Seroprevalence and factors associated with SARS-CoV-2 infection among education workers after the first wave: the first cross-sectional study in Brazil

ABSTRACT Background: The school community was heavily impacted by the Covid-19 pandemic, especially with the long time of school closures. This study aimed to analyze the seroprevalence of SARS-CoV-2 antibodies and possible factors associated with seropositivity for COVID-19 in teachers and other school staff, and to estimate the fraction of asymptomatic individuals by sex and age group. Methods: We conducted a serological survey of SARS-CoV-2 infections. An analytical cross-sectional study was conducted in Fortaleza, Brazil. Teachers and other staff members from pre-schools to universities of higher education to were investigated. Results: A total of 1,901 professionals participated in the study, of which 1,021 were staff and 880 were teachers. The seroprevalence of SARS-CoV-2 was 8.0% (152/1901). In the seropositive group, 48.3% were asymptomatic. There was a predominance of women (68.4%); and, 47.1% of the participants were between 31 and 45 years old. There was an increase in prevalence with increasing age. An inverse relationship was found for education level: more professionals with less education tested positive for COVID-19. The presence of an infected person living in the same household was significantly associated with positive results for COVID-19 among the professionals. Conclusions: This is the first study to report the seroprevalence of IgG against SARS-CoV-2 in Brazilian educational staff after the first wave of the disease. In this study, the seroprevalence was much lower than that in the general population. During school reopening, a small fraction of school workers showed serologically detectable signs of SARS-CoV-2 exposure.

Circumventing the side effects of L-asparaginase.

L-asparaginase is an enzyme that catalyzes the degradation of asparagine and successfully used in the treatment of acute lymphoblastic leukemia. L-asparaginase toxicity is either related to hypersensitivity to the foreign protein or to a secondary L-glutaminase activity that causes inhibition of protein synthesis. PEGylated versions have been incorporated into the treatment protocols to reduce immunogenicity and an alternative L-asparaginase derived from Dickeya chrysanthemi is used in patients with anaphylactic reactions to the E. coli L-asparaginase. Alternative approaches commonly explore new sources of the enzyme as well as the use of protein engineering techniques to create less immunogenic, more stable variants with lower L-glutaminase activity. This article reviews the main strategies used to overcome L-asparaginase shortcomings and introduces recent tools that can be used to create therapeutic enzymes with improved features.

Expression of a recombinant bacterial L-asparaginase in human cells.

OBJECTIVE: L-Asparaginase (ASNase) is an enzyme used in the treatment of acute lymphoblastic leukemia (ALL). As the therapeutic ASNases has bacterial origin, severe side effects are associated with its use, among them hypersensitivity and inactivation of the enzyme. In this context, the objective of this work was to produce a recombinant ASNase of bacterial origin in human cells in order to determine the presence and consequences of potential post-translational modifications on the enzyme. RESULTS: Recombinant ASNase was expressed in human cells with a molecular weight of 60 kDa, larger than in Escherichia coli, which is 35 kDa. N-glycosylation analysis demonstrated that the increased molecular weight resulted from the addition of glycans to the protein by mammalian cells. The glycosylated ASNase presented in vitro activity at physiological pH and temperature. Given that glycosylation can act to reduce antigenicity by masking protein epitopes, our data may contribute to the development of an alternative ASNase in the treatment of ALL in patients who demonstrate side effects to currently marketed enzymes.

Boosting half-life and effector functions of therapeutic antibodies by Fc-engineering: An interaction-function review.

Due mainly to their high level of affinity and specificity, therapeutic monoclonal antibodies (mAbs) have been frequently selected as treatment for cancer, autoimmune or chronic inflammatory diseases. Despite the increasing number of mAbs and related products in the biopharmaceutical market, they are still expensive, can cause undesired side effects, and eventually cause resistance. Antibody engineering, which emerged to overcome limitations faced by mAb therapy, has supported the development of modified mAbs for immunotherapy. As part of this approach, researchers have invested in obtaining antibody fragments, as well as in Fc region modifications, since interactions with Fc receptors influence an antibody's half-life and mechanism of action. Thus, Fc engineering results in antibodies with more desirable characteristics and functions for which they are intended, creating "fit-for-purpose" antibodies with reduced side effects. Furthermore, aglycosylated antibodies, produced in bacterial cultivation, have been an alternative to create new effector functional human immunotherapeutics, while reducing mAb therapy costs. This review highlights some features that enhance mAb performance, related to the improvement of antibody half-life and effector responses by both Fc-engineering and glycoengineering.