Adventitious Virus Detection in Cells by High-Throughput Sequencing of Newly Synthesized RNAs: Unambiguous Differentiation of Cell Infection from Carryover of Viral Nucleic Acids

The use of high-throughput sequencing (HTS) to identify viruses in biologicals differs from current molecular approaches, since its use enables an unbiased approach to detection without the need to design specific primers to preamplify target sequences. Its broad range of detection and analytical sensitivity make it an important tool to ensure that biologicals are free from adventitious viruses. Similar to other molecular methods, however, identification of viral sequences in cells by HTS does not prove viral infection, since this could reflect carryover of inert viral sequences from reagents or other sources or the presence of transcriptionally inactive cellular sequences. Due to the broad range of detection associated with HTS, the above can potentially be perceived as a drawback for the testing of pharmaceutical biological products using this method. In order to avoid the identification of inert viral sequences, we present a methodology based on metabolic RNA labeling and sequencing, which enables the specific identification of newly synthesized viral RNAs in infected cells, resulting in the ability to unambiguously distinguish active infection by DNA or RNA viruses from inert nucleic acids. In the present study, we report the ability to differentiate Vero cells acutely infected by a single-stranded positive-sense RNA virus (tick-borne encephalitis virus) from cells which have been in contact with nonreplicating virus particles. Additionally, we also found a laboratory contamination by the squirrel monkey retrovirus of our Vero cell line, which was derived from an Old World (African green) monkey, a type of contamination which until now has been identified only in cells derived from primates from the New World.The use of high-throughput sequencing (HTS) to identify viral contamination of biological products is extremely sensitive and provides a broad range of detection. Nevertheless, viral sequences identified can also be inert. Examples include contamination resulting from reagents or the presence of inactivated viruses in animal-derived components of the cell culture medium. We therefore developed a method that relies on the sequencing of newly synthesized RNAs, an unequivocal sign of the presence of a transcriptionally active virus. This improvement in the specificity of viral testing increases the acceptability of HTS as a standard test for cells used in manufacturing biologicals and in biotherapies

Identification et validation d’une signature transcriptomique sanguine d’aide au diagnostic de la maladie d’Alzheimer (ACLARUSDX™).

National audienc

Identification et validation d’une signature transcriptomique sanguine d’aide au diagnostic de la maladie d’Alzheimer (ACLARUSDX™).

National audienc

Validation of AclarusDx™, a blood-based transcriptomic signature for the diagnosis of Alzheimer's disease.

International audienceAbstract: Biomarkers have gained an increased importance in the past years in helping physicians to diagnose Alzheimer's disease (AD). This study was designed to identify a blood-based, transcriptomic signature that can differentiate AD patients from control subjects. The performance of the signature was then evaluated for robustness in an independent blinded sample population. RNA was extracted from 177 blood samples (90 AD patients and 87 controls) and gene expression profiles were generated using the human Genome-Wide Splice Array™. These profiles were used to establish a signature to differentiate AD patients from controls. Subsequently, prediction results were optimized by establishing grey zone boundaries that discount prediction scores near the disease status threshold. Signature validation was then performed on a blinded independent cohort of 209 individuals (111 AD and 98 controls). The AclarusDx™ signature consists of 170 probesets which map to 136 annotated genes, a significant number of which are associated with inflammatory, gene expression, and cell death pathways. Additional signature genes are known to interact with pathways involved in amyloid and tau metabolism. The validation sample set, after removal of 45 individuals with prediction profile scores within the grey zone, consisted of 164 subjects. The AclarusDx™ performance on this validation cohort had a sensitivity of 81.3% (95% CI: [73.3%; 89.3%]); and a specificity of 67.1% (95% CI: [56.3%; 77.9%]). AclarusDx™ is a non-invasive blood-based transcriptomic test that, in combination with standard assessments, can provide physicians with objective information to support the diagnosis of AD

Metagenomic shotgun sequencing of blood to identify bacteria and viruses in leukemic febrile neutropenia.

Despite diagnostic advances in microbiology, the etiology of neutropenic fever remains elusive in most cases. In this study, we evaluated the utility of a metagenomic shotgun sequencing based assay for detection of bacteria and viruses in blood samples of patients with febrile neutropenia. We prospectively enrolled 20 acute leukemia patients and obtained blood from these patients at three time points: 1) anytime from onset of neutropenia until before development of neutropenic fever, 2) within 24 hours of onset of neutropenic fever, 3) 5-7 days after onset of neutropenic fever. Blood samples underwent sample preparation, sequencing and analysis using the iDTECT® Dx Blood v1® platform (PathoQuest, Paris, France). Clinically relevant viruses or bacteria were detected in three cases each by metagenomic shotgun sequencing and blood cultures, albeit with no concordance between the two. Further optimization of sample preparation methods and sequencing platforms is needed before widespread adoption of this technology into clinical practice