Production of high-quality SARS-CoV-2 antigens: Impact of bioprocess and storage on glycosylation, biophysical attributes, and ELISA serologic tests performance

Serological assays are valuable tools to study SARS-CoV-2 spread and, importantly, to identify individuals that were already infected and would be potentially immune to a virus reinfection. SARS-CoV-2 Spike protein and its receptor binding domain (RBD) are the antigens with higher potential to develop SARS-CoV-2 serological assays. Moreover, structural studies of these antigens are key to understand the molecular basis for Spike interaction with angiotensin converting enzyme 2 receptor, hopefully enabling the development of COVID-19 therapeutics. Thus, it is urgent that significant amounts of this protein became available at the highest quality. In this study, we produced Spike and RBD in two human derived cell hosts: HEK293-E6 and Expi293F™. We evaluated the impact of different and scalable bioprocessing approaches on Spike and RBD production yields and, more importantly, on these antigens' quality attributes. Using negative and positive sera collected from human donors, we show an excellent performance of the produced antigens, assessed in serologic enzyme-linked immunosorbent assay (ELISA) tests, as denoted by the high specificity and sensitivity of the test. We show robust Spike productions with final yields of approx. 2 mg/L of culture that were maintained independently of the production scale or cell culture strategy. To the best of our knowledge, the final yield of 90 mg/L of culture obtained for RBD production, was the highest reported to date. An in-depth characterization of SARS-CoV-2 Spike and RBD proteins was performed, namely the antigen's oligomeric state, glycosylation profiles, and thermal stability during storage. The correlation of these quality attributes with ELISA performance show equivalent reactivity to SARS-CoV-2 positive serum, for all Spike and RBD produced, and for all storage conditions tested. Overall, we provide straightforward protocols to produce high-quality SARS-CoV-2 Spike and RBD antigens, that can be easily adapted to both academic and industrial settings; and integrate, for the first time, studies on the impact of bioprocess with an in-depth characterization of these proteins, correlating antigen's glycosylation and biophysical attributes to performance of COVID-19 serologic tests.

Laryngeal papillomatosis in children: The impact of late recognition over evolution

To assess the impact of the delay in recognition of the initial symptoms of laryngeal papillomatosis in children over the evolution of the disease. Retrospective study of patients with respiratory papillomatosis referred from general pediatric practices to a tertiary hospital with pediatric laryngology specialization. Gender, age at time of diagnosis, symptom duration, sites affected at the time of diagnosis, treatment, and evolution of the disease over time were evaluated. From January 2003 to December 2013, 21 patients (15 females and 6 males) were identified and followed for at least 3 years. The average age at which symptoms first appeared was 40.2 months, and the average age at the time of initial treatment was 76 months. The most frequent clinical manifestation was hoarseness. The most common site of involvement was the glottis followed by the supraglottis and subglottis, respectively. Three of the 21 patients required tracheostomy. The average time from symptom onset to diagnosis was 52.3 months. There were no fatalities. On average 3.7 procedures were performed per patient. Patients presenting more than 1 year from the symptom onset to the time of first treatment required a greater number of procedures to control disease. Delay in diagnosis can have negative clinical consequences due to disease progression. The later the diagnosis the more surgeries are needed to control the disease. Involvement of the subglottic larynx is a risk factor for emergent tracheostomy.

Programmed cell death in the pathogenesis of murine IDDM: resistance to apoptosis induced in lymphocytes by cyclophosphamide

The non-obese diabetic (NOD) mouse displays several immune related defects, each of which could potentially contribute to the immunopathogenesis of diabetes that spontaneously develops in these mice. The reported resistance of NOD-lymphocytes to several apoptosis-inducing signals constitutes one such factor. Apoptosis plays a key role in the homeostasis of the immune system, as a means of selecting lymphocyte repertoires both in primary lymphoid organs and in the periphery; distortions in the apoptotic machinery may therefore be hypothesized to be implicated in the pathogenesis of autoimmune disorders. We now report that cyclophosphamide constitutes an apoptosis signal to peripheral lymphocytes and we provide evidence that NOD B cells as well as both CD4 and CD8 T cells display resistance to cyclophosphamide-induced apoptosis. These observations support the notion that apoptosis resistance in NOD mice exists at various levels, and suggest that the CY-sensitive lymphoid population, believed to play an important role in inhibiting the disease in diabetes resistant NOD mice (particularly males), may be controlled by mechanisms that are mediated by apoptosis.