The impact of the COVID-19 pandemic caused by the SARS-CoV-2 virus underscored the crucial role of laboratorial tests as a strategy to control the disease, mainly to indicate the presence of specific antibodies in human samples from infected patients. Therefore, suitable recombinant antigens are relevant for the development of reliable tests, and so far, single recombinant proteins have been used. In this context, B-cell epitopes-based chimeric proteins can be an alternative to obtain tests with high accuracy through easier and cheaper production. The present study used bioinformatics tools to select specific B-cell epitopes from the spike (S) and the nucleocapsid (N) proteins from the SARS-CoV-2 virus, aiming to produce a novel recombinant chimeric antigen (N4S11-SC2). Eleven S and four N-derived B-cell epitopes were predicted and used to construct the N4S11-SC2 protein, which was analyzed in a recombinant format against serum and urine samples, by means of an in house-ELISA. Specific antibodies were detected in the serum and urine samples of COVID-19 patients, which were previously confirmed by qRT-PCR. Results showed that N4S11-SC2 presented 83.7% sensitivity and 100% specificity when using sera samples, and 91.1% sensitivity and 100% specificity using urine samples. Comparable findings were achieved with paired urine samples when compared to N and S recombinant proteins expressed in prokaryotic systems. However, better results were reached for N4S11-SC2 in comparison to the S recombinant protein when using paired serum samples. Anti-N4S11-SC2 antibodies were not clearly identified in Janssen Ad26.COV2.S COVID-19-vaccinated subjects, using serum or paired urine samples. In conclusion, this study presents a new chimeric recombinant antigen expressed in a prokaryotic system that could be considered as an alternative diagnostic marker for the SARS-CoV-2 infection, with the potential benefits to be used on serum or urine from infected patients.

Introduction The escalating resistance of microorganisms to antimicrobials poses a significant public health threat. Strategies that use biomarkers to guide antimicrobial therapy—most notably Procalcitonin (PCT) and C-reactive protein (CRP)—show promise in safely reducing patient antibiotic exposure. While CRP is less studied, it offers advantages such as lower cost and broader availability compared with PCT. Methods and analysis This randomised clinical trial aims to evaluate a novel algorithm for non-critically ill adult patients. The algorithm incorporates key clinical variables and CRP behaviour. It will be applied through a mobile application as a digital clinical decision support system. The primary goal will be to assess the algorithm’s effectiveness in reducing treatment duration compared with standard care based on current guidelines, while ensuring patient safety by monitoring the occurrence of adverse events. Ethics and dissemination Only patients who agree to participate in the study after reading the informed consent form will be included. This project was submitted for consideration to the Research Ethics Committee of the Federal University of Minas Gerais (COEP-UFMG) and received approval (Approval Number: 5.905.290). Collection of clinical and laboratory data from 200 patients is expected, extracted from electronic medical records and laboratory systems, along with serum samples stored for potential future analyses. Data will be preserved using the Research Electronic Data Capture platform, and serum samples will be stored in a regulated biorepository at UFMG. Access will be controlled via credentials, with privacy protections and anonymisation prior to sharing, which will occur during scientific publications. Trial registration number This trial was registered on ClinicalTrials.gov (NCT05841875) and was last updated on 5 December 2024 at 12:49.

Aims: This pilot study aimed to evaluate the usefulness of a sequential lung ultrasound score (LUS) in immunosuppressed patients with oncohematologic diseases and acute respiratory dysfunction hospitalized in an intensive care unit (ICU).Materials and methods: LUS was calculated at ICU admission, after 24 h, 48 h and at discharge. A score ranging from 0 to 26 was attributed according to the number of B lines, presence of lung consolidation and pleural effusion.Results: Twenty-six patients were included. The median age was 50 years [interquartile range (IQR) 21] and 14 (54%) were male. LUS on the day of ICU admission was significantly higher in non-survivors compared to survivors (13 [5] vs 9 [9], respectively; p=0.047). The median delta LUS (LUS_D2 – LUS_D1) did not show difference between survivors and non-survivors (2 [0-7.5] vs 1 [-1.5 – 5], p=0.33). Among patients initially submitted to noninvasive mechanical ventilation (NIMV), no difference in LUS at inclusion or after 24 h was found between those who succeeded or failed on this support.Conclusion: The use of LUS to quantify lung aeration loss in oncohematologic patients hospitalized in an ICU due to acute respiratory dysfunction might be a helpful tool to predict the severity of the illness.