Mathematical Analysis on a General Delayed HBV Model with Capsids and Two Infection Routes

Considering that HBV belongs to the DNA virus family and is hepatotropic,we model the HBV DNA-containing capsids as a compartment.In this paper,a delayed HBV infection model is established,where the general incidence function and two infection routes including cell-virus infection and cell-cell infection are introduced.According to some preliminaries,including well-posedness,basic reproduction number and existence of two equilibria,we obtain the threshold dynamics for the model.We illustrate numerical simulations to verify the above theoretical results,and furthermore explore the impacts of intracellular delay and cell-cell infection on the global dynamics of the model.

Perceived infection transmission routes, infection control practices, psychosocial changes, and management of COVID-19 infected healthcare workers in a tertiary acute care hospital in Wuhan: a cross-sectional survey

Background:Many healthcare workers were infected by coronavirus disease 2019(COVID-19)early in the epidemic posing a big challenge for epidemic control.Hence,this study aims to explore perceived infection routes,influencing factors,psychosocial changes,and management procedures for COVID-19 infected healthcare workers.Methods:This is a cross-sectional,single hospital-based study.We recruited all 105 confirmed COVID-19 healthcare workers in the Zhongnan Hospital of Wuhan University from February 15 to 29,2020.All participants completed a validated questionnaire.Electronic consent was obtained from all participants.Perceived causes of infection,infection prevention,control knowledge and behaviour,psychological changes,symptoms and treatment were measured.Results:Finally,103 professional staff with COVID-19 finished the questionnaire and was included(response rate:98.1%).Of them,87 cases(84.5%)thought they were infected in working environment in hospital,one(1.0%)thought their infection was due to the laboratory environment,and 5(4.9%)thought they were infected in daily life or community environment.Swab of throat collection and physical examination were the procedures perceived as most likely causing their infection by nurses and doctors respectively.Forty-three(41.8%)thought their infection was related to protective equipment,utilization of common equipment(masks and gloves).The top three first symptoms displayed before diagnosis were fever(41.8%),lethargy(33.0%)and muscle aches(30.1%).After diagnosis,88.3%staff experienced psychological stress or emotional changes during their isolation period,only 11.7%had almost no emotional changes.Arbidol(Umifenovir;an anti-influza drug;69.2%)was the drug most commonly used to target infection in mild and moderate symptoms.Conclusion:The main perceived mode of transmission was not maintaining protection when working at a close distance and having intimate contact with infected cases.Positive psychological intervention is necessary.

3D engineered tissue models for studying human-specific infectious viral diseases

Viral infections cause damage to various organ systems by inducing organ-specific symptoms or systemic multi-organ damage.Depending on the infection route and virus type,infectious diseases are classified as respiratory,nervous,immune,digestive,or skin infections.Since these infectious diseases can widely spread in the com-munity and their catastrophic effects are severe,identification of their causative agent and mechanisms un-derlying their pathogenesis is an urgent necessity.Although infection-associated mechanisms have been studied in two-dimensional(2D)cell culture models and animal models,they have shown limitations in organ-specific or human-associated pathogenesis,and the development of a human-organ-mimetic system is required.Recently,three-dimensional(3D)engineered tissue models,which can present human organ-like physiology in terms of the 3D structure,utilization of human-originated cells,recapitulation of physiological stimuli,and tight cell–cell interactions,were developed.Furthermore,recent studies have shown that these models can recapitulate infection-associated pathologies.In this review,we summarized the recent advances in 3D engineered tissue models that mimic organ-specific viral infections.First,we briefly described the limitations of the current 2D and animal models in recapitulating human-specific viral infection pathology.Next,we provided an overview of recently reported viral infection models,focusing particularly on organ-specific infection pathologies.Finally,a future perspective that must be pursued to reconstitute more human-specific infectious diseases is presented.

Environmental siblings of black agents of human chromoblastomycosis

Agents of human chromoblastomycosis,a skin disease almost exclusively caused by members of the order Chaetothyriales,are assumed to be traumatically inoculated into the skin with sharp environmental materials such as plant thorns or wooden splinters carrying the respective opportunist.In the supposition that such fungi should have their main habitat in the environment,we investigated the occurrence of black fungi in living areas of patients with chromoblastomycosis.In South America Fonsecaea agents are prevalent as agents of the disease,while also related Cladophialophora species,known from other types of skin infections,are known from the continent.Ninety environmental isolates were preliminarily selected as possible agents of chromoblastomycosis,based on morphology.Judging from ITS sequence data isolates were attributed to the genera Cladophialophora,Cyphellophora,Exophiala,Fonsecaea,Phialophora,and Veronaea.A total of 45 fungi morphologically identified as Fonsecaea or Cladophialophora isolated from debris and thorns of living prickly plants in Brazil were processed for taxonomic studies.Phylogenetic analysis revealed that the isolates indeed belonged to the Chaetothyriales,but only rarely an agent of chromoblastomycosis was concerned;only two strains of F.pedrosoi and one F.monophora were isolated from debris plants.The remaining isolates belonged to hitherto unknown molecular siblings of Fonsecaea.Two novel taxa are introduced.