RESUMEN

The COVID-19 pandemic caused a significant loss of human lives and a worldwide decline in quality of life. Although our understanding of the pandemic has improved significantly since the beginning, the natural history of COVID-19 and its impacts on under-represented populations, such as Indigenous people from America, remain largely unknown. We performed a retrospective serological survey with two Brazilian Indigenous populations (n=624), Tupiniquim and Guarani-Mbyá. Samples were collected between September 2020 and July 2021: a period comprising the dissemination of SARS-CoV-2 variants and the beginning of COVID-19 vaccination in Brazil. Seroconversions against S and N antigens were assessed using three different commercially available ELISA kits. Samples were also used to assess the prevalence of tuberculosis (TB) in the same population (n=529). Seroconversion against SARS-CoV-2 antigens was considered positive if at least one of the three ELISA kits detected levels of specific antibodies above the threshold specified by the manufacturer. In this sense, we report 56.0% (n=349/623) of seroconverted individuals. Relative seroconversion peaked after introduction of the Coronavac vaccine in February 2021. Vaccination increased the production of anti-S IgG from 3.9% to 48.6%. Our results also indicated that 11.0% (n=46/417) of all individuals were positive for TB. Seroconversion to SARS-CoV-2 was similar between individuals with positive tuberculosis test results to those with negative test results. Most vaccinated individuals seroconverted to SARS-CoV-2, indicating that Coronavac may be as protective in individuals from these indigenous groups as observed in the general Brazilian population. COVID-19 severity was minimal regardless of incomplete vaccine coverage, suggesting that vaccination may not be the only factor protecting individuals from severe COVID-19. Tuberculosis is highly prevalent and not associated with increased seroconversion to SARS-CoV-2.

Asunto(s)

Anticuerpos Antivirales , COVID-19 , SARS-CoV-2 , Seroconversión , Tuberculosis , Vacunación , Humanos , COVID-19/inmunología , COVID-19/prevención & control , COVID-19/epidemiología , SARS-CoV-2/inmunología , Brasil/epidemiología , Femenino , Masculino , Adulto , Tuberculosis/inmunología , Tuberculosis/epidemiología , Tuberculosis/prevención & control , Anticuerpos Antivirales/sangre , Anticuerpos Antivirales/inmunología , Persona de Mediana Edad , Estudios Retrospectivos , Pueblos Indígenas , Adulto Joven , Vacunas contra la COVID-19/inmunología , Adolescente , Anciano , Glicoproteína de la Espiga del Coronavirus/inmunología , Niño

RESUMEN

INTRODUCTION: Mayaro fever is an emerging viral disease that manifests as an acute febrile illness. The disease is self-limiting, however joint pain can persist for months leading to chronic arthralgia. There is no specific treatment available, which ultimately leads to socioeconomic losses in populations at risk as well as strains to the public health systems. AREAS COVERED: We reviewed the candidate treatments proposed for Mayaro virus (MAYV) infection and disease, including antiviral compounds targeting viral or host mechanisms, and pathways involved in disease development and pathogenicity. We assessed compound screening technologies and experimental infection models used in these studies and indicated the advantages and limitations of available technologies and intended therapeutic strategies. EXPERT OPINION: Although several compounds have been suggested as candidate treatments against MAYV infection, notably those with antiviral activity, most compounds were assessed only in vitro. Compounds rarely progress toin vivo or preclinical studies, and such difficulty may be associated with limited experimental models. MAYV biology is largely inferred from related alphaviruses and reflected by few studies focusing on target proteins or mechanisms of action for MAYV. Therapeutic strategies targeting pathogenic inflammatory responses have shown potential against MAYV-induced disease in vivo, which might reduce long-term sequelae.

Asunto(s)

Infecciones por Alphavirus , Antivirales , Descubrimiento de Drogas , Animales , Antivirales/farmacología , Humanos , Infecciones por Alphavirus/tratamiento farmacológico , Infecciones por Alphavirus/virología , Alphavirus , Artralgia/tratamiento farmacológico , Desarrollo de Medicamentos , Terapia Molecular Dirigida , Modelos Animales de Enfermedad

RESUMEN

St. Louis encephalitis virus (SLEV) is a neglected mosquito-borne Flavivirus that may cause severe neurological disease in humans and other animals. There are no specific treatments against SLEV infection or disease approved for human use, and drug repurposing may represent an opportunity to accelerate the development of treatments against SLEV. Here we present a scalable, medium-throughput phenotypic cell culture-based screening assay on Vero CCL81 cells to identify bioactive compounds that could be repurposed against SLEV infection. We screened eighty compounds from the Medicines for Malaria Venture (MMV) COVID Box library to identify nine (11%) compounds that protected cell cultures from SLEV-induced cytopathic effects, with low- to mid-micromolar potencies. We validated six hit compounds using viral plaque-forming assays to find that the compounds ABT-239, Amiodarone, Fluphenazine, Posaconazole, Triparanol, and Vidofludimus presented varied levels of antiviral activity and selectivity depending on the mammalian cell type used for testing. Importantly, we identified and validated the antiviral activity of the anti-flavivirus nucleoside analog 7DMA against SLEV. Triparanol and Fluphenazine reduced infectious viral loads in both Vero CCL81 and HBEC-5i cell cultures and, similar to the other validated compounds, are likely to exert antiviral activity through a molecular target in the host.

Asunto(s)

Encefalitis de San Luis , Flavivirus , Malaria , Triparanol , Animales , Humanos , Virus de la Encefalitis de San Luis , Encefalitis de San Luis/diagnóstico , Flufenazina , Antivirales/farmacología , Mamíferos

RESUMEN

Brazilian mammarenavirus, or Sabiá virus (SABV), is a New World (NW) arenavirus associated with fulminant hemorrhagic disease in humans and the sole biosafety level 4 microorganism ever isolated in Brazil. Since the isolation of SABV in the 1990s, studies on viral biology have been scarce, with no available countermeasures against SABV infection or disease. Here we provide a comprehensive review of SABV biology, including key aspects of SABV replication, and comparisons with related Old World and NW arenaviruses. SABV is most likely a rodent-borne virus, transmitted to humans, through exposure to urine and feces in peri-urban areas. Using protein structure prediction methods and alignments, we analyzed shared and unique features of SABV proteins (GPC, NP, Z, and L) that could be explored in search of therapeutic strategies, including repurposing intended application against arenaviruses. Highly conserved catalytic activities present in L protein could be targeted for broad-acting antiviral activity among arenaviruses, while protein-protein interactions, such as those between L and the matrix protein Z, have evolved in NW arenaviruses and should be specific to SABV. The nucleoprotein (NP) also shares targetable interaction interfaces with L and Z and exhibits exonuclease activity in the C-terminal domain, which may be involved in multiple aspects of SABV replication. Envelope glycoproteins GP1 and GP2 have been explored in the development of promising cross-reactive neutralizing antibodies and vaccines, some of which could be repurposed for SABV. GP1 remains a challenging target in SABV as evolutive pressures render it the most variable viral protein in terms of both sequence and structure, while antiviral strategies targeting the Z protein remain to be validated. In conclusion, the prediction and analysis of protein structures should revolutionize research on viruses such as SABV by facilitating the rational design of countermeasures while reducing dependence on sophisticated laboratory infrastructure for experimental validation.

Asunto(s)

Infecciones por Arenaviridae , Arenavirus del Nuevo Mundo , Humanos , Proteínas Virales/genética , Infecciones por Arenaviridae/prevención & control , Antivirales , Biología Molecular

RESUMEN

Zika virus (ZIKV) has re-emerged in recent decades, leading to outbreaks of Zika fever in Africa, Asia, and Central and South America. Despite its drastic re-emergence and clinical impact, no vaccines or antiviral compounds are available to prevent or control ZIKV infection. This study evaluated the potential antiviral activity of quercetin hydrate against ZIKV infection and demonstrated that this substance inhibits virus particle production in A549 and Vero cells under different treatment conditions. In vitro antiviral activity was long-lasting (still observed 72 h post-infection), suggesting that quercetin hydrate affects multiple rounds of ZIKV replication. Molecular docking indicates that quercetin hydrate can efficiently interact with the specific allosteric binding site cavity of the NS2B-NS3 proteases and NS1-dimer. These results identify quercetin as a potential compound to combat ZIKV infection in vitro.

Asunto(s)

Infección por el Virus Zika , Virus Zika , Animales , Chlorocebus aethiops , Humanos , Antivirales/uso terapéutico , Quercetina/farmacología , Quercetina/uso terapéutico , Células Vero , Simulación del Acoplamiento Molecular , Replicación Viral

RESUMEN

Ultraviolet C (UVC) light has long been used as a sterilizing agent, primarily through devices that emit at 254 nm. Depending on the dose and duration of exposure, UV 254 nm can cause erythema and photokeratitis and potentially cause skin cancer since it directly modifies nitrogenated nucleic acid bases. Filtered KrCl excimer lamps (emitting mainly at 222 nm) have emerged as safer germicidal tools and have even been proposed as devices to sterilize surgical wounds. All the studies that showed the safety of 222 nm analyzed cell number and viability, erythema generation, epidermal thickening, the formation of genetic lesions such as cyclobutane pyrimidine dimers (CPDs) and pyrimidine-(6-4)-pyrimidone photoproducts (6-4PPs) and cancer-inducing potential. Although nucleic acids can absorb and be modified by both UV 254 nm and UV 222 nm equally, compared to UV 254 nm, UV 222 nm is more intensely absorbed by proteins (especially aromatic side chains), causing photooxidation and cross-linking. Here, in addition to analyzing DNA lesion formation, for the first time, we evaluated changes in the proteome and cellular pathways, reactive oxygen species formation, and metalloproteinase (MMP) levels and activity in full-thickness in vitro reconstructed human skin (RHS) exposed to UV 222 nm. We also performed the longest (40 days) in vivo study of UV 222 nm exposure in the HRS/J mouse model at the occupational threshold limit value (TLV) for indirect exposure (25 mJ/cm2) and evaluated overall skin morphology, cellular pathological alterations, CPD and 6-4PP formation and MMP-9 activity. Our study showed that processes related to reactive oxygen species and inflammatory responses were more altered by UV 254 nm than by UV 222 nm. Our chronic in vivo exposure assay using the TLV confirmed that UV 222 nm causes minor damage to the skin. However, alterations in pathways related to skin regeneration raise concerns about direct exposure to UV 222 nm.

Asunto(s)

Daño del ADN , Ácidos Nucleicos , Ratones , Animales , Humanos , Especies Reactivas de Oxígeno/metabolismo , Dímeros de Pirimidina/metabolismo , Piel/efectos de la radiación , Rayos Ultravioleta , Ácidos Nucleicos/metabolismo , Eritema

RESUMEN

A short 3-step synthesis of the antiviral agent 7DMA is described herein. The nature of a major by-product formed during the key N-glycosylation of 6-chloro-7-deaza-7-iodopurine with perbenzoylated 2-methyl-ribose under Vorbrüggen conditions was also investigated. Spectroscopic analyses support that the solvent itself is converted into a nucleophilic species competing with the nucleobase and further reacting with the activated riboside in an unanticipated fashion. These findings call for a revision of reaction conditions when working with weakly reactive nucleobases in the presence of Lewis acids. 7DMA thus obtained was evaluated for its efficacy against an emerging flavivirus in vitro.

RESUMEN

Mayaro virus (MAYV) is an emerging arthropod-borne virus endemic in Latin America and the causative agent of arthritogenic febrile disease. Mayaro fever is poorly understood; thus, we established an in vivo model of infection in susceptible type-I interferon receptor-deficient mice (IFNAR-/-) to characterize the disease. MAYV inoculations in the hind paws of IFNAR-/- mice result in visible paw inflammation, evolve into a disseminated infection and involve the activation of immune responses and inflammation. The histological analysis of inflamed paws indicated edema at the dermis and between muscle fibers and ligaments. Paw edema affected multiple tissues and was associated with MAYV replication, the local production of CXCL1 and the recruitment of granulocytes and mononuclear leukocytes to muscle. We developed a semi-automated X-ray microtomography method to visualize both soft tissue and bone, allowing for the quantification of MAYV-induced paw edema in 3D with a voxel size of 69 µm3. The results confirmed early edema onset and spreading through multiple tissues in inoculated paws. In conclusion, we detailed features of MAYV-induced systemic disease and the manifestation of paw edema in a mouse model extensively used to study infection with alphaviruses. The participation of lymphocytes and neutrophils and expression of CXCL1 are key features in both systemic and local manifestations of MAYV disease.

Asunto(s)

Infecciones por Alphavirus , Alphavirus , Animales , Ratones , Infecciones por Alphavirus/patología , Inflamación , Sincrotrones , Microtomografía por Rayos X

RESUMEN

Ilhéus virus (ILHV) is a neglected mosquito-borne flavivirus. ILHV infection may lead to Ilhéus fever, an emerging febrile disease like dengue fever with the potential to evolve into a severe neurological disease characterized by meningoencephalitis; no specific treatments are available for this disease. This study assessed the antiviral properties of caffeic acid, an abundant component of plant-based food products that is also compatible with the socioeconomic limitations associated with this neglected infectious disease. The in vitro activity of caffeic acid on ILHV replication was investigated in Vero and A549 cell lines using plaque assays, quantitative RT-PCR, and immunofluorescence assays. We observed that 500 µM caffeic acid was virucidal against ILHV. Molecular docking indicated that caffeic acid might interact with an allosteric binding site on the envelope protein.

Asunto(s)

Antivirales , Animales , Humanos , Simulación del Acoplamiento Molecular , Células A549 , Sitio Alostérico , Antivirales/farmacología

RESUMEN

This is the third year of the SARS-CoV-2 pandemic, and yet most children remain unvaccinated. COVID-19 in children manifests as mostly mild or asymptomatic, however high viral titers and strong cellular and humoral responses are observed upon acute infection. It is still unclear how long these responses persist, and if they can protect from re-infection and/or disease severity. Here, we analyzed immune memory responses in a cohort of children and adults with COVID-19. Important differences between children and adults are evident in kinetics and profile of memory responses. Children develop early N-specific cytotoxic T cell responses, that rapidly expand and dominate their immune memory to the virus. Children's anti-N, but not anti-S, antibody titers increase over time. Neutralization titers correlate with N-specific antibodies and CD8+T cells. However, antibodies generated by infection do not efficiently cross-neutralize variants Gamma or Delta. Our results indicate that mechanisms that protect from disease severity are possibly different from those that protect from reinfection, bringing novel insights for pediatric vaccine design. They also underline the importance of vaccination in children, who remain at risk for COVID-19 despite having been previously infected.

Asunto(s)

COVID-19 , SARS-CoV-2 , Humanos , Adulto , Niño , Memoria Inmunológica , Linfocitos T CD8-positivos , Nucleocápside , Anticuerpos

RESUMEN

The nucleocapsid (N) protein plays critical roles in coronavirus genome transcription and packaging, representing a key target for the development of novel antivirals, and for which structural information on ligand binding is scarce. We used a novel fluorescence polarization assay to identify small molecules that disrupt the binding of the N protein to a target RNA derived from the SARS-CoV-2 genome packaging signal. Several phenolic compounds, including L-chicoric acid (CA), were identified as high-affinity N-protein ligands. The binding of CA to the N protein was confirmed by isothermal titration calorimetry, 1H-STD and 15N-HSQC NMR, and by the crystal structure of CA bound to the N protein C-terminal domain (CTD), further revealing a new modulatory site in the SARS-CoV-2 N protein. Moreover, CA reduced SARS-CoV-2 replication in cell cultures. These data thus open venues for the development of new antivirals targeting the N protein, an essential and yet underexplored coronavirus target.

Asunto(s)

COVID-19 , SARS-CoV-2 , Humanos , Ligandos , Proteínas de la Nucleocápside/genética , ARN/metabolismo , Antivirales/farmacología , Unión Proteica

RESUMEN

Visceral adiposity is a risk factor for severe COVID-19, and a link between adipose tissue infection and disease progression has been proposed. Here we demonstrate that SARS-CoV-2 infects human adipose tissue and undergoes productive infection in fat cells. However, susceptibility to infection and the cellular response depends on the anatomical origin of the cells and the viral lineage. Visceral fat cells express more ACE2 and are more susceptible to SARS-CoV-2 infection than their subcutaneous counterparts. SARS-CoV-2 infection leads to inhibition of lipolysis in subcutaneous fat cells, while in visceral fat cells, it results in higher expression of pro-inflammatory cytokines. Viral load and cellular response are attenuated when visceral fat cells are infected with the SARS-CoV-2 gamma variant. A similar degree of cell death occurs 4-days after SARS-CoV-2 infection, regardless of the cell origin or viral lineage. Hence, SARS-CoV-2 infects human fat cells, replicating and altering cell function and viability in a depot- and viral lineage-dependent fashion.

Asunto(s)

COVID-19 , SARS-CoV-2 , Tejido Adiposo , Enzima Convertidora de Angiotensina 2 , Citocinas , Humanos

RESUMEN

The mosquito-borne disease caused by the Rocio virus is a neglected threat, and new immune inputs for serological testing are urgently required for diagnosis in low-resource settings and epidemiological surveillance. We used in silico approaches to identify a specific antigenic peptide (p_ROCV2) in the NS1 protein of the Rocio virus that was theoretically predicted to be stable and exposed on its surface, where it demonstrated key properties allowing it to interact with antibodies. These findings related to the molecular dynamics of this peptide provide important insights for advancing diagnostic platforms and investigating therapeutic alternatives.

Asunto(s)

Flavivirus , Simulación de Dinámica Molecular , Animales , Pruebas Inmunológicas , Simulación del Acoplamiento Molecular , Péptidos , Proteínas no Estructurales Virales/química

RESUMEN

Ultraviolet (UV) light can inactivate SARS-CoV-2. However, the practicality of UV light is limited by the carcinogenic potential of mercury vapor-based UV lamps. Recent advances in the development of krypton chlorine (KrCl) excimer lamps hold promise, as these emit a shorter peak wavelength (222 nm), which is highly absorbed by the skin's stratum corneum and can filter out higher wavelengths. In this sense, UV 222 nm irradiation for the inactivation of virus particles in the air and surfaces is a potentially safer option as a germicidal technology. However, these same physical properties make it harder to reach microbes present in complex solutions, such as saliva, a critical source of SARS-CoV-2 transmission. We provide the first evaluation for using a commercial filtered KrCl excimer light source to inactivate SARS-CoV-2 in saliva spread on a surface. A conventional germicidal lamp (UV 254 nm) was also evaluated under the same condition. Using plaque-forming units (PFU) and Median Tissue Culture Infectious Dose (TCID50) per milliliter we found that 99.99% viral clearance (LD99.99) was obtained with 106.3 mJ/cm2 of UV 222 nm for virus in DMEM and 2417 mJ/cm2 for virus in saliva. Additionally, our results showed that the UV 254 nm had a greater capacity to inactivate the virus in both vehicles. Effective (after discounting light absorption) LD99.99 of UV 222 nm on the virus in saliva was ∼30 times higher than the value obtained with virus in saline solution (PBS), we speculated that saliva might be protecting the virus from surface irradiation in ways other than just by intensity attenuation of UV 222 nm. Due to differences between UV 222/254 nm capacities to interact and be absorbed by molecules in complex solutions, a higher dose of 222 nm will be necessary to reduce viral load in surfaces with contaminated saliva.

Asunto(s)

COVID-19 , Fotoquimioterapia , Desinfección/métodos , Humanos , Fotoquimioterapia/métodos , SARS-CoV-2 , Saliva , Rayos Ultravioleta

RESUMEN

The ongoing COVID-19 pandemic caused a significant loss of human lives and a worldwide decline in quality of life. Treatment of COVID-19 patients is challenging, and specific treatments to reduce COVID-19 aggravation and mortality are still necessary. Here, we describe the discovery of a novel class of epiandrosterone steroidal compounds with cationic amphiphilic properties that present antiviral activity against SARS-CoV-2 in the low micromolar range. Compounds were identified in screening campaigns using a cytopathic effect-based assay in Vero CCL81 cells, followed by hit compound validation and characterization. Compounds LNB167 and LNB169 were selected due to their ability to reduce the levels of infectious viral progeny and viral RNA levels in Vero CCL81, HEK293, and HuH7.5 cell lines. Mechanistic studies in Vero CCL81 cells indicated that LNB167 and LNB169 inhibited the initial phase of viral replication through mechanisms involving modulation of membrane lipids and cholesterol in host cells. Selection of viral variants resistant to steroidal compound treatment revealed single mutations on transmembrane, lipid membrane-interacting Spike and Envelope proteins. Finally, in vivo testing using the hACE2 transgenic mouse model indicated that SARS-CoV-2 infection could not be ameliorated by LNB167 treatment. We conclude that anti-SARS-CoV-2 activities of steroidal compounds LNB167 and LNB169 are likely host-targeted, consistent with the properties of cationic amphiphilic compounds that modulate host cell lipid biology. Although effective in vitro, protective effects were cell-type specific and did not translate to protection in vivo, indicating that subversion of lipid membrane physiology is an important, yet complex mechanism involved in SARS-CoV-2 replication and pathogenesis.

Asunto(s)

Tratamiento Farmacológico de COVID-19 , SARS-CoV-2 , Animales , Antivirales/farmacología , Chlorocebus aethiops , Células HEK293 , Humanos , Lípidos , Ratones , Pandemias , Calidad de Vida , Células Vero , Replicación Viral

RESUMEN

The nucleocapsid (N) protein of the SARS-CoV-2 virus, the causal agent of COVID-19, is a multifunction phosphoprotein that plays critical roles in the virus life cycle, including transcription and packaging of the viral RNA. To play such diverse roles, the N protein has two globular RNA-binding modules, the N- (NTD) and C-terminal (CTD) domains, which are connected by an intrinsically disordered region. Despite the wealth of structural data available for the isolated NTD and CTD, how these domains are arranged in the full-length protein and how the oligomerization of N influences its RNA-binding activity remains largely unclear. Herein, using experimental data from electron microscopy and biochemical/biophysical techniques combined with molecular modeling and molecular dynamics simulations, we show that, in the absence of RNA, the N protein formed structurally dynamic dimers, with the NTD and CTD arranged in extended conformations. However, in the presence of RNA, the N protein assumed a more compact conformation where the NTD and CTD are packed together. We also provided an octameric model for the full-length N bound to RNA that is consistent with electron microscopy images of the N protein in the presence of RNA. Together, our results shed new light on the dynamics and higher-order oligomeric structure of this versatile protein.

Asunto(s)

Proteínas de la Nucleocápside de Coronavirus , SARS-CoV-2 , COVID-19 , Proteínas de la Nucleocápside de Coronavirus/química , Proteínas de la Nucleocápside de Coronavirus/metabolismo , Humanos , Microscopía Electrónica , Simulación de Dinámica Molecular , Proteínas de la Nucleocápside/química , Proteínas de la Nucleocápside/metabolismo , Fosfoproteínas/metabolismo , Unión Proteica , ARN Viral/genética , SARS-CoV-2/química , SARS-CoV-2/genética , SARS-CoV-2/metabolismo

RESUMEN

COVID-19 manifests as a milder disease in children than adults, but the underlying mechanisms are not fully characterized. Here we assess the difference in cellular or humoral immune responses of pediatric and adult COVID-19 patients to see if these factors contribute to the severity dichotomy. Children's non-specific immune profile is dominated by naive lymphocytes and HLA-DRhighCX3CR1low dendritic cells; meanwhile, children show strong specific antibody and T cell responses for viral structural proteins, with their T cell responses differing from adults by having weaker CD8+TNF+ T cells responses to S peptide pool but stronger responses to N and M peptide pools. Finally, viral mRNA is more abundant in pediatric patients. Our data thus support a scenario in which SARS-CoV-2 infected children contribute to transmission yet are less susceptible to COVID-19 symptoms due to strong and differential responses to the virus.

Asunto(s)

Anticuerpos Antivirales/inmunología , COVID-19/inmunología , Inmunidad Humoral , ARN Viral , SARS-CoV-2/genética , Vacunas Sintéticas/inmunología , Adolescente , Adulto , Anciano , Anticuerpos Antivirales/sangre , Brasil , Linfocitos T CD4-Positivos/inmunología , Linfocitos T CD8-positivos , COVID-19/prevención & control , Vacunas contra la COVID-19 , Niño , Preescolar , Citocinas/sangre , Femenino , Humanos , Inmunidad Innata , Masculino , Persona de Mediana Edad , ARN Mensajero , Glicoproteína de la Espiga del Coronavirus/inmunología , Linfocitos T , Proteínas Estructurales Virales/inmunología , Adulto Joven , Vacunas de ARNm

RESUMEN

Neutrophils are first-line responders to infections and are recruited to target tissues through the action of chemoattractant molecules, such as chemokines. Neutrophils are crucial for the control of bacterial and fungal infections, but their role in the context of viral infections has been understudied. Flaviviruses are important human viral pathogens transmitted by arthropods. Infection with a flavivirus may result in a variety of complex disease manifestations, including hemorrhagic fever, encephalitis or congenital malformations. Our understanding of flaviviral diseases is incomplete, and so is the role of neutrophils in such diseases. Here we present a comprehensive overview on the participation of neutrophils in severe disease forms evolving from flavivirus infection, focusing on the role of chemokines and their receptors as main drivers of neutrophil function. Neutrophil activation during viral infection was shown to interfere in viral replication through effector functions, but the resulting inflammation is significant and may be detrimental to the host. For congenital infections in humans, neutrophil recruitment mediated by CXCL8 would be catastrophic. Evidence suggests that control of neutrophil recruitment to flavivirus-infected tissues may reduce immunopathology in experimental models and patients, with minimal loss to viral clearance. Further investigation on the roles of neutrophils in flaviviral infections may reveal unappreciated functions of this leukocyte population while increasing our understanding of flaviviral disease pathogenesis in its multiple forms.

RESUMEN

Mayaro virus (MAYV) is an emerging arbovirus of the Americas that may cause a debilitating arthritogenic disease. The biology of MAYV is not fully understood and largely inferred from related arthritogenic alphaviruses. Here, we present the structure of MAYV at 4.4 Å resolution, obtained from a preparation of mature, infective virions. MAYV presents typical alphavirus features and organization. Interactions between viral proteins that lead to particle formation are described together with a hydrophobic pocket formed between E1 and E2 spike proteins and conformational epitopes specific of MAYV. We also describe MAYV glycosylation residues in E1 and E2 that may affect MXRA8 host receptor binding, and a molecular "handshake" between MAYV spikes formed by N262 glycosylation in adjacent E2 proteins. The structure of MAYV is suggestive of structural and functional complexity among alphaviruses, which may be targeted for specificity or antiviral activity.

Asunto(s)

Infecciones por Alphavirus/virología , Alphavirus/ultraestructura , Microscopía por Crioelectrón , Espectrometría de Masas , Alphavirus/inmunología , Infecciones por Alphavirus/inmunología , Animales , Anticuerpos Neutralizantes , Chlorocebus aethiops , Glicosilación , Humanos , Inmunoglobulinas , Proteínas de la Membrana , Células Vero

RESUMEN

Although the widespread epidemic of Zika virus (ZIKV) and its neurological complications are well-known there are still no approved drugs available to treat this arboviral disease or vaccine to prevent the infection. Flavonoids from Pterogyne nitens have already demonstrated anti-flavivirus activity, although their target is unknown. In this study, we virtually screened an in-house database of 150 natural and semi-synthetic compounds against ZIKV NS2B-NS3 protease (NS2B-NS3p) using docking-based virtual screening, as part of the OpenZika project. As a result, we prioritized three flavonoids from P. nitens, quercetin, rutin and pedalitin, for experimental evaluation. We also used machine learning models, built with Assay Central® software, for predicting the activity and toxicity of these flavonoids. Biophysical and enzymatic assays generally agreed with the in silico predictions, confirming that the flavonoids inhibited ZIKV protease. The most promising hit, pedalitin, inhibited ZIKV NS2B-NS3p with an IC50 of 5 µM. In cell-based assays, pedalitin displayed significant activity at 250 and 500 µM, with slight toxicity in Vero cells. The results presented here demonstrate the potential of pedalitin as a candidate for hit-to-lead (H2L) optimization studies towards the discovery of antiviral drug candidates to treat ZIKV infections.

Asunto(s)

Antivirales/farmacología , Proteínas no Estructurales Virales/antagonistas & inhibidores , Proteínas Virales/antagonistas & inhibidores , Virus Zika/metabolismo , Animales , Antivirales/química , Supervivencia Celular/efectos de los fármacos , Chlorocebus aethiops , Inhibidores Enzimáticos/química , Inhibidores Enzimáticos/farmacología , Flavonas/farmacología , Aprendizaje Automático , Modelos Moleculares , Simulación del Acoplamiento Molecular , Conformación Proteica , Quercetina/farmacología , Rutina/farmacología , Serina Endopeptidasas , Células Vero