Publications by authors named "Marc Eloit"

Background: Ticks are significant vectors of pathogens, including viruses, bacteria, and protozoa. With approximately 900 tick species worldwide, many are expanding their geographical range due to changing socioeconomic and climate factors. The Danube Delta, one of Europe's largest wetlands, is an ecosystem that, despite its ecological importance, remains understudied concerning the risk of introducing new tick-borne viruses.

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  • A novel human circovirus, named HCirV-1, was discovered in a 66-year-old immunocompromised woman suffering from sudden hepatitis.
  • Researchers found HCirV-1 genetic material in the patient's liver cells and also in her blood, stool, and urine over an extended period.
  • HCirV-1 is recognized as an emerging human pathogen that can persist in individuals with weakened immune systems.
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  • The human immune system continues to develop for several years after birth, affecting how young children respond to infections, such as SARS-CoV-2.
  • Researchers studied T cell responses in children and adults before, during, and after SARS-CoV-2 infection, revealing that younger children (under 5) had a weaker CD4 T cell response compared to older children and adults with mild disease.
  • Following infection, preschool-age children produced similar neutralizing antibodies to adults but had different T cell characteristics and fewer memory B cells, indicating a gradual maturation of their adaptive immune responses.
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In this multicenter study conducted in France, we challenged the hypothesis of the transmission of pathogens other than spp. in 22 patients developing erythema migrans following a tick bite. Using a combination of high-throughput microfluidic PCRs and agnostic metagenomics on skin biopsies and blood samples, no microorganisms other than spp.

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  • Researchers isolated a coronavirus called BANAL-20-236 (B236) from Malayan horseshoe bats and found it lacks a key site in its spike protein that is present in SARS-CoV-2.
  • * They compared B236's characteristics using human-derived cells and hamster infection experiments, discovering it's less pathogenic and grows slower in respiratory cells compared to SARS-CoV-2, but grows better in intestinal cells.
  • * The study suggests that SC2r-CoVs like B236 may primarily replicate in the intestines rather than the respiratory system, supporting prior findings about its behavior in other models.
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Mosquitoes harbor a large diversity of eukaryotic viruses. Those viromes probably influence mosquito physiology and the transmission of human pathogens. Nevertheless, their ecology remains largely unstudied.

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The human skin virome, unlike commensal bacteria, is an under investigated component of the human skin microbiome. We developed a sensitive, quantitative assay to detect cutaneous human resident papillomaviruses (HPV) and polyomaviruses (HPyV) and we first used it to describe these viral populations at the skin surface of two patients with atopic dermatitis (AD) and psoriasis (PSO). We performed skin swabs on lesional and non-lesional skin in one AD and one PSO patient at M0, M1 and M3.

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Background: Metagenomic next-generation sequencing (mNGS) allows untargeted identification of a broad range of pathogens, including rare or novel microorganisms. Despite the recognition of mNGS as a valuable diagnostic tool for infections, the most relevant indications for this innovative strategy remain poorly defined. We aimed to assess the determinants of positivity and clinical utility of mNGS.

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  • Human Circovirus 1 and 2 were recently detected in a few cases of hepatitis in France and among drug users in China, raising concerns about their potential impact on the safety of plasma derivatives.
  • Researchers conducted tests on 48 plasma pools from healthy donors in Europe, the USA, and Japan to check for these viruses.
  • The findings showed no presence of Human Circovirus 1 and 2, suggesting that these viruses are not commonly found in plasma donations.
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Bats are a major reservoir of zoonotic viruses, including coronaviruses. Since the emergence of SARS-CoV in 2002/2003 in Asia, important efforts have been made to describe the diversity of circulating in bats worldwide, leading to the discovery of the precursors of epidemic and pandemic sarbecoviruses in horseshoe bats. We investigated the viral communities infecting horseshoe bats living in Northern Vietnam, and report here the first identification of sarbecoviruses in and bats.

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The diversity and circulation of arboviruses are not much studied in Madagascar. The fact is that arboviral emergences are rarely detected. The existing surveillance system primarily relies on serological detection and records only a few human infections annually.

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Arthropod-borne viruses (arboviruses) pose a significant global health threat and are primarily transmitted by mosquitoes. In Cambodia, there are currently 290 recorded mosquito species, with at least 17 of them considered potential vectors of arboviruses to humans. Effective surveillance of virome profiles in mosquitoes from Cambodia is vital, as it could help prevent and control arbovirus diseases in a country where epidemics occur frequently.

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Our knowledge of the diversity of eukaryotic viruses has recently undergone a massive expansion. This diversity could influence host physiology through yet unknown phenomena of potential interest to the fields of health and food production. However, the assembly processes of this diversity remain elusive in the eukaryotic viromes of terrestrial animals.

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The viral safety of biological products is ensured by tests throughout the production chain, and, for certain products, by steps in the manufacturing process enabling the elimination or inactivation of viruses. Current testing programs include sample inoculation in animals and embryonic eggs. Following the 3Rs principles of replacement, reduction, and refinement of animal-use methods, such techniques are intended to be replaced not only for ethical reasons but also because of their inherent technical limitations, their long turnaround times, and their limits in virus detection.

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The improvement of our knowledge of the virosphere, which includes unknown viruses, is a key area in virology. Metagenomics tools, which perform taxonomic assignation from high throughput sequencing datasets, are generally evaluated with datasets derived from biological samples or in silico spiked samples containing known viral sequences present in public databases, resulting in the inability to evaluate the capacity of these tools to detect novel or distant viruses. Simulating realistic evolutionary directions is therefore key to benchmark and improve these tools.

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  • A study involving 20 COVID-19 cases identified cerebral microangiopathy in six patients, marked by changes in white matter and small artery diseases as seen on MRI.
  • The condition featured perivascular alterations such as vacuolization, macrophage clusters, and large axonal swellings, suggesting blood-brain barrier disruption without evidence of direct viral presence in the brain.
  • Detection of the SARS-CoV-2 spike protein in brain endothelial cells, particularly within the Golgi apparatus, indicates a unique interaction that might affect vascular permeability and contribute to long-term neurological effects of COVID-19.
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  • Metagenomic next-generation sequencing (mNGS) was utilized to study patients with primary or secondary immune deficiencies (PIDs and SIDs) who exhibited immunopathological issues.
  • The study involved 30 symptomatic and 59 asymptomatic patients, with mNGS revealing Aichi virus (AiV) in tissue from some infected patients, confirming the potential link between AiV and immunodysregulation.
  • Results showed that AiV was associated with significant clinical symptoms, including multiorgan involvement, and symptoms improved after treatment, supporting the idea that AiV may be a causal factor in these patients.
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Bat sarbecovirus BANAL-236 is highly related to SARS-CoV-2 and infects human cells, albeit lacking the furin cleavage site in its spike protein. BANAL-236 replicates efficiently and pauci-symptomatically in humanized mice and in macaques, where its tropism is enteric, strongly differing from that of SARS-CoV-2. BANAL-236 infection leads to protection against superinfection by a virulent strain.

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Tick-borne diseases are responsible for many vector-borne diseases within Europe. Recently, novel viruses belonging to a new viral family of the order were discovered in numerous tick species. In this study, we used metatranscriptomics to detect the virome, including novel viruses, associated with collected from Romania and France.

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  • Allogenic hematopoietic stem cell transplantation (HSCT) and gene therapy (GT) are potential cures for severe combined immunodeficiency (SCID), but patients often face late-onset issues like persistent hepatitis.
  • A study of SCID patients revealed that 11 out of 44 experienced persistent hepatitis linked to chronic enteric viral infections, particularly enteric viruses not found in non-hepatitis SCID patients.
  • Treatments like retransplantation or gene therapy showed promise, as 5 patients achieved remission of hepatitis and viral clearance, highlighting the importance of addressing immune dysregulation in these patients.
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In March 2022, a 61-year-old woman in France who had received a heart-lung transplant sought treatment with chronic hepatitis mainly characterized by increased liver enzymes. After ruling out common etiologies, we used metagenomic next-generation sequencing to analyze a liver biopsy sample and identified an unknown species of circovirus, tentatively named human circovirus 1 (HCirV-1). We found no other viral or bacterial sequences.

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We present Microseek, a pipeline for virus identification and discovery based on RVDB-prot, a comprehensive, curated and regularly updated database of viral proteins. Microseek analyzes metagenomic Next Generation Sequencing (mNGS) raw data by performing quality steps, de novo assembly, and by scoring the Lowest Common Ancestor (LCA) from translated reads and contigs. Microseek runs on a local computer.

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Crimean-Congo hemorrhagic fever (CCHF) is a tick-borne disease that can be contracted by direct contact with viremic animals or humans. Domestic animals are accidental hosts and contribute to the spread and amplification of the virus. The main objective of this study was to provide updated information related to CCHF virus (CCHFV) infection in Southern Romania by assessing the seroprevalence of CCHF in small ruminants (sheep and goats) using a double-antigen sandwich enzyme-linked immunosorbent assay and by detection of CCHFV in engorged ticks and serum samples using real-time RT-PCR.

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