Experimental infection with Yersinia pseudotuberculosis in European brown hare(Lepus europaeus,Pallas)

Objective:To investigate clinicopathological,bacteriological and pathological aspects of an experimental infection with Yersinia pseudotuberculosis(Y.pseudotuberculosis)in hares in order to verify the efficacy of serology for the in vivo diagnosis.Moreover,the pathogenicity of two Y.pseudotuberculosis strains was investigated in order to detect potential differences.Methods:Twelve European brown hares(Lepus europaeus,Pallas)were experimentally infected per os and via conjunctival mucosae with Y.pseudotuberculosis:six subjects were infected with a strain isolated from a naturally infected hare(YpH)and six subjects with a strain isolated from a naturally infected rabbit(YpR).Two hares were used as negative controls.All animals were subjected to clinical,bacteriological and serological examinations during 9 weeks following the infection and,at the end of the control period,subjects still alive were euthanized and submitted to a complete post mortem examination.Results:All faecal samples collected during the control period were positive for bacteriological examinations and to a PCR for the inv gene of Y.pseudotuberculosis,while only one Yp H-infected hare showed a positive haemocultures.From the 2nd to the 9th week post infection(pi),serological analysis revealed specific antibodies with titers ranging from 1:10 to 1:160 in all YpH-infected and two YpR-infected subjects.All the Yp H-infected and two Yp R-infected hares scored positive for Y.pseudotuberculosis by means of bacteriological investigations.Grossly,suppurative multifocal lesions were detected in liver,spleen,kidney and sub-mandibular lymph nodes in both YpH-and YpR-infected hares and confirmed with histopathology.Pulmonary lesions were observed only in Yp H-infected subjects.Immunohistochemistry confirmed the presence of bacterial antigen in all infected animals.Conclusion:Results of this study revealed that YpH strain is more pathogenic for hares than the YpR strain;moreover the serological test performed in this study could be used for the diagnosis of pseudotuberculosis in hares,whereas post mortem diagnosis should be confirmed by means of bacteriological examination,PCR,histopathology and immunohistochemistry.

Identification of druggable host dependency factors shared by multiple SARS-CoV-2 variants of concern

The high mutation rate of SARS-CoV-2 leads to the emergence of multiple variants,some of which are resistant to vaccines and drugs targeting viral elements.Targeting host dependency factors,e.g.cellular proteins required for viral replication,would help prevent the development of resistance.However,it remains unclear whether different SARS-CoV-2 variants induce conserved cellular responses and exploit the same core host factors.To this end,we compared three variants of concern and found that the host transcriptional response was conserved,differing only in kinetics and magnitude.Clustered regularly interspaced short palindromic repeats screening identified host genes required for each variant during infection.Most of the genes were shared by multiple variants.We validated our hits with small molecules and repurposed the US Food and Drug Administration-approved drugs.All the drugs were highly active against all the tested variants,including new variants that emerged during the study(Delta and Omicron).Mechanistically,we identified reactive oxygen species production as a key step in early viral replication.Antioxidants such as N-acetyl cysteine(NAC)were effective against all the variants in both human lung cells and a humanized mouse model.Our study supports the use of available antioxidant drugs,such as NAC,as a general and effective anti-COVID-19 approach.