An update on clinical presentation and responses to therapy of patients with hereditary hypophosphatemic rickets with hypercalciuria (HHRH).

Pathogenic variants in solute carrier family 34, member 3 (SLC34A3), the gene encoding the sodium-dependent phosphate cotransporter 2c (NPT2c), cause hereditary hypophosphatemic rickets with hypercalciuria (HHRH). Here, we report a pooled analysis of clinical and laboratory records of 304 individuals from 145 kindreds, including 20 previously unreported HHRH kindreds, in which two novel SLC34A3 pathogenic variants were identified. Compound heterozygous/homozygous carriers show above 90% penetrance for kidney and bone phenotypes. The biochemical phenotype for heterozygous carriers is intermediate with decreased serum phosphate, tubular reabsorption of phosphate (TRP (%)), fibroblast growth factor 23, and intact parathyroid hormone, but increased serum 1,25-dihydroxy vitamin D, and urine calcium excretion causing idiopathic hypercalciuria in 38%, with bone phenotypes still observed in 23% of patients. Oral phosphate supplementation is the current standard of care, which typically normalizes serum phosphate. However, although in more than half of individuals this therapy achieves correction of hypophosphatemia it fails to resolve the other outcomes. The American College of Medical Genetics and Genomics score correlated with functional analysis of frequent SLC34A3 pathogenic variants in vitro and baseline disease severity. The number of mutant alleles and baseline TRP (%) were identified as predictors for kidney and bone phenotypes, baseline TRP (%) furthermore predicted response to therapy. Certain SLC34A3/NPT2c pathogenic variants can be identified with partial responses to therapy, whereas with some overlap, others present only with kidney phenotypes and a third group present only with bone phenotypes. Thus, our report highlights important novel clinical aspects of HHRH and heterozygous carriers, raises awareness to this rare group of disorders and can be a foundation for future studies urgently needed to guide therapy of HHRH.

Application of Doehlert design in optimizing the solid-state hydrogenogenic stage augmented with biomass fly ash in a two-stage biohythane production process.

This study aimed to optimize the solid-state hydrogenogenic stage supplemented with biomass fly ash in a two-stage anaerobic digestion (AD) process for biohythane production from the organic fraction of municipal solid waste (OFMSW). Doehlert's experimental design was used to obtain the optimal set of two investigated variables, namely total solids (TS) content and biomass fly ash dosage in the defined ranges of 0-20 g/L and 20-40%, respectively. Applying the optimal conditions of TS content (29.1%) and fly ash dosage (19.2 g/L) in the first stage led not only to a total H2 yield of 95 mL/gVSadded, which was very close to the maximum H2 yield predicted by the developed model (97 mL/gVSadded), but also to a high CH4 yield of 400 mL/gVSadded (76% of the theoretical CH4 yield). Moreover, the biohythane obtained from the optimized two-stage process met the standards of a biohythane fuel with an H2 content of 19% v/v.

Transcriptomic clustering of critically ill COVID-19 patients

Infections caused by SARS-CoV-2 may cause a severe disease, termed COVID-19, with significant mortality. Host responses to this infection, mainly in terms of systemic inflammation, have emerged as key pathogenetic mechanisms, and their modulation is the only therapeutic strategy that has shown a mortality benefit. Herein, we used peripheral blood transcriptomes of critically-ill COVID-19 patients obtained at admission in an Intensive Care Unit (ICU), to identify two transcriptomic clusters characterized by expression of either interferon-related or immune checkpoint genes, respectively. These profiles have different ICU outcome, in spite of no major clinical differences at ICU admission. A transcriptomic signature was used to identify these clusters in an external validation cohort, yielding similar results. These findings reveal different underlying pathogenetic mechanisms and illustrate the potential of transcriptomics to identify patient endotypes in severe COVID-19, aimed to ultimately personalize their therapies.

Tracing the trajectories of SARS-CoV-2 variants of concern between December 2020 and September 2021 in the Canary Islands (Spain)

Several variants of concern (VOCs) explain most of the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) epidemic waves in Europe. We aimed to dissect the spread of the SARS-CoV-2 VOCs in the Canary Islands (Spain) between December 2020 and September 2021 at a micro-geographical level. We sequenced the viral genome of 8,224 respiratory samples collected in the archipelago. We observed that Alpha (B.1.1.7) and Delta (B.1.617.2 and sub-lineages) were ubiquitously present in the islands, while Beta (B.1.351) and Gamma (P.1/P.1.1) had a heterogeneous distribution and were responsible for fewer and more controlled outbreaks. This work represents the largest effort for viral genomic surveillance in the Canary Islands so far, helping the public health bodies in decision-making throughout the pandemic.

IFIH1 rs1990760 variants, systemic inflammation and outcome in critically-ill COVID-19 patients

RationaleOutcomes in patients with severe SARS-CoV-2 infection (COVID-19) are conditioned by virus clearance and regulation of inflammation. Variants in IFIH1, a gene coding the cytoplasmatic RNA sensor MDA5, regulate the response to viral infections. ObjectiveTo characterize the impact of IFIH1 rs199076 variants on host response and outcomes after severe COVID-19. MethodsPatients admitted to an intensive care unit (ICU) with confirmed COVID-19 were prospectively studied and rs1990760 variants determined. Peripheral blood gene expression, cell populations and immune mediators were measured. Peripheral blood mononuclear cells from healthy volunteers were exposed to an MDA5 agonist and dexamethasone ex-vivo, and changes in gene expression assessed. ICU discharge and hospital death were modelled using rs1990760 variants and dexamethasone as factors in this cohort and in-silico clinical trials. Measurements and Main Results227 patients were studied. Patients with the IFIH1 rs1990760 TT variant showed a lower expression of inflammation-related pathways, an anti-inflammatory cell profile and lower concentrations of pro-inflammatory mediators. Cells with TT variant exposed to a MDA5 agonist showed an increase in IL6 expression after dexamethasone treatment. All patients with the TT variant not treated with steroids (N=14) survived their ICU stay (HR 2.49, 95% confidence interval 1.29-4.79). Patients with a TT variant treated with dexamethasone (N=50) showed an increased hospital mortality (HR 2.19, 95% confidence interval 1.01-4.87) and serum IL-6. In-silico clinical trials supported these findings. ConclusionsCOVID-19 patients with the IFIH1 rs1990760 TT variant show an attenuated inflammatory response and better outcomes. Dexamethasone may reverse this anti-inflammatory phenotype.

Monitoring the rise of the SARS-CoV-2 lineage B.1.1.7 in Tenerife (Spain) since mid-December 2020

Starting in December 2020, a sharp increase of COVID-19 cases occurred in Tenerife compared to the rest of the Canary Islands (Spain). Because of the direct touristic connections between Tenerife and the UK, and the rapid transmission and dominance of the SARS-CoV-2 B.1.1.7 variant of concern (VOC-202012/01) by the end of November 2020 in South England, here we measured the proportion of B.1.1.7 cases occurring between the 18th of December 2020 and the 25th of February 2021. Out of the 2,091 COVID-19 positive nasopharyngeal swab samples assessed, 226 showed a spike gene target failure (SGTF). Subsequent viral genome sequencing further confirmed that 93.2% of them corresponded to the B.1.1.7 lineage. Furthermore, a rapid increase in the proportion of SGTF variants was detected in up to 10.7% of positive cases during the Christmas season despite stricter measures for containing the transmission were imposed in Tenerife in the period. These results support the local transmission of SARS-CoV-2 B.1.1.7 lineage in Tenerife since late December 2020 although it is not yet dominant.

The CCR5-delta32 variant might explain part of the association between COVID-19 and the chemokine-receptor gene cluster

A polymorphism in the LZTFL1 gene located in the chemokine-receptor gene cluster (chromosome 3p) has been associated with the risk of developing COVID-19. The chemokine receptor-5 (CCR5) maps to this region, and the common 32 bp deletion variant ({Delta}32) has been associated with the extent of inflammatory disease and the outcome in several viral diseases. Several studies have also suggested that the pharmacological targeting of CCR5 could reduce the impact of SARS-CoV-2 infection and the severity of COVID-19. We sought to investigate whether this polymorphism was associated with the risk of moderate-severe COVID-19. We genotyped 294 patients who required hospitalization due to COVID-19 (85 were severe cases) and 460 controls. We found a significantly lower frequency of CCR5-{Delta}32 among the COVID-19 patients (0.10 vs 0.18 in controls; p=0.002, OR=0.48, 95%CI=0.29-0.76). The difference was mainly due to the reduced frequency of CCR5-{Delta}32 carriers in the severe, significantly lower than in the non-severe patients (p=0.036). Of note, we did not find deletion-homozygotes among the patients compared to 1% among controls. We also confirmed the association between a LZTFL1 variant and COVID-19. Our study points to CCR5 as a promising target for treatment of COVID-19, but requires validation in additional large cohorts. In confirmed by others, the genetic analysis of CCR5-variants (such as {Delta}32) might help to identify patients with a higher susceptibility to severe COVID-19.

Increasing SARS-CoV-2 RT-qPCR testing capacity by sample pooling

ObjectivesLimited testing capacity has characterized the ongoing COVID-19 pandemic in Spain, hampering a timely control of outbreaks and the possibilities to reduce the escalation of community transmissions. Here we investigated the potential of using pooling of samples followed by one-step retrotranscription and quantitative PCR (RT-qPCR) to increase SARS-CoV-2 testing capacity. MethodsWe first evaluated different sample pooling (1:5, 1:10 and 1:15) prior to RNA extractions followed by standard RT-qPCR for SARS-CoV-2/COVID-19 diagnosis. The pool size achieving reproducible results in independent tests was then used for assessing nasopharyngeal samples in a tertiary hospital during August 2020. ResultsWe found that pool size of five samples achieved the highest sensitivity compared to pool sizes of 10 and 15, showing a mean ({+/-} SD) Ct shift of 3.5 {+/-} 2.2 between the pooled test and positive samples in the pool. We then used a pool size of five to test a total of 895 pools (4,475 prospective samples) using two different RT-qPCR kits available at that time. The Real Accurate Quadruplex corona-plus PCR Kit (PathoFinder) reported the lowest mean Ct ({+/-} SD) shift (2.2 {+/-} 2.4) among the pool and the individual samples. The strategy allows detecting individual samples in the positive pools with Cts in the range of 16.7-39.4. ConclusionsWe found that pools of five samples combined with RT-qPCR solutions helped to increase SARS-CoV-2 testing capacity with minimal loss of sensitivity compared to that resulting from testing the samples independently.

Sensitivity of different RT-qPCR solutions for SARS-CoV-2 detection

ObjectiveThe ongoing COVID-19 pandemic continues imposing a demand for diagnostic screening. In anticipation that the recurrence of outbreaks and the measures for lifting the lockdown worldwide may cause supply chain issues over the coming months, we assessed the sensitivity of a number of one-step retrotranscription and quantitative PCR (RT-qPCR) solutions to detect SARS-CoV-2. MethodsWe evaluated six different RT-qPCR alternatives for SARS-CoV-2/COVID-19 diagnosis based on standard RNA extractions. That of best sensitivity was also assessed with direct nasopharyngeal swab viral transmission medium (VTM) heating, overcoming the RNA extraction step. ResultsWe found a wide variability in the sensitivity of RT-qPCR solutions that associated with a range of false negatives from as low as 2% (0.3-7.9%) to as much as 39.8% (30.2-50.2). Direct preheating of VTM combined with the best solution provided a sensitivity of 72.5% (62.5-81.0), in the range of some of the solutions based on standard RNA extractions. ConclusionsWe evidenced sensitivity limitations of currently used RT-qPCR solutions. Our results will help to calibrate the impact of false negative diagnoses of COVID-19, and to detect and control new SARS-CoV-2 outbreaks and community transmissions.

Fast SARS-CoV-2 detection by RT-qPCR in preheated nasopharyngeal swab samples

The current reference for COVID-19 diagnosis is based on the detection of SARS-CoV-2 on RNA extracts using one-step retrotranscription and quantitative PCR (RT-qPCR). Based on the urgent need for high-throughput COVID-19 screening, we tested the performance of three alternative, simple and affordable protocols to rapidly detect SARS-CoV-2, overcoming the long and tedious RNA extraction step. Although with an average increase of 6.1 ({+/-} 1.6) cycles compared to standard tests with RNA extracts, we show that RT-qPCR yielded consistent results in nasopharyngeal swab samples that were subject to a direct 70{degrees}C incubation for 10 min. Our findings provide viable options to overcome any supply chain issue and help to increase the throughput of diagnostic tests by using any qPCR device, thereby complementing standard COVID-19 testing.

A method for obtaining RNA from Hemileia vastatrix appressoria produced in planta, suitable for transcriptomic analyses.

Appressoria are the first infection structures developed by rust fungi and require specific topographic signals from the host for their differentiation. The ease in obtaining appressoria in vitro for these biotrophic fungi led to studies concerning gene expression and gene discovery at appressorial level, avoiding the need to distinguish plant and fungal transcripts. However, in some pathosystems, it was observed that gene expression in appressoria seems to be influenced by host-derived signals, suggesting that transcriptomic analyses performed from in planta differentiated appressoria would be potentially more informative than those from in vitro differentiated appressoria. Nevertheless analysing appressorial RNA obtained from in planta samples is often hampered by an excessive dilution of fungal RNA within plant RNA, besides uncertainty regarding the fungal or plant origin of RNA from highly conserved genes. To circumvent these difficulties, we have recovered Hemileia vastatrix appressoria from Arabica coffee leaf surface using a film of nitrocellulose dissolved in butyl and ethyl acetates (nail polish), and extracted fungal RNA from the polish peel. RNA thus obtained is of good quality and usable for cDNA synthesis and transcriptomic (quantitative PCR) studies. This method could provide the means to investigate specific host-induced appressoria-related fungal pathogenicity factors.

Validation of RT-qPCR reference genes for in planta expression studies in Hemileia vastatrix, the causal agent of coffee leaf rust.

Hemileia vastatrix is a biotrophic fungus, causing coffee leaf rust in all coffee growing countries, leading to serious social and economic problems. Gene expression studies may have a key role unravelling the transcriptomics of this pathogen during interaction with the plant host. Reverse transcription quantitative real-time polymerase chain reaction (RT-qPCR) is currently the golden standard for gene expression analysis, although an accurate normalisation is essential for adequate conclusions. Reference genes are often used for this purpose, but the stability of their expression levels requires validation under experimental conditions. Moreover, pathogenic fungi undergo important biomass variations along their infection process in planta, which raises the need for an adequate method to further normalise the proportion of fungal cDNA in the total plant and fungus cDNA pool. In this work, the expression profiles of seven reference genes [glyceraldehyde-3-phosphate dehydrogenase (GADPH), elongation factor (EF-1), Beta tubulin (ß-tubulin), cytochrome c oxidase subunit III (Cyt III), cytochrome b (Cyt b), Hv00099, and 40S ribosomal protein (40S_Rib)] were analysed across 28 samples, obtained in vitro (germinated uredospores and appressoria) and in planta (post-penetration fungal growth phases). Gene stability was assessed using the statistical algorithms incorporated in geNorm and NormFinder tools. Cyt b, 40S_Rib, and Hv00099 were the most stable genes for the in vitro dataset, while 40S_Rib, GADPH, and Cyt III were the most stable in planta. For the combined datasets (in vitro and in planta), 40S_Rib, GADPH, and Hv00099 were selected as the most stable. Subsequent expression analysis for a gene encoding an alpha subunit of a heterotrimeric G-protein showed that the reference genes selected for the combined dataset do not differ significantly from those selected specifically for the in vitro and in planta datasets. Our study provides tools for correct validation of reference genes in obligate biotrophic plant pathogens, as well as the basis for RT-qPCR studies in H. vastatrix.