Intranasal administration of a single dose of a candidate live attenuated vaccine derived from an NSP16-deficient SARS-CoV-2 strain confers sterilizing immunity in animals

Live attenuated vaccines might elicit mucosal and sterilizing immunity against SARS-CoV-2 that the existing mRNA,adenoviral vector and inactivated vaccines fail to induce.Here,we describe a candidate live attenuated vaccine strain of SARS-CoV-2 in which the NSP16 gene,which encodes 2′-O-methyltransferase,is catalytically disrupted by a point mutation.This virus,designated d16,was severely attenuated in hamsters and transgenic mice,causing only asymptomatic and nonpathogenic infection.A single dose of d16 administered intranasally resulted in sterilizing immunity in both the upper and lower respiratory tracts of hamsters,thus preventing viral spread in a contact-based transmission model.It also robustly stimulated humoral and cell-mediated immune responses,thus conferring full protection against lethal challenge with SARS-CoV-2 in a transgenic mouse model.The neutralizing antibodies elicited by d16 effectively cross-reacted with several SARS-CoV-2 variants.Secretory immunoglobulin A was detected in the blood and nasal wash of vaccinated mice.Our work provides proof-of-principle evidence for harnessing NSP16-deficient SARS-CoV-2 for the development of live attenuated vaccines and paves the way for further preclinical studies of d16 as a prototypic vaccine strain,to which new features might be introduced to improve safety,transmissibility,immunogenicity and efficacy.

Macrophage-derived IL-1α promotes sterile inflammation in a mouse model of acetaminophen hepatotoxicity

The metabolic intermediate of acetaminophen(APAP)can cause severe hepatocyte necrosis,which triggers aberrant immune activation of liver non-parenchymal cells(NPC).Overzealous hepatic inflammation determines the morbidity and mortality of APAP-induced liver injury(AILI).Interleukin-1 receptor(IL-1R)signaling has been shown to play a critical role in various inflammatory conditions,but its precise role and underlying mechanism in AILI remain debatable.Herein,we show that NLRP3 inflammasome activation of IL-1βis dispensable to AILI,whereas IL-1α,the other ligand of IL-1R1,accounts for hepatic injury by a lethal dose of APAP.Furthermore,Kupffer cells function as a major source of activated IL-1αin the liver,which is activated by damaged hepatocytes through TLR4/MyD88 signaling.Finally,IL-1αis able to chemoattract and activate CD11b^(+)Gr-1^(+) myeloid cells,mostly neutrophils and inflammatory monocytes,to amplify deteriorated inflammation in the lesion.Therefore,this work identifies that MyD88-dependent activation of IL-1αin Kupffer cells plays a central role in the immunopathogenesis of AILI and implicates that IL-1αis a promising therapeutic target for AILI treatment.