Internal Validation of the ASFV MONODOSE dtec-qPCR Kit for African Swine Fever Virus Detection under the UNE-EN ISO/IEC 17025:2005 Criteria.

African swine fever virus is considered an emerging virus that causes African swine fever, a disease characterised by high mortality and elevated transmission rates and that, as it is for most other viral diseases, cannot be treated with specific drugs. Effective and reliable detection of the virus is relevant to prevent uncontrolled contagion among boar populations and to reduce economic losses. Moreover, animal health laboratories are demanding standardisation, optimisation and quality assurance of the available diagnostic assays. In the present study, the ASFV MONODOSE dtec-qPCR kit was validated following the UNE-EN ISO/IEC 17025:2005 guidelines. Analytical validation terms include in silico and in vitro specificity, sensitivity, efficiency and reliability (repeatability/reproducibility). Diagnostic validation of the method was assessed through the analysis of a total of 181 porcine samples originating from six different matrix types doped with African swine fever virus DNA received from the European reference laboratory for African Swine Fever (INIA-CISA, Madrid, Spain): whole blood, blood serum, kidney, heart, liver and tonsil. Results agreed with those obtained from a reference detection method also based on real-time PCR, endorsed by WOAH, but the ASFV MONODOSE dtec-qPCR kit incorporates some technical innovations and improvements which may benefit end-users. This kit, available worldwide with full analytical and diagnostic validation, can recognise all known ASFV genotypes and brings additional benefits to the current qPCR technology.

Internal Validation of a Real-Time qPCR Kit following the UNE/EN ISO/IEC 17025:2005 for Detection of the Re-Emerging Monkeypox virus.

Human mpox is caused by the Monkeypox virus, a microorganism closely related to the Variola virus, both belonging to the Orthopoxvirus genus. Mpox had been considered a rare disease until a global outbreak occurred in 2022. People infected with the virus present similar symptoms to patients suffering smallpox and other rash illnesses, hindering diagnosis. The WHO indicated that no commercial PCR or serology kits are currently widely available. In the present study, the MPXV MONODOSE dtec-qPCR kit was validated following guidelines of the UNE/EN ISO/IEC 17025:2005. The parameters evaluated for the acceptance of the assay were in silico and in vitro specificity, quantitative phase analysis, reliability, and sensitivity. The assay passed validation criteria and yielded an efficiency of 95.8%, high repeatability, reproducibility, and a Limit of Detection and Quantification of at least 10 copies. Results from the validation of the MPXV dtec-qPCR kit were satisfactory. The use of the MONODOSE format (dehydrated single PCR-tubes, ready to use) provided considerable advantages allowing the detection of the Monkeypox virus to be accurately achieved. This detection kit may be considered a reliable, fast, simple, and universally available option.

Correction: Martínez-Murcia et al. SARS-CoV-2 Variants Identification; A Fast and Affordable Strategy Based on Partial S-Gene Targeted PCR Sequencing. Viruses 2022, 14, 2588.

In the original publication [...].

SARS-CoV-2 Variants Identification; A Fast and Affordable Strategy Based on Partial S-Gene Targeted PCR Sequencing.

A considerable number of new SARS-CoV-2 lineages have emerged since the first COVID-19 cases were reported in Wuhan. As a few variants showed higher COVID-19 disease transmissibility and the ability to escape from immune responses, surveillance became relevant at that time. Single-nucleotide mutation PCR-based protocols were not always specific, and consequently, determination of a high number of informative sites was needed for accurate lineage identification. A detailed in silico analysis of SARS-CoV-2 sequences retrieved from GISAID database revealed the S gene 921 bp-fragment, positions 22784-23705 of SARS-CoV-2 reference genome, as the most informative fragment (30 variable sites) to determine relevant SARS-CoV-2 variants. Consequently, a method consisting of the PCR-amplification of this fragment, followed by Sanger's sequencing and a "single-click" informatic program based on a reference database, was developed and validated. PCR-fragments obtained from clinical SARS-CoV-2 samples were compared with homologous variant-sequences and the resulting phylogenetic tree allowed the identification of Alpha, Delta, Omicron, Beta, Gamma, and other variants. The data analysis procedure was automatized and simplified to the point that it did not require specific technical skills. The method is faster and cheaper than current whole-genome sequencing methods; it is available worldwide, and it may help to enhance efficient surveillance in the fight against the COVID-19 pandemic.

qPCR Detection of Candida auris Using the GPS™ CanAur MONODOSE dtec-qPCR Test.

Candida auris is a multidrug-resistant pathogenic ascomycete yeast of increasing health concern. C. auris colonizes patient's skin and can persist for weeks on surfaces, so it can be transmitted within and between hospitals. The most common diagnostic platforms in microbiology use reference databases that have not yet incorporated C. auris, misidentifying it. This chapter describes how to detect C. auris by qPCR with the GPS™ CanAur MONODOSE dtec-qPCR Test (Alicante, Spain) in less than 45 min, using ready-to-use tubes with all the components dehydrated. This commercial kit was subjected to validation following the guidelines of the UNE-EN ISO/IEC 17025:2005 and French Standard NF T90-471:2010.

Current RT-qPCR to detect SARS-CoV-2 may give positive results for related coronaviruses.

Some weeks after the first CoVID-19 outbreak, the World Health Organization published some real-time PCR (qPCR) protocols developed by different health reference centers. These qPCR designs are being used worldwide to detect SARS-CoV-2 in the population, to monitor the prevalence of the virus during the pandemic. Moreover, some of these protocols to detect SARS-CoV-2 have widely been applied to environmental samples for epidemiological surveillance purposes. In the present work, the specificity of these currently used RT-qPCR designs was validated in vitro using SARS-CoV-2 and highly related coronaviral genomic sequences and compared to performance of the commercially available GPS™ CoVID-19 dtec-RT-qPCR Test. Assays performed with SARS-CoV-2-related genomes showed positive amplification when using some of these qPCR methods, indicating they may give SARS-CoV-2 false positives. This finding may be particularly relevant for SARS-CoV-2 monitoring of environmental samples, where an unknown pool of phylogenetically close-related viruses may exist.

Internal validation of GPS™ MONODOSE CanAur dtec-qPCR kit following the UNE/EN ISO/IEC 17025:2005 for detection of the emerging yeast Candida auris.

Candida auris is an emerging multidrug resistant pathogenic fungus that causes candidaemia with high mortality rates and exhibits the ability to persist within the hospital environment. Candida auris is phylogenetically closely related to Candida haemulonii, C. lusitaniae, C. pseudohaemulonii and C. duobushaemulonii and is frequently misidentified by commercial identification methods. In the present study, the GPS™ MONODOSE dtec-qPCR kit (dried single-dose PCR tubes) for the detection of C. auris was validated following the guidelines of the UNE/EN ISO/IEC 17025:2005, the French Standard NF T90-471:2010 and using fast-cycling protocols. Validation terms included in vitro specificity (inclusivity/exclusivity), quantitative phase analysis (10-106  standard DNA copies), reliability (repeatability/reproducibility) and sensitivity (detection/quantification limits). GPS™ dtec-qPCR kits passed validation with strict acceptance criteria (n ≥ 10 repetitions). In silico specificity was proven by the designer (GPS™ ). Experimental inclusiveness was achieved in two independent laboratories by testing strain JCM15448T and 117 clinical C. auris isolates from Asia, the Middle-East Africa, Latin America and Europe. Exclusiveness was evaluated with 25 strains of closely related Candida spp. Use of the MONODOSE format provided considerable advantages allowing the detection of C. auris to be accurately achieved in less than an hour. The GPS™ MONODOSE dtec-qPCR kit is ready to undergo clinical evaluation.

Aeromonas lusitana sp. nov., Isolated from Untreated Water and Vegetables.

During previous studies to evaluate the phylogenetic diversity of Aeromonas from untreated waters and vegetables intended for human consumption, a group of isolates formed a unique gyrB phylogenetic cluster, separated from those of all other species described so far. A subsequent extensive phenotypic characterization, DNA-DNA hybridization, 16S rRNA gene sequencing, multi-locus phylogenetic analysis of the concatenated sequence of seven housekeeping genes (gyrB, rpoD, recA, dnaJ, gyrA, dnaX, and atpD; 4705 bp), and ERIC-PCR, were performed in an attempt to ascertain the taxonomy position of these isolates. This polyphasic approach confirmed that they belonged to a novel species of the genus Aeromonas, for which the name Aeromonas lusitana sp. nov. is proposed, with strain A.11/6(T) (=DSMZ 24095(T), =CECT 7828(T)) as the type strain.

Mutation of Ser-50 and Cys-66 in Snapin modulates protein structure and stability.

Snapin is a 15 kDa protein present in neuronal and non-neuronal cells that has been implicated in the regulation of exocytosis and endocytosis. Protein kinase A (PKA) phosphorylates Snapin at Ser-50, modulating its function. Likewise, mutation of Cys-66, which mediates protein dimerization, impairs its cellular activity. Here, we have investigated the impact of mutating these two positions on protein oligomerization, structure, and thermal stability, along with the interaction with SNARE proteins. We found that recombinant purified Snapin in solution appears mainly as dimers in equilibrium with tetramers. The protein exhibits modest secondary structure elements and notable thermal stability. Mutation of Cys-66 to Ser abolished subunit dimerization, but not higher-order oligomers. This mutant augmented the presence of α-helical structure and slightly increased the protein thermal stability. Similarly, the S50A mutant, mimicking the unphosphorylated protein, also exhibited a higher helical secondary structure content than the wild type, along with greater thermal stability. In contrast, replacement of Ser-50 with Asp (S50D), emulating the protein-phosphorylated state, produced a loss of α-helical structure, concomitant with a decrease in protein thermal stability. In vitro, the wild type and mutants weakly interacted with SNAP-25 and the reconstituted SNARE complex, although S50D exhibited the strongest binding to the SNARE complex, consistent with the observed higher cellular activity of PKA-phosphorylated Snapin. Our observations suggest that the stronger binding of S50D to SNAREs might be due to a destabilization of tetrameric assemblies of Snapin that favor the interaction of protein dimers with the SNARE proteins. Therefore, phosphorylation of Ser-50 has an important impact on the protein structure and stability that appears to underlie its functional modulation.