Laboratory biosafety for handling emerging viruses

Emerging viruses are viruses whose occurrence has risen within the past twenty years,or whose presence is likely to increase in the near future.Diseases caused by emerging viruses are a major threat to global public health.In spite of greater awareness of safety and containment procedures,the handling of pathogenic viruses remains a likely source of infection,and mortality,among laboratory workers.There is a steady increase in both the number of laboratories and scientist handling emerging viruses for diagnostics and research.The potential for harm associated to work with these infectious agents can be minimized through the application of sound biosafety concepts and practices.The main factors to the prevention of laboratory-acquired infection are well-trained personnel who are knowledgable and biohazard aware,who are perceptive of the various ways of transmission,and who are professional in safe laboratory practice management.In addition,we should emphasize that appropriate facilities,practices and procedures are to be used by the laboratory workers for the handling of emerging viruses in a safe and secure manner.This review is aimed at providing researchers and laboratory personnel with basic biosafety principles to protect themselves from exposure to emerging viruses while working in the laboratory.This paper focuses on what emerging viruses are,why emerging viruses can cause laboratory-acquired infection,how to assess the risk of working with emerging viruses,and how laboratory-acquired infection can be prevented.Control measures used in the laboratory designed as such that they protect workers from emerging viruses and safeguard the public through the safe disposal of infectious wastes are also addressed.

Rapid inactivation of human respiratory RNA viruses by deep ultraviolet irradiation from light-emitting diodes on a high-temperatureannealed AlN/Sapphire template

Efficient and eco-friendly disinfection of air-borne human respiratory RNA viruses is pursued in both public environment and portable usage.The AlGaN-based deep ultraviolet(DUV)light-emission diode(LED)has high practical potentials because of its advantages of variable wavelength,rapid sterilization,environmental protection,and miniaturization.Therefore,whether the emission wavelength has effects on the disinfection as well as whether the device is feasible to sterilize various respiratory RNA viruses under portable conditions is crucial.Here,we fabricate AlGaN-based DUV LEDs with different wavelength on high-temperature-annealed(HTA)AlN/Sapphire templates and investigate the inactivation effects for several respiratory RNA viruses.The AlN/AlGaN superlattices are employed between the template and upper n-AlGaN to release the strong compressive stress(SCS),improving the crystal quality and interface roughness.DUV LEDs with the wavelength of 256,265,and 278 nm,corresponding to the light output power of 6.8,9.6,and 12.5 mW,are realized,among which the 256 nm-LED shows the most potent inactivation effect in human respiratory RNA viruses,including SARS-CoV-2,influenza A virus(IAV),and human parainfluenza virus(HPIV),at a similar light power density(LPD)of~0.8 mW/cm2 for 10 s.These results will contribute to the advanced DUV LED application of disinfecting viruses with high potency and broad spectrum in a portable and eco-friendly use.

Animal models to study Mycobacterium tuberculosis and HIV co-infection

Mycobacterium tuberculosis(M.tb) and human immunodeficiency virus(HIV) co-infection has become a public health issue worldwide. Up to now, there have been many unresolved issues either in the clinical diagnosis and treatment of M.tb/HIV coinfection or in the basic understanding of the mechanisms for the impairments to the immune system by interactions of these two pathogens. One important reason for these unsolved issues is the lack of appropriate animal models for the study of M.tb/HIV coinfection. This paper reviews the recent development of research on the animal models of M.tb/HIV co-infection, with a focus on the non-human primate models.

Transposable elements in <i>Escherichia coli</i>antimicrobial resistance

Transposable elements are capable of switching their positions on the genome thereby causing gene arrangements and contributing to genome evolution. The aim of this review is to specifically discuss the role of transposable elements in transferring antimicrobial resistance genes in E. coli, thus contributing to increase in virulence and conferring the possibility of multidrug resistance. Different types of transposable elements such as transposons and integrons and their profound influence on E. coli antimicrobial resistance are the focus of this review.

Bacteriophages in <i>Escherichia coli</i>antimicrobial resistance

The continuous battle between humans and the multitude of pathogenic microorganisms in the environment has sought relief in the form of antimicrobials. But the counter attack by pathogenic organisms in the form of multidrug resistance, acquired by various mechanisms such as transformation, transposition, conjugation and transduction is a major reason for concern. Bacteriophages have contributed in a significant way to dissemination of genes encoding antimicrobial resistance, heavy metal resistance and virulence factors through the phenomenon of transduction. This review aims at compiling information about the different mechanisms by which bacteriophages aid in transferring genes involved in antimicrobial resistance to Escherischia coli in various environments.

Networking for training Level 3/4 biosafety laboratory staff

Worldwide,public health systems are continually challenged by emerging and re-emerging viruses.It is therefore important that high-containment labs coordinate and communicate globally to share their experiences and lessons to improve their capacity to respond to threats.The National Biosafety(Level 4)Laboratory in Wuhan,CAS,which is the first Level 4 biosafety laboratory(BSL-4)in China,has been certified recently and it is expected to play an important role in the prevention and control of highly infectious agents in future.Trained and experienced staff in such organizations is the most important factor contributing to safety and security.Therefore,it is imperative to develop a standard training program.Accordingly,in the present study,we developed an improved training program and assessment system based on policies and practices developed by BSL-3/4s in other countries.It included the following three components:(1)A flexible modularized theoretical training:This training comprised 14 modularized theoretical topics such that staffs with different backgrounds could take this theoretical training with different topic combinations according to their knowledge and skill levels;(2)A standardized practical training assessment:This comprehensive assessment,which could be used with biosafety laboratory staff before,during,and after training,included standard operation procedures to meet the special requirements of trainees with different scores;and(3)An applicable documentation system:A certification system was established to evaluate the ability of all staff working inside or outside the laboratory,implemented by a special committee.This certification was approved and authorized by the director of the laboratory and was classified into three grades with corresponding minimal requirements.Further,the present study examined the importance of and need for networking for training BSL-3/4 staff.The establishment of rigorous standards for training BSL-3/4 staff will instill confidence in the public,policy makers,and security officials.Additionally,the expanded international network of BSL-3/4s will continue to be operated safely and will pose no risk to scientific staff,local communities,surrounding environment,and host nations.The clarification and coordination of training standards will help develop a highly-qualified biocontainment workforce and will result in a series of programs that will enable scientists to develop measures to deal with existing threat agents and new diseases that emerge.

RETRACTED ARTICLE:SARS-CoV-2 infects T lymphocytes through its spike protein-mediated membrane fusion

The authors have retracted this article [1]. After the publication ofthis article, it came to the authors attention that in order tosupport the conclusions of the study, the authors should haveused primary T cells instead of T cell lines. Additionally, there areconcerns that the flow cytometry methodology applied here wasflawed. These points resulted in the conclusions being consideredinvalid.

The host-targeting compound peruvoside has a broad-spectrum antiviral activity against positive-sense RNA viruses

Positive-sense RNA viruses modify intracellular calcium stores,endoplasmic reticulum and Golgi apparatus(Golgi)to generate membranous replication organelles known as viral factories.Viral factories provide a conducive and substantial enclave for essential virus replication via concentrating necessary cellular factors and viral proteins in proximity.Here,we identified the vital role of a broadspectrum antiviral,peruvoside in limiting the formation of viral factories.Mechanistically,we revealed the pleiotropic cellular effect of Src and PLC kinase signaling via cyclin-dependent kinase 1 signaling leads to Golgi-specific brefeldin A-resistance guanine nucleotide exchange factor 1(GBF1)phosphorylation and Golgi vesiculation by peruvoside treatment.The ramification of GBF1 phosphorylation fosters GBF1 deprivation consequentially activating downstream antiviral signaling by dampening viral factories formation.Further investigation showed signaling of ERK1/2 pathway via cyclin-dependent kinase 1 activation leading to GBF1 phosphorylation at Threonine 1337(T1337).We also showed 100%of protection in peruvoside-treated mouse model with a significant reduction in viral titre and without measurable cytotoxicity in serum.These findings highlight the importance of dissecting the broad-spectrum antiviral therapeutics mechanism and pave the way for consideration of peruvoside,host-directed antivirals for positive-sense RNA virus-mediated disease,in the interim where no vaccine is available.

A core epitope targeting antibody of SARS-CoV-2

Dear Editor,Tremendous efforts have been made globally to develop therapeutics and prophylactics against severe acute respiratory syndrome coronavirus-2(SARS-CoV-2)which has caused thousands of millions of infections and deaths worldwide.A series of potent neutralizing antibodies with defined epitopes targeting RBD have been recently identified with different strategies.However,being an RNA virus,the instability of the SARS-CoV-2 genome results in numerous S-protein variants with altered viral phenotypes.

Genomic sequencing and analysis of the first imported Middle East Respiratory Syndrome Coronavirus(MERS CoV) in China

Dear Editors,Middle East Respiratory Syndrome(MERS)has spread to more than 23 countries since the first case of a MERS coronavirus(MERS Co V)infection was confirmed in Sep2012[1].Because MERS Co V has led to mortality as high as 40%,it has become one of the most important emerging pathogens threatening human health.Recently,the outbreak of MERS Co V,which resulted in 172 infections and

Retraction Note to:SARS-CoV-2 infects T lymphocytes through its spike protein-mediated membrane fusion

The authors have retracted this article1.After the publication of this article,it came to the authors attention that in order to support the conclusions of the study,the authors should have used primary T cells instead of T-cell lines.In addition,there are concerns that the flow cytometry methodology applied here was flawed.These points resulted in the conclusions being considered invalid.

An ultrapotent pan-β-coronavirus lineage B(β-CoV-B)neutralizing antibody locks the receptor-binding domain in closed conformation by targeting its conserved epitope

New threats posed by the emerging circulating variants of SARS-CoV-2 highlight the need to find conserved neutralizing epitopes for therapeutic antibodies and efficient vaccine design.Here,we identified a receptorbinding domain(RBD)-binding antibody,XG014,which potently neutralizesβ-coronavirus lineage B(β-CoV-B),including SARS-CoV-2,its circulating variants,SARSCoV and bat SARSr-CoV WIV1.Interestingly,antibody family members competing with XG014 binding show reduced levels of cross-reactivity and induce antibodydependent SARS-CoV-2 spike(S)protein-mediated cellcell fusion,suggesting a unique mode of recognition by XG014.Structural analyses reveal that XG014 recognizes a conserved epitope outside the ACE2 binding site and completely locks RBD in the non-functional“down”conformation,while its family member XG005 directly competes with ACE2 binding and position the RBD“up”.Single administration of XG014 is effective in protection against and therapy of SARS-CoV-2 infection in vivo.Our findings suggest the potential to develop XG014 as pan-β-CoV-B therapeutics and the importance of the XG014 conserved antigenic epitope for designing broadly protective vaccines againstβ-CoV-B and newly emerging SARS-CoV-2 variants of concern.

HIV-1 Vif suppresses antiviral immunity by targeting STING

HIV-1 infection-induced cGAS–STING–TBK1–IRF3 signaling activates innate immunity to produce type I interferon(IFN).The HIV-1 nonstructural protein viral infectivity factor(Vif)is essential in HIV-1 replication,as it degrades the host restriction factor APOBEC3G.However,whether and how it regulates the host immune response remains to be determined.In this study,we found that Vif inhibited the production of type I IFN to promote immune evasion.HIV-1 infection induced the activation of the host tyrosine kinase FRK,which subsequently phosphorylated the immunoreceptor tyrosine-based inhibitory motif(ITIM)of Vif and enhanced the interaction between Vif and the cellular tyrosine phosphatase SHP-1 to inhibit type I IFN.Mechanistically,the association of Vif with SHP-1 facilitated SHP-1 recruitment to STING and inhibited the K63-linked ubiquitination of STING at Lys337 by dephosphorylating STING at Tyr162.However,the FRK inhibitor D-65495 counteracted the phosphorylation of Vif to block the immune evasion of HIV-1 and antagonize infection.These findings reveal a previously unknown mechanism through which HIV-1 evades antiviral immunity via the ITIM-containing protein to inhibit the posttranslational modification of STING.These results provide a molecular basis for the development of new therapeutic strategies to treat HIV-1 infection.

Structural and functional basis for pan-CoV fusion inhibitors against SARS-CoV-2 and its variants with preclinical evaluation

The COVID-19 pandemic poses a global threat to public health and economy.The continuously emerging SARS-CoV-2 variants present a major challenge to the development of antiviral agents and vaccines.In this study,we identified that EK1 and cholesterol-coupled derivative of EK1,EK1C4,as pan-CoV fusion inhibitors,exhibit potent antiviral activity against SARS-CoV-2 infection in both lung-and intestine-derived cell lines(Calu-3 and Caco2,respectively).They are also effective against infection of pseudotyped SARS-CoV-2 variants B.1.1.7(Alpha)and B.l.1.248(Gamma)as well as those with mutations in S protein,including N417T,E484K,N501Y,and D614G,which are common in South African and Brazilian variants.Crystal structure revealed that EK1 targets the HR1 domain in the SARS-CoV-2 S protein to block virus-cell fusion and provide mechanistic insights into its broad and effective antiviral activity.Nasal administration of EK1 peptides to hACE2 transgenic mice significantly reduced viral titers in lung and intestinal tissues.EK1 showed good safety profiles in various animal models,supporting further clinical development of EK1-based pan-CoV fusion inhibitors against SARS-CoV-2 and its variants.

Microbial resistance to nanotechnologies:An important but understudied consideration using antimicrobial nanotechnologies in orthopaedic implants

Microbial resistance to current antibiotics therapies is a major cause of implant failure and adverse clinical outcomes in orthopaedic surgery.Recent developments in advanced antimicrobial nanotechnologies provide numerous opportunities to effective remove resistant bacteria and prevent resistance from occurring through unique mechanisms.With tunable physicochemical properties,nanomaterials can be designed to be bactericidal,antifouling,immunomodulating,and capable of delivering antibacterial compounds to the infection region with spatiotemporal accuracy.Despite its substantial advancement,an important,but under-explored area,is potential microbial resistance to nanomaterials and how this can impact the clinical use of antimicrobial nanotechnologies.This review aims to provide a better understanding of nanomaterial-associated microbial resistance to accelerate bench-to-bedside translations of emerging nanotechnologies for effective control of implant associated infections.

Calcitriol enhances pyrazinamide treatment of murine tuberculosis

Background: Tuberculosis is a leading cause of morbidity and mortality in humans worldwide. There is an urgent need for new and effective drugs to treat tuberculosis and shorten the duration of tuberculosis therapy. 1, 25-dihydroxy vitamin D3 (1,25 (OH)2D3) has been reported to have a synergistic effect with pyrazinamide (PZA) in killing tubercle bacilli in vitro. The addition of 1,25 (OH)2D3 to standard tuberculosis treatment should benefit patients if the adjunctive drug has a synergistic effect in vivo. Thus, in this study, calcitriol (bioactive 1,25 (OH)2D3) was administered to mice undergoing treatment for Mycobacterium tuberculosis (M.tb) infection with PZA, a first-line anti-tuberculosis drug, to determine whether vitamin D3 enhances the therapeutic effect. Methods: C57BL/6 female mice were infected with the M.tb H37Rv strain through aerosol exposure. Calcitriol and PZA, either alone or in combination, were orally administered to the M.tb infected mice. The effect of calcitriol on PZA activity was determined by evaluating the bacterial burden and analyzing the histopathological lesions in the lungs and spleen. To investigate the expression of inflammatory cytokines and anti-microbial peptide genes, we determined the transcriptional levels of interferon-γ(IFN-γ), interleukin-4 (IL-4), mouse β-defensin-2 (mBD2), and cathelicidin LL-37 through real-time quantitative polymerase chain reaction. The protein levels of IFN-γ were detected by enzyme-linked immunosorbent assay. Differences between groups were analyzed with independent samples t-test or one-way analysis of variance. Results: Calcitriol alone had little effect on tuberculosis infection, whereas PZA, compared with saline control treatment, decreased the bacterial burden (spleens: PZA vs. saline, 4.82 ± 0.22 vs. 5.22 ± 0.40 Log10 colony-forming units [CFU]/gram, t = 2.13, P < 0.05;lungs: PZA vs. saline, 5.55 ± 0.15 vs. 6.83 ± 0.46 Log10 CFU/gram, t = 6.56, P < 0.01) and pathological lesions in the lungs. Simultaneous administration of calcitriol with PZA, compared with PZA alone, decreased the bacterial load (spleen: calcitriol + PZA vs. PZA, 4.37 ± 0.13 vs. 4.82 ± 0.22 Log10 CFU/gram, t = 4.36, P < 0.01;lung: calcitriol + PZA vs. PZA, 5.03 ± 0.32 vs. 5.55 ± 0.15 Log10 CFU/gram, t = 3.58, P < 0.01) and attenuated the lung lesions (gross pathological score: calcitriol + PZA vs. PZA, 3.25 ± 0.50 vs. 2.50 ± 0.58, t = 1.96, P < 0.05;affected area of total lung area: calcitriol + PZA vs. PZA, 30.75%± 6.50% vs. 21.55%± 2.99%, t = 2.66, P < 0.05). Further studies demonstrated calcitriol significantly increased the expression of anti-inflammatory cytokine IL-4 but suppressed production of the pro-inflammatory cytokine IFN-γ(IL-4: calcitriol vs. saline, 5.69 ± 0.50 vs. 2.80 ± 0.56 fold of control, t= 6.74, P < 0.01;IFN-γ: calcitriol vs. saline, 1.36 ± 0.11 vs. 4.13 ± 0.83 fold of control, t= 5.77, P < 0.01). In addition, calcitriol alone or in combination with PZA significantly enhanced the transcriptional level of anti-microbial peptides (cathelicidin LL-37: calcitriol vs. saline, 10.59 ± 1.03 vs. 2.80 ± 0.90 fold of control, t = 9.85, P < 0.01;mBD2: calcitriol vs. saline, 7.92 ± 0.62 vs. 1.79 ± 0.45 fold of control, t = 13.82, P < 0.01), whereas PZA exerted a negative effect on anti-microbial peptide gene expression. Conclusions: Calcitriol as adjunctive treatment can result in beneficial treatment outcomes in M.tb infection by suppressing the inflammatory response and up-regulating the expression of anti-microbial peptides. These results indicate the feasibility of using calcitriol adjunctively with standard chemotherapy for the treatment of M.tb infection.

Ebola virus and other Filoviruses:an overview

Filoviruses,including Ebola and Marburg viruses,are recognized as a significant warning to public health.They are zoonotic agents with bats as primary reservoir.Those viruses can cause severe human infection with hemorrhagic syndrome leading to death.The mortality rate can be higher than 90%.In West Africa,recent Ebola virus outbreak occurred in March 2014,has caused more than 8300 infections with more than 4000 deaths.That shows the critical state of this country,and the critical context in worldwide.In order to fight this deadly scourge,it is necessary to understand the epidemiology of disease and to establish a good diagnosis protocols and protective measures.In recent decades,traditional techniques of virus isolation are replaced by molecular biology techniques which are faster,more sensitive and specific.Until now,no specific Ebola virus treatment or vaccine but many studies are in progress with promising results.

Immunoengineered adjuvants for universal vaccines against respiratory viruses

Over the past 100 years,several pandemics have wreaked havoc across the world.Respiratory viruses,such as Influenza viruses and,more recently,Coronaviruses,have been the major causative pathogens of these pandemics.During 1918-1919,the 1918 influenza pandemic was speculated to cause 50-100 million deaths worldwide.Thereafter,pandemics caused by descendants of the 1918 virus occurred repeatedly in 1957,1968,and 2009[1].Each took a heavy toll on human life,as well as signifcant societal costs.As the most recent and ongoing pan-demic,a newly emerged coronavirus,SARS CoV-2,have caused more than 95 millin confirmed cases and 2 milion deaths globally by Jan 18,2021.