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Whole-genome characterisation in clinical microbiology enables to detect trends in infection dynamics and disease transmission. Here, we report a case of bacteraemia due to Campylobacter fetus subsp. fetus in a rural worker under cancer treatment that was diagnosed with cellulitis; the patient was treated with antibiotics and recovered. The routine typing methods were not able to identify the microorganism causing the infection, so it was further analysed by molecular methods and whole-genome sequencing. The multi-locus sequence typing (MLST) revealed the presence of the bovine-associated ST-4 genotype. Whole-genome comparisons with other C. fetus strains revealed an inconsistent phylogenetic position based on the core genome, discordant with previous ST-4 strains. To the best of our knowledge, this is the first C. fetus subsp. fetus carrying the ST-4 isolated from humans and represents a probable case of zoonotic transmission from cattle.

Biocatalysis exploits the versatility of enzymes to catalyse a variety of processes for the production of novel compounds and natural products. Enzyme immobilization enhances the stability and hence applicability of biomolecules as reusable and robust biocatalysts. Biomimetic mineralization reactions have emerged as a versatile tool for generating excellent supports for enzyme stabilization. The methodology utilizes biological templates and synthetic analogues to catalyse the formation of inorganic oxides. Such materials provide biocompatible environments for enzyme immobilization. The utility of the method is further enhanced by entraining and attaching encapsulated catalysts to a variety of supports. This review discusses biomimetic and bioinspired mineral formation as a technique for the immobilization of enzymes with potential application to a wealth of biocatalytic processes.

Campylobacter fetus is a venereal pathogen of cattle and sheep, and an opportunistic human pathogen. It is often assumed that C. fetus infection occurs in humans as a zoonosis through food chain transmission. Here we show that mammalian C. fetus consists of distinct evolutionary lineages, primarily associated with either human or bovine hosts. We use whole-genome phylogenetics on 182 strains from 17 countries to provide evidence that C. fetus may have originated in humans around 10,500 years ago and may have “jumped” into cattle during the livestock domestication period. We detect C. fetus genomes in 8% of healthy human fecal metagenomes, where the human-associated lineages are the dominant type (78%). Thus, our work suggests that C. fetus is an unappreciated human intestinal pathobiont likely spread by human to human transmission. This genome-based evolutionary framework will facilitate C. fetus epidemiology research and the development of improved molecular diagnostics and prevention schemes for this neglected pathogen. Human infections with Campylobacter fetus are often assumed to be derived from livestock. Here, Iraola et al. provide evidence that healthy humans may act as carriers and dispersers, and C. fetus may have originated in humans as an intestinal pathobiont and then adapted as a livestock pathogen.

The release of omega-3 fatty acids by the mild enzymatic hydrolysis of sardine oil was studied. The derivatives of different lipases physically adsorbed on hydrophobic porous supports Hydrophobic Lipase Derivatives (HLD) were tested. These immobilized lipases can only hydrolyze oil molecules partitioned into the aqueous phase of a biphasic reaction system. HLD biocatalysts were compared to other enzyme derivatives that were obtained by very mild covalent immobilization on CNBr-activated Sepharose Cyanogen bromide Lipase Derivatives (CNLD) that behave almost identically to soluble enzymes (CNLD). In general, HLD biocatalysts were found to be more active and more selective for the release of eicosapentaenoic acid (EPA) than CNLD. The most interesting biocatalyst was the HLD derivative of Yarrowia lipolytica lipase, which was found to be sevenfold more active and tenfold more selective than CNLD. On the other hand, the most active (but non-selective) derivative was the HLD of Pseudomonas fluorescens lipase (PFL). The activity of this derivative was 0.6 International Units under non-optimal reaction conditions. High-loaded PFL derivatives could be very interesting for the release of mixtures of EPA and docosahexaenoic acid. Hydrophobic supports promote the interfacial activation of lipases, similar to the interaction promoted by oil drops on soluble enzymes. The most effective overactivation obtained in this work ranged from 6- to 20-fold. The hydrolytic process was carried out under very mild conditions (pH 7.0 and 25 °C), and all lipase derivatives remained fully active for at least 15 days under these conditions.

Disulfide reduction of Kluyveromyces lactis and Aspergillus oryzae beta-galactosidases and beta-lactoglobulin was assessed. Reduction was performed using one of two thiol-containing agents: dithiothreitol (DTT) or thiopropyl-agarose with a high degree of substitution (1000 micromol of SH groups/g of dried gel). Both reductants allowed an increase of three- (for K. lactis beta-galactosidase) and fourfold (for A. oryzae beta-galactosidase) in the initial content of SH groups in the lactases. Nearly sevenfold fewer micromoles of SH groups per milligram of protein were needed to perform the reduction of K. lactis beta-galactosidase with thiopropyl-agarose than for the same reduction with DTT. However, for A. oryzae beta-galactosidase, nearly twice as many micromoles of SH groups per milligram of protein were needed with thiopropylagarose than with DTT. Disulfide bonds in beta-lactoglobulin were not accessible to thiopropyl-agarose, since this reduction was only possible in the presence of 6 M urea. These results proved that highly substituted thiopropyl-agarose is as good a reducing agent as DTT, for the reduction of disulfide bonds in proteins. Moreover, excess reducing agent was very simply separated from the reduced protein by filtration, making it easier to control the reaction and providing reduced protein solutions free of reductant. All these advantages substantially cut down the time required and therefore the cost of the overall process.

The aim of this study was to evaluate the effects of increasing dietary arachidonic acid (ARA) levels (from 1 to 6% of total fatty acids) on European sea bass (Dicentrarchus labrax) juveniles’ growth performance, tissue fatty acid profile, liver morphology as well as long-chain polyunsaturated fatty acids (LC-PUFA) biosynthesis, triglyceride and cholesterol synthesis and lipid transport. A diet with total fish oil (FO) replacement and defatted fish meal (FM) containing a 0.1-g ARA g−1 diet was added to the experimental design as a negative control diet. Dietary ARA inclusion levels below 0.2 g ARA g−1 diet significantly worsened growth even only 30 days after the start of the feeding trial, whereas dietary ARA had no effect on fish survival. Liver, muscle and whole body fatty acid profile mainly reflected dietary contents and ARA content increased accordingly with ARA dietary levels. Tissue eicosapentaenoic acid (EPA), docosapentaenoic acid (DPA) and docosahexaenoic acid (DHA) levels were positively correlated among them. Hepatic lipid vacuolization increased with reduced dietary ARA levels. Expressions of fatty acyl desaturase 2 and 3-hydroxy-3-methylglutaryl-coenzyme genes were upregulated in fish fed the negative control diet compared to the rest of the dietary treatments denoting the influence of ARA on lipid metabolism. Results obtained highlight the need to include adequate n-6 levels and not only n-3 LC-PUFA levels in European sea bass diets.

This study aimed to assess whether the expression of ACE2 and TMPRSS2 is associated with susceptibility to and severity of COVID-19 across age groups. We also evaluated the role of children in household transmission of SARS-CoV-2. We conducted a cross-sectional observational study including 258 households in Gran Canaria between March 10 and June 2, 2020. A total of 650 individuals (including 89 children under 18 years of age) were evaluated using a combined serological testing strategy to confirm past SARS-CoV-2 infection. Gene expression of ACE2 and TMPRSS2 was quantified from saliva samples. Demographic, clinical, and household exposure data were collected for analysis. The combined serological approach increased diagnostic sensitivity by 10%. Antibody levels decreased with age in children but increased with age and disease severity in adults. ACE2 expression was slightly elevated in younger children; however, after correction for multiple comparisons, there was no statistically significant association between ACE2 expression and age, antibody titers, or symptom severity.. TMPRSS2 expression did not correlate with any studied variable. Children were less frequently infected (OR = 0.56), and when infected, they experienced milder symptoms and reduced disease severity. Risk factors for transmission included older age and sharing a bedroom with the index case. In adults, risk increased with age; in children, younger age was associated with higher transmission risk. Our findings do not support a strong relationship between ACE2 or TMPRSS2 expression levels and susceptibility to or severity of COVID-19. Children appear to be less susceptible to SARS-CoV-2 infection and tend to experience a milder disease course.

In this study, different molecular typing tools were applied to characterize 95 Salmonella enterica blood isolates collected between 2008 and 2013 from patients at nine public hospitals in Lima, Peru. Combined results of multiplex PCR serotyping, two- and seven-loci multilocus sequence typing (MLST) schemes, serotyping, IS200 amplification and RAPD fingerprints, showed that these infections were caused by eight different serovars: Enteritidis, Typhimurium, Typhi, Choleraesuis, Dublin, Paratyphi A, Paratyphi B and Infantis. Among these, Enteritidis, Typhimurium and Typhi were the most prevalent, representing 45, 36 and 11% of the isolates, respectively. Most isolates (74%) were not resistant to ten primarily used antimicrobial drugs; however, 37% of the strains showed intermediate susceptibility to ciprofloxacin (ISC). Antimicrobial resistance integrons were carried by one Dublin (dfra1 and aadA1) and two Infantis (aadA1) isolates. The two Infantis isolates were multidrug resistant and harbored a large megaplasmid. Amplification of spvC and spvRA regions showed that all Enteritidis (n = 42), Typhimurium (n = 34), Choleraesuis (n = 3) and Dublin (n = 1) isolates carried the Salmonella virulence plasmid (pSV). We conclude that the classic serotyping method can be substituted by the multiplex PCR and, when necessary, sequencing of only one or two loci of the MLST scheme is a valuable tool to confirm the results. The effectiveness and feasibility of different typing tools is discussed.

Whole-exome sequencing reveals that a rare variant of phospholipase D3 ( PLD3 ( V232M )) segregates with Alzheimer’s disease status in two independent families and doubles risk for the disease in case–control series, and that several other PLD3 variants increase risk for Alzheimer’s disease in African Americans and people of European descent. New genetic risk variant for Alzheimer's disease The identification of mutations causing Alzheimer's disease in amyloid-β precursor protein, presenilin 1 and presenilin 2 led to a better understanding of the pathobiology of the condition. Further mutations are expected to be implicated, but the identification of such variants has been challenging. These authors used exome sequencing to identify low-frequency coding variants with large effects on late-onset Alzheimer's disease. They report several coding variants in the gene PLD3 , coding for phospholipase D3, that increase disease risk at least twofold. PLD3 may have a role in the processing of amyloid-β and may have potential as a novel therapeutic target. Genome-wide association studies (GWAS) have identified several risk variants for late-onset Alzheimer's disease (LOAD) 1 , 2 . These common variants have replicable but small effects on LOAD risk and generally do not have obvious functional effects. Low-frequency coding variants, not detected by GWAS, are predicted to include functional variants with larger effects on risk. To identify low-frequency coding variants with large effects on LOAD risk, we carried out whole-exome sequencing (WES) in 14 large LOAD families and follow-up analyses of the candidate variants in several large LOAD case–control data sets. A rare variant in PLD3 (phospholipase D3; Val232Met) segregated with disease status in two independent families and doubled risk for Alzheimer’s disease in seven independent case–control series with a total of more than 11,000 cases and controls of European descent. Gene-based burden analyses in 4,387 cases and controls of European descent and 302 African American cases and controls, with complete sequence data for PLD3 , reveal that several variants in this gene increase risk for Alzheimer’s disease in both populations. PLD3 is highly expressed in brain regions that are vulnerable to Alzheimer’s disease pathology, including hippocampus and cortex, and is expressed at significantly lower levels in neurons from Alzheimer’s disease brains compared to control brains. Overexpression of PLD3 leads to a significant decrease in intracellular amyloid-β precursor protein (APP) and extracellular Aβ42 and Aβ40 (the 42- and 40-residue isoforms of the amyloid-β peptide), and knockdown of PLD3 leads to a significant increase in extracellular Aβ42 and Aβ40. Together, our genetic and functional data indicate that carriers of PLD3 coding variants have a twofold increased risk for LOAD and that PLD3 influences APP processing. This study provides an example of how densely affected families may help to identify rare variants with large effects on risk for disease or other complex traits.

Nicholas Feasey and colleagues report whole-genome sequence analysis of 675 isolates of Salmonella enterica serovar Enteritidis from 45 countries. They find evidence for a global epidemic clade associated with enterocolitis and two novel clades restricted to distinct regions of Africa and associated with invasive disease. An epidemiological paradox surrounds Salmonella enterica serovar Enteritidis. In high-income settings, it has been responsible for an epidemic of poultry-associated, self-limiting enterocolitis, whereas in sub-Saharan Africa it is a major cause of invasive nontyphoidal Salmonella disease, associated with high case fatality. By whole-genome sequence analysis of 675 isolates of S. Enteritidis from 45 countries, we show the existence of a global epidemic clade and two new clades of S. Enteritidis that are geographically restricted to distinct regions of Africa. The African isolates display genomic degradation, a novel prophage repertoire, and an expanded multidrug resistance plasmid. S. Enteritidis is a further example of a Salmonella serotype that displays niche plasticity, with distinct clades that enable it to become a prominent cause of gastroenteritis in association with the industrial production of eggs and of multidrug-resistant, bloodstream-invasive infection in Africa.