RESUMO
Coronavirus disease 2019 (COVID-19), caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, was first reported in Wuhan, China, in December 2019. Diagnostic methods for the detection of the virus and seroconversion of neutralizing antibodies (NAbs) in plasma have been developed specifically, but some of them require a BSL3 facility. In this study, we used the SARS-CoV-2 Surrogate Virus Neutralization Test Kit to determine the presence or absence of NAbs anti-receptor binding domain of the viral spike (S) glycoprotein in a BSL2 facility. The sample population was chosen in Quito, Ecuador, with a total of 88 COVID-19 positive convalescent patients. We determined that 97.7% of the analyzed convalescent sera maintained the presence of NAbs with neutralizing activity, and this activity remained until 10 months after the infection in some cases. In addition, the relationship between the presence of NAbs and immunoglobulin G was significant compared to immunoglobulin M, which tended to be absent over time.
Assuntos
COVID-19 , SARS-CoV-2 , Anticorpos Neutralizantes , Anticorpos Antivirais , COVID-19/diagnóstico , COVID-19/terapia , Equador , Humanos , Imunização Passiva , Glicoproteína da Espícula de Coronavírus , Soroterapia para COVID-19RESUMO
A strategy to optimize biotechnological process design is illustrated for the production of fructose-rich syrups via enzymatic hydrolysis of agave fructo-oligosaccharides. The optimization process includes ecological studies from natural fermentations leading to the selection of a strain with capacity for inulinase synthesis, and variable optimization for the synthesis, and enzymatic hydrolysis using the response surface methodology. The results lead to the selection of Kluyveromyces marxianus , endogenous strains isolated from aguamiel (natural fermented sugary sap from agave plants), as the main strain with high capacity for enzyme synthesis with inulinase activity. Production optimization at bioreactor level revealed that operation at 30.6 degrees C, 152 rpm, 1.3 VVM of aeration, and pH 6.3 leads to maximum inulinase synthesis, whereas 31 degrees C, 50 rpm, and pH 6.2 leads to maximum hydrolysis of agave fructo-oligosaccharides. HPLC analysis of the fructose-rich syrups obtained at these optimal conditions showed an average composition of 95% of fructose and 5% of glucose and the absence of sucrose. The analysis also revealed that the syrups are free of residues and toxic compounds, an undesirable occurrence often present when traditional methods based on thermal or acid hydrolysis are applied for their obtainment. Therefore, the product may be suitable for use as additive in many applications in the food and beverage industries.