tests, 18 patients had positive IgM, and 20 patients with clinical and epidemiological links were assumed to be probable dengue cases. There were no cases of severe dengue. Conclusion. Early clinical suspicion and recognition of laboratory parameters associated with alarm signs are essential for an adequate approach to the disease and early supportive treatment during dengue infection.
Introducción. El dengue es una infección viral que puede cursar de forma asintomática o incluir manifestaciones graves. El objetivo del trabajo es describir las características de una población pediátrica durante el brote epidémico del 2023. Población y métodos. Estudio de corte transversal que incluyó pacientes con dengue probable o confirmado atendidos del 13 de marzo de 2023 al 19 de mayo de 2023 en un hospital pediátrico de la Ciudad Autónoma de Buenos Aires. Resultados. Se incluyeron 112 pacientes. La mediana de edad fue 12 años; el 58 % fueron varones. El 76 % procedía de la Ciudad Autónoma de Buenos Aires. El 25 % tenía convivientes con sintomatología compatible con caso sospechoso. Las manifestaciones clínicas más frecuentes fueron fiebre, cefalea con dolor retroocular y mioartralgias. Las alteraciones de laboratorio más frecuentes fueron la leucopenia (65 %) y la elevación de transaminasas (60 %). El 21 % (24/112) presentó signos de alarma y requirió internación. La leucopenia, la plaquetopenia y el aumento de transaminasas se asociaron con la presencia de signos de alarma. Se confirmaron 53 pacientes por PCR-RT detectable, el serotipo 2 fue el más frecuente. Se asumieron como casos probables de dengue 21 pacientes con prueba NS1 positiva, 18 pacientes con IgM positiva y 20 pacientes con clínica y nexo epidemiológico. No hubo casos de dengue grave. Conclusión. Durante la infección por dengue, la sospecha clínica precoz y el reconocimiento de los parámetros de laboratorio asociados a los signos de alarma resultan esenciales para un adecuado abordaje de la enfermedad y un tratamiento de sostén precoz.
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BACKGROUND: Humoral immune response against the pre-fusion (pre-F) conformation of respiratory syncytial virus (RSV) F protein has been proposed to play a protective role against infection. An RSV pre-F maternal vaccine has been recently approved in several countries to protect young infants against RSV. We aimed to assess serum IgG titers against the pre-F and post-F conformations of RSV F protein and their association with life-threatening RSV disease (LTD) in previously healthy infants. METHODS: A prospective cohort study including hospitalized infants <12 months with a first RSV infection was conducted during 2017-2019. Patients with LTD required intensive care and mechanical respiratory assistance. RSV pre-F exclusive and post-F antibody responses were determined by post-F competition and non-competition immunoassays, respectively, and neutralizing activity was measured by plaque reduction neutralization test. RESULTS: Fifty-eight patients were included; the median age was 3.5 months and 41 % were females. Fifteen patients developed LTD. RSV F-specific antibody titers positively correlated with neutralizing antibody titers in acute and convalescent phases but, importantly, they did not associate with LTD. Acute RSV pre-F exclusive and post-F IgG titers negatively correlated with patient age (P = 0.0007 and P < 0.0001), while a positive correlation was observed between the fold changes in RSV F-specific antibody titers between convalescent and acute phase and patient age (P = 0.0014 and P < 0.0001). Infants ≤2 months exhibited significantly lower fold-changes in RSV F-specific and neutralizing antibody titers between convalescence and acute phase than older infants. Additionally, acute RSV antibody titers showed no correlation with nasal RSV load and, furthermore, nasal viral load was not associated with the development of LTD. CONCLUSIONS: This study highlights that protection against life-threatening RSV disease is not necessarily antibody-dependent. Further characterization of the immune response against RSV and its role in protection against severe disease is important for the development of the safest possible preventive strategies.
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Anticorpos Neutralizantes , Anticorpos Antivirais , Imunoglobulina G , Infecções por Vírus Respiratório Sincicial , Vírus Sincicial Respiratório Humano , Proteínas Virais de Fusão , Humanos , Infecções por Vírus Respiratório Sincicial/imunologia , Infecções por Vírus Respiratório Sincicial/prevenção & controle , Feminino , Lactente , Anticorpos Antivirais/sangue , Anticorpos Antivirais/imunologia , Proteínas Virais de Fusão/imunologia , Estudos Prospectivos , Vírus Sincicial Respiratório Humano/imunologia , Masculino , Anticorpos Neutralizantes/imunologia , Anticorpos Neutralizantes/sangue , Imunoglobulina G/sangue , Imunoglobulina G/imunologia , Conformação Proteica , Vacinas contra Vírus Sincicial Respiratório/imunologia , Recém-NascidoRESUMO
BACKGROUND: During the American epidemic, Zika virus (ZIKV) expanded rapidly through dengue virus (DENV)-endemic regions. We analyzed the presentation of ZIKV infection in patients from the City of Orán, Argentina, and compared some of its features with dengue presentation in the same region. METHODS: A retrospective study was conducted at San Vicente de Paul Hospital during 2016-2018. Clinical and demographic characteristics, pre-existing immunity to DENV, viral load and type I interferon (IFN) responses were studied in 63 patients with ZIKV infection. RESULTS: Clinical manifestations of ZIKV infection were generally mild compared with dengue, although rash (p<0.001) and itching (p<0.001) were significantly more prevalent in ZIKV patients. ZIKV patients aged <15 y manifested relatively mild disease compared with older ZIKV patients, showing a decreased prevalence of headache (p=0.008), retro-orbital pain (p=0.001) and arthralgia (p=0.001). Increased Zika incidence was observed in female patients (60.3%). Serum viral load was low to undetectable in ZIKV patients and was not associated with serum anti-DENV IgG titers. Interferon-α and IFN-ß serum levels did not correlate with serum viral load in ZIKV patients. CONCLUSIONS: Clinical presentation of ZIKV and DENV infections is largely overlapping, presenting a challenge for diagnosis and risk assessment for uniquely at-risk populations.
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Vírus da Dengue , Dengue , Infecção por Zika virus , Zika virus , Humanos , Feminino , Infecção por Zika virus/diagnóstico , Infecção por Zika virus/epidemiologia , Dengue/diagnóstico , Estudos Retrospectivos , Argentina/epidemiologia , Surtos de Doenças , Anticorpos Antivirais , Reações CruzadasRESUMO
BACKGROUND: Coronavirus disease 2019 (COVID-19) is usually mild and self-limited in children. However, a few Severe acute respiratory syndrome coronavirus 2 (SARS-CoV2) infections in children may progress to severe disease with respiratory distress or can result in a multisystem inflammatory syndrome (MIS-C) associated with COVID-19. The immune mechanisms for these differential clinical outcomes are largely unknown. METHODS: A prospective cohort study was performed to analyze the laboratory parameters, antibody response, immune phenotypes and cytokine profiles of 51 children with different clinical presentations of COVID-19. RESULTS: We found that the absolute lymphocyte counts gradually decreased with disease severity. Furthermore, SARS-CoV-2 IgG levels in the acute phase and convalescence were not significantly different in patients with different disease severity. A decrease in CD3 + , CD4 + and CD8 + T cells was observed as disease severity increased. Both CD4 + and CD8 + T cells were activated in children with COVID-19, but no difference in the percentage of HLADR + -expressing cells was detected across the severity groups. In contrast, MIS-C patients exhibited augmented exhausted effector memory CD8 + T cells. Interestingly, the cytokine profile in sera of moderate/severe and MIS-C patients revealed an increase in anti-inflammatory IL-1RA and a suppression of tumor necrosis factor-α, RANTES, eotaxin and PDGF-BB. MIS-C patients also exhibited augmented IL-1ß. CONCLUSIONS: We report distinct immune profiles dependent on severity in pediatric COVID-19 patients. Further investigation in a larger population will help unravel the immune mechanisms underlying pediatric COVID-19.
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COVID-19 , Citocinas , Becaplermina , COVID-19/complicações , COVID-19/imunologia , Quimiocina CCL5 , Citocinas/imunologia , Humanos , Imunoglobulina G , Proteína Antagonista do Receptor de Interleucina 1 , Fenótipo , Estudos Prospectivos , RNA Viral , SARS-CoV-2 , Síndrome de Resposta Inflamatória Sistêmica , Fator de Necrose Tumoral alfaRESUMO
INTRODUCTION: Dengue virus (DENV) is the causative agent of the most prevalent human disease transmitted by mosquitoes in tropical and subtropical regions worldwide. At present, no antiviral drug is available and the difficulties to develop highly protective vaccines against the four DENV serotypes maintain the requirement of effective options for dengue chemotherapy. AREAS COVERED: The availability of animal models that reproduce human disease is a very valuable tool for the preclinical evaluation of potential antivirals. Here, the main murine models of dengue infection are described, including immunocompetent wild-type mice, immunocompromised mice deficient in diverse components of the interferon (IFN) pathway and humanized mice. The main findings in antiviral testing of DENV inhibitory compounds in murine models are also presented. EXPERT OPINION: At present, there is no murine model that fully recapitulates human disease. However, immunocompromised mice deficient in IFN-α/ß and -γ receptors, with their limitations, have shown to be the most suitable system for antiviral preclinical testing. In fact, the AG129 mouse model allowed the identification of celgosivir, an inhibitor of cellular glucosidases, as a promising option for DENV therapy. However, clinical trials still were not successful, emphasizing the difficulties in the transition from preclinical testing to human treatment.
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Vírus da Dengue , Dengue , Animais , Antivirais/farmacologia , Antivirais/uso terapêutico , Dengue/prevenção & controle , Modelos Animais de Doenças , Descoberta de Drogas , Humanos , CamundongosRESUMO
BACKGROUND: Genetic background may be an important host determinant of respiratory syncytial virus (RSV) disease severity, but full characterization of susceptibility genes remains unclear. This study aimed to assess the presence of specific single-nucleotide polymorphisms (SNPs) in selected genes codifying for different components of the antiviral innate immune response, to determine their role for developing RSV life-threatening disease (LTD). METHODS: Prospective cohort study including previously healthy full-term infants hospitalized with a first RSV infection during 2017-2018. RSV detection, quantification and subgroup determination, and genotyping for SNPs in Toll-like receptor 4 (TLR4 rs4986790, rs4986791), Toll-like receptor 8 (TLR8 rs3761624), macrophage receptor with collagenous structure(MARCO rs1318645) and myxovirus resistance 1(MX1 rs469390) were performed by real-time polymerase chain reaction in nasopharyngeal aspirates obtained on admission. Patients with LTD were those admitted to the intensive care unit requiring ventilatory support. RESULTS: Seventy-five patients were studied, 15 (20%) developed LTD. Infants with concurrent SNPs in MX1 and TLR8, MARCO and TLR8 or MARCO, MX1 and TLR8 had an increased risk of developing LTD. Multivariable logistic regression analysis confirmed this significant association (odds ratio [OR] = 3.75, P = 0.046; OR = 3.92, P = 0.040; OR = 5.56, P = 0.010, respectively). No differences were seen in viral load of patients with LTD compared with those with better outcome (P = 0.737). In addition, no differences in viral load were seen in patients with the described high-risk SNPs compared with those without these polymorphisms. CONCLUSIONS: Life-threatening RSV infection in previously healthy infants was significantly associated with the presence of combined SNPs in MARCO, MX1 and TLR8.
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Predisposição Genética para Doença , Polimorfismo de Nucleotídeo Único , Infecções por Vírus Respiratório Sincicial/genética , Criança Hospitalizada , Feminino , Humanos , Imunidade Inata , Lactente , Masculino , Proteínas de Resistência a Myxovirus/genética , Estudos Prospectivos , Receptores Imunológicos/genética , Infecções por Vírus Respiratório Sincicial/imunologia , Receptor 4 Toll-Like/genética , Receptor 8 Toll-Like/genética , Carga ViralRESUMO
Type I interferons (IFN-I) are a group of related proteins that help regulate the activity of the immune system and play a key role in host defense against viral infections. Upon infection, the IFN-I are rapidly secreted and induce a wide range of effects that not only act upon innate immune cells but also modulate the adaptive immune system. While IFN-I and many IFN stimulated genes are well-known for their protective antiviral role, recent studies have associated them with potential pathogenic functions. In this review, we summarize the current knowledge regarding the complex effects of human IFN-I responses in respiratory as well as reemerging flavivirus infections of public health significance and the molecular mechanisms by which viral proteins antagonize the establishment of an antiviral host defense. Antiviral effects and immune modulation of IFN-stimulated genes is discussed in resisting and controlling pathogens. Understanding the mechanisms of these processes will be crucial in determining how viral replication can be effectively controlled and in developing safe and effective vaccines and novel therapeutic strategies.
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Antivirais/metabolismo , Flavivirus/fisiologia , Interferon Tipo I/metabolismo , Infecções Respiratórias/imunologia , Vacinas Virais/imunologia , Viroses/imunologia , Animais , Humanos , Imunidade Inata , Saúde Pública , Vacinação , Replicação ViralRESUMO
OBJECTIVE: Delineate risk factors associated with severe hypoxemia (O2 sat ≤87%) in infants and children younger than 2 years hospitalized with single pathogen HRV infection. STUDY DESIGN: Prospective study in a yearly catchment population of 56 560 children <2 years old between 2011 and 2013 in Argentina. All children with respiratory signs and O2 sat <93% on admission were included. HRV infections were identified by reverse transcriptase-polymerase chain reaction. Epidemiologic, clinical, viral, and immunological risk factors were assessed. RESULTS: Among 5012 hospitalized patients, HRV was detected as a single pathogen in 347 (6.92%) subjects. Thirty-two (9.2%) had life-threatening disease. Traditional risk factors for severe bronchiolitis did not affect severity of illness. HRV viral load, HRV groups, and type II and III interferons did not associate with severe hypoxemia. Interleukin-13 Levels in respiratory secretions at the time of admission (OR = 7.43 (3-18.4); P < 0.001 for IL-13 >10 pg/mL) predisposed to life-threatening disease. CONCLUSIONS: Targeted interventions against IL-13 should be evaluated to decrease severity of HRV illness in infancy and early childhood.
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Bronquiolite/imunologia , Hipóxia/imunologia , Interleucina-13/imunologia , Infecções por Picornaviridae/imunologia , Infecções Respiratórias/imunologia , Rhinovirus , Argentina/epidemiologia , Bronquiolite/epidemiologia , Bronquiolite/virologia , Feminino , Hospitalização , Humanos , Hipóxia/epidemiologia , Hipóxia/virologia , Lactente , Recém-Nascido , Masculino , Infecções por Picornaviridae/epidemiologia , Infecções por Picornaviridae/virologia , Estudos Prospectivos , Infecções Respiratórias/epidemiologia , Infecções Respiratórias/virologiaRESUMO
Infection by any of the four dengue virus (DENV) serotypes produces a wide spectrum of clinical illness in humans. Differences in clinical manifestation and severity have been associated with secondary heterologous infection, patient age, and virus serotype. In this context, this retrospective study sought to analyze the presentation of dengue in patients during the 2014 DENV-4 outbreak affecting the City of Orán, Salta Province, Argentina. Demographic data, clinical manifestations, and laboratory abnormalities of laboratory-confirmed dengue patients were compared between age groups and between patients with and without warning signs. Of 301 patients with laboratory-confirmed dengue, 37.9% presented dengue with warning signs. Although nearly half of all patients had secondary DENV infections, no severe dengue cases, or deaths were reported. Furthermore, no association was found between incidence of warning signs and pre-existing immunity to DENV. Pediatric patients were least likely to present warning signs and showed significantly decreased risk of fever, retro-orbital pain, arthalgia, diarrhea and thrombocytopenia, and higher risk of rash compared to older patients. Female patients of all ages were also at higher risk of developing several symptoms. The characterization of DENV-4 infection in humans, a DENV serotype recently reported in Argentina, revealed differences in clinical manifestations, laboratory parameters and the presence/absence of warning signs based on age group. Further investigation of these age-related differences should contribute to better assessment of dengue disease in at risk populations.
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Dengue/epidemiologia , Dengue/patologia , Surtos de Doenças , Adolescente , Adulto , Fatores Etários , Idoso , Idoso de 80 Anos ou mais , Argentina/epidemiologia , Criança , Pré-Escolar , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Estudos Retrospectivos , Fatores Sexuais , Adulto JovemRESUMO
BACKGROUND: Infection with dengue virus (DENV) produces a wide spectrum of clinical illness ranging from asymptomatic infection to mild febrile illness, and to severe forms of the disease. Type I interferons (IFNs) represent an initial and essential host defense response against viruses. DENV has been reported to trigger a robust type I IFN response; however, IFN-α/ß profile in the progression of disease is not well characterized. OBJECTIVES AND STUDY DESIGN: In this context, we conducted a retrospective study assessing the circulating serum levels of type I IFNs and related cytokines at different phases of illness in children during the 2011 outbreak of DENV in Paraguay. Demographic, clinical, laboratory and virological data were analyzed. RESULTS: During defervescence, significantly higher levels of IFN-ß, IL-6 and MIP-1ß, were detected in severe vs. non-severe dengue patients. Additionally, a significant positive correlation between INF-α and viremia was detected in children with severe dengue. A significant positive correlation was also observed between IFN-ß serum levels and hematocrit during the febrile phase, whereas IFN-α levels negatively correlated with white blood cells during defervescence in severe dengue patients. Furthermore, previous serologic status of patients to DENV did not influence type I IFN production. CONCLUSIONS: The distinct type I IFN profile in children with dengue and severe dengue, as well as its association with viral load, cytokine production and laboratory manifestations indicate differences in innate and adaptive immune responses that should be investigated further in order to unveil the association of immunological and physiological pathways that underlie in DENV infection.
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Dengue/imunologia , Interferon Tipo I/imunologia , Dengue Grave/imunologia , Imunidade Adaptativa , Adolescente , Criança , Pré-Escolar , Citocinas/sangue , Citocinas/imunologia , Dengue/epidemiologia , Dengue/virologia , Vírus da Dengue/imunologia , Feminino , Hematócrito , Humanos , Imunidade Inata , Interferon Tipo I/sangue , Interferon beta/sangue , Interferon beta/imunologia , Masculino , Paraguai/epidemiologia , Estudos Retrospectivos , Dengue Grave/epidemiologia , Dengue Grave/virologia , Carga Viral , ViremiaRESUMO
RATIONALE: Respiratory syncytial virus (RSV) is the most frequent cause of hospitalization and an important cause of death in infants in the developing world. The relative contribution of social, biologic, and clinical risk factors to RSV mortality in low-income regions is unclear. OBJECTIVES: To determine the burden and risk factors for mortality due to RSV in a low-income population of 84,840 infants. METHODS: This was a prospective, population-based, cross-sectional, multicenter study conducted between 2011 and 2013. Hospitalizations and deaths due to severe lower respiratory tract illness (LRTI) were recorded during the RSV season. All-cause hospital deaths and community deaths were monitored. Risk factors for respiratory failure (RF) and mortality due to RSV were assessed using a hierarchical, logistic regression model. MEASUREMENTS AND MAIN RESULTS: A total of 2,588 (65.5%) infants with severe LRTI were infected with RSV. A total of 157 infants (148 postneonatal) experienced RF or died with RSV. RSV LRTI accounted for 57% fatal LRTI tested for the virus. A diagnosis of sepsis (odds ratio [OR], 17.03; 95% confidence interval [CI], 13.14-21.16 for RF) (OR, 119.39; 95% CI, 50.98-273.34 for death) and pneumothorax (OR, 17.15; 95% CI, 13.07-21.01 for RF) (OR, 65.49; 95% CI, 28.90-139.17 for death) were the main determinants of poor outcomes. CONCLUSIONS: RSV was the most frequent cause of mortality in low-income postneonatal infants. RF and death due to RSV LRTI, almost exclusively associated with prematurity and cardiopulmonary diseases in industrialized countries, primarily affect term infants in a developing world environment. Poor outcomes at hospitals are frequent and associated with the cooccurrence of bacterial sepsis and clinically significant pneumothoraxes.
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Infecções por Vírus Respiratório Sincicial/mortalidade , Vírus Sinciciais Respiratórios , Argentina/epidemiologia , Efeitos Psicossociais da Doença , Estudos Transversais , Feminino , Hospitalização/estatística & dados numéricos , Humanos , Lactente , Modelos Logísticos , Masculino , Pneumotórax/etiologia , Pneumotórax/mortalidade , Estudos Prospectivos , Infecções por Vírus Respiratório Sincicial/complicações , Infecções por Vírus Respiratório Sincicial/diagnóstico , Fatores de Risco , Sepse/etiologia , Sepse/mortalidade , Fatores Sexuais , Fatores SocioeconômicosRESUMO
The λ-carrageenan (λ-car) is a potent and selective inhibitor of dengue virus (DENV) infection targeted to virus adsorption and internalization, due to the structural similarities with the mammalian cell receptor heparan sulfate. To further characterize the antiviral activity of λ-car, the selection and the phenotypic and genomic features of λ-car resistant DENV-2 variants are studied here in comparison to control virus. Resistant variants were rapidly selected in Vero cells after three passages in presence of the drug. No difference was detected in the growth profiles in Vero and C6/36 cells between resistant and control viruses. By contrast, the kinetics of adsorption and internalization of resistant variants in Vero cells was significantly diminished whereas entry to C6/36 cells was unaffected. By plaque purification and sequence analysis of the population, two types of resistant clones were found: some clones presented two mutations in E protein, K126E, and F422L; but other equally λ-car resistant clones had no mutations in E. Furthermore, no mutations were found in other viral proteins like prM, C, or NS1. The genomic disparity in E protein was also associated to differences in phenotype stability. The stable genomic resistance here described provides information about determinants in E protein involved in receptor binding and membrane fusion for uncoating.
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Carragenina/farmacologia , Vírus da Dengue/efeitos dos fármacos , Vírus da Dengue/genética , Farmacorresistência Viral/genética , Mutação , Animais , Antivirais/farmacologia , Linhagem Celular , Chlorocebus aethiops , Vírus da Dengue/fisiologia , Genoma Viral , Genótipo , Fenótipo , Células Vero , Proteínas do Envelope Viral/genética , Proteínas não Estruturais Virais/genética , Proteínas Virais/genética , Replicação Viral/efeitos dos fármacosRESUMO
BACKGROUND: Dengue virus (DENV), a member of the family Flaviviridae, is at present the most widespread causative agent of a human viral disease transmitted by mosquitoes. Despite the increasing incidence of this pathogen, there are no antiviral drugs or vaccines currently available for treatment or prevention. In a previous screening assay, we identified a group of N-allyl acridones as effective virus inhibitors. Here, the antiviral activity and mode of action targeted to viral RNA replication of one of the most active DENV-2 inhibitors was further characterized. RESULTS: The compound 10-allyl-7-chloro-9(10H)-acridone, designated 3b, was active to inhibit the in vitro infection of Vero cells with the four DENV serotypes, with effective concentration 50% (EC50) values in the range 12.5-27.1 µM, as determined by virus yield inhibition assays. The compound was also effective in human HeLa cells. No cytotoxicity was detected at 3b concentrations up to 1000 µM. Mechanistic studies demonstrated that virus entry into the host cell was not affected, whereas viral RNA synthesis was strongly inhibited, as quantified by real time RT-PCR. The addition of exogenous guanosine together with 3b rescued only partially the infectivity of DENV-2. CONCLUSIONS: The acridone derivative 3b selectively inhibits the infection of Vero cells with the four DENV serotypes without a direct interaction with the host cell or the virion but interfering specifically with the intracellular virus multiplication. The mode of antiviral action for this acridone apparently involves the cellular enzyme inosine-monophospahe dehydrogenase together with another still unidentified target related to DENV RNA synthesis.
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Acridonas/farmacologia , Compostos Alílicos/farmacologia , Antivirais/farmacologia , Vírus da Dengue/efeitos dos fármacos , Replicação Viral/efeitos dos fármacos , RNA Viral/metabolismoRESUMO
The aim of the present study was to analyze the influence of virus origin, mammalian or mosquito cell-derived, on antiviral susceptibility of DENV-2 to entry inhibitors and the association of this effect with any alteration in the mode of entry into the cell. To this end, ten serial passages of DENV-2 were performed in mosquito C6/36 cells or monkey Vero cells and the antiviral susceptibility of each virus passage to sulfated polysaccharides (SPs), like heparin and carrageenans, was evaluated by a virus plaque reduction assay. After serial passaging in Vero cells, DENV-2 became increasingly resistant to SP inhibition whereas the antiviral susceptibility was not altered in virus propagated in C6/36 cells. The change in antiviral susceptibility was associated to a differential mode of entry into the host cell. The route of endocytic entry for productive Vero cell infection was altered from a non-classical clathrin independent pathway for C6/36-grown virus to a clathrin-mediated endocytosis when the virus was serially propagated in Vero cells. Our results show the impact of the cellular system used for successive propagation of DENV on the initial interaction between the host cell and the virion in the next round of infection and the relevant consequences it might have during the in vitro evaluation of entry inhibitors.
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Adaptação Biológica , Antivirais/farmacologia , Vírus da Dengue/efeitos dos fármacos , Vírus da Dengue/crescimento & desenvolvimento , Farmacorresistência Viral , Internalização do Vírus/efeitos dos fármacos , Animais , Carragenina/farmacologia , Linhagem Celular , Chlorocebus aethiops , Culicidae , Análise Mutacional de DNA , Endocitose/efeitos dos fármacos , Heparina/farmacologia , Dados de Sequência Molecular , RNA Viral/genética , Análise de Sequência de DNA , Inoculações Seriadas , Ensaio de Placa ViralRESUMO
BACKGROUND: The immune response to dengue virus (DENV) primary infection in infants and young children is not well characterized. In Northern Argentina, >90% of the population was DENV-naïve before the 2009 outbreak, allowing evaluation of age-dependent primary responses to infection. METHODS: We conducted a comparative study of the immune response to DENV in 27 infected infants, young children and their mothers. Lymphocyte T helper (Th) 1, Th2, Th17 and inflammatory responses were assayed in blood during the 2009 DENV-1 epidemic. RESULTS: The immune response to DENV-1 was significantly biased to Th2 in infected infants and young children, compared to infants with other febrile illnesses (for IL-4 p < 0.001) and to their infected mothers (for IL-4 p < 0.01). In addition, IL-17 suppression was observed in the memory response to DENV-1 in infected infants (p < 0.01 vs placebo). CONCLUSION: Age-related differences in the primary response to DENV, characterized by an immature Th2 polarization and Th17 suppression in infants, should be studied further in order to expand our understanding of the mechanism of dengue pathogenesis.
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Vírus da Dengue/imunologia , Dengue/imunologia , Interleucina-17/imunologia , Células Th2/imunologia , Adulto , Anticorpos Neutralizantes/sangue , Anticorpos Antivirais/análise , Argentina/epidemiologia , Pré-Escolar , Citocinas/imunologia , Epidemias , Feminino , Humanos , Imunidade Celular/imunologia , Imunoglobulina G/sangue , Lactente , Recém-Nascido , Masculino , Linfócitos T Auxiliares-Indutores/imunologiaRESUMO
The antiviral activity against dengue virus-2 (DENV-2) of carrageenans reported here has shown a differential susceptibility of C6/36 HT and Vero cells, taken as models of mosquito and mammalian cells, depending on the structural class of polysaccharides: all polysaccharides blocked DENV-2 infection in monkey Vero cells, but only iota-carrageenans were virus inhibitors in mosquito cells. However, iota-carrageenans were less effective in mosquito cells in comparison with mammalian cells with effective concentration 50â% (EC(50)) values in C6/36 HT cells 4.9-17.5-fold higher than in Vero cells, as determined by virus yield reduction assay. The mode of action of iota-carrageenan in both cell types was strikingly different: in Vero cells the inhibitory activity was exerted only at the initiation of the cycle, affecting virion binding, whereas in mosquito cells DENV-2 adsorption was not affected and comparable levels of inhibition were obtained if the compound was added to cells together with the virus, after 8 h of infection or by cell pre-treatment before infection. Furthermore, iota-carrageenans induced a subtle alteration in mosquito cells, detected by cell proliferation and protein synthesis analyses, suggesting that a probable cellular target may be responsible for the refractory state of mosquito cells to DENV-2 infection produced by this class of polysulfates. The failure of iota-carrageenan to block DENV-2 adsorption to mosquito cells appeared to be related to the low presence of adequate heparan sulfate (HS) in C6/36 HT cell surface and is indicative of a differential participation of HS residues for DENV-2 entry in both types of cells.
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Carragenina/farmacologia , Vírus da Dengue/efeitos dos fármacos , Animais , Linhagem Celular , Chlorocebus aethiops , Culicidae , Dengue/virologia , Vírus da Dengue/fisiologia , Células Vero , Replicação Viral/efeitos dos fármacosRESUMO
Herein we describe the synthesis of 1,2,4-triazolyl-3-thione;1,3,4-oxadiazole, and imidazo[2,1-b]thiazole derivatives from carbohydrates. The antiviral activity of these compounds was tested against Dengue and Junin virus (the etiological agent of Argentine hemorrhagic fever). The 3-(p-bromobenzoyl)-5-(1,2-O-isopropylidene-3-O-methyl-alpha-d-xylofuranos-5-ulos-5-yl)imidazo[2,1-b]thiazole was able to inhibit the replication of both viruses in Vero cells at concentration significantly lower than the CC(50).
Assuntos
Antivirais/síntese química , Antivirais/farmacologia , Azóis/síntese química , Azóis/farmacologia , Carboidratos/química , Vírus da Dengue/efeitos dos fármacos , Vírus Junin/efeitos dos fármacos , Animais , Antivirais/toxicidade , Azóis/química , Azóis/toxicidade , Chlorocebus aethiops , Concentração Inibidora 50 , Testes de Toxicidade , Células Vero/efeitos dos fármacosRESUMO
The DL-galactan hybrid C2S-3, isolated from the red seaweed Cryptonemia crenulata (Halymeniaceae, Halymeniales), is a potent and selective inhibitor of the multiplication of diverse strains of DENV-2 in Vero cells with higher effectiveness than the reference polysaccharide heparin. The presence of the compound either only at virus adsorption or at virus internalization exerted a significant and dose-dependent inhibition in DENV-2 plaque number. The compound failed to inactivate DENV-2 directly by incubation of virus before cell infection as well as to induce a refractory state by cell pretreatment. Thus, the inhibitory effect was exclusively exerted through a blockade in virus multiplication during the infectious process. When the entry of DENV-2 particles into the cell is bypassed, as occurs in virus RNA transfection, the polysaccharide C2S-3 failed to block the completion of the multiplication cycle. Furthermore, the antiviral properties of C2S-3 are not correlated with anticoagulant activity.
Assuntos
Antivirais/farmacologia , Vírus da Dengue/efeitos dos fármacos , Eucariotos/química , Galactanos/farmacologia , Animais , Antivirais/química , Chlorocebus aethiops , Relação Dose-Resposta a Droga , Galactanos/química , Estrutura Molecular , Células VeroRESUMO
This study demonstrated that the lambda- and iota-carrageenans, sulfated polysaccharides containing linear chains of galactopyranosyl residues, are potent inhibitors of dengue virus type 2 (DENV-2) and 3 (DENV-3) multiplication in Vero and HepG2 cells, with values of effective concentration 50% from 0.14 to 4.1 microg/ml. This activity was assayed by plaque reduction, virus yield inhibition and antigen expression tests, and was independent of the input multiplicity of infection in the range 0.001-1. The inhibitory action of the lambda-carrageenan, an heparan sulfate (HS)-imitative compound, was exerted by a dual interference with virus adsorption and internalization of nucleocapsid into the cytoplasm. Although virus particles may enter the cell when compound was added after DENV-2 adsorption, as shown by intracellular uptake of radiolabeled DENV-2 particles and quantitative RT-PCR, infectious center and virion uncoating assays have shown that carrageenan-treated virions cannot be released from the endosomes. Viral protein synthesis, the first step of macromolecular synthesis after DENV entry to the host cell, was not affected by the carrageenan. Furthermore, no inhibition of virus multiplication was detected when the entry process was bypassed through DENV-2 RNA transfection into the cell. The dual sites of action of an HS-like molecule suggest that, at least in monkey kidney and human hepatic cells, the HS residues in the cell membrane appear to act as mediators for DENV-2 entry, an interesting alternative target for flavivirus therapy.
Assuntos
Carragenina/farmacologia , Vírus da Dengue/efeitos dos fármacos , Dengue/virologia , Animais , Carragenina/química , Linhagem Celular , Vírus da Dengue/fisiologia , Relação Dose-Resposta a Droga , Humanos , Replicação Viral/efeitos dos fármacosRESUMO
The replication of herpes simplex virus (HSV) type 1 in Vero cells is inhibited in the presence of (22S,23S)-3beta-bromo-5alpha,22,23-trihydroxystigmastan-6-one (6b), a synthetic brassinosteroid derivative. Since a late step of virus multiplication is hindered by 6b, we performed studies of drug-drug combination with acyclovir (ACV) and foscarnet (FOS). It was determined that 6b would act synergistically with low concentrations of ACV and moderate concentrations of FOS against HSV. The best drug combination tested in this study resulted in an increase of 29.3 and 47.2% in antiviral activity for ACV (0.036 microM) and FOS (37.5 microM) in the presence of 14.8 and 6.9 microM of 6b, respectively.