Antibody Response in Healthcare Workers before and after the Third Dose of Anti-SARS-CoV-2 Vaccine: A Pilot Study.

The SARS-CoV-2 pandemic led to the development of various vaccines. The BNT162b2 mRNA vaccine was the first approved due to its efficacy in eliciting a humoral immunity response after the second dose. However, a decrease in the antibody concentration was observed over time. Therefore, the administration of a third dose was scheduled, primarily for frail people and workers of essential public activities. The aim of this study was to assess the level of antibodies against the spike (S) RBD of SARS-CoV-2 in healthcare workers before and after the third dose of BNT162b2 vaccine, according to sex, age, and the time interval between vaccine doses and tests. All 37 (12 males, 25 females, 19 < 50 years old, 18 ≥ 50 years old) healthcare workers recruited showed a consistent antibody titer increase after the third dose. Data analysis showed that the antibody concentration before the third dose significantly decreased as the time interval up to the test increased, and a significantly higher level was shown in young than older people. Cluster analysis revealed that young females had a higher antibody level than older females before the third dose (p < 0.05). This study indicated the benefit of the third dose of BNT162b2 vaccine and its effect on leveling up the humoral immune response.

Codon usage, phylogeny and binding energy estimation predict the evolution of SARS-CoV-2.

In the frames of a One Health strategy, i.e. a strategy should be able to predict susceptibility to infection in both humans and animals, developing a SARS-CoV-2 mutation tracking system is a goal. We observed that the phylogenetic proximity of vertebrate ACE2 receptors does not affect the binding energy for the viral spike protein. However, all viral variants seem to bind ACE2 better in many animals than in humans. Moreover, two observations highlight that the evolution of the virus started at the beginning of 2020 and culminated with the appearance of the variants. First, codon usage analysis shows that the B.1.1.7 (alpha), B.1.351 (beta) and B.1.617.2 (delta) variants, similar in the use of codons, are also similar to a virus sampled in January 2020. Second, the host-specific D614G mutation becomes prevalent starting from March 2020. Overall, we show that SARS-CoV-2 undergoes a process of molecular evolution that begins with the optimization of codons followed by the functional optimization of the spike protein.

Seasonal Variability of the Airborne Eukaryotic Community Structure at a Coastal Site of the Central Mediterranean.

The atmosphere represents an underexplored temporary habitat for airborne microbial communities such as eukaryotes, whose taxonomic structure changes across different locations and/or regions as a function of both survival conditions and sources. A preliminary dataset on the seasonal dependence of the airborne eukaryotic community biodiversity, detected in PM10 samples collected from July 2018 to June 2019 at a coastal site representative of the Central Mediterranean, is provided in this study. Viridiplantae and Fungi were the most abundant eukaryotic kingdoms. Streptophyta was the prevailing Viridiplantae phylum, whilst Ascomycota and Basidiomycota were the prevailing Fungi phyla. Brassica and Panicum were the most abundant Streptophyta genera in winter and summer, respectively, whereas Olea was the most abundant genus in spring and autumn. With regards to Fungi, Botrytis and Colletotrichum were the most abundant Ascomycota genera, reaching the highest abundance in spring and summer, respectively, while Cryptococcus and Ustilago were the most abundant Basidiomycota genera, and reached the highest abundance in winter and spring, respectively. The genus community structure in the PM10 samples varied day-by-day, and mainly along with the seasons. The impact of long-range transported air masses on the same structure was also proven. Nevertheless, rather few genera were significantly correlated with meteorological parameters and PM10 mass concentrations. The PCoA plots and non-parametric Spearman's rank-order correlation coefficients showed that the strongest correlations generally occurred between parameters reaching high abundances/values in the same season or PM10 sample. Moreover, the screening of potential pathogenic fungi allowed us to detect seven potential pathogenic genera in our PM10 samples. We also found that, with the exception of Panicum and Physcomitrella, all of the most abundant and pervasive identified Streptophyta genera could serve as potential sources of aeroallergens in the studied area.

IgM and IgG Profiles Reveal Peculiar Features of Humoral Immunity Response to SARS-CoV-2 Infection.

The emergence of coronavirus disease 2019 (COVID-19) is globally a major healthcare threat. There is little information regarding the mechanisms and roles of the humoral response in SARS-CoV-2 infection. The aim of this study was to analyze the antibody levels (IgM and IgG) by chemiluminescence immunoassay in 54 subjects positive to SARS-CoV-2 swab test in relation to their clinical status (whether asymptomatic, pauci-symptomatic or with mild, sever or critical symptoms), the time from the symptom onset, sex, age, and comorbidities. Overall, the presence of comorbidities and the age of subjects were associated with their clinical status. The IgG concentrations were significantly higher in patients who developed critical and severe symptoms and seemed to be independent from age, sex and comorbidities. IgG titers peaked around day 60, and then began gradually to drop, decreasing by approximately 50% on the 180th day, while the IgM titers progressively decreased as early as the tenth day, but they could be detected even at later time points. Despite the small number of individuals, some peculiar characteristics of the humoral response in COVID-19 emerged. We observed a high inter-individual variability, an ephemeral IgG half-life in several patients, and a persistence of IgM in others.

Molecular docking simulation reveals ACE2 polymorphisms that may increase the affinity of ACE2 with the SARS-CoV-2 Spike protein.

There is increasing evidence that ACE2 gene polymorphism can modulate the interaction between ACE2 and the SARS-CoV-2 spike protein affecting the viral entry into the host cell, and/or contribute to lung and systemic damage in COVID-19. Here we used in silico molecular docking to predict the effects of ACE2 missense variants on the interaction with the spike protein of SARS-CoV-2. HDOCK and FireDock simulations identified 6 ACE2 missense variants (I21T, A25T, K26R, E37K, T55A, E75G) with higher affinity for SARS-CoV-2 Spike protein receptor binding domain (RBD) with respect to wild type ACE2, and 11 variants (I21V, E23K, K26E, T27A, E35K, S43R, Y50F, N51D, N58H, K68E, M82I) with lower affinity. This result supports the hypothesis that ACE2 genetic background may represent the first "genetic gateway" during the disease progression.

Renin-angiotensin system at the heart of COVID-19 pandemic.

Significant aspects of COVID-19 pandemic remain obscure. Angiotensin converting enzyme 2 (ACE2), a component of the renin-angiotensin system, whose expression dominates on lung alveolar epithelial cells, is the human cell receptor of SARS-CoV-2, the causative agent of COVID-19. We strongly encourage the concept that thorough considerations of receptor-ligand interactions should be kept at the heart of scientific debate on infection. In this idea, the whole renin-angiotensin system has to be evaluated. We hypothesize that factors related to ethnicity, environment, behaviors, associated illness, and medications involving this complex system are probably responsible for situations regarded as anomalous from both an epidemiological and a clinical point of view, but, taken together, such factors may explain most of the aspects of current outbreak. We decided to use the analogy of a play and speculate about the possible impact in this tragedy of 1) air pollution via the interference of nitrogen dioxide on ACE2 expression; 2) the dual role of nicotine; 3) the hypothetical involvement of ACE2 polymorphisms, the relationships of which with ethnic factors and susceptibility to cardiovascular disease seems intriguing; 4) the impact on the severity of infection of hypertension and related medications acting on the renin/angiotensin system, and, finally, 5) the possible helpful role of chloroquine, thanks to its capacity of modifying ACE2 affinity to the viral spike protein by altering glycosylation. This hypothesis paper is an urgent call for the development of research programs that aim at questioning whether the putative protagonists of this tragedy are real-life actors in COVID-19.