The coronavirus disease 2019 (COVID-19) pandemic is caused by infection with the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which is spread primary via respiratory droplets and infects the lungs. Currently widely used cell lines and animals are unable to accurately mimic human physiological conditions because of the abnormal status of cell lines (transformed or cancer cells) and species differences between animals and humans. Organoids are stem cell-derived self-organized three-dimensional culture in vitro and model the physiological conditions of natural organs. Here we showed that SARS-CoV-2 infected and extensively replicated in human embryonic stem cells (hESCs)-derived lung organoids, including airway and alveolar organoids which covered the complete infection and spread route for SARS-CoV-2 within lungs. The infected cells were ciliated, club, and alveolar type 2 (AT2) cells, which were sequentially located from the proximal to the distal airway and terminal alveoli, respectively. Additionally, RNA-seq revealed early cell response to virus infection including an unexpected downregulation of the metabolic processes, especially lipid metabolism, in addition to the well-known upregulation of immune response. Further, Remdesivir and a human neutralizing antibody potently inhibited SARS-CoV-2 replication in lung organoids. Therefore, human lung organoids can serve as a pathophysiological model to investigate the underlying mechanism of SARS-CoV-2 infection and to discover and test therapeutic drugs for COVID-19.
Adenosine Monophosphate/therapeutic use* ; Alanine/therapeutic use* ; Alveolar Epithelial Cells/virology* ; Antibodies, Neutralizing/therapeutic use* ; COVID-19/virology* ; Down-Regulation ; Drug Discovery ; Human Embryonic Stem Cells/metabolism* ; Humans ; Immunity ; Lipid Metabolism ; Lung/virology* ; RNA, Viral/metabolism* ; SARS-CoV-2/physiology* ; Virus Replication/drug effects*

Coronaviruses are a type of positive-sense single-stranded RNA virus with envelope and widely exist in nature to cause respiratory infectious diseases. The novel coronavirus is a new outbreak virus that is susceptible to all people. Up to now, the disease has been widely spread in the world and poses a great threat to public health. In this review, the genomic features, key proteins, host infection and replication of coronaviruses and novel coronaviruses are reviewed in order to provide theoretical basis for the study of the pathogenic mechanism of virus infection on host cells and to provide basic support for the development of specific antiviral drugs.
Betacoronavirus/physiology* ; COVID-19 ; Coronavirus Infections/virology* ; Humans ; Pandemics ; Pneumonia, Viral/virology* ; SARS-CoV-2 ; Virus Replication

Adaptation, Physiological ; Adenosine Monophosphate ; administration & dosage ; analogs & derivatives ; pharmacology ; therapeutic use ; Administration, Intranasal ; Alanine ; administration & dosage ; analogs & derivatives ; pharmacology ; therapeutic use ; Animals ; Betacoronavirus ; genetics ; physiology ; Chlorocebus aethiops ; Coronavirus Infections ; drug therapy ; virology ; Disease Models, Animal ; Female ; Host Specificity ; genetics ; Lung ; pathology ; virology ; Male ; Mice ; Mice, Inbred BALB C ; Mice, Inbred C57BL ; Mutation, Missense ; Nasal Mucosa ; virology ; Pandemics ; Pneumonia, Viral ; drug therapy ; virology ; RNA, Viral ; administration & dosage ; genetics ; Turbinates ; virology ; Vero Cells ; Viral Load ; Virus Replication

The three known human highly pathogenic coronaviruses are severe acute respiratory syndrome coronavirus (SARS-CoV), Middle East respiratory syndrome coronavirus, (MERS-CoV), and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Human highly pathogenic coronaviruses are composed of non-structural proteins, structural proteins and accessory proteins. Viral particles recognize host receptors via spike glycoprotein (S protein), enter host cells by membrane fusion, replicate in host cells through large replication-transcription complexes, and promote proliferation by interfering with and suppressing the host's immune response. Human highly pathogenic coronaviruses are hosted by humans and vertebrates. Viral particles are transmitted through droplets, contact and aerosols or likely through digestive tract, urine, eyes and other routes. This review discusses the mechanisms of proliferation and transmission of highly pathogenic human coronaviruses based on the results of existing research, providing basis for future study on interrupting the transmission and pathogenicity of human highly pathogenic coronaviruses.
Animals ; Betacoronavirus ; physiology ; Coronavirus Infections ; immunology ; transmission ; virology ; Humans ; Middle East Respiratory Syndrome Coronavirus ; physiology ; Pandemics ; Pneumonia, Viral ; immunology ; transmission ; virology ; SARS Virus ; physiology ; Virus Replication ; physiology

Emerging and re-emerging RNA viruses occasionally cause epidemics and pandemics worldwide, such as the on-going outbreak of the novel coronavirus SARS-CoV-2. Herein, we identified two potent inhibitors of human DHODH, S312 and S416, with favorable drug-likeness and pharmacokinetic profiles, which all showed broad-spectrum antiviral effects against various RNA viruses, including influenza A virus, Zika virus, Ebola virus, and particularly against SARS-CoV-2. Notably, S416 is reported to be the most potent inhibitor so far with an EC of 17 nmol/L and an SI value of 10,505.88 in infected cells. Our results are the first to validate that DHODH is an attractive host target through high antiviral efficacy in vivo and low virus replication in DHODH knock-out cells. This work demonstrates that both S312/S416 and old drugs (Leflunomide/Teriflunomide) with dual actions of antiviral and immuno-regulation may have clinical potentials to cure SARS-CoV-2 or other RNA viruses circulating worldwide, no matter such viruses are mutated or not.
Animals ; Antiviral Agents ; pharmacology ; therapeutic use ; Betacoronavirus ; drug effects ; physiology ; Binding Sites ; drug effects ; Cell Line ; Coronavirus Infections ; drug therapy ; virology ; Crotonates ; pharmacology ; Cytokine Release Syndrome ; drug therapy ; Drug Evaluation, Preclinical ; Gene Knockout Techniques ; Humans ; Influenza A virus ; drug effects ; Leflunomide ; pharmacology ; Mice ; Mice, Inbred BALB C ; Orthomyxoviridae Infections ; drug therapy ; Oseltamivir ; therapeutic use ; Oxidoreductases ; antagonists & inhibitors ; metabolism ; Pandemics ; Pneumonia, Viral ; drug therapy ; virology ; Protein Binding ; drug effects ; Pyrimidines ; biosynthesis ; RNA Viruses ; drug effects ; physiology ; Structure-Activity Relationship ; Toluidines ; pharmacology ; Ubiquinone ; metabolism ; Virus Replication ; drug effects

OBJECTIVE: To analyze the characteristics of BK polymavirus (BKV) infection and the optimal time window for intervention in kidney transplant recipients (KTRs). METHODS: We retrospectively analyzed the clinical data and treatment regimens in 226 KTRs in our center between January, 2013 and January, 2018. Among the recipients, 157 had a urine BKV load ≥1.0×10 copy/mL after transplantation, and 69 had a urine BKV load below 1.0×10 copy/mL (control group). RESULTS: Among the 157 KTRs, 60 (38.2%) recipients were positive for urine BKV, 66 (42.0%) had BKV viruria, and 31(19.7%) had BKV viremia. The incidence of positive urine occult blood was significantly higher in BKV-positive recipients than in the control group ( < 0.05). The change of urine BKV load was linearly related to that of Tacrolimus trough blood level (=0.351, < 0.05). In urine BKV positive group, the average estimated glomerular filtration rate (eGFR) was below the baseline level (60 mL·min·1.73 m) upon diagnosis of BKV infection reactivation, and recovered the normal level after intervention. In patients with BKV viruria and viremia, the average eGFR failed to return to the baseline level in spite of improvement of the renal function after intervention. CONCLUSIONS Positive urine occult blood after transplantation may be associated with BKV infection reactivation in some of the KTRs. BKV infection is sensitive to changes of plasma concentration of immunosuppressive agents. Early intervention of BKV replication in KTRs with appropriate dose reduction for immunosuppression can help to control virus replication and stabilize the allograft function.
BK Virus ; physiology ; Humans ; Kidney Transplantation ; Polyomavirus Infections ; virology ; Retrospective Studies ; Transplant Recipients ; Tumor Virus Infections ; virology ; Viral Load ; Virus Replication

Herpes simplex virus (HSV), including HSV-1 and HSV-2, is an important pathogen that can cause many diseases. Usually these diseases are recurrent and incurable. After lytic infection on the surface of peripheral mucosa, HSV can enter sensory neurons and establish latent infection during which viral replication ceases. Moreover, latent virus can re-enter the replication cycle by reactivation and return to peripheral tissues to start recurrent infection. This ability to escape host immune surveillance during latent infection and to spread during reactivation is a viral survival strategy and the fundamental reason why no drug can completely eradicate the virus at present. Although there are many studies on latency and reactivation of HSV, and much progress has been made, many specific mechanisms of the process remain obscure or even controversial due to the complexity of this process and the limitations of research models. This paper reviews the major results of research on HSV latency and reactivation, and discusses future research directions in this field.
Herpes Simplex ; virology ; Herpesvirus 1, Human ; physiology ; Humans ; Virus Activation ; physiology ; Virus Latency ; physiology ; Virus Replication

To investigate the susceptibility of Chukars to duck avian influenza virus H9N2 and explore their role in interspecies transmission of influenza viruses. Chukars were inoculated with duck avian influenza viruses H9N2. The present study demonstrated that inflammatory lesions and virus antigen were present in the trachea, bronchus, and parabronchus, and the viruses could be isolated from throat swabs and lung tissue homogenate supernatants. At 14 d post virus inoculation, anti-H9 influenza virus antibody in the serum was detected. The results indicated that Chukars are susceptible to duck avian influenza virus and serve as an intermediate host, thereby facilitating viral gene evolution and supporting the need for continued surveillance of epidemiology and evolution of the influenza virus in Chukars.
Animals ; Galliformes ; Influenza A Virus, H9N2 Subtype ; pathogenicity ; physiology ; Influenza in Birds ; virology ; Respiratory System ; pathology ; virology ; Virus Replication ; physiology

To study the effect and underlying mechanism of Mahuang Tang against influenza A virus ， the influenza virus-infected Madin-Darby canine kidney(MDCK) cells were used as the carrier in this study to detect the median tissue culture-infective dose(TCID₅₀) of influenza A virus strains(A/PR8/34) on MDCK cells with cytopathic effect(CPE) assay. Blocking influenza virus invading host cells and anti-influenza virus biosynthesis were used as two different administration methods， and then the methyl thiazolyl tetrazolium(MTT) assay was utilized to determine the antiviral effective rate(ER)， median efficacious concentration(EC₅₀) and therapeutic index(TI) of Mahuang Tang. The quantitative Real-time polymerase chain reaction(RT-PCR) was used to measure virus load and the mRNA expression levels of TLR4， TLR7， MyD88 and TRAF6 in MDCK cells at 24， 48 h after the treatment. The experiment results indicated that TCID₅₀ of A/PR8/34 for MDCK cells was 1×10-4.32/mL. The EC₅₀ values of two different treatment methods were 4.92，1.59 g·L⁻¹ respectively， the TI values were 12.53， 38.78 respectively， and when the concentration of Mahuang Tang was 5.00 g·L⁻¹， ER values were 50.21%， 98.41% respectively， showing that Mahuang Tang can block influenza virus into the host cells and significantly inhibit their biosynthesis. Meanwhile， as compared with the virus group， the virus load was significantly inhibited in Mahuang Tang groups， and Mahuang Tang high and middle doses had the significant effect on decreasing the mRNA expression of TLR4， TLR7，MyD88 and TRAF6 at 24， 48 h after the treatment. It can be demonstrated that the mechanisms of Mahuang Tang against influenza A virus are related to the inhibition of influenza virus replication and the mRNA expression of correlative genes in TLR4 and TLR7 signaling pathways.
Animals ; Antiviral Agents ; pharmacology ; Dogs ; Drugs, Chinese Herbal ; pharmacology ; Influenza A Virus, H1N1 Subtype ; drug effects ; physiology ; Madin Darby Canine Kidney Cells ; Orthomyxoviridae Infections ; Toll-Like Receptor 4 ; metabolism ; Toll-Like Receptor 7 ; metabolism ; Virus Replication ; drug effects

Viral infection of cells is a highly intricate process that involves the complex virus-cell interactions. Recently, virologists can monitor the virus life cycle at the primary infection site in real-time using various virus tracking techniques. Herpesviruses, a class of large enveloped DNA viruses, are important pathogens threatening the health of humans and animals. This review discussed the applications of different virus tracking techniques in herpesvirus studies, to provide new insights into virus-cell interactions and replication mechanisms of herpesviruses. Though the techniques have widely been exploited, some issues need to be addressed, such as the selection of the optimal site to insert reporters and the inability to track the whole process of the virus life cycle. With the updated tracking techniques, hopefully, more complex replication mechanismsof herpesviruses will be revealed in detail.
Animals ; Herpesviridae ; pathogenicity ; physiology ; Humans ; Virus Diseases ; Virus Physiological Phenomena ; Virus Replication