Genome sequence analysis of the first human West Nile virus isolated in Italy in 2009.

In 2009, six new human cases of West Nile neuroinvasive disease (WNND) were identified in Veneto region, following the six cases already reported in 2008. A human West Nile virus (WNV) isolate was obtained for the first time from an asymptomatic blood donor. Whole genome sequence of the human WNV isolate showed close phylogenetic relatedness to the Italy-1998-WNV strain and to other WNV strains recently isolated in Europe, with the new acquisition of the NS3-Thr249Pro mutation, a trait associated with avian virulence, increased virus transmission, and the occurrence of outbreaks in humans

Clinical and virological findings in the ongoing outbreak of West Nile virus Livenza strain in northern Italy, July to September 2012.

Binary file ES_Abstracts_Final_ECDC.txt matche

Insight into the mechanism of ferroptosis inhibition by ferrostatin-1

Ferroptosis is a form of cell death primed by iron and lipid hydroperoxides and prevented by GPx4. Ferrostatin-1 (fer-1) inhibits ferroptosis much more efficiently than phenolic antioxidants. Previous studies on the antioxidant efficiency of fer-1 adopted kinetic tests where a diazo compound generates the hydroperoxyl radical scavenged by the antioxidant. However, this reaction, accounting for a chain breaking effect, is only minimally useful for the description of the inhibition of ferrous iron and lipid hydroperoxide dependent peroxidation. Scavenging lipid hydroperoxyl radicals, indeed, generates lipid hydroperoxides from which ferrous iron initiates a new peroxidative chain reaction. We show that when fer-1 inhibits peroxidation, initiated by iron and traces of lipid hydroperoxides in liposomes, the pattern of oxidized species produced from traces of pre-existing hydroperoxides is practically identical to that observed following exhaustive peroxidation in the absence of the antioxidant. This supported the notion that the anti-ferroptotic activity of fer-1 is actually due to the scavenging of initiating alkoxyl radicals produced, together with other rearrangement products, by ferrous iron from lipid hydroperoxides. Notably, fer-1 is not consumed while inhibiting iron dependent lipid peroxidation. The emerging concept is that it is ferrous iron itself that reduces fer-1 radical. This was supported by electroanalytical evidence that fer-1 forms a complex with iron and further confirmed in cells by fluorescence of calcein, indicating a decrease of labile iron in the presence of fer-1. The notion of such as pseudo-catalytic cycle of the ferrostatin-iron complex was also investigated by means of quantum mechanics calculations, which confirmed the reduction of an alkoxyl radical model by fer-1 and the reduction of fer-1 radical by ferrous iron. In summary, GPx4 and fer-1 in the presence of ferrous iron, produces, by distinct mechanism, the most relevant anti-ferroptotic effect, i.e the disappearance of initiating lipid hydroperoxides

Rapid SARS-CoV-2 intra-host and within-household emergence of novel haplotypes

In February 2020, the municipality of Vo’, a small town near Padua (Italy) was quarantined due to the first coronavirus disease 19 (COVID-19)-related death detected in Italy. To investigate the viral prevalence and clinical features, the entire population was swab tested in two sequential surveys. Here we report the analysis of 87 viral genomes, which revealed that the unique ancestor haplotype introduced in Vo’ belongs to lineage B, carrying the mutations G11083T and G26144T. The viral sequences allowed us to investigate the viral evolution while being transmitted within and across households and the effectiveness of the non-pharmaceutical interventions implemented in Vo’. We report, for the first time, evidence that novel viral haplotypes can naturally arise intra-host within an interval as short as two weeks, in approximately 30% of the infected individuals, regardless of symptom severity or immune system deficiencies. Moreover, both phylogenetic and minimum spanning network analyses converge on the hypothesis that the viral sequences evolved from a unique common ancestor haplotype that was carried by an index case. The lockdown extinguished both the viral spread and the emergence of new variant

Organochalcogen peroxidase mimetics as potential drugs: a long story of a promise still unfulfilled

Organochalcogen compounds have attracted the interest of a multitude of studies to design potential therapeutic agents mimicking the peroxidase activity of selenium-based glutathione peroxidases (GPx's). Starting from the pioneering ebselen, various compounds have been synthesized over the years, which may be traced in three major classes of molecules: cyclic selenenyl amides, diaryl diselenides, and aromatic or aliphatic monoselenides. These compounds share common features and determinants needed to exert an efficient GPx-like activity, such as polarizing groups in close proximity to selenium and steric effects. Nonetheless, the reactivity of selenium, and tellurium as well, poses serious problems for the predictability of the biological effects of these compounds in vivo when used as potential drugs. These molecules, indeed, interfere with thiols of redox-regulated proteins and enzymes, leading to unexpected biological effects. The various chemical aspects of the reaction mechanism of peroxidase mimetics are surveyed here, focusing on experimental evidence and quantum mechanics calculations of organochalcogen representatives of the various classes

Novel insights on the mechanistic aspects of GPx-catalyzed H2O2 reduction: a DFT computational study

A state-of-the-art accurate quantum chemistry computational approach is proposed to investigate the mechanism of H2O2 reduction at the active site of GPx. In the model we consider explicitly six amino acids surrounding the catalytic SEC or CYS residue. The geometries of the plausible intermediate species and transition states as well as the energetics are carefully predicted. The computational protocol, rooted in advanced Density Functional Theory methodologies, is employed to explore possible mechanistic paths involving different initial active species (Se-; SeH; S- ; SH) and stability of protonated surrounding amino acids, in particular Gln (O), Gly (N) and Trp (N). The data so far acquired have demonstrated the following: i) the chosen amino acids forming the catalytic \u201ccage\u201d are fully optimized and their minimum energy conformation is perfectly superimposed to the initial crystal structure (see Fig. 1) and no difference has been observed when the active site contains either Se or S; ii) the proton of selenol or thiol has been dislocated in all of the available surrounding amino acids and it has been optimized in most of the tested locations leading to the conclusion that it is displaced in the positively charged catalytic pocket rather than exclusively bound to selenium or sulphur, iii) hydrogen peroxide is extremely instable in the active site and selenenic/sulphenic acid and water are formed instantaneously. This transition is the minimum energy path of the system and account for the non saturation kinetics of GPx where there is no evidence for the formation of a stable enzyme substrate complex. This set of data strongly suggests that for the catalysis of H2O2 reduction the active site of GPx is crucial, while the redox residue can be either SEC or CYS

Possible mechanistic paths of the enzymatic activity of GPx

Glutathione peroxidases (GPx, Fig. 1) belong to a widespread family of proteins that, over the years, have been discovered in almost all kingdoms of life.[1] They catalyze the reduction of H2O2 or organic hydroperoxides to water or corresponding alcohols, thus mitigating their toxicity.[2] The global reaction is ROOH+2GSH \uf0e0 GSSG+ROH+H2O, where GSH indicates glutathione. In the GPx family the active site SeCys or Cys is surrounded by highly conserved residues (Asn, Gln and Trp) forming the catalytic tetrad. One of the main open questions is about the specific role of either SeCys or Cys in the catalysis: it is not yet clear why selenium rather than sulphur has been chosen by nature selection given that a complex and energetically very expensive co-traslational insertion machinery for SeCys is needed. Fig. 1 GPx Fig. 2 Model catalytic site The basic catalytic scheme involves three main steps, i.e. (i) O-O bond cleavage and formation of selenenic/sulphenic acid Se/S-OH and ROH; (ii) formation of a seleno-sulfide (disulfide) intermediate and elimination of H2O; (iii) formation of the disulfide product and regeneration of the catalyst. We present a detailed investigation of different possible paths of the reduction of H2O2 catalyzed by Se-based as well as S-based GPxs with the aim of validating at quantum chemistry (DFT) level the experimental findings obtained by recent mass spectrometry and biochemistry methods (enzymatic kinetics); a core of seven aminoacids has been identified, which suitably represents the GPx core (Fig. 2). From our results a complex energy landscape emerges, where novel mechanistic paths are possible and novel perspectives on the intriguing behaviour of GPx can be outlined