The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) responsible for coronavirus disease 2019 (COVID-19) was discovered in December 2019 in Wuhan, China. Since that time, the virus has spread around the world, which resulted in an announcement of the World Health Organization (WHO), dated in March 2020, that COVID-19 was a worldwide pandemic, and since then, the world has been struggling with this disease. SARS-CoV-2, similar to other RNA viruses, continually mutates, and new variants are appearing. Among large numbers of detected SARS-CoV-2 variants, only an insignificant amount of them are able to pose a risk to public health, as they are more contagious and cause more severe conditions. The emerged variants were classified by the Centers for Disease Control and Prevention (CDC) in collaboration with SARS-CoV-2 Interagency Group (SIG) according to strictly defined pattern. Variants were classified as variants of concern, variants of interest, and variants of high consequence. In the last few months, three variants of concern (B.1.1.7, B.1.351, and P.1) and four variants of interests (B.1.526, B.1.525, B.1.427/B.1.429, and P.2) were distinguished and are essential for close monitoring. This analysis summarizes the principal information concerning SARS-CoV-2 variants, such as their infectivity, severity, mutations, and immune susceptibility.

The Emerging Concern and Interest SARS-CoV-2 Variants

White-tailed deer (Odocoileus virginianus) are highly susceptible to infection by SARS-CoV-2, with multiple reports of widespread spillover of virus from humans to free-living deer. While the recently emerged SARS-CoV-2 B.1.1.529 Omicron variant of concern (VoC) has been shown to be notably more transmissible amongst humans, its ability to cause infection and spillover to non-human animals remains a challenge of concern. We found that 19 of the 131 (14.5%; 95% CI: 0.10–0.22) white-tailed deer opportunistically sampled on Staten Island, New York, between December 12, 2021, and January 31, 2022, were positive for SARS-CoV-2 specific serum antibodies using a surrogate virus neutralization assay, indicating prior exposure. The results also revealed strong evidence of age-dependence in antibody prevalence. A significantly (χ2, p < 0.001) greater proportion of yearling deer possessed neutralizing antibodies as compared with fawns (OR=12.7; 95% CI 4–37.5). Importantly, SARS-CoV-2 nucleic acid was detected in nasal swabs from seven of 68 (10.29%; 95% CI: 0.0–0.20) of the sampled deer, and whole-genome sequencing identified the SARS-CoV-2 Omicron VoC (B.1.1.529) is circulating amongst the white-tailed deer on Staten Island. Phylogenetic analyses revealed the deer Omicron sequences clustered closely with other, recently reported Omicron sequences recovered from infected humans in New York City and elsewhere, consistent with human to deer spillover. Interestingly, one individual deer was positive for viral RNA and had a high level of neutralizing antibodies, suggesting either rapid serological conversion during an ongoing infection or a “breakthrough” infection in a previously exposed animal. Together, our findings show that the SARS-CoV-2 B.1.1.529 Omicron VoC can infect white-tailed deer and highlights an urgent need for comprehensive surveillance of susceptible animal species to identify ecological transmission networks and better assess the potential risks of spillback to humans. Key Findings These studies provide strong evidence of infection of free-living white-tailed deer with the SARS-CoV-2 B.1.1.529 Omicron variant of concern on Staten Island, New York, and highlight an urgent need for investigations on human-to-animal-to-human spillovers/spillbacks as well as on better defining the expanding host-range of SARS-CoV-2 in non-human animals and the environment.

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Detection of SARS-CoV-2 Omicron variant (B.1.1.529) infection of white-tailed deer

Abstract This document, endorsed by the IFCC Working Group on SARS-CoV-2 Variants, aims to update previous indications for diagnosing acute SARS-CoV-2 infection, taking into consideration the evidence that has emerged after the origin and spread of new lineages and sub-lineages of the virus characterized by mutated genetics and altered biochemical, biological and clinical characteristics. These indications encompass the use of different diagnostic strategies in specific clinical settings, such as high risk of SARS-CoV-2 infection (symptomatic patients), low risk of SARS-CoV-2 infection (asymptomatic subjects) at hospital admission/contact tracing, testing in asymptomatic subjects, in epidemiologic surveys and/or population screening, along with tentative indications for identification of new lineages and/or sub-lineages of SARS-CoV-2.

Ad interim recommendations for diagnosing SARS-CoV-2 infection by the IFCC SARS-CoV-2 variants working group

RT-PCR testing on nasopharyngeal swabs is a key component in the COVID-19 fighting, provided to use sensitive and specific SARS-CoV2 genome targets. In this study, we aimed to evaluate and to compare 4 widely used WHO approved RT-PCR protocols on real clinical specimens, to decrypt the reasons of the diverging results and to propose recommendations for the choice of the genome targets.260 nasopharyngeal samples were randomly selected among the samples tested between Week-16, 2020 and week-16 2021, in the Institut Pasteur de Tunis, Tunisia, one of the referent laboratories of COVID-19 in Tunisia. All samples were tested by Charité, Berlin protocol (singleplex envelop (E) and singleplex RNA-dependent RNA polymerase (RdRp)), Hong Kong Universiy, China protocol (singleplex nucleoprotein (N) and singleplex Open reading frame Orf1b), commercial test DAAN Gene® (using the CDC China protocol), (triplex N, Orf1ab with internal control) and Institut Pasteur Paris protocol (IPP) (triplex IP2(nsp9) and IP4 (nsp12) with internal control). For IPP, a selection from samples positive by IP2 but negative with IP4 was re-tested by exactly the same protocol but this time in singleplex. New results were described and analyzed.In vitro analysis showed discordant results in 29.2% of cases (76 out of 260). The most discordant protocol is DAAN Gene® due to the false positive late signals with N target. Discordant results between the two protocol's targets are more frequent when viral load are low (high Ct values). Our results demonstrated that the multiplexing has worsened the sensitivity of the IP4 target.We provide concise recommendations for the choice of the genome targets, the interpretation of the results and the alarm signals which makes suspect a gene mutation. 

/pdf/sars-cov2-rt-pcr-assays-in-vitro-comparison-of-4-who-2pqhtlto.pdf

SARS-CoV2 RT-PCR assays: In vitro﻿ comparison of 4 WHO approved protocols on clinical specimens and its implications for real laboratory practice through variant emergence

Currently, SARS‐CoV‐2 RNA detection using real‐time reverse‐transcription PCR (rRT‐PCR) is the standard diagnostic test for COVID‐19 infection. Various rRT‐PCR assays are currently used worldwide, targeting different genes of the SARS‐CoV‐2. Here, we compared the analytical sensitivity and clinical performance (sensitivity and specificity) of Allplex SARS‐CoV‐2/FluA/FluB/RSV assay (Seegene), Standard M nCoV real‐time detection kit (SD Biosensor), and U‐TOP COVID‐19 detection kit (Seasun Biomaterials) for SARS‐CoV‐2 detection.

Comparison of three molecular diagnostic assays for SARS‐CoV‐2 detection: Evaluation of analytical sensitivity and clinical performance

SARS-CoV-2 N gene dropout and N gene Ct value shift as indicator for the presence of B.1.1.7 lineage in a commercial multiplex PCR assay.

A novel species within the genus Eikenella is described, based on the phenotypical, biochemical and genetic characterization of a strain of a facultatively anaerobic, Gram-negative rod-shaped bacterium. Strain S3360T was isolated from the throat swab of a patient sampled during routine care at a hospital. Phylogenetic analyses (full-length 16S rRNA gene and whole-genome sequences) placed the strain in the genus Eikenella, separate from all recognized species but with the closest relationship to Eikenella longinqua (NML 02-A-017T). Eikenella is one of the genera in the HACEK group known to be responsible for rare cases of endocarditis in humans. Until the recent descriptions of Eikenella exigua, Eikenella halliae and Eikenella longinqua, Eikenella corrodens had been the only validly published species in this genus since its description as Bacteroides corrodens in 1958. Unlike these species, strain S3360T is able to metabolize carbohydrates (glucose). The average nucleotide identities of strain S3360T with E. longinqua (NML 02-A-017T) and E. corrodens (NCTC 10596T), the type species of the genus, were 90.5 and 84.7 %, respectively, and the corresponding genome-to-genome distance values were 41.3 and 29.0 %, respectively. The DNA G+C content of strain S3360T was 58.4 mol%. Based on the phenotypical, biochemical and genetic findings, strain S3360T is considered to represent a novel species within the genus Eikenella, for which the name Eikenella glucosivorans sp. nov. is proposed. The type strain is S3360T (DSM 110714T=CCOS 1935T=CCUG 74293T). In addition, an emendation of the genus Eikenella is proposed to include species which are saccharolytic.

Eikenella glucosivorans sp. nov., isolated from a human throat swab, and emendation of the genus Eikenella to include saccharolytic species.

ObjectivesIncreased importance in detection and surveillance of SARS-CoV-2 has been demonstrated due to the emergence of variants of concern (VOCs). In this study we evaluated if a commercially available real-time SARS-CoV-2 PCR assay can identify B.1.1.7 lineage samples by a specific N gene dropout or Ct value shift compared to the S or RdRP gene. MethodsPatients samples with confirmed B.1.1.7 variant by whole-genome sequencing and variant-specific PCR (n=48) and non-B.1.1.7 samples (n=53) were tested by the Allplex SARS-CoV-2/FluA/FluB/RSV PCR assay for presence of S, RdRP and N gene of SARS CoV-2. The N gene coding sequence of SARS-CoV-2 with and without D3L mutation (specific for B.1.1.7) were cloned into pCR(R)-TOPO vectors and Allplex SARS-CoV-2/FluA/FluB/RSV PCR assay was performed. ResultsAll studied B.1.1.7 patient samples showed significantly higher Ct values ({Delta} 6-10, N-gene dropout on Ct values >29) in the N gene compared to the respective values of S and RdRP gene. Receiver operating characteristic (ROC) curve analysis resulted in 100% sensitivity and specificity for {Delta}Ct N/RdRP and {Delta}Ct N/S. As a result of the reversed genetic experiments we found also the shift in Ct values for the 3L variant N-gene. ConclusionsN gene dropout or Ct value shift is specific for B.1.1.7 positive samples using the Allplex SARS-CoV-2/FluA/FluB/RSV PCR assay. This approach can be used as a rapid tool for B.1.1.7 detection in single assay high throughput diagnostics.

https://www.medrxiv.org/content/medrxiv/early/2021/03/26/2021.03.23.21254171.full.pdf

Michael Buhl

Papers

SARS-CoV-2 N gene dropout and N gene Ct value shift as indicator for the presence of B.1.1.7 lineage in a commercial multiplex PCR assay.

Eikenella glucosivorans sp. nov., isolated from a human throat swab, and emendation of the genus Eikenella to include saccharolytic species.

SARS-CoV-2 N gene dropout and N gene Ct value shift as indicator for the presence of B.1.1.7 lineage in a widely used commercial multiplex PCR assay