Flavonoids from Pterogyne nitens as Zika virus NS2B-NS3 protease inhibitors.

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.

Competing interests during the key N-glycosylation of 6-chloro-7-deaza-7-iodopurine for the synthesis of 7-deaza-2'-methyladenosine using Vorbrüggen conditions.

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.

Pediatric COVID-19 patients in South Brazil show abundant viral mRNA and strong specific anti-viral responses.

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.

Elevated Glucose Levels Favor SARS-CoV-2 Infection and Monocyte Response through a HIF-1α/Glycolysis-Dependent Axis.

COVID-19 can result in severe lung injury. It remained to be determined why diabetic individuals with uncontrolled glucose levels are more prone to develop the severe form of COVID-19. The molecular mechanism underlying SARS-CoV-2 infection and what determines the onset of the cytokine storm found in severe COVID-19 patients are unknown. Monocytes and macrophages are the most enriched immune cell types in the lungs of COVID-19 patients and appear to have a central role in the pathogenicity of the disease. These cells adapt their metabolism upon infection and become highly glycolytic, which facilitates SARS-CoV-2 replication. The infection triggers mitochondrial ROS production, which induces stabilization of hypoxia-inducible factor-1α (HIF-1α) and consequently promotes glycolysis. HIF-1α-induced changes in monocyte metabolism by SARS-CoV-2 infection directly inhibit T cell response and reduce epithelial cell survival. Targeting HIF-1ɑ may have great therapeutic potential for the development of novel drugs to treat COVID-19.

Padronização e aplicação do teste de avidez anti-HCV IgG para confirmar exposição recente ao vírus da hepatite C

A identificação da fase aguda da infecção pelo vírus da hepatite C (HCV) é realizada pela avaliação clinico laboratorial e confirmada pela soroconversão de anti-HCV associada a HCVRNA positivo. Entretanto, os indivíduos infectados são predominantemente assintomáticos e a informação sorológica prévia dos pacientes é normalmente escassa. O diagnóstico da fase aguda da hepatite C com base na detecção de IgM não é utilizado devido a este anticorpo estar presente durante todo o curso da doença. Diversos estudos voltados para análise da força de ligação (avidez) anticorpo-antígeno tem sido descritos como forma de identificação da fase aguda da hepatite C. No entanto, apesar da existência destas pesquisas, testes de avidez como diagnóstico de rotina para a detecção de casos agudos da infecção ainda não estão disponíveis no Brasil. Desta forma, o presente estudo visa padronizar, avaliar e aplicar a técnica em questão a partir da adaptação do kit ELISA comercial Anti-HCV Murex (4.0 version). Para esta finalidade, foram empregadas 570 amostras de 147 pacientes em diferentes fases da infecção pelo HCV, acompanhados pelo Ambulatório de Hepatites Virais \2013 AHV (Laboratório de Hepatites Virais/IOC/Fiocruz). O teste de avidez consistiu na adição de uma etapa de incubação com guanidina 1,5M ao protocolo do kit comercial. A partir da utilização de amostras de pacientes com soroconversão comprovada e data de infecção conhecida foi possível diferenciar as fases da doença em agudo recente (até 4 meses), agudo tardio (5-6 meses), crônica (acima de 6 meses) Empregando-se o valor de corte de \226464% para fase aguda, zona cinza entre 65-77% e \F0B378% para fase crônica, foram obtidos: sensibilidade de 90% e especificidade de 95% até 4 meses após infecção, e sensibilidade de 73% e especificidade de 75% entre 5-6 meses após infecção. Do terceiro ao sexto mês após infecção o índice de avidez elevou de 37% para 65%. O acompanhamento longitudinal de pacientes desde a fase aguda até 30 meses demonstrou elevação do índice de avidez até o oitavo mês de infecção, mantendo-se elevado e com baixa variação subsequente em pacientes que evoluíram para a fase crônica da doença, no entanto, ocorreu a queda do índice de avidez a partir de 10 meses de infecção em indivíduos que evoluíram para resolução espontânea. Não houve diferença significativa do índice de avidez na fase aguda entre pacientes que evoluíram para cronicidade e que evoluíram para resolução espontânea. De junho de 2014 a janeiro de 2016, o teste de avidez identificou 20% dos pacientes com hepatite C aguda dentre os casos suspeitos na rotina de diagnóstico ambulatorial. O primeiro teste de avidez desenvolvido no país apresentou elevadas sensibilidade e especificidade, e demonstrou ser útil para a identificação das fases da infecção pelo HCV