Crimean-Congo haemorrhagic fever (CCHF), a potentially severe zoonotic viral disease causing fever and haemorrhagic manifestations in humans. As the Crimean-Congo haemorrhagic fever virus (CCHFV) has been detected in ticks in Spain and antibodies against the virus in ruminant sera in Corsica, it was necessary to know more about the situation in France. In 2022-2023, CCHFV was detected in 155 ticks collected from horses and cattle in southern France.

BACKGROUND:Ebola (EBOV) and Sudan (SUDV) orthoebolaviruses are responsible for lethal hemorrhagic fever outbreaks in humans in Central and West Africa, and in apes that can be at the source of human outbreaks for EBOV. METHODS:To assess the risk of exposure to orthoebolaviruses through contact with nonhuman primates (NHP), we tested the presence of antibodies against different viral proteins with a microsphere-based multiplex immunoassay in a case-control study on bites from NHPs in forest areas from Cameroon (n = 795) and in cross-sectional surveys from other rural populations (n = 622) of the same country. RESULTS:Seroreactivities against at least 2 viral proteins were detected in 13% and 12% of the samples for EBOV and SUDV, respectively. Probability of seroreactivity was not associated with history of NHP bites, but was 3 times higher in Pygmies compared to Bantus. Although no neutralizing antibodies to EBOV and SUDV were detected in a selected series of highly reactive samples, avidity results indicate strong affinity to SUDV antigens. CONCLUSIONS:The detection of high level of seroreactivities against orthoebolaviruses in rural Cameroon, where no outbreaks have been reported, raises the possibilities of silent circulation of orthoebolaviruses, or of other not yet documented filoviruses, in these forested regions. ARTICLE'S MAIN POINT:Our study found high seroreactivities to Ebola and Sudan orthoebolavirus antigens in rural Cameroonian populations, especially among Pygmies, despite no reported outbreaks. This suggests potential silent circulation of orthoebolaviruses or unknown filoviruses, highlighting the need for further surveillance and research.

Sudan ebolavirus (SUDV) is one of four members of the Ebolavirus genus known to cause Ebola Virus Disease (EVD) in humans, which is characterized by hemorrhagic fever and a high case fatality rate. While licensed therapeutics and vaccines are available in limited number to treat infections of Zaire ebolavirus, there are currently no effective licensed vaccines or therapeutics for SUDV. A well-characterized animal model of this disease is needed for the further development and testing of vaccines and therapeutics. In this study, twelve cynomolgus macaques (Macaca fascicularis) were challenged intramuscularly with 1000 PFUs of SUDV and were followed under continuous telemetric surveillance. Clinical observations, body weights, temperature, viremia, hematology, clinical chemistry, and coagulation were analyzed at timepoints throughout the study. Death from SUDV disease occurred between five and ten days after challenge at the point that each animal met the criteria for euthanasia. All animals were observed to exhibit clinical signs and lesions similar to those observed in human cases which included: viremia, fever, dehydration, reduced physical activity, macular skin rash, systemic inflammation, coagulopathy, lymphoid depletion, renal tubular necrosis, hepatocellular degeneration and necrosis. The results from this study will facilitate the future preclinical development and evaluation of vaccines and therapeutics for SUDV.

The SARS-CoV-2 detection campaign is a key element in the viral pandemic response. Here we present a monocentric study to evaluate a simplified molecular amplification technology alternative to classical RT-qPCR platforms. The test, C4Covid-19 HumanTM makes use of saliva as a starting sample allowing for self, painless collection, avoiding risk of viral transmission for the operator who performs the nasopharyngeal (NP) procedure. Total time to result is 30 minutes. The principle relies on an extraction-free detection of two targets within the viral genomic RNA, RdRp and N genes, by real-time reverse transcription loop mediated isothermal amplification (RT-LAMP). Saliva and NP swabs were collected simultaneously from 1491 symptomatic or contact cases and analyzed in parallel by RT-LAMP and RT-qPCR respectively. The 249 positives RT-qPCR samples had a Ct <37. Sensitivity and specificity of RT-LAMP were 85.7% (95% CI 80.4 to 89.7) and 97.3% (95% CI 96.1 to 98.1) respectively. Among the total cohort, the 56.9% of asymptomatic subjects showed higher sensitivity (90.6% with a 95% CI of 81.0 to 95.6) while specificity remained unchanged (97.4% with a 95% CI of 95.6 to 98.4). C4Covid-19 HumanTM is a rapid, simple and reliable SARS-CoV-2 detection test for population screening.

We report two outbreaks of Lassa fever that occurred in Benin in 2014 and 2016 with 20 confirmed cases and 50% (10/20) mortality. Benin was not previously considered to be an endemic country for Lassa fever, resulting in a delay to diagnose the disease and its human transmission. Molecular investigations showed the viral genomes to be similar to that of the Togo strain, which is genetically very different from other known strains and confirms the existence of a new lineage. Endemic circulation of Lassa virus in a new territory and the genetic diversity thus confirm that this virus represents a growing threat for West African people. Given the divergence of the Benin strain from the prototypic Josiah Sierra Leone strain frequently used to generate vaccine candidates, the efficacy of vaccine candidates should also be demonstrated with this strain.

Background: In spite of recurrent and dramatic outbreaks, there are no therapeutics approved against Ebola virus disease. Favipiravir, a RNA polymerase inhibitor active against several RNA viruses, recently demonstrated significant but not complete protection in a non-human primate model of Ebola virus disease. In this study, we assessed the benefit of the combination of favipiravir and ribavirin, another broad spectrum antiviral agent, in the same model. Methods: 15 female cynomolgus macaques were challenged intramuscularly with 1,000 FFU of Ebola virus Gabon 2001 strain and followed for 21 days. All animals received favipiravir 180 mg/kg twice a day (BID), either as monotherapy (n = 5) or in combination with ribavirin (n = 10). Ribavirin was given either at the dose 10 mg/kg BID (n = 5) or 5 mg/kg BID (n = 5). Favipiravir and ribavirin were initiated two and one days before viral challenge respectively and treatment were continued for 14 days. Treatment effects on viral and hematological markers were assessed using a mathematical model. Survival rate of 0% and 20% were obtained in macaques receiving favipiravir plus ribavirin 10 and 5 mg/kg BID, respectively, compared to 40% in the favipiravir monotherapy group (P = 0.061 when comparing monotherapy and bitherapy, log rank). Viral dynamic modeling analysis did not identify an association between plasma concentrations of ribavirin and viral load levels. Using a model of erythropoiesis, plasma concentrations of ribavirin were strongly associated with a hemoglobin drop (p = 0.0015). Conclusion: Ribavirin plus favipiravir did not extend survival rates and did not lower viral replication rate compared to favipiravir monotherapy in this animal model. Patients receiving this combination in other indications, such as Lassa fever, should be closely monitored to prevent potential toxicity associated with anemia.

The egcSEs comprise five genetically linked staphylococcal enterotoxins, SEG, SEI, SEIM, SEIN, and SEIO and two pseudotoxins which constitute an operon present in up to 80% of Staphylococcus aureus isolates. A preparation containing these proteins was recently used to treat advanced lung cancer with pleural effusion. We investigated the hypothesis that egcSEs induce nitric oxide (NO) and associated cytokine production and that these agents may be involved in tumoricidal effects against a broad panel of clinically relevant human tumor cells. Preliminary studies showed that egcSEs and SEA activated T cells (range: 11-25%) in a concentration dependent manner. Peripheral blood mononuclear cells (PBMCs) stimulated with equimolar quantities of egcSEs expressed NO synthase and generated robust levels of nitrite (range: 200-250 mu M), a breakdown product of NO; this reaction was inhibited by NG-monomethyl-Larginine (L-NMMA) (0.3 mM), an NO synthase antagonist. Cell free supernatants (CSFs) of all egcSE-stimulated PBMCs were also equally effective in inducing concentration dependent tumor cell apoptosis in a broad panel of human tumor cells. The latter effect was due in part to the generation of NO and TNF-alpha since it was significantly abolished by L-NMMA, anti-TNF-alpha antibodies, respectively, and a combination thereof. A hierarchy of tumor cell sensitivity to these CFSs was as follows: lung carcinoma > osteogenic sarcoma > melanoma > breast carcinoma > neuroblastoma. Notably, SEG induced robust activation of NO/TNF-alpha-dependent tumor cell apoptosis comparable to the other egcSEs and SEA despite INF-alpha and IFN-gamma levels that were 2 and 8 fold lower, respectively, than the other egcSEs and SEA. Thus, egcSEs produced by S. aureus induce NO synthase and the increased NO formation together with INF-alpha appear to contribute to egcSE-mediated apoptosis against a broad panel of human tumor cells.

Menstrual toxic shock syndrome (MTSS) is a severe toxin-mediated disease associated with Staphylococcus aureus producing toxic shock syndrome toxin 1 (TSST-1), a superantigen that mediates a potent activation of Vβ-2 T cells. In animal models, superantigen treatment of responsive T cells induces their initial proliferation, followed by unresponsiveness upon further superantigen stimulation. To determine whether T cell unresponsiveness occurs in humans during the acute phase of MTSS, we collected T cells from a patient with MTSS and restimulated them ex vivo with recombinant TSST-1. The expansion of T cells collected during the acute phase of disease was compared with positive controls including basal-state T cells (collected 70 days after MTSS) restimulated with TSST-1, and T cells stimulated with enterotoxin B superantigen. We found that TSST-1-induced expansion of acute phase T cells was not inferior to that observed in positive controls. We conclude that T cells were still reactive to TSST-1 during the acute phase of MTSS in this patient. As the persistence of TSST-1 production could thus be associated with further expansion of TSST-1-reactive T cells and a rapid worsening of symptoms, this study adds further support to the need for immediate eradication of the focus of infection as soon as MTSS is suspected.

ABSTRACT Panton-Valentine leukocidin (PVL) is a synergohymenotropic toxin (SHT) produced by Staphylococcus aureus. At present, there are conflicting reports on the leukotoxic activity of PVL and its consequent role as a virulence factor in USA300. In this work, we compared the cytolytic effects induced by wild-type PVL and those of PVL harboring a histidine-to-arginine substitution at amino acid 176 in the S. aureus USA300 strain. We also investigated the capacity of wild-type and H176R LukS-PV to recruit and form pores with the F components of other SHTs. For this purpose, we assayed polymorphonuclear neutrophils for leukotoxicity after incubation with either culture supernatants from strains bearing different PVL haplotypes or recombinant toxins from different types of SHT. We show here that the H176R variation in the PVL sequence causes no change in leukotoxicity and that the R variant is as efficient as wild-type PVL at inducing pore formation in leukocytes.

ABSTRACTStaphylococcus aureuscan produce a wide variety of exotoxins, including toxic shock syndrome toxin 1 (TSST-1), staphylococcal enterotoxins, and staphylococcal enterotoxin-like toxins. These toxins share superantigenic activity. To investigate the β chain (Vβ) specificities of each of these toxins, TSST-1 and all knownS. aureusenterotoxins and enterotoxin-like toxins were produced as recombinant proteins and tested for their ability to induce the selective in vitro expansion of human T cells bearing particular Vβ T-cell receptors (TCR). Although redundancies were observed between the toxins and the Vβ populations, each toxin induced the expansion of distinct Vβ subsets, including enterotoxin H and enterotoxin-like toxin J. Surprisingly, the Vβ signatures were not associated with a specific phylogenic group of toxins. Interestingly, each human Vβ analyzed in this study was stimulated by at least one staphylococcal superantigen, suggesting that the bacterium derives a selective advantage from targeting the entire human TCR Vβ panel.

This study focuses on the estimation of car dynamic variables for the improvement of vehicle safety, handling characteristics and comfort. More specifically, a new estimation process is proposed to estimate longitudinal/lateral tire-road forces, velocity, sideslip angle and wheel cornering stiffness. This\break method uses measurements from currently available standard sensors (yaw rate, longitudinal/lateral accelerations, steering angle and angular wheel velocities). The estimation process is separated into two blocks: the first block contains an observer whose principal role is to calculate tire-road forces without a descriptive force model, while in the second block an observer estimates sideslip angle and cornering stiffness with an adaptive tire-force model. The different observers are based on an Extended Kalman Filter (EKF). The estimation process is applied and compared to real experimental data, notably sideslip angle and wheel force measurements. Experimental results show the accuracy and potential of the estimation process.

We report the case of a 12-year-old boy who developed staphylococcal toxic shock syndrome associated with S. aureus pharyngeal colonization or infection. The diagnosis was rapidly confirmed by detecting the Vbeta signature of the toxic shock syndrome toxin-1 in peripheral blood, based on transient T cell depletion rapidly followed by massive expansion of Vbeta 2-positive T cells.

Methicillin-resistant Staphylococcus aureus is increasingly responsible for staphylococcal infections in the community. A large percentage of the community-acquired methicillin-resistant (CA-MRSA) strains in the USA produce Panton-Valentine leukocidin (PVL), which is associated with severe infections. The virulence of the clinical CA-MRSA strain USA300 was compared to that of its isogenic pvl-deleted mutant, and it was shown that PVL contributes to lung and muscle tissue destruction, respectively, in murine necrotizing pneumonia and skin infection models. Mice infected with the USA300 strain developed a dominant anti-PVL response. The PVL subunits were therefore tested as vaccinogens against this isolate, and their vaccine efficacy correlated with both the route of vaccination and infection. These data suggest that PVL is a virulence factor in murine CA-MRSA infections.

The aim of this study was to examine the production of superantigenic toxins in vivo and in vitro in two patients with streptococcal toxic shock syndrome (TSS). In the first patient, a woman with puerperal fever and Streptococcus pyogenes peritonitis, flow cytometry of blood cells and in vitro studies of the isolate showed massive expansion of Vbeta 2-positive T cells corresponding to SpeC production. In the second case, involving a patient with streptococcal TSS and purpura fulminans following non-steroidal anti-inflammatory drug (NSAID) therapy, no Vbeta expansion of T cells was observed in vivo, but the SpeC Vbeta signature was also detected in vitro. In this latter patient, NSAID administration and/or severe disseminated infection might partly explain the absence of Vbeta T cell expansion in vivo. Combined in vivo and in vitro detection of a superantigenic toxin Vbeta signature may be useful to determine which superantigenic toxin is involved in individual cases of streptococcal TSS.

Most clinical isolates of Staphylococcus aureus harbour genes encoding superantigenic toxins that bind the Vbeta domain of T-cells, but little information is available concerning superantigenic toxin production during staphylococcal toxic shock syndrome (TSS) and septic shock. This prospective study investigated 14 patients with staphylococcal TSS or septic shock; the toxin gene profile of each isolate was determined and flow-cytometry was used to identify the discriminant Vbeta signature (DVbetaS) of each superantigenic toxin in vitro. Attempts were also made to identify in-vivo production of superantigenic toxin DVbetaS in patients' blood. The DVbetaS identified in vitro were: toxic shock syndrome toxin (TSST)-1, Vbeta 2; staphylococcal enterotoxin (SE), Vbeta 9, Vbeta 22; SEB, Vbeta 3, Vbeta 14, Vbeta 17; SED, Vbeta 1, Vbeta 8; egc, Vbeta 5.3, Vbeta 7.1, Vbeta 9, Vbeta 23; and SElK, Vbeta 5.1. The DVbetaS of TSST-1 and SEB were detected in patients with menstrual and non-menstrual TSS, respectively, whereas no Vbeta signature was detected during septic shock. All patients with septic shock (but only one patient with TSS) had lymphopenia and/or impaired cellular immunity. Detection of a superantigenic toxin DVbetaS may help to show which toxin is produced during staphylococcal TSS, thus confirming the diagnosis and hastening the administration of anti-toxin therapy. In contrast, this approach failed to demonstrate superantigenic toxin involvement in cases of septic shock. In this latter condition, a superantigenic toxin may not be produced by S. aureus, or its production may occur without expansion of targeted T-cells because of T-cell apoptosis and/or anergy.

Diagnostic development and public health surveillance require technologies that provide specific identification and absolute quantification of protein biomarkers. Beside immunologically related techniques (e.g. enzyme-linked immunosorbent assay), MS is gaining increasing interest due to its high sensitivity and specificity. Furthermore, MS-based analyses are extremely accurate quantitatively, provided that suitable reference standards are available. Recently, the use of chemically synthesized isotope-labeled marker peptides for MS-based absolute quantification of proteins has led to major advances. However, we show here that the use of such peptides can lead to severe biases. In this work, we present an innovative strategy (Protein Standard Absolute Quantification) that uses in vitro-synthesized isotope-labeled full-length proteins as standards for absolute quantification. As those protein standards perfectly match the biochemical properties of the target proteins, they can be directly added into the samples to be analyzed, allowing a highly accurate quantification of proteins even in prefractionated complex samples. The power of our Protein Standard Absolute Quantification methodology for accurate absolute quantification of biomarkers was demonstrated both on water and urine samples contaminated with Staphylococcus aureus superantigenic toxins as typical biomarkers of public health interest.

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The molecular mechanism of Staphylococcus aureus phathogenicity is complex and involves several toxins, including the famous staphylococcal enterotoxin (SE) and toxic shock syndrome toxin-1 (TSST-1). Although these toxins were discovered in specific clinical contexts of food poisoning and menstrual toxic shock syndrome, they share common biochemical and biological properties. As superantigens they are able to massively activate mononuclear cells and T cells regardless of the antigenic specificity of the T cells. To date, 19 different enterotoxins and related toxins have been described in S. aureus with some differences in structure and biological activity. It has been clearly demonstrated that most human S. aureus isolates harbor at least one gene encoding for these toxins. It is suspected that S. aureus produces SEs and TSST-1 in humans from colonization to infection, whatever the clinical situation. It is proposed that the production of SEs plays a role not only in classical staphylococcal infections but also in noninfectious diseases. This review will focus on recent findings related to staphylococcal superantigens and their impact on human diseases.

In women with newly diagnosed breast cancer, preoperative staging is required to assess disease extent, enabling us to decide on the most optimal treatment strategy. For locoregional staging, assessment of intramammary tumor extent and presence of axillary and perhaps also internal mammary lymph node metastases is required. Due to the similarity in the underlying principle, contrast-enhanced mammography is increasingly considered instead of breast MRI for this purpose. When considering the combination of CEM and US as a single appointment imaging strategy for preoperative staging of breast cancer, there is only limited room for an additional benefit of breast MRI. For tumor size measurements, equal performance of both CEM and MRI are observed. Sensitivity of both techniques for detecting breast cancer is comparable, meaning that both techniques are capable of detecting additional ipsilateral or contralateral tumor foci. However, specificity is in favor of CEM, meaning that there is a slightly lower chance of having false positive findings in preoperative staging of the breast. Axillary US can be performed during the same appointment as CEM, with equal performance and limitations as evaluation of the axilla on standard breast MRI examinations. Finally, there is no need to actively pursue the detection of IMLN metastases, meaning that additional MRI to do so is not required. This review provides a ‘pro-CEM’ perceptive on the arguments why breast MRI is hardly necessary when CEM in combination with US has been performed as a single appointment imaging strategy in breast cancer patients.

The severity of Staphylococcus aureus sepsis is positively associated with staphylococcal enterotoxin A (SEA) and negatively associated with the enterotoxin gene cluster (egc), which encodes five staphylococcal enterotoxins [ 1 ]. We postulated that the variable, clinical severity of S. aureus sepsis might be a result of differences in the inflammatory properties of staphylococcal superantigens. We therefore compared the inflammatory properties of SEA with those of staphylococcal entérotoxin G (SEG), a member of the five egc superantigens. We found that SEA and SEG had similar superantigenic properties, as they induced CD69 expression on T lymphocytes and selective expansion of Vβ subpopulations. Contrary to SEG, however, SEA induced a strong proinflammatory/Th1 response, including TNF‐α and MIP‐1α production. These results suggest that the association of SEA with the severity of S. aureus septic shock, characterized by a deleterious, inflammatory cascade, may be explained partly by the specific proinflammatory properties of this superantigen.