Analogous comparison unravels heightened antiviral defense and boosted viral infection upon immunosuppression in bat organoids

Horseshoe bats host numerous SARS-related coronaviruses without overt disease signs.Bat intestinal organoids,a unique model of bat intestinal epithelium,allow direct comparison with human intestinal organoids.We sought to unravel the cellular mechanism(s)underlying bat tolerance of coronaviruses by comparing the innate immunity in bat and human organoids.We optimized the culture medium,which enabled a consecutive passage of bat intestinal organoids for over one year.Basal expression levels of IFNs and IFN-stimulated genes were higher in bat organoids than in their human counterparts.Notably,bat organoids mounted a more rapid,robust and prolonged antiviral defense than human organoids upon Poly(I:C)stimulation.TLR3 and RLR might be the conserved pathways mediating antiviral response in bat and human intestinal organoids.The susceptibility of bat organoids to a bat coronavirus CoV-HKU4,but resistance to EV-71,an enterovirus of exclusive human origin,indicated that bat organoids adequately recapitulated the authentic susceptibility of bats to certain viruses.Importantly,TLR3/RLR inhibition in bat organoids significantly boosted viral growth in the early phase after SARS-CoV-2 or CoV-HKU4 infection.Collectively,the higher basal expression of antiviral genes,especially more rapid and robust induction of innate immune response,empowered bat cells to curtail virus propagation in the early phase of infection.

Identification of novel small-molecule inhibitors of SARS-CoV-2 by chemical genetics

There are only eight approved small molecule antiviral drugs for treating COVID-19.Among them,four are nucleotide analogues(remdesivir,JT001,molnupiravir,and azvudine),while the other four are protease inhibitors(nirmatrelvir,ensitrelvir,leritrelvir,and simnotrelvir-ritonavir).Antiviral resistance,unfavourable drug‒drug interaction,and toxicity have been reported in previous studies.Thus there is a dearth of new treatment options for SARS-CoV-2.In this work,a three-tier cell-based screening was employed to identify novel compounds with anti-SARS-CoV-2 activity.One compound,designated 172,demonstrated broad-spectrum antiviral activity against multiple human pathogenic coronaviruses and different SARS-CoV-2 variants of concern.Mechanistic studies validated by reverse genetics showed that compound 172 inhibits the 3-chymotrypsin-like protease(3CLpro)by binding to an allosteric site and reduces 3CLpro dimerization.A drug synergistic checkerboard assay demonstrated that compound 172 can achieve drug synergy with nirmatrelvir in vitro.In vivo studies confirmed the antiviral activity of compound 172 in both Golden Syrian Hamsters and K18 humanized ACE2 mice.Overall,this study identified an alternative druggable site on the SARS-CoV-23CLpro,proposed a potential combination therapy with nirmatrelvir to reduce the risk of antiviral resistance and shed light on the development of allosteric protease inhibitors for treating a range of coronavirus diseases.

Angiotensin-converting enzyme 2:virus accomplice or host defender?

Objective:Coronavirus disease 2019(COVID-19)caused by severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)has led to social disruptions,mainly because we know too little about SARS-CoV-2.Methods and Results:In this study,we integrated RNA sequencing results and found that SARS-CoV-2 infection alters aerobic glycolysis,the oxidative pentose phosphate pathway(oxiPPP),and DNA replication in lung tissues and cells.However,the direction of metabolic flux and DNA replication are dominated by angiotensin-converting enzyme 2(ACE2),a host cell-expressed viral receptor protein.More interestingly,although hosts with a high expression of ACE2 are more likely to be infected with SARS-CoV-2,the invading virus cannot perform nucleic acid replication well due to the restriction of glucose metabolism,eventually resulting in a prolonged infection cycle or infection failure.Conclusion:Our findings preliminarily explain the reasons for the emergence of asymptomatic infections at an early stage,which will provide assistance for the development of detection methods for diagnosing COVID-19.

P21-activated kinase 1 (PAK1)-mediated cytoskeleton rearrangement promotes SARS-CoV-2 entry and ACE2 autophagic degradation

Severe acute respiratory syndrome coronavirus 2(SARS-CoV-2),the causative agent of coronavirus disease 2019(COVID-19),has had a significant impact on healthcare systems and economies worldwide.The continuous emergence of new viral strains presents a major challenge in the development of effective antiviral agents.Strategies that possess broad-spectrum antiviral activities are desirable to control SARS-CoV-2 infection.ACE2,an angiotensin-containing enzyme that prevents the overactivation of the renin angiotensin system,is the receptor for SARS-CoV-2.ACE2 interacts with the spike protein and facilitates viral attachment and entry into host cells.Yet,SARS-CoV-2 infection also promotes ACE2 degradation.Whether restoring ACE2 surface expression has an impact on SARS-CoV-2 infection is yet to be determined.Here,we show that the ACE2-spike complex is endocytosed and degraded via autophagy in a manner that depends on clathrin-mediated endocytosis and PAK1-mediated cytoskeleton rearrangement.In contrast,free cellular spike protein is selectively cleaved into S1 and s2 subunits in a lysosomal-dependent manner.Importantly,we show that the pan-PAK inhibitor FRAX-486 restores ACE2 surface expression and suppresses infection by different SARS-CoV-2 strains.FRAX-486-treated Syrian hamsters exhibit significantly decreased lung viral load and alleviated pulmonary inflammation compared with untreated hamsters.In summary,our findings have identified novel pathways regulating viral entry,as well as therapeutic targets and candidate compounds for controlling the emerging strains of SARS-CoV-2 infection.

Leptotrichia hongkongensis sp.nov.,a novel Leptotrichia species with the oral cavity as its natural reservoir

A straight, non-sporulating, Gram-variable bacillus (HKU24T) was recovered from the blood culture of a patient with metastatic breast carcinoma. After repeated subculturing in BACTEC Plus Anaerobic/F blood culture broth, HKU24T grew on brucella agar as non-hemolytic, pinpoint colonies after 96 h of incubation at 37 °C in an anaerobic environment and aerobic environment with 5% CO2. Growth was enhanced with a streak of Staphylococcus aureus. HKU24T was non-motile and catalase-negative, but positive for alkaline phosphatase, β-glucosidase, and α-glucosidase. It hydrolyzed phenylphosphonate and reduced resazurin. 16S rRNA, groEL, gyrB, recA, and rpoB sequencing showed that HKU24T occupies a distinct phylogenetic position among the Leptotrichia species, being most closely related to Leptotrichia trevisanii. Using HKU24T groEL, gyrB, recA, and rpoB gene-specific primers, fragments of these genes were amplified from one of 20 oral specimens. Based on phenotypic and genotypic characteristics, we propose a new species, Leptotrichia hongkongensis sp. nov., to describe this bacterium.

Peptidic defective interfering gene nanoparticles against Omicron,Delta SARS-CoV-2 variants and influenza A virus in vivo

Defective interfering genes(DIGs)are short viral genomes and interfere with wild-type viral replication.Here,we demonstrate that the new designed SARS-CoV-2 DIG(CD3600)can significantly inhibit the replication of SARS-CoV-2 including Alpha,Delta,Kappa and Omicron variants in human HK-2 cells and influenza DIG(PAD4)can significantly inhibit influenza virus replication in human A549 cells.One dose of influenza DIGs prophylactically protects 90%mice from lethal challenge of A(H1N1)pdm09 virus and CD3600 inhibits SARS-CoV-2 replication in hamster lungs when DIGs are administrated to lungs one day before viral challenge.To further investigate the gene delivery vector in the respiratory tract,a peptidic TAT2-P1&LAH4,which can package genes to form small spherical nanoparticles with high endosomal escape ability,is demonstrated to dramatically increase gene expression in the lung airway.TAT2-P1&LAH4,with the dual-functional TAT2-P1(gene-delivery and antiviral),can deliver CD3600 to significantly inhibit the replication of Delta and Omicron SARS-CoV-2 in hamster lungs.This peptide-based nanoparticle system can effectively transfect genes in lungs and deliver DIGs to inhibit SARS-CoV-2 variants and influenza virus in vivo,which provides the new insight into the drug delivery system for gene therapy against respiratory viruses.

Lemierre’s Syndrome Associated With Campylobacter rectus Bacteremia

Introduction Campylobacter rectus is a Gram-negative,anaerobic rod,first described in 1981 as Wolinella recta,subsequently re-classified to Campylobacter based on phylogenetic analysis in 1991.1 It is found in the oral cavity and gastrointestinal tract,and is mainly implicated in oral and periodontal infections.So far,there are only a handful of case reports in the literature describing extra-oral invasive C.rectus infections.2–6 Recently,we described a case of fatal C.rectus infection,due to subdural empyema and ruptured mycotic intracranial aneurysm.2 In this article,we report a case of Lemierre’s syndrome associated with C.rectus bacteremia.

First Report of Tsukamurella conjunctivitidis CAPD-related Peritonitis

Introduction Using the information obtained from analysis of 16S rRNA gene sequences,Tsukamurella was first proposed as a genus in 1988,1 despite the fact that the first strain of this group of bacteria was described in 1941,2 and the first human isolate was reported in 1971.3 Similar to related genera of the order Corynebacteriales,such as Nocardia,Rhodococcus,and Gordonia,members of Tsukamurella are Gram-positive,aerobic,catalase-positive,and partially acid-fast as a result of the presence of mycolic acid in the cell envelope.Due to their similar phenotypic properties,differentiation of these genera and speciation within these genera is difficult in most clinical microbiology laboratories.

Streptococcus agalactiae Anterior Cervical Space and Superior Mediastinum Abscess in a Liver Transplant Recipient

Introduction Streptococcus agalactiae is most commonly associated with pregnancy-related infections,neonatal sepsis,and infections in patients with immunocompromised states,such as diabetes mellitus and malignancies.1 Although abscesses caused by S.agalactiae are sometimes encountered in immunocompromised patients,S.agalactiae abscess in transplant recipients is extremely rare.S.agalactiae abscesses have never been reported in liver transplant recipients.In this article,we report a case of S.agalactiae abscess in the anterior cervical space extending to the superior mediastinum in a liver transplant recipient.