Reemergence of Sylvatic Dengue Virus Serotype 2 in Kedougou, Senegal, 2020.

In 2020, a sylvatic dengue virus serotype 2 infection outbreak resulted in 59 confirmed dengue cases in Kedougou, Senegal, suggesting those strains might not require adaptation to reemerge into urban transmission cycles. Large-scale genomic surveillance and updated molecular diagnostic tools are needed to effectively prevent dengue virus infections in Senegal.

An amplicon-based sequencing approach for Usutu virus characterization.

Usutu virus (USUV), an arbovirus from the Flaviviridae family, genus Flavivirus, has recently gained increasing attention because of its potential for emergence. After his discovery in South Africa, USUV spread to other African countries, then emerged in Europe where it was responsible for epizootics. The virus has recently been found in Asia. USUV infection in humans is considered to be most often asymptomatic or to cause mild clinical signs. However, a few cases of neurological complications such as encephalitis or meningo-encephalitis have been reported in both immunocompromised and immunocompetent patients. USUV natural life cycle involves Culex mosquitoes as its main vector, and multiple bird species as natural viral reservoirs or amplifying hosts, humans and horses can be incidental hosts. Phylogenetic studies carried out showed eight lineages, showing an increasing genetic diversity for USUV. This work describes the development and validation of a novel whole-genome amplicon-based sequencing approach to Usutu virus. This study was carried out on different strains from Senegal and Italy. The new approach showed good coverage using samples derived from several vertebrate hosts and may be valuable for Usutu virus genomic surveillance to better understand the dynamics of evolution and transmission of the virus.

Molecular characterization of circulating Dengue virus 2 during an outbreak in Northern Senegal's Saint-Louis region in 2018.

Globally, 390 million people are at risk of dengue infection and over the past 50 years, the virus incidence increased thirty-fold. In Senegal, an unprecedented occurrence of outbreaks and sporadic cases have been noticed since 2017. In October 2018, an outbreak of Dengue virus 2 (DENV-2) was reported in the north of Senegal affecting multiple areas including Saint-Louis, Richard Toll, and Rosso which are located at the border with Mauritania. Of these 173 blood specimen samples collected from patients, 27 were positive for dengue by quantitative reverse transcription PCR (qRT-PCR), and eight were serologically confirmed to be positive for DENV immunoglobulin M (IgM). Serotyping using qRT-PCR reveals that isolates were positive for DENV-2. A subset of DENV-2 positive samples was selected and subjected to whole-genome sequencing followed by phylogenetic analysis. Analysis of six nearly complete genome sequences revealed that the isolates belong to the cosmopolitan genotype and are closely related to the Mauritanian strains detected between 2017 and 2018 and those detected in many West African countries such as Burkina Faso or Cote d'Ivoire. Our results suggest a transboundary circulation of the DENV-2 cosmopolitan genotype between Senegal and Mauritania and call for a need for coordinated surveillance of arboviruses between these two countries. Interestingly, a high level of homology between West African isolates highlights endemicity and calls for the set-up of subregional viral genomic surveillance which will lead to a better understanding of viral dynamics, transmission, and spread across Africa.

Full genome analysis of circulating DENV-2 in Senegal reveals a regional diversification into separate clades.

To assess the genetic diversity of circulating dengue virus 2 (DENV-2) in Senegal, we analyzed nine newly generated complete genomes of strains isolated during the 2018 outbreaks and 06 sequences obtained in 2018 and 2019 from Thiès and Rosso, respectively. Phylogenetic analyses revealed that Senegalese strains belonged to the cosmopolitan genotype of DENV-2, but we observed intragenotype variability leading to a divergence in two clades associated with specific geographic distribution. We report two DENV-2 variants belonging to two distinct clades. Isolates from the "Northern clade" (n = 8) harbored three nonsynonymous mutations (V1183M, R1405K, P2266T) located respectively on NS2A, NS2B, and NS4A, while isolates from the "Western clade" (n = 7) had two nonsynonymous mutations (V1185E, V3214E) located respectively in the NS2A and NS5 genes. These findings call for phylogeographic analysis to investigate routes of introductions, dispersal patterns, and in-depth in vitro and functional study to elucidate the impact of observed mutations on viral fitness, spread, epidemiology, and pathology.

CFTR deletion affects mouse osteoblasts in a gender-specific manner.

Advancements in research and care have contributed to increase life expectancy of individuals with cystic fibrosis (CF). With increasing age comes a greater likelihood of developing CF bone disease, a comorbidity characterized by a low bone mass and impaired bone quality, which displays gender differences in severity. However, pathophysiological mechanisms underlying this gender difference have never been thoroughly investigated. We used bone marrow-derived osteoblasts and osteoclasts from Cftr+/+ and Cftr-/- mice to examine whether the impact of CF transmembrane conductance regulator (CFTR) deletion on cellular differentiation and functions differed between genders. To determine whether in vitro findings translated into in vivo observations, we used imaging techniques and three-point bending testing. In vitro studies revealed no osteoclast-autonomous defect but impairment of osteoblast differentiation and functions and aberrant responses to various stimuli in cells isolated from Cftr-/- females only. Compared with wild-type controls, knockout mice exhibited a trabecular osteopenic phenotype that was more pronounced in Cftr-/- males than Cftr-/- females. Bone strength was reduced to a similar extent in knockout mice of both genders. In conclusion, we find a trabecular bone phenotype in Cftr-/- mice that was slightly more pronounced in males than females, which is reminiscent of the situation found in patients. However, at the osteoblast level, the pathophysiological mechanisms underlying this phenotype differ between males and females, which may underlie gender differences in the way bone marrow-derived osteoblasts behave in absence of CFTR.

T-type Ca2+ channels elicit pro-proliferative and anti-apoptotic responses through impaired PP2A/Akt1 signaling in PASMCs from patients with pulmonary arterial hypertension.

Idiopathic pulmonary arterial hypertension (iPAH) is characterized by obstructive hyperproliferation and apoptosis resistance of distal pulmonary artery smooth muscle cells (PASMCs). T-type Ca2+ channel blockers have been shown to reduce experimental pulmonary hypertension, although the impact of T-type channel inhibition remains unexplored in PASMCs from iPAH patients. Here we show that T-type channels Cav3.1 and Cav3.2 are present in the lung and PASMCs from iPAH patients and control subjects. The blockade of T-type channels by the specific blocker, TTA-A2, prevents cell cycle progression and PASMCs growth. In iPAH cells, T-type channel signaling fails to activate phosphatase PP2A, leading to an increase in ERK1/2, P38 activation. Moreover, T-type channel signaling is redirected towards the activation of the kinase Akt1, leading to increased expression of the anti-apoptotic protein survivin, and a decrease in the pro-apoptotic mediator FoxO3A. Finally, in iPAH cells, Akt1 is no longer able to regulate caspase 9 activation, whereas T-type channel overexpression reverses PP2A defect in iPAH cells but reinforces the deleterious effects of Akt1 activation. Altogether, these data highlight T-type channel signaling as a strong trigger of the pathological phenotype of PASMCs from iPAH patients (hyper-proliferation/cells survival and apoptosis resistance), suggesting that both T-type channels and PP2A may be promising therapeutic targets for pulmonary hypertension.

Genomic Characterization of a Bataï Orthobunyavirus, Previously Classified as Ilesha Virus, from Field-Caught Mosquitoes in Senegal, Bandia 1969.

Bataï virus (BATV), belonging to the Orthobunyavirus genus, is an emerging mosquito-borne virus with documented cases in Asia, Europe, and Africa. It causes various symptoms in humans and ruminants. Another related virus is Ilesha virus (ILEV), which causes a range of diseases in humans and is mainly found in African countries. This study aimed to genetically identify and characterize a BATV strain previously misclassified as ILEV in Senegal. The strain was reactivated and subjected to whole genome sequencing using an Illumina-based approach. Genetic analyses and phylogeny were performed to assess the evolutionary relationships. Genomic analyses revealed a close similarity between the Senegal strain and the BATV strains UgMP-6830 from Uganda. The genetic distances indicated high homology. Phylogenetic analysis confirmed the Senegal strain's clustering with BATV. This study corrects the misclassification, confirming the presence of BATV in West Africa. This research represents the first evidence of BATV circulation in West Africa, underscoring the importance of genomic approaches in virus classification. Retrospective sequencing is crucial for reevaluating strains and identifying potential public health threats among neglected viruses.

Detection of a cluster of Omicron's BA.4 sublineage in Northern Senegal and identification of the first XAS recombinant variant in Senegal.

In Senegal, since its first detection in early March 2020, genomic surveillance of SARS-CoV-2 isolates has led to the identification of the emergence of the Omicron BA.4 and BA.5 sublineages from early June 2022. To investigate the origin of a cluster of cases in Northern Senegal on July 2022, isolates were analysed using Next-generation sequencing and phylogeny. Our data provided evidence of the origin of the cluster of BA.4 cases from a XAS recombinant, that is to date, the first reported sequence of this variant from Senegal. Continuous genomic surveillance of positive SARS-CoV-2 samples is a crucial need.

Emergence of Crimean-Congo Hemorrhagic Fever Virus in Eastern Senegal in 2022.

Crimean-Congo hemorrhagic fever (CCHF), the most widespread tick-borne viral human infection, poses a threat to global health. In this study, clinical samples collected through national surveillance systems were screened for acute CCHF virus (CCHFV) infection using RT-PCR and for exposure using ELISA. For any CCHF-positive sample, livestock and tick samples were also collected in the neighborhood of the confirmed case and tested using ELISA and RT-PCR, respectively. Genome sequencing and phylogenetic analyses were also performed on samples with positive RT-PCR results. In Eastern Senegal, two human cases and one Hyalomma tick positive for CCHF were identified and a seroprevalence in livestock ranging from 9.33% to 45.26% was detected. Phylogenetic analyses revealed that the human strain belonged to genotype I based on the available L segment. However, the tick strain showed a reassortant profile, with the L and M segments belonging to genotype I and the S segment belonging to genotype III. Our data also showed that our strains clustered with strains isolated in different countries, including Mauritania. Therefore, our findings confirmed the high genetic variability inside the CCHF genotypes and their introduction to Senegal from other countries. They also indicate an increasing CCHF threat in Senegal and emphasize the need to reinforce surveillance using a one-health approach.

Genomic characterization of a reemerging Chikungunya outbreak in Kedougou, Southeastern Senegal, 2023.

Chikungunya virus has caused millions of cases worldwide over the past 20 years, with recent outbreaks in Kedougou region in the southeastern Senegal, West Africa. Genomic characterization highlights that an ongoing epidemic in Kedougou in 2023 is not due to an introduction event but caused by the re-emergence of an endemic strain evolving linearly in a sylvatic context.

Seroprevalence of Crimean-Congo Hemorrhagic Fever Virus and Rift Valley Fever Virus in human population in Senegal from October to November 2020.

Objectives: Rift Valley Fever and Crimean-Congo Hemorrhagic Fever are two infections classified among the emerging diseases to be monitored with highest priority. Studies undertaken in human and animals have shown endemicity of these two arboviruses in several African countries. However, most of the investigations were carried out on domestic cattle and the studies conducted on human populations are either outdated or limited to a small number of well-known endemic areas. It is then critical to better evaluate the burden of these viruses in Senegal at a national scale. Methods: This work relies on a previous seroprevalence survey undertaken in all regions of Senegal at the end of 2020. The existing biobank was used to determine the immunoglobulin G [IgG] Rift Valley Fever and Crimean-Congo Hemorrhagic Fever seroprevalences by indirect enzyme-linked immunosorbent assay. Results: The crude seroprevalences of Rift Valley Fever and Crimean-Congo Hemorrhagic Fever were 3.94% and 0.7% respectively, with the northern and central part of the countries as the main exposed areas. However, acute infections reported in both high and low exposed regions suggest sporadic introductions. Conclusions: This study gives updated information and could be of interest to support the stakeholders in the management of these zoonoses.

First introduction of dengue virus type 3 in Niger, 2022.

Dengue fever is the most important mosquito-borne viral disease of humans, with a significant disease burden in tropical and subtropical countries. The disease is caused by four distinct dengue virus (DENV) serotypes, DENV-1 to -4, all of which belong to the family Flaviviridae, genus Flavivirus. Approximately 3.6 billion people live in areas where they are at risk of transmission of DENVs, resulting in up to 390 million infections and 96 million symptomatic cases annually. Although the disease is highly endemic in the West Africa region, little is known about the prevalence and distribution of DENVs in Niger. We hereby report the first laboratory-confirmed case of dengue in Niger.

An amplicon-based Illumina and nanopore sequencing workflow for Chikungunya virus West Africa genotype.

The Chikungunya virus, a global arbovirus, is currently causing a major outbreak in the Western African region, with the highest cases reported in Senegal and Burkina Faso. Recent molecular evolution analyses reveal that the strain responsible for the epidemic belongs to the West African genotype, with new mutations potentially impacting viral replication, antigenicity, and host adaptation. Real-time genomic monitoring is needed to track the virus's spread in new regions. A scalable West African genotype amplicon-based Whole Genome Sequencing for multiple Next Generation Sequencing platforms has been developed to support genomic investigations and identify epidemiological links during the virus's ongoing spread. This technology will help identify potential threats and support real-time genomic investigations in the ongoing spread of the virus.

T-type Ca²âº signalling downregulates MEK1/2 phosphorylation and cross-talk with the RAAS transcriptional response in cardiac myocytes.

Cardiac dysfunction is often associated with an increase in the activity of the renin-angiotensin II-aldosterone system (RAAS). Here, we highlight the cross-talk between the Ca(2+) signalling generated by cardiac T-type current (I(CaT)) and RAAS signalling. Neonatal rat cardiomyocytes exposed to aldosterone, angiotensin II or aldosterone plus angiotensin II co-treatment (AA) show an increase in I(CaT) density, with no cumulative effect of the AA co-treatment. AA increases the amount of T-type channel Ca(v)3.1 mRNA in a time-dependent manner. Angiotensin II increases Ca(v)3.1 mRNA stability, whereas aldosterone increases the transcriptional activity of the Ca(v)3.1 gene promoter. However, in AA-treated cells, angiotensin II decreases aldosterone-induced promoter activity, and aldosterone decreases angiotensin II-induced mRNA stability. The mitogen-activated protein kinase kinase (MEK1/2), which is synergically phosphorylated in AA-treated cells, alters the translocation of glucocorticoid receptors (GR) into the nucleus and attenuates aldosterone-induced promoter activity. In contrast, MEK1/2 has no effect on the NFkB-induced increase in Ca(v)3.1 mRNA and MEK1/2 promoted CREB-target gene transcription. Aldosterone and AA-induced I(CaT) signalling result in a time-dependent activation of the phosphatase PP2A, which dephosphorylates MEK1/2 and CREB. Finally, angiotensin II alone also activates PP2A, which targets MEK1/2, but this activation is independent of I(CaT) calcium signalling and has no effect on CREB phosphorylation. In conclusion, our data demonstrate the cross-talk between a GR-mediated aldosterone response, angiotensin II and the I(CaT) signalling pathways and identify MEK1/2 as a point of connection. This cross-talk results in the fine control of GR- and/or CREB-target gene expression.

SARS-CoV-2 Lineage A.27: New Data from African Countries and Dynamics in the Context of the COVID-19 Pandemic.

SARS-CoV-2 is constantly evolving with lineages emerging and others eclipsing. Some lineages have an important epidemiological impact and are known as variants of interest (VOIs), variants under monitoring (VUMs) or variants of concern (VOCs). Lineage A.27 was first defined as a VUM since it holds mutations of concern. Here, we report additional lineage A.27 data and sequences from five African countries and describe the molecular characteristics, and the genetic history of this lineage worldwide. Based on the new sequences investigated, the most recent ancestor (tMRCA) of lineage A.27 was estimated to be from April 2020 from Niger. It then spread to Europe and other parts of the world with a peak observed between February and April 2021. The detection rate of A.27 then decreased with only a few cases reported during summer 2021. The phylogenetic analysis revealed many sub-lineages. Among them, one was defined by the substitution Q677H in the spike (S) gene, one was defined by the substitution D358N in the nucleoprotein (N) gene and one was defined by the substitution A2143V in the ORF1b gene. This work highlights the importance of molecular characterization and the timely submission of sequences to correctly describe the circulation of particular strains in order to be proactive in monitoring the pandemic.

Impaired rib bone mass and quality in end-stage cystic fibrosis patients.

BACKGROUND: Advancements in research and clinical care have considerably extended the life expectancy of cystic fibrosis (CF) patients. However, with this extended survival come comorbidities. One of the leading co-morbidities is CF-related bone disease (CFBD), which progresses with disease severity and places patients at high risk for fractures, particularly of the ribs and vertebrae. Evidence that CF patients with vertebral fractures had higher bone mineral density (BMD) than the nonfracture group led us to postulate that bone quality is impaired in these patients. We therefore examined rib specimens resected at the time of lung transplant in CF patients to measure parameters of bone quantity and quality. METHODS: In this exploratory study, we analysed 19 end-stage CF and 13 control rib specimens resected from otherwise healthy lung donors. BMD, bone microarchitecture, static parameters of bone formation and resorption and microcrack density of rib specimens were quantified by imaging, histomorphometric and histological methods. Variables reflecting the mineralization of ribs were assessed by digitized microradiography. The degree of bone mineralization (g/cm3) and the heterogeneity index of the mineralization (g/cm3) were calculated for trabecular and cortical bone. RESULTS: Compared to controls, CF ribs exhibited lower areal and trabecular volumetric BMD, decreased trabecular thickness and osteoid parameters, and increased microcrack density, that was particularly pronounced in specimens from patients with CF-related diabetes. Static parameters of bone resorption were similar in both groups. Degree of mineralization of total bone, but not heterogeneity index, was increased in CF specimens. CONCLUSION: The combination of reduced bone mass, altered microarchitecture, imbalanced bone remodeling (maintained bone resorption but decreased formation), increased microdamage and a small increase of the degree of mineralization, may lead to decreased bone strength, which, when coupled with chronic coughing and chest physical therapy, may provide an explanation for the increased incidence of rib fractures previously reported in this population.