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.

Human T-cell immunity against the emerging and re-emerging viruses

Over the past decade, we have seen an alarming number of high-profile outbreaks of newly emerging and re-emerging viruses.Recent outbreaks of avian influenza viruses, Middle East respiratory syndrome coronaviruses, Zika virus and Ebola virus present great threats to global health. Considering the pivotal role of host T-cell immunity in the alleviation of symptoms and the clearance of viruses in patients, there are three issues to be primarily concerned about T-cell immunity when a new virus emerges: first, does the population possess pre-existing T-cells against the new virus through previous infections of genetically relevant viruses; second, does a proper immune response arise in the patients to provide protection through an immunopathogenic effect; lastly, how long can the virus-specific immune memory persist. Herein, we summarize the current updates on the characteristics of human T-cell immunological responses against recently emerged or re-emerged viruses, and emphasize the necessity for timely investigation on the T-cell features of these viral diseases, which may provide beneficial recommendations for clinical diagnosis and vaccine development.

Development of small-molecule viral inhibitors targeting various stages of the life cycle of emerging and re-emerging viruses

In recent years, unexpected outbreaks of infectious diseases caused by emerging and re-emerging viruses have become more frequent, which is possibly due to environmental changes. These outbreaks result in the loss of life and economic hardship. Vaccines and therapeutics should be developed for the prevention and treatment of infectious diseases. In this review, we summarize and discuss the latest progress in the development of small-molecule viral inhibitors against highly pathogenic coronaviruses, including severe acute respiratory syndrome coronavirus and Middle East respiratory syndrome coronavirus, Ebola virus, and Zika virus. These viruses can interfere with the specific steps of viral life cycle by blocking the binding between virus and host cells, disrupting viral endocytosis, disturbing membrane fusion, and interrupting viral RNA replication and translation, thereby demonstrating potent therapeutic effect against various emerging and re-emerging viruses. We also discuss some general strategies for developing small-molecule viral inhibitors.

Conditionally Reprogrammed Human Normal Airway Epithelial Cells at ALI: A Physiological Model for Emerging Viruses

Cancer cell lines have been used widely in cancer biology, and as biological or functional cell systems in many biomedical research fields. These cells are usually defective for many normal activities or functions due to significant genetic and epigenetic changes. Normal primary cell yields and viability from any original tissue specimens are usually relatively low or highly variable. These normal cells cease after a few passages or population doublings due to very limited proliferative capacity. Animal models(ferret, mouse, etc.) are often used to study virus-host interaction. However, viruses usually need to be adapted to the animals by several passages due to tropism restrictions including viral receptors and intracellular restrictions. Here we summarize applications of conditionally reprogrammed cells(CRCs), long-term cultures of normal airway epithelial cells from human nose to lung generated by conditional cell reprogramming(CR) technology, as an ex vivo model in studies of emerging viruses. CR allows to robustly propagate cells from non-invasive or minimally invasive specimens, for example, nasal or endobronchial brushing. This process is rapid(2 days) and conditional. The CRCs maintain their differentiation potential and lineage functions, and have been used for studies of adenovirus, rhinovirus, respiratory syncytial virus, influenza viruses, parvovirus, and SARS-CoV. The CRCs can be easily used for airliquid interface(ALI) polarized 3 D cultures, and these coupled CRC/ALI cultures mimic physiological conditions and are suitable for studies of viral entry including receptor binding and internalization, innate immune responses, viral replications, and drug discovery as an ex vivo model for emerging viruses.

Emerging New Phylogenetic Groups of Rabies Virus in Chinese Ferret Badgers

Chinese ferret badger（FB）-transmitted rabies is a serious threat to public health in southeast China. Although mostly associated with dogs, the rabies virus（RABV） presents genetic diversity and has a significantly wide host range in China. Instead of the dog-and wildlife-associated China ⅠI lineage in the past decades, the China Ⅰ lineage has become the main epidemic group hosted and transmitted by dogs. In this study, four new lineages, including 43 RABVs from FBs, have been classified within the dog-dominated China Ⅰ lineage since 2014. FBRABVs have been previously categorized in the China Ⅱ lineage. Moreover, FB-hosted viruses seem to have become the main independent FB-associated clade in the phylogenetic tree. This claim suggests that the increasing genetic diversity of RABVs in FBs is a result of the selective pressure from coexisting dog rabies. FB transmission has become complicated and serious with the coexistence of dog rabies. Therefore, apart from targeting FB rabies, priority should be provided by the appropriate state agencies to perform mass immunization of dog against rabies.

Tomato leaf curl New Delhi virus:an emerging plant begomovirus threatening cucurbit production

Tomato leaf curl New Delhi virus(ToLCNDV),a bipartite begomovirus,was first reported to infect tomato and has recently spread rapidly as an emerging disease to Cucurbitaceae crops.To date,the virus has been reported to infect more than 11 cucurbit crops,in 16 countries and regions,causing severe yield losses.In autumn 2022,ToLCNDV was first isolated from cucurbit plants in Southeastern coastal areas of China.Phylogenetic analysis established that these isolates belong to the Asian ToLCNDV clade,and shared high nucleotide identity and closest genetic relationship with the DNA-A sequence from the Chinese tomato-infecting ToLCNDV isolate(Accession no.OP356207)and the tomato New Delhi ToLCNDV-Severe isolate(Accession no.HM159454).In this review,we summarize the occurrence and distribution,host range,detection and diagnosis,control strategies,and genetic resistance of ToLCNDV in the Cucurbitaceae.We then summarize pathways that could be undertaken to improve our understanding of this emerging disease,with the objective to develop ToLCNDV-resistant cucurbit cultivars.

The genomic characteristics and pathogenicity of a mammalian orthoreovirus within a new lineage from wild pika in plateau

Emerging and re-emerging viruses from wild animals have seriously threatened the health of humans and domesticated animals in recent years.Herein,we isolated a new mammalian orthoreovirus(MRV),Pika/MRV/GCCDC7/2019(PMRV-GCCDC7),in the Qinghai-Tibet Plateau wild pika(Ochotona curzoniae).Though the PMRVGCCDC7 shows features of a typical reovirus with ten gene segments arranged in 3:3:4 in length,the virus belongs to an independent evolutionary branch compared to other MRVs based on phylogenetic tree analysis.The results of cellular susceptibility,species tropism,and replication kinetics of PMRV-GCCDC7 indicated the virus could infect four human cell lines(A549,Huh7,HCT,and LoVo)and six non-human cell lines,including Vero-E6,LLCMK2,BHK-21,N2a,MDCK,and RfKT cell,derived from diverse mammals,i.e.monkey,mice,canine and bat,which revealed the potential of PMRV-GCCDC7 to infect a variety of hosts.Infection of BALB/c mice with PMRVGCCDC7 via intranasal inoculation led to relative weight loss,lung tissue damage and inflammation with the increase of virus titer,but no serious respiratory symptoms and death occurred.The characterization of the new reovirus from a plateau-based wild animal has expanded our knowledge of the host range of MRV and provided insight into its risk of trans-species transmission and zoonotic diseases.

Mayaro fever:A brief review on the immune profile

Mayaro virus is an emergent alphavirus that infects humans,leading to Mayaro fever.Approximately fifty percent of infected patients develop arthritis symptoms in the recovery phase,a phase that can last up to a year.The literature about Mayaro virus infection and its immune response is scarce,which may hamper the development of treatment strategies.We summarize changes in cytokines and chemokines in the acute and recovery phase in Mayaro virus infected patients,and relate this molecular characterization with the immune response.VEGF and IL-12/p70 show pronounced changes in patients in the acute phase,suggesting the development of cellular immunity and Th1 response.IL-6,IL-7,CXCL8/IL-8,IL-13,IL-17,and IFN-γare elevated in patients with arthritis symptoms in the long-term recovery phase,which may be related to the continuous inflammatory process,a possible Th2 inhibiting and promoting Th17 process.Although few studies discuss the issue,with a small number of patients and different backgrounds,inflammatory and immune response and manifestations seem to be closely linked.This information may help to develop the appropriate treatment strategies in Mayaro virus infection.Therefore,we analyzed and summarized data available in literature.

Plant virology in the 21st century in China:Recent advances and future directions

Plant viruses are a group of intracellular pathogens that persistently threaten global food security.Significant advances in plant virology have been achieved by Chinese scientists over the last 20 years,including basic research and technologies for preventing and controlling plant viral diseases.Here,we review these milestones and advances,including the identification of new crop-infecting viruses,dissection of pathogenic mechanisms of multiple viruses,examination of multilayered interactions among viruses,their host plants,and virus-transmitting arthropod vectors,and in-depth interrogation of plantencoded resistance and susceptibility determinants.Notably,various plant virus-based vectors have also been successfully developed for gene function studies and target gene expression in plants.We also recommend future plant virology studies in China.

Prediction of the Receptorome for the Human-Infecting Virome

The virus receptors are key for the viral infection of host cells.Identification of the virus receptors is still challenging at present.Our previous study has shown that human virus receptor proteins have some unique features including high N-glycosylation level,high number of interaction partners and high expression level.Here,a random-forest model was built to identify human virus receptorome from human cell membrane proteins with an accepted accuracy based on the combination of the unique features of human virus receptors and protein sequences.A total of 1424 human cell membrane proteins were predicted to constitute the receptorome of the human-infecting virome.In addition,the combination of the random-forest model with protein–protein interactions between human and viruses predicted in previous studies enabled further prediction of the receptors for 693 human-infecting viruses,such as the enterovirus,norovirus and West Nile virus.Finally,the candidate alternative receptors of the SARS-Co V-2 were also predicted in this study.As far as we know,this study is the first attempt to predict the receptorome for the human-infecting virome and would greatly facilitate the identification of the receptors for viruses.