Genomic characterization and phylogenetic analysis of sars-cov-2 in libya

The COVID-19 epidemic started in Libya in March 2020 and rapidly spread. To shed some light on the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) strains circulating in Libya, viruses isolated from 10 patients in this country were sequenced, characterized at the genomic level, and compared to genomes isolated in other parts of the world. As nine genomes out of 10 belonged to the SS1 cluster and one to SS4, three datasets were built. One included only African strains and the other two contained internationally representative SS1 and SS4 genomes. Genomic analysis showed that the Libyan strains have some peculiar features in addition to those reported in other world regions. Considering the countries in which the strains are genetically more similar to the Libyan strains, SARS-CoV-2 could have entered Libya from a North African country (possibly Egypt), sub-Saharan Africa (e.g., Ghana, Mali, Nigeria), the Middle East (e.g., Saudi Arabia), or Asia (India, Bangladesh).Copyright © 2021 by the authors. Licensee MDPI, Basel, Switzerland.

Analysis of Mutations in Conserved and Susceptible Regions Across the Whole Genome Sequencing Analysis for SARS-CoV-2 in Iraqi Patients

This study aimed to get a better understanding of molecular epidemiology and genetic variation in the spike glycoprotein as a key viral component involved in viral entrance into host cells and as a potential vaccination target. Three Iraqi SARSCoV- 2 strains were investigated using whole-genome sequencing, with two of them clustering into the 20A (GH) clade, and the remaining strain is clustered in 20E (GV) clade, belonging to the B.1.36.1 and B.1.177.80 lineage, respectively. Wholegenome sequencing of the viral RNA samples revealed nine sporadic nonsynonymous uncommon mutations with frequency ranged from 0.00 to 0.19%. The ORF1ab, ORF1a, ORF3a, S, N, intergenic, ORF7 and ORF8 areas have seen the most changes. Furthermore, in all of our sequences, we discovered a D614G (aspartic acid to glycine) mutation in spike protein that co-occurred with an NSP12 P323L (viral RNA-dependent RNA polymerase) mutation. The findings point to several viral introductions in Iraq and provide new genetic information on SARSCoV- 2 at the worldwide level. Pathogenesis, diagnostics and vaccine development require information such as SNPs and mutations. © 2023 Publishing house Mining book. All rights reserved.

The COVID-19 Pandemic Sparked Off a Large-Scale Outbreak of Carbapenem-Resistant Acinetobacter baumannii from the Endemic Strains at an Italian Hospital.

Acinetobacter baumannii is a nosocomial pathogen that poses a serious threat due to the rise of incidence of multidrug-resistant (MDR) strains. During the COVID-19 pandemic, MDR A. baumannii clones have caused several outbreaks worldwide. Here, we describe a detailed investigation of an MDR A. baumannii outbreak that occurred at Policlinico San Matteo (Pavia, Italy). A total of 96 A. baumannii strains, isolated between January and July 2020 from 41 inpatients (both SARS-CoV-2 positive and negative) in different wards, were characterized by phenotypic and genomic analyses combining Illumina and Nanopore sequencing. Antibiotic susceptibility testing revealed that all isolates were resistant to carbapenems, and the sequence analysis attributed this to the carbapenemase gene blaOXA-23. Virulence factor screening unveiled that all strains carried determinants for biofilm formation, while plasmid analysis revealed the presence of two plasmids, one of which was ~100 kbp long and encoded a phage sequence. A core genome-based phylogeny was inferred to integrate outbreak strain genomes with background genomes from public databases and the local surveillance program. All strains belonged to the globally disseminated sequence type 2 (ST2) clone and were mainly divided into two clades. Isolates from the outbreak clustered with surveillance isolates from 2019, suggesting that the outbreak was caused by two strains that were already circulating in the hospital before the start of the pandemic. The intensive spread of A. baumannii in the hospital was enhanced by the extreme emergency situation of the first COVID-19 pandemic wave that resulted in reduced attention to infection prevention and control practices. IMPORTANCE The COVID-19 pandemic, especially during the first wave, posed a great challenge to the hospital management and generally promoted nosocomial pathogen dissemination. MDR A. baumannii can easily spread and persist for a long time on surfaces, causing outbreaks in health care settings. Infection prevention and control practices, epidemiological surveillance, and microbiological screening are fundamental in order to control such outbreaks. Here, we sequenced the genomes of 96 isolates from an outbreak of MDR A. baumannii strains using both short- and long-read technology in order to reconstruct the outbreak events in fine detail. The sequence data demonstrated that two endemic clones of MDR A. baumannii were the source of this large hospital outbreak during the first COVID-19 pandemic wave, confirming the effect of COVID-19 emergency disrupting the protection provided by the use of the standard prevention procedures.

High Throughput SARS-CoV-2 Genome Sequencing from 384 Respiratory Samples Using the Illumina COVIDSeq Protocol.

The emergence of the Coronavirus Disease 2019 (COVID-19) pandemic has fostered the use of high-throughput techniques to sequence the entire severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) genome and track its evolution. The present study proposes a rapid and relatively less expensive sequencing protocol for 384 samples by adapting the use of an Illumina NovaSeq library to an Illumina MiSeq flow cell instrument. The SARS-CoV-2 genome sequences obtained with Illumina NovaSeq and those obtained using MiSeq instruments were compared with the objective to validate the new, modified protocol. A total of 356 (94.6%) samples yielded interpretable sequences using the modified Illumina COVIDSeq protocol, with an average coverage of 91.6%. By comparison, 357 (94.9%) samples yielded interpretable sequences with the standard COVIDSeq protocol, with an average coverage of 95.6%. Our modified COVIDSeq protocol could save 14,155 euros per run and yield results from 384 samples in 53.5 h, compared to four times 55.5 h with the standard Illumina MiSeq protocol. The modified COVIDSeq protocol thus provides high quality results comparable to those obtained with the standard COVIDSeq protocol, four times faster, while saving money.

Intensity of sample processing methods impacts wastewater SARS-CoV-2 whole genome amplicon sequencing outcomes.

Wastewater SARS-CoV-2 surveillance has been deployed since the beginning of the COVID-19 pandemic to monitor the dynamics in virus burden in local communities. Genomic surveillance of SARS-CoV-2 in wastewater, particularly efforts aimed at whole genome sequencing for variant tracking and identification, are still challenging due to low target concentration, complex microbial and chemical background, and lack of robust nucleic acid recovery experimental procedures. The intrinsic sample limitations are inherent to wastewater and are thus unavoidable. Here, we use a statistical approach that couples correlation analyses to a random forest-based machine learning algorithm to evaluate potentially important factors associated with wastewater SARS-CoV-2 whole genome amplicon sequencing outcomes, with a specific focus on the breadth of genome coverage. We collected 182 composite and grab wastewater samples from the Chicago area between November 2020 to October 2021. Samples were processed using a mixture of processing methods reflecting different homogenization intensities (HA + Zymo beads, HA + glass beads, and Nanotrap), and were sequenced using one of the two library preparation kits (the Illumina COVIDseq kit and the QIAseq DIRECT kit). Technical factors evaluated using statistical and machine learning approaches include sample types, certain sample intrinsic features, and processing and sequencing methods. The results suggested that sample processing methods could be a predominant factor affecting sequencing outcomes, and library preparation kits was considered a minor factor. A synthetic SARS-CoV-2 RNA spike-in experiment was performed to validate the impact from processing methods and suggested that the intensity of the processing methods could lead to different RNA fragmentation patterns, which could also explain the observed inconsistency between qPCR quantification and sequencing outcomes. Overall, extra attention should be paid to wastewater sample processing (i.e., concentration and homogenization) for sufficient and good quality SARS-CoV-2 RNA for downstream sequencing.

SARS-CoV-2 Omicron Variant Genomic and Phylogenetic Analysis in Iraqi Kurdistan Region.

Omicron variants have been classified as Variants of Concern (VOC) by the World Health Organization (WHO) ever since they first emerged as a result of a significant mutation in this variant, which showed to have an impact on transmissibility and virulence of the virus, as evidenced by the ongoing modifications in the SARS-CoV-2 virus. As a global pandemic, the Omicron variant also spread among the Kurdish population. This study aimed to analyze different strains from different cities of the Kurdistan region of Iraq to show the risk of infection and the impact of the various mutations on immune responses and vaccination. A total of 175 nasopharyngeal/oropharyngeal specimens were collected at West Erbil Emergency Hospital and confirmed for SARS-CoV-2 infection by RT-PCR. The genomes of the samples were sequenced using the Illumina COVID-Seq Method. The genome analysis was established based on previously published data in the GISAID database and compared to previously detected mutations in the Omicron variants, and that they belong to the BA.1 lineage and include most variations determined in other studies related to transmissibility, high infectivity and immune escape. Most of the mutations were found in the RBD (receptor binding domain), the region related to the escape from humoral immunity. Remarkably, these point mutations (G339D, S371L, S373P, S375F, T547K, D614G, H655Y, N679K and N969K) were also determined in this study, which were unique, and their impact should be addressed more. Overall, the Omicron variants were more contagious than other variants. However, the mortality rate was low, and most infectious cases were asymptomatic. The next step should address the potential of Omicron variants to develop the next-generation COVID-19 vaccine.

Characterization of SARS-CoV-2 isolated from a patient in Iran compared to SARS-CoV-2 different variants.

Since the onset of the global epidemic of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), whole genome sequencing of virus in all countries has been considered to track and predict virus transmission and variation patterns. In the current study we reported a novel complete genome sequence of SARS-CoV-2 isolated from Iran. Genomics variations and protein sequences were evaluated for the isolated sequence and seven Iranian complete genome sequences of SARS-CoV-2 from NCBI using the reference genome of the SARS-CoV-2 Wuhan-Hu-1. The results showed six nucleotide substitutions. The multiple sequence alignment of the spike protein of the Wuhan-Hu-1 strain and the emerging variants indicated similar its residue pattern in the current sequence to the Wuhan-Hu-1 strain. There were relatively similar binding affinity and residues involved in the interactions of the spike receptor-binding domain (RBD) of the Wuhan-Hu-1 strain, the variants and Hormozgan With angiotensin-converting enzyme 2 (ACE2). Tracing the phylogeny of virus indicated distinct clustering of Iranian variants in branches close to the Asian countries. The mutation effect study on the function of proteins predicted neutral impact of all six nucleotide substitutions. However, the free energy calculations indicated a decreasing the protein stability related to the mutations. This data, consistent with similar studies, showed that despite the high similarity in the nucleotide sequence of the SARS-CoV-2, the mutation pattern varies from country to country. Therefore, any country can benefit from these studies to track and find appropriate strategies for treating and controlling the epidemic.Communicated by Ramaswamy H. Sarma.

Optimization of the Illumina COVIDSeq™ protocol for decentralized, cost-effective genomic surveillance.

A decentralized surveillance system to identify local outbreaks and monitor SARS-CoV-2 Variants of Concern is one of the primary strategies for the pandemic's containment. Although next-generation sequencing (NGS) is a gold standard for genomic surveillance and variant discovery, the technology is still cost-prohibitive for decentralized sequencing, particularly in small independent labs with limited resources. We have optimized the Illumina COVIDSeq™ protocol for the Illumina MiniSeq instrument to reduce cost without compromising accuracy. We slashed the library preparation cost by half by using 50% of recommended reagents at each step and normalizing the libraries before pooling to achieve uniform coverage. Reagent-only cost (∼$43.27/sample) for SARS-CoV-2 variant analysis with this normalized input protocol on MiniSeq instruments is comparable to what is achieved on high throughput instruments such as NextSeq and NovaSeq. Using this modified protocol, we tested 153 clinical samples, and 90% of genomic coverage was achieved for 142/153 samples analyzed in this study. The lineage was correctly assigned to all samples (152/153) except for one. This modified protocol can help laboratories with constrained resources to contribute in decentralized COVID-19 surveillance in the post-vaccination era.

Standing up FungiNet: Genomic epidemiology and surveillance of fungal diseases

Objectives: With the advent of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) sequencing, the public health landscape for genomic epidemiology and surveillance has transformed for a variety of pathogens. For fungal diseases, the U. S. Centers for Disease Control and Prevention (CDC) is working with global partners to stand up FungiNet, a network that aims to equip scientists with laboratory, bioinformatics, and informatics resources to harness genomic data. FungiNet partners will use genomic and epidemiologic data to detect outbreaks, identify introductions, and characterize transmission of fungal infections. In 2022, FungiNet aims to onboard nine state and local health departments in the United States and two global partners, the Instituto Nacional de Salud in Colombia and the National Institute for Communicable Diseases in South Africa, with a focus on Candida auris. Method(s): To streamline the onboarding process, CDC generated standardized operating procedures (SOPs) specific to C. auris. For DNA extraction, SOPs were created for workflows using the Zymo Research Quick-DNA TM (ZR) Fungal/Bacterial Miniprep, Qiagen Dneasy Blood and Tissue, and Epicentre (Illumina) MasterPure Yeast DNA Purification kits. For library preparation and Illumina sequencing, PulseNet methods used for foodborne pathogens were validated for C. auris. For NCBI data submissions, required data elements were defined. For SNP and phylogenetic analyses, the bioinformatics workflow My-coSNP was adapted to use Nextflow software and the Terra platform. For visualization with epidemiologic data, guidance documents and tutorials for Microreact were created. Finally, for data reporting, processes are being designed in REDCap and in laboratory information management systems to rapidly share genomic-related data. Result(s): To date, 11 partners have committed to building capacity for C. auris genomic sequencing and analysis as a FungiNet partner. Of these, seven have validated methods for DNA extraction, and nine have generated high-quality sequencing data. Only one partner has installed and locally run MycoSNP, and none have submitted raw sequence data to NCBI. Conclusion(s): Currently, 11 FungiNet partners are working to onboard C. auris genomic sequencing and bioinformatics analysis in 2022. This process is complex, requiring several laboratories, bioinformatics, and informatics workflows. For many partners, bioinformatics analysisand NCBIsubmission are themost challenging activities with the installationof MycoSNPand the ability to batch upload data to NCBI as the main barriers. Next steps will focus on the validation of informatics methods to link genomic and epidemiologic data.

Simultaneous SARS-CoV-2 Genome Sequencing of 384 Samples on an Illumina MiSeq Instrument through Protocol Optimization.

In the present study, we propose a high-throughput sequencing protocol using aNextera XT Library DNA kit on an Illumina MiSeq instrument. We made major modifications to this library preparation in order to multiplex 384 samples in a single Illumina flow cell. To validate our protocol, we compared the sequences obtained with the modified Illumina protocol to those obtained with the GridION Nanopore protocol. For the modified Illumina protocol, our results showed that 94.9% (357/376) of the sequences were interpretable, with a viral genome coverage between 50.5% and 99.9% and an average depth of 421×. For the GridION Nanopore protocol, 94.6% (356/376) of the sequences were interpretable, with a viral genome coverage between 7.0% and 98.6% and an average depth of 2123×. The modified Illumina protocol allows for gaining EUR 4744 and returning results of 384 samples in 53.5 h versus four times 55.5 h with the standard Illumina protocol. Our modified MiSeq protocol yields similar genome sequence data as the GridION Nanopore protocol and has the advantage of being able to handle four times more samples simultaneously and hence is much less expensive.

A Comparison of Bioinformatics Pipelines for Enrichment Illumina Next Generation Sequencing Systems in Detecting SARS-CoV-2 Virus Strains.

Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) is a newly emerging virus well known as the major cause of the worldwide pandemic due to Coronavirus Disease 2019 (COVID-19). Major breakthroughs in the Next Generation Sequencing (NGS) field were elucidated following the first release of a full-length SARS-CoV-2 genome on the 10 January 2020, with the hope of turning the table against the worsening pandemic situation. Previous studies in respiratory virus characterization require mapping of raw sequences to the human genome in the downstream bioinformatics pipeline as part of metagenomic principles. Illumina, as the major player in the NGS arena, took action by releasing guidelines for improved enrichment kits called the Respiratory Virus Oligo Panel (RVOP) based on a hybridization capture method capable of capturing targeted respiratory viruses, including SARS-CoV-2; therefore, allowing a direct map of raw sequences data to SARS-CoV-2 genome in downstream bioinformatics pipeline. Consequently, two bioinformatics pipelines emerged with no previous studies benchmarking the pipelines. This study focuses on gaining insight and understanding of target enrichment workflow by Illumina through the utilization of different bioinformatics pipelines named as 'Fast Pipeline' and 'Normal Pipeline' to SARS-CoV-2 strains isolated from Yogyakarta and Central Java, Indonesia. Overall, both pipelines work well in the characterization of SARS-CoV-2 samples, including in the identification of major studied nucleotide substitutions and amino acid mutations. A higher number of reads mapped to the SARS-CoV-2 genome in Fast Pipeline and merely were discovered as a contributing factor in a higher number of coverage depth and identified variations (SNPs, insertion, and deletion). Fast Pipeline ultimately works well in a situation where time is a critical factor. On the other hand, Normal Pipeline would require a longer time as it mapped reads to the human genome. Certain limitations were identified in terms of pipeline algorithm, whereas it is highly recommended in future studies to design a pipeline in an integrated framework, for instance, by using NextFlow, a workflow framework to combine all scripts into one fully integrated pipeline.

Molecular Analysis of SARS-CoV-2 Lineages in Armenia.

The sequencing of SARS-CoV-2 provides essential information on viral evolution, transmission, and epidemiology. In this paper, we performed the whole-genome sequencing of SARS-CoV-2 using nanopore and Illumina sequencing to describe the circulation of the virus lineages in Armenia. The analysis of 145 full genomes identified six clades (19A, 20A, 20B, 20I, 21J, and 21K) and considerable intra-clade PANGO lineage diversity. Phylodynamic and transmission analysis allowed to attribute specific clades as well as infer their importation routes. Thus, the first two waves of positive case increase were caused by the 20B clade, the third peak caused by the 20I (Alpha), while the last two peaks were caused by the 21J (Delta) and 21K (Omicron) variants. The functional analyses of mutations in sequences largely affected epitopes associated with protective HLA loci and did not cause the loss of the signal in PCR tests targeting ORF1ab and N genes as confirmed by RT-PCR. We also compared the performance of nanopore and Illumina short-read sequencing and showed the utility of nanopore sequencing as an efficient and affordable alternative for large-scale molecular epidemiology research. Thus, our paper describes new data on the genomic diversity of SARS-CoV-2 variants in Armenia in the global context of the virus molecular genomic surveillance.

Optimizing the Illumina COVIDSeq laboratorial and bioinformatics pipeline on thousands of samples for SARS-CoV-2 Variants of Concern tracking.

The SARS-CoV-2 Variants of Concern tracking via Whole Genome Sequencing represents a pillar of public health measures for the containment of the pandemic. The ability to track down the lineage distribution on a local and global scale leads to a better understanding of immune escape and to adopting interventions to contain novel outbreaks. This scenario poses a challenge for NGS laboratories worldwide that are pressed to have both a faster turnaround time and a high-throughput processing of swabs for sequencing and analysis. In this study, we present an optimization of the Illumina COVID-seq protocol carried out on thousands of SARS-CoV-2 samples at the wet and dry level. We discuss the unique challenges related to processing hundreds of swabs per week such as the tradeoff between ultra-high sensitivity and negative contamination levels, cost efficiency and bioinformatics quality metrics.

Comparison of SARS-CoV-2 sequencing using the ONT GridION and the Illumina MiSeq.

BACKGROUND: Over 4 million SARS-CoV-2 genomes have been sequenced globally in the past 2 years. This has been crucial in elucidating transmission chains within communities, the development of new diagnostic methods, vaccines, and antivirals. Although several sequencing technologies have been employed, Illumina and Oxford Nanopore remain the two most commonly used platforms. The sequence quality between these two platforms warrants a comparison of the genomes produced by the two technologies. Here, we compared the SARS-CoV-2 consensus genomes obtained from the Oxford Nanopore Technology GridION and the Illumina MiSeq for 28 sequencing runs. RESULTS: Our results show that the MiSeq had a significantly higher number of consensus genomes classified by Nextclade as good and mediocre compared to the GridION. The MiSeq also had a significantly higher genome coverage and mutation counts than the GridION. CONCLUSION: Due to the low genome coverage, high number of indels, and sensitivity to SARS-CoV-2 viral load noted with the GridION when compared to MiSeq, we can conclude that the MiSeq is more favourable for SARS-CoV-2 genomic surveillance, as successful genomic surveillance is dependent on high quality, near-whole consensus genomes.

Robust Mutation Profiling of SARS-CoV-2 Variants from Multiple Raw Illumina Sequencing Data with Cloud Workflow.

Several variants of the novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are emerging all over the world. Variant surveillance from genome sequencing has become crucial to determine if mutations in these variants are rendering the virus more infectious, potent, or resistant to existing vaccines and therapeutics. Meanwhile, analyzing many raw sequencing data repeatedly with currently available code-based bioinformatics tools is tremendously challenging to be implemented in this unprecedented pandemic time due to the fact of limited experts and computational resources. Therefore, in order to hasten variant surveillance efforts, we developed an installation-free cloud workflow for robust mutation profiling of SARS-CoV-2 variants from multiple Illumina sequencing data. Herein, 55 raw sequencing data representing four early SARS-CoV-2 variants of concern (Alpha, Beta, Gamma, and Delta) from an open-access database were used to test our workflow performance. As a result, our workflow could automatically identify mutated sites of the variants along with reliable annotation of the protein-coding genes at cost-effective and timely manner for all by harnessing parallel cloud computing in one execution under resource-limitation settings. In addition, our workflow can also generate a consensus genome sequence which can be shared with others in public data repositories to support global variant surveillance efforts.

Targeted Sanger sequencing to recover key mutations in SARS-CoV-2 variant genome assemblies produced by next-generation sequencing.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is adaptively evolving to ensure its persistence within human hosts. It is therefore necessary to continuously monitor the emergence and prevalence of novel variants that arise. Importantly, some mutations have been associated with both molecular diagnostic failures and reduced or abrogated next-generation sequencing (NGS) read coverage in some genomic regions. Such impacts are particularly problematic when they occur in genomic regions such as those that encode the spike (S) protein, which are crucial for identifying and tracking the prevalence and dissemination dynamics of concerning viral variants. Targeted Sanger sequencing presents a fast and cost-effective means to accurately extend the coverage of whole-genome sequences. We designed a custom set of primers to amplify a 401 bp segment of the receptor-binding domain (RBD) (between positions 22698 and 23098 relative to the Wuhan-Hu-1 reference). We then designed a Sanger sequencing wet-laboratory protocol. We applied the primer set and wet-laboratory protocol to sequence 222 samples that were missing positions with key mutations K417N, E484K, and N501Y due to poor coverage after NGS sequencing. Finally, we developed SeqPatcher, a Python-based computational tool to analyse the trace files yielded by Sanger sequencing to generate consensus sequences, or take preanalysed consensus sequences in fasta format, and merge them with their corresponding whole-genome assemblies. We successfully sequenced 153 samples of 222 (69 %) using Sanger sequencing and confirmed the occurrence of key beta variant mutations (K417N, E484K, N501Y) in the S genes of 142 of 153 (93 %) samples. Additionally, one sample had the Y508F mutation and four samples the S477N. Samples with RT-PCR Ct scores ranging from 13.85 to 37.47 (mean=25.70) could be Sanger sequenced efficiently. These results show that our method and pipeline can be used to improve the quality of whole-genome assemblies produced using NGS and can be used with any pairs of the most used NGS and Sanger sequencing platforms.

Assessment of the environmental distribution of the protozoan parasite Perkinsus olseni by next-generation sequencing, qPCR and histopathology allows the identification of alternative bivalve hosts

Perkinsus olseni is a protozoan parasite that infects a wide variety of molluscs worldwide, causing economic losses in the aquaculture sector. Consequently, Perkinsosis has been catalogued by the World Organization for Animal Health (O.I.E.) as a notifiable disease, and international measures have been established to control it (O.I.E., 2019). In the present study, we analysed the spatial and temporal distribution of transmissible stages of Perkinsus olseni in an endemic area of the parasite from 2016 to 2018. The pathogen was detected using high-throughput sequencing of the 18S rRNA gene and a specific real-time PCR assay (qPCR) in samples of water, sediment and several bivalve species. Histopathological assays were also conducted on bivalve samples. P. olseni was not detected in environmental samples by qPCR;however, eDNA sequencing revealed its presence in both the water and sediment at all sampled points, showing a seasonal pathogen prevalence. As expected, the parasite was detected in clams, but a few cases were also found in mussels and cockles. The presence of the parasite was confirmed in Cerastoderma edule by histology and qPCR using RNA to evaluate the presence of proliferative life stages of the parasite. Therefore, this is the first time that P. olseni has been found in C. edule but with low abundance and infection intensity levels. [Display omitted] • The metabarcoding assay allowed the detection of P. olseni in sediment and water. • Different Perkinsus life stages could be related to each environmental fraction. • Proliferative and non-proliferative P. olseni were detected by qPCR in clams. • C. edule could be a new host of P. olseni , as detected by histology, qPCR and NGS. • A similar seasonal abundance pattern was obtained in clams and sediment by sequencing. [ FROM AUTHOR] Copyright of Aquaculture is the property of Elsevier B.V. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full . (Copyright applies to all s.)

Investigation of patient and viral characteristics associated with SARS-CoV-2 vaccine breakthrough infections in Atlanta, GA

Purpose of Study Despite the tremendous success of SARSCoV- 2 vaccines, breakthrough infections occur and are being recognized with increasing frequency. It is unclear whether breakthrough infections are the result of host and/or viral factors. We examined clinical and viral genomic data from patients with SARS-CoV-2 infection after vaccination to elucidate factors contributing to breakthrough. Methods Used This study was conducted in the Emory Healthcare (EHC) System. Patients with vaccine breakthrough infection, defined as a positive PCR test ≥14 days after the final dose of an FDA approved vaccine, were identified by both routine surveillance and notification by treating clinicians. Vaccination status was obtained from the Georgia Registry of Immunization Transactions and Services records by the Georgia Emerging Infections Program. Clinical information was derived from electronic medical records and was compared to data from 2-3 matched controls per case. Residual SARS-CoV-2 positive nasopharyngeal (NP) samples were collected and underwent RNA extraction. SARSCoV- 2 genome sequencing was performed using random-primer cDNA synthesis, Nextera XT library preparation, and Illumina sequencing. Summary of Results Forty vaccine breakthrough cases were identified between March 22 and July 16, 2021. The median time from final vaccine dose to positive COVID-19 test was 91 days (range 15-163). Compared to 94 controls, vaccine breakthrough cases were significantly older (median 57.5 years vs 42.0 years, p<.0001). Individuals over 60 accounted for half of all breakthrough cases, and individuals over 40 accounted for 80%. Immunosuppressed individuals represented 37.5% of breakthrough cases compared to 25% of unvaccinated controls. Rates of symptomatic infection and severe disease leading to hospitalization were similar between cases and controls. There was no difference in SARS-CoV-2 RT-PCR cycle threshold (Ct) between cases (n=32, median Ct=20.7, interquartile range (IQR)- 10.3) and controls (n=94, median Ct=24.0, IQR= 7.0;p=0.34). SARS-CoV-2 genome sequences from 24 cases were compared to 116 baseline surveillance sequences from unvaccinated EHC patients. There was no distinct phylogenetic clustering of vaccine breakthrough cases, and their sequences belonged to the predominant lineage of the time. From March 22-June 19, B.1.1.7 (alpha) accounted for 78% of breakthrough infections and 77% of surveillance sequences. From June 20-July 16, B.1.617.2 (delta) accounted for 86% of breakthrough infections and 72% of surveillance sequences. No spike mutations or deletions were associated with vaccine breakthrough infections. Conclusions Overall, our findings suggest that host factors, such as older age and immunosuppression, play a more important role than viral factors in SARS-CoV-2 vaccine breakthrough infections. Further studies are needed to understand the potential impacts of waning immunity or poor immunogenicity in individuals who experience vaccine breakthrough infections.

Prediction of SARS-CoV-2 Variant Lineages Using the S1-Encoding Region Sequence Obtained by PacBio Single-Molecule Real-Time Sequencing.

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is the causal agent of the COVID-19 pandemic that emerged in late 2019. The outbreak of variants with mutations in the region encoding the spike protein S1 sub-unit that can make them more resistant to neutralizing or monoclonal antibodies is the main point of the current monitoring. This study examines the feasibility of predicting the variant lineage and monitoring the appearance of reported mutations by sequencing only the region encoding the S1 domain by Pacific Bioscience Single Molecule Real-Time sequencing (PacBio SMRT). Using the PacBio SMRT system, we successfully sequenced 186 of the 200 samples previously sequenced with the Illumina COVIDSeq (whole genome) system. PacBio SMRT detected mutations in the S1 domain that were missed by the COVIDseq system in 27/186 samples (14.5%), due to amplification failure. These missing positions included mutations that are decisive for lineage assignation, such as G142D (n = 11), N501Y (n = 6), or E484K (n = 2). The lineage of 172/186 (92.5%) samples was accurately determined by analyzing the region encoding the S1 domain with a pipeline that uses key positions in S1. Thus, the PacBio SMRT protocol is appropriate for determining virus lineages and detecting key mutations.

Strategy and Performance Evaluation of Low-Frequency Variant Calling for SARS-CoV-2 Using Targeted Deep Illumina Sequencing.

The ongoing COVID-19 pandemic, caused by SARS-CoV-2, constitutes a tremendous global health issue. Continuous monitoring of the virus has become a cornerstone to make rational decisions on implementing societal and sanitary measures to curtail the virus spread. Additionally, emerging SARS-CoV-2 variants have increased the need for genomic surveillance to detect particular strains because of their potentially increased transmissibility, pathogenicity and immune escape. Targeted SARS-CoV-2 sequencing of diagnostic and wastewater samples has been explored as an epidemiological surveillance method for the competent authorities. Currently, only the consensus genome sequence of the most abundant strain is taken into consideration for analysis, but multiple variant strains are now circulating in the population. Consequently, in diagnostic samples, potential co-infection(s) by several different variants can occur or quasispecies can develop during an infection in an individual. In wastewater samples, multiple variant strains will often be simultaneously present. Currently, quality criteria are mainly available for constructing the consensus genome sequence, and some guidelines exist for the detection of co-infections and quasispecies in diagnostic samples. The performance of detection and quantification of low-frequency variants using whole genome sequencing (WGS) of SARS-CoV-2 remains largely unknown. Here, we evaluated the detection and quantification of mutations present at low abundances using the mutations defining the SARS-CoV-2 lineage B.1.1.7 (alpha variant) as a case study. Real sequencing data were in silico modified by introducing mutations of interest into raw wild-type sequencing data, or by mixing wild-type and mutant raw sequencing data, to construct mixed samples subjected to WGS using a tiling amplicon-based targeted metagenomics approach and Illumina sequencing. As anticipated, higher variation and lower sensitivity were observed at lower coverages and allelic frequencies. We found that detection of all low-frequency variants at an abundance of 10, 5, 3, and 1%, requires at least a sequencing coverage of 250, 500, 1500, and 10,000×, respectively. Although increasing variability of estimated allelic frequencies at decreasing coverages and lower allelic frequencies was observed, its impact on reliable quantification was limited. This study provides a highly sensitive low-frequency variant detection approach, which is publicly available at https://galaxy.sciensano.be, and specific recommendations for minimum sequencing coverages to detect clade-defining mutations at certain allelic frequencies. This approach will be useful to detect and quantify low-frequency variants in both diagnostic (e.g., co-infections and quasispecies) and wastewater [e.g., multiple variants of concern (VOCs)] samples.