Optimized intramuscular immunization with VSV-vectored spike protein triggers a superior immune response to SARS-CoV-2.

Immunization with vesicular stomatitis virus (VSV)-vectored COVID-19 vaccine candidates expressing the SARS-CoV-2 spike protein in place of the VSV glycoprotein relies implicitly on expression of the ACE2 receptor at the muscular injection site. Here, we report that such a viral vector vaccine did not induce protective immunity following intramuscular immunization of K18-hACE2 transgenic mice. However, when the viral vector was trans-complemented with the VSV glycoprotein, intramuscular immunization resulted in high titers of spike-specific neutralizing antibodies. The vaccinated animals were fully protected following infection with a lethal dose of SARS-CoV-2-SD614G via the nasal route, and partially protected if challenged with the SARS-CoV-2Delta variant. While dissemination of the challenge virus to the brain was completely inhibited, replication in the lung with consequent lung pathology was not entirely controlled. Thus, intramuscular immunization was clearly enhanced by trans-complementation of the VSV-vectored vaccines by the VSV glycoprotein and led to protection from COVID-19, although not achieving sterilizing immunity

A safe, effective and adaptable live-attenuated SARS-CoV-2 vaccine to reduce disease and transmission using one-to-stop genome modifications.

Approved vaccines are effective against severe COVID-19, but broader immunity is needed against new variants and transmission. Therefore, we developed genome-modified live-attenuated vaccines (LAV) by recoding the SARS-CoV-2 genome, including 'one-to-stop' (OTS) codons, disabling Nsp1 translational repression and removing ORF6, 7ab and 8 to boost host immune responses, as well as the spike polybasic cleavage site to optimize the safety profile. The resulting OTS-modified SARS-CoV-2 LAVs, designated as OTS-206 and OTS-228, are genetically stable and can be intranasally administered, while being adjustable and sustainable regarding the level of attenuation. OTS-228 exhibits an optimal safety profile in preclinical animal models, with no side effects or detectable transmission. A single-dose vaccination induces a sterilizing immunity in vivo against homologous WT SARS-CoV-2 challenge infection and a broad protection against Omicron BA.2, BA.5 and XBB.1.5, with reduced transmission. Finally, this promising LAV approach could be applicable to other emerging viruses

The spike gene is a major determinant for the SARS-CoV-2 Omicron-BA.1 phenotype.

Variant of concern (VOC) Omicron-BA.1 has achieved global predominance in early 2022. Therefore, surveillance and comprehensive characterization of Omicron-BA.1 in advanced primary cell culture systems and animal models are urgently needed. Here, we characterize Omicron-BA.1 and recombinant Omicron-BA.1 spike gene mutants in comparison with VOC Delta in well-differentiated primary human nasal and bronchial epithelial cells in vitro, followed by in vivo fitness characterization in hamsters, ferrets and hACE2-expressing mice, and immunized hACE2-mice. We demonstrate a spike-mediated enhancement of early replication of Omicron-BA.1 in nasal epithelial cultures, but limited replication in bronchial epithelial cultures. In hamsters, Delta shows dominance over Omicron-BA.1, and in ferrets Omicron-BA.1 infection is abortive. In hACE2-knock-in mice, Delta and a Delta spike clone also show dominance over Omicron-BA.1 and an Omicron-BA.1 spike clone, respectively. Interestingly, in naïve K18-hACE2 mice, we observe Delta spike-mediated increased replication and pathogenicity and Omicron-BA.1 spike-mediated reduced replication and pathogenicity, suggesting that the spike gene is a major determinant of replication and pathogenicity. Finally, the Omicron-BA.1 spike clone is less well-controlled by mRNA-vaccination in K18-hACE2-mice and becomes more competitive compared to the progenitor and Delta spike clones, suggesting that spike gene-mediated immune evasion is another important factor that led to Omicron-BA.1 dominance

The spike gene is a major determinant for the SARS-CoV-2 Omicron-BA. 1 phenotype

Variant of concern (VOC) Omicron-BA.1 has achieved global predominance in early 2022. Therefore, surveillance and comprehensive characterization of Omicron-BA.1 in advanced primary cell culture systems and animal models are urgently needed. Here, we characterize Omicron-BA.1 and recombinant Omicron-BA.1 spike gene mutants in comparison with VOC Delta in well-differentiated primary human nasal and bronchial epithelial cells in vitro, followed by in vivo fitness characterization in hamsters, ferrets and hACE2-expressing mice, and immunized hACE2-mice. We demonstrate a spike-mediated enhancement of early replication of Omicron-BA.1 in nasal epithelial cultures, but limited replication in bronchial epithelial cultures. In hamsters, Delta shows dominance over Omicron-BA.1, and in ferrets Omicron-BA.1 infection is abortive. In hACE2-knock-in mice, Delta and a Delta spike clone also show dominance over Omicron-BA.1 and an Omicron-BA.1 spike clone, respectively. Interestingly, in naïve K18-hACE2 mice, we observe Delta spike-mediated increased replication and pathogenicity and Omicron-BA.1 spike-mediated reduced replication and pathogenicity, suggesting that the spike gene is a major determinant of replication and pathogenicity. Finally, the Omicron-BA.1 spike clone is less well-controlled by mRNA-vaccination in K18-hACE2-mice and becomes more competitive compared to the progenitor and Delta spike clones, suggesting that spike gene-mediated immune evasion is another important factor that led to Omicron-BA.1 dominance

Study of expression and function of solube molecules of inflammation, the CXCL14 chemokine and the IL-18 binding protein, during viral hepatitis : new biomarkers and therapeutic targets

Les hépatites virales constituent la forme la plus fréquente d’hépatite, avec plus de 360 millions de cas dans le Monde. L’infection virale entraine la mobilisation de la réponse immunitaire via la production de cytokines, en particulier de chimiokines et d’interleukines. Une première partie de nos travaux a porté sur l’étude du rôle de la protéine IL-18bp. Pour cela, un modèle d’hépatite murine virale fulminante par l’inoculation du virus de l’hépatite murine (MHV-3) a été développé chez des souris sauvages et des souris déficientes pour la protéine IL-18bp. Suite à l’infection, nous avons mis en évidence que la protéine IL-18bp n’impactait pas le développement de l’hépatite fulminante chez la souris. La seconde partie de nos travaux a porté sur l’étude de la chimiokine CXCL14. Nous avons mis en évidence que cette chimiokine était exprimée puis relarguée par les hépatocytes lors de leur lyse induite par l’infection virale. Notre étude a également démontré que la chimiokine était présente à de fortes concentrations dans le sérum de patients présentant une hépatite aiguë d’origine virale. Le modèle d’hépatite virale induite par le MHV-3 a été développé chez des souris sauvages et des souris déficientes pour CXCL14. L’infection de ces souris par le MHV-3 n’a pas démontré de rôle spécifique de la chimiokine CXCL14. Cependant, des différences de réponse immunitaire chez les souris non infectées ont mis en évidence un rôle de CXCL14 dans la surveillance immunitaire. En effet, les souris déficientes pour CXCL14 démontrent une activité immunitaire médiée par les lymphocytes B plus active que celle observée chez les souris sauvages. La chimiokine CXCL14 serait donc un acteur central de la réponse immunitaire.Viral hepatitis is the most common form of hepatitis, with more than 360 million cases worldwide. Viral infection leads to the mobilization of the immune response via cytokines production, in particular chemokines and interleukins. The first part of our work focused on studying the role of the IL-18bp protein. For this, a model of murine hepatitis fulminant by inoculation of the murine hepatitis virus (MHV-3) was developed in wild-type mice and mice deficient in the protein IL-18bp. Following infection, we demonstrated that IL-18bp protein did not affect the development of fulminant hepatitis in mice. The second part of our work focused on the study of the chemokine CXCL14. We have demonstrated that this chemokine is expressed and then released by the hepatocytes during their lysis induced by viral infection. Our study also demonstrated that chemokine is present in high concentrations in the serum of patients with acute viral hepatitis. The MHV-3- induced viral hepatitis model was developed in wildtype mice and mice deficient in CXCL14. Infection of these mice with MHV-3 did not demonstrate a specific role for the chemokine CXCL14. However, differences in the immune response in uninfected mice have demonstrated a role for CXCL14 in immune surveillance. In fact, mice deficient in CXCL14 demonstrate a more active immune activity mediated by B lymphocytes than that observed in wild-type mice. The chemokine CXCL14 would therefore be a central actor in the immune response

Etude de l'expression et du rôle de molécules solubles de l'inflammation, la chimiokine CXCL14 et la protéine IL-18bp, dans le contexte des hépatites virales : nouveaux biomarqueurs et cibles thérapeutiques

Viral hepatitis is the most common form of hepatitis, with more than 360 million cases worldwide. Viral infection leads to the mobilization of the immune response via cytokines production, in particular chemokines and interleukins. The first part of our work focused on studying the role of the IL-18bp protein. For this, a model of murine hepatitis fulminant by inoculation of the murine hepatitis virus (MHV-3) was developed in wild-type mice and mice deficient in the protein IL-18bp. Following infection, we demonstrated that IL-18bp protein did not affect the development of fulminant hepatitis in mice. The second part of our work focused on the study of the chemokine CXCL14. We have demonstrated that this chemokine is expressed and then released by the hepatocytes during their lysis induced by viral infection. Our study also demonstrated that chemokine is present in high concentrations in the serum of patients with acute viral hepatitis. The MHV-3- induced viral hepatitis model was developed in wildtype mice and mice deficient in CXCL14. Infection of these mice with MHV-3 did not demonstrate a specific role for the chemokine CXCL14. However, differences in the immune response in uninfected mice have demonstrated a role for CXCL14 in immune surveillance. In fact, mice deficient in CXCL14 demonstrate a more active immune activity mediated by B lymphocytes than that observed in wild-type mice. The chemokine CXCL14 would therefore be a central actor in the immune response.Les hépatites virales constituent la forme la plus fréquente d’hépatite, avec plus de 360 millions de cas dans le Monde. L’infection virale entraine la mobilisation de la réponse immunitaire via la production de cytokines, en particulier de chimiokines et d’interleukines. Une première partie de nos travaux a porté sur l’étude du rôle de la protéine IL-18bp. Pour cela, un modèle d’hépatite murine virale fulminante par l’inoculation du virus de l’hépatite murine (MHV-3) a été développé chez des souris sauvages et des souris déficientes pour la protéine IL-18bp. Suite à l’infection, nous avons mis en évidence que la protéine IL-18bp n’impactait pas le développement de l’hépatite fulminante chez la souris. La seconde partie de nos travaux a porté sur l’étude de la chimiokine CXCL14. Nous avons mis en évidence que cette chimiokine était exprimée puis relarguée par les hépatocytes lors de leur lyse induite par l’infection virale. Notre étude a également démontré que la chimiokine était présente à de fortes concentrations dans le sérum de patients présentant une hépatite aiguë d’origine virale. Le modèle d’hépatite virale induite par le MHV-3 a été développé chez des souris sauvages et des souris déficientes pour CXCL14. L’infection de ces souris par le MHV-3 n’a pas démontré de rôle spécifique de la chimiokine CXCL14. Cependant, des différences de réponse immunitaire chez les souris non infectées ont mis en évidence un rôle de CXCL14 dans la surveillance immunitaire. En effet, les souris déficientes pour CXCL14 démontrent une activité immunitaire médiée par les lymphocytes B plus active que celle observée chez les souris sauvages. La chimiokine CXCL14 serait donc un acteur central de la réponse immunitaire

Circulating levels of CXCL11 and CXCL12 are biomarkers of cirrhosis in patients with chronic hepatitis C infection

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The anti-fibrotic role of mast cells in the liver is mediated by HLA-G and interaction with hepatic stellate cells

International audienceBackground & aims - We have reported a significant association between HLA-G expression or the number of hepatic mast cells and liver fibrosis. Here, we investigated the role of HLA-G and mast cells in liver fibrosis, focusing, in particular, on interactions between human mast and stellate cells. Methods - Human mast cells (HMC cell line, CD34-derived mast cells, or tissue-derived mast cells) were co-cultured with purified human hepatic stellate cells (HSCs), and collagen I production by HSCs was evaluated. Mast cells and HSCs were characterized by immunocytochemistry. Various conditions were tested: different times in direct or indirect contact, presence or absence of cytokines, addition or not of HLA-G, and presence or absence of specific protease inhibitors. Results - The reciprocal interaction between HSCs and mast cells led to the attraction of mast cells to HSCs in vivo and in vitro, and to a significant decrease in collagen production, at all times of co-culture, following the direct or indirect contact of mast cells with HSCs alone or in the presence of TGF-β, IFN-α or IL-10. We identified the diffusible factors involved in collagen I degradation as mast cell proteases. Moreover, HLA-G expression increased during the co-culture of HSCs and mast cells, with HLA-G acting on both mast cells and HSCs, to enhance collagen I degradation. Conclusions - Mast cells play a beneficial, anti-fibrotic role in liver fibrosis, via the HLA-G-mediated decrease of collagen I. These findings are consistent with high levels of cross-communication between mast cells and hepatic stellate cells and the role of HLA-G

Serum CXCL10, CXCL11, CXCL12, and CXCL14 chemokine patterns in patients with acute liver injury

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Neutrophil proteases are protective against SARS-CoV-2 by degrading the spike protein and dampening virus-mediated inflammation.

Studies on severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) have highlighted the crucial role of host proteases for viral replication and the immune response. The serine proteases furin and TMPRSS2 and lysosomal cysteine proteases were shown to facilitate virus entry by limited proteolytic processing of the spike (S) protein. While neutrophils are recruited to the lungs during COVID-19 pneumonia, little is known about the role of the neutrophil serine proteases (NSPs) cathepsin G (CatG), elastase (NE), and proteinase 3 (PR3) on SARS-CoV-2 entry and replication. Furthermore, the current paradigm is that NSPs may contribute to the pathogenesis of severe COVID-19. Here, we show that these proteases cleave the S protein at multiple sites and abrogate virus entry and replication in vitro. In mouse models, CatG significantly inhibited viral replication in the lung. Importantly, lung inflammation and pathology were increased in mice deficient in NE and/or CatG. These results reveal that NSPs contribute to innate defenses against SARS-CoV-2 infection via proteolytic inactivation of the S protein and that NE and CatG limit lung inflammation in vivo. We conclude that therapeutic interventions aiming to reduce the activity of NSPs may interfere with virus clearance and inflammation in COVID-19 patients