High throughput sequencing of Vero, A549, CaCO2, and HRT18 cells infected with SARS-CoV2
ABSTRACT: Purpose: The goals of this study are to monitor the evolution pattern of SARS-CoV2 in depending host cells by viral transcriptome sequencing analysis of Vero, A549, Caco2, and HRT18 cells infected with SARS-CoV2. Methods: SARS-CoV-2 isolate was passaged 4 time on Vero cells and used to extract RNA for the high-throughput sequencing. The 8×104 PFU of SARS-CoV2 stocks passaged on vero cells were inoculated to the monolayer of A549, CaCO2, and HRT-18 cell lines in 75T flask for 1hour at 37℃ in a 5% CO2 incubator with gentle shaking of 15 minutes interval. After that, the infected cells were washed two times with DPBS and incubated with the fresh maintenance medium for 3 days. The virus inoculation was performed in triplicate for each cell lines. In case of the first passage, the infected cell pellets were resuspended to 250µl with fresh medium, to extract RNA for the high-throughput sequencing. The cultured cell supernatant of the virus-infected A549, CaCO2, and HRT18 cells was centrifuged at 3,000g for 10min to use for the next passage, and stored at -80℃. The serial passage of SARS-CoV-2 on A549, CaCO2, and HRT18 cell lines were continued to passage 12 and the cultured cell supernatant of the infected cells in passage 12 was centrifuged at 3,000g for 10 min, and used to extract RNA for the high-throughput sequencing. The RNA samples were sequenced with illumine TruSeq Strand Total RNA LT kit and illumine NovaSeq6000 plaform form Macrogen, Inc (Seoul, Korea) for high throughput sequencing. The raw reads were trimmed with BBDuk and mapped the isolate SARS-CoV-2/human/KOR/KCDC03-NCCP43326/2020 (Genebank accession number. MW466791) with Bowtie 2 using Geneious program 2021.2.2 Result: Using SNP analysis workflow, our result showed the sequence variations pattern of SARS-CoV2 depending on host cell (A549, CaCO2, and HRT18 cell lines) and it was confirmed that a relatively large number of SNPs were commonly observed in spike protein. Some SNPs affect amino acid changes, and a common pattern of amino acid changes was observed the genomic sequence of SARS-CoV2 passaged in A549, CaCO2 and HRT18 cells. Conclusion: In this study, we tried to monitor the SARS-CoV-2 (GenBank accession No. MW466791 in 2020, Korea) evolution pattern in different host cells using high throughput sequencing analysis, and compare the selected mutations by each host cells with natural mutations found in currently circulating SARS-CoV-2 variants. Overall design: Monitor of mutation pattern of SARS-CoV2 transcript depending on host cells by high throghput sequencing analysis
Project description:To understand the pathogenesis and develop an animal model of severe acute respiratory syndrome (SARS)-associated coronavirus (SARS-CoV), the Frankfurt 1 SARS-CoV isolate was passaged serially in young F344 rats. Young rats were susceptible to SARS-CoV but cleared the virus rapidly within 3 to 5 days of intranasal inoculation. After 10 serial passages, replication and virulence of SARS-CoV were increased in the respiratory tract of young rats without clinical signs. By contrast, adult rats infected with the passaged virus showed respiratory symptoms and severe pathological lesions in the lung. Levels of inflammatory cytokines in sera and lung tissues were significantly higher in adult F344 rats than in young rats. During in vivo passage of SARS-CoV, a single amino acid substitution was introduced within the binding domain of the viral spike protein recognizing angiotensin-converting enzyme 2 (ACE2), which is known as a SARS-CoV receptor. The rat-passaged virus more efficiently infected CHO cells expressing rat ACE2 than did the original isolate. These results strongly indicate that host and virus factors such as advanced age and virus adaptation are critical for the development of SARS in rats.
Project description:K777 is a di-peptide analog that contains an electrophilic vinyl-sulfone moiety and is a potent, covalent inactivator of cathepsins. Vero E6, HeLa/ACE2, Caco-2, A549/ACE2, and Calu-3, cells were exposed to SARS-CoV-2, and then treated with K777. K777 reduced viral infectivity with EC50 values of inhibition of viral infection of: 74 nM for Vero E6, <80 nM for A549/ACE2, and 4 nM for HeLa/ACE2 cells. In contrast, Calu-3 and Caco-2 cells had EC50 values in the low micromolar range. No toxicity of K777 was observed for any of the host cells at 10-100 ?M inhibitor. K777 did not inhibit activity of the papain-like cysteine protease and 3CL cysteine protease, encoded by SARS-CoV-2 at concentrations of ? 100 ?M. These results suggested that K777 exerts its potent anti-viral activity by inactivation of mammalian cysteine proteases which are essential to viral infectivity. Using a propargyl derivative of K777 as an activity-based probe, K777 selectively targeted cathepsin B and cathepsin L in Vero E6 cells. However only cathepsin L cleaved the SARS-CoV-2 spike protein and K777 blocked this proteolysis. The site of spike protein cleavage by cathepsin L was in the S1 domain of SARS-CoV-2 , differing from the cleavage site observed in the SARS CoV-1 spike protein. These data support the hypothesis that the antiviral activity of K777 is mediated through inhibition of the activity of host cathepsin L and subsequent loss of viral spike protein processing.
Project description:Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causative agent of coronavirus disease (COVID-19), continues to be a pressing health concern. In this study, we investigated the impact of SARS-CoV-2 infection on host microRNA (miRNA) populations in three human lung-derived cell lines, as well as in nasopharyngeal swabs from SARS-CoV-2–infected individuals. We did not detect any major and consistent differences in host miRNA levels after SARS-CoV-2 infection. However, we unexpectedly discovered a viral miRNA-like small RNA, named CoV2-miR-O7a (for SARS-CoV-2 miRNA-like ORF7a-derived small RNA). Its abundance ranges from low to moderate as compared to host miRNAs and it associates with Argonaute proteins—core components of the RNA interference pathway. We identify putative targets for CoV2-miR-O7a, including Basic Leucine Zipper ATF-Like Transcription Factor 2 (BATF2), which participates in interferon signaling. We demonstrate that CoV2-miR-O7a production relies on cellular machinery, yet is independent of Drosha protein, and is enhanced by the presence of a strong and evolutionarily conserved hairpin formed within the ORF7a sequence. Overall design: Calu-3, PC-9 and A459-hACE2 cells were infected with SARS-CoV-2 at different MOIs and time points, and small RNA sequencing was performed. In addition, anti-Ago immunoprecipitation followed by small RNA sequencing was performed on extracts from SARS-CoV-2 infected cells.
Project description:BACKGROUND:Since the first outbreak of SARS-CoV-2, the clinical characteristics of the Coronavirus Disease 2019 (COVID-19) have been progressively changed. Data reporting a viral intra-host and inter-host evolution favouring the appearance of mild SARS-CoV-2 strains are since being accumulating. To better understand the evolution of SARS-CoV-2 pathogenicity and its adaptation to the host, it is therefore crucial to investigate the genetic and phenotypic characteristics of SARS-CoV-2 strains circulating lately in the epidemic. METHODS:Nasopharyngeal swabs have been analyzed for viral load in the early (March 2020) and late (May 2020) phases of epidemic in Brescia, Italy. Isolation of SARS-CoV-2 from 2 high viral load specimens identified on March 9 (AP66) and on May 8 (GZ69) was performed on Vero E6 cells. Amount of virus released was assessed by quantitative PCR. Genotypic characterization of AP66 and GZ69 was performed by next generation sequencing followed by an in-depth in silico analysis of nucleotide mutations. RESULTS:The SARS-CoV-2 GZ69 strain, isolated in May from an asymptomatic healthcare worker, showed an unprecedented capability of replication in Vero E6 cells in the absence of any evident cytopathic effect. Vero E6 subculturing, up to passage 4, showed that SARS-CoV-2 GZ69 infection was as productive as the one sustained by the cytopathic strain AP66. Whole genome sequencing of the persistently replicating SARS-CoV-2 GZ69 has shown that this strain differs from the early AP66 variant in 9 nucleotide positions (C2939T; C3828T; G21784T; T21846C; T24631C; G28881A; G28882A; G28883C; G29810T) which lead to 6 non-synonymous substitutions spanning on ORF1ab (P892S; S1188L), S (K74N; I95T) and N (R203K, G204R) proteins. CONCLUSIONS:Identification of the peculiar SARS-CoV-2 GZ69 strain in the late Italian epidemic highlights the need to better characterize viral variants circulating among asymptomatic or paucisymptomatic individuals. The current approach could unravel the ways for future studies aimed at analyzing the selection process which favours viral mutations in the human host.
Project description:Here we analyzed the gene expression profile of cells that stably express the severe acute respiratory syndrome coronavirus (SARS-CoV) 3a protein to determine its effects on host functions. A lung epithelial cell-line, A549, was chosen for this study because the lung is the primary organ infected by SARS-CoV and fatalities resulted mainly from pulmonary complications. Our results showed that the expression of 3a up-regulates the mRNA levels of all three subunits, Aalpha, Bbeta, and gamma, of fibrinogen. Consequently, the intracellular levels as well as the secretion of fibrinogen were increased. We also observed increased fibrinogen levels in SARS-CoV-infected Vero E6 cells.
Project description:To determine the effects of SARS-CoV-2 infection on the host transcriptional profile, total RNA was isolated from infected cells and analyzed by microarray. For these studies, we took into account that the SARS-CoV-2 replication cycle in cell culture is 6-16 h, followed by death of infected cells 28. Therefore, to evaluate the direct effects of virus infection and avoid the analysis of secondary infection events or cell death effects, we did not extend our analysis beyond 24 h post infection. Analysis of significantly differentially expressed genes showed substantial transcriptomic changes in Calu-3 cells with a total of 3215 differentially expressed genes (FDR< 10%). Overall design: 2 cell lines (A549-ACE2 and Calu3, 4 time point 4,8,12,24 hours, mock treated vs SARS-CoV2-infected
Project description:Repurposing FDA-approved drugs that treat respiratory infections caused by coronaviruses, such as SARS-CoV-2 and MERS-CoV, could quickly provide much needed antiviral therapies. In the current study, the potency and cellular toxicity of four fluoroquinolones (enoxacin, ciprofloxacin, levofloxacin, and moxifloxacin) were assessed in Vero cells and A549 cells engineered to overexpress ACE2, the SARS-CoV-2 entry receptor. All four fluoroquinolones suppressed SARS-CoV-2 replication at high micromolar concentrations in both cell types, with enoxacin demonstrating the lowest effective concentration 50 value (EC<sub>50</sub>) of 126.4 ?M in Vero cells. Enoxacin also suppressed the replication of MERS-CoV-2 in Vero cells at high micromolar concentrations. Cellular toxicity of levofloxacin was not found in either cell type. In Vero cells, minimal toxicity was observed following treatment with ?37.5 ?M enoxacin and 600 ?M ciprofloxacin. Toxicity in both cell types was detected after moxifloxacin treatment of ?300 ?M. In summary, these results suggest that the ability of fluoroquinolones to suppress SARS-CoV-2 and MERS-CoV replication in cultured cells is limited.
Project description:OBJECTIVES:Respiratory and intestinal tract are two primary target organs of SARS-CoV-2 infection. However, detailed characterization of the host-virus interplay in infected human lung and intestinal epithelial cells is lacking. METHODS:We utilized immunofluorescence assays, flow cytometry, and RT-qPCR to delineate the virological features and the innate immune response of the host cells against SARS-CoV-2 infection in two prototype human cell lines representing the human lung (Calu3) and intestinal (Caco2) epithelium when compared with SARS-CoV. RESULTS:Lung epithelial cells were significantly more susceptible to SARS-CoV-2 compared to SARS-CoV. However, SARS-CoV-2 infection induced an attenuated pro-inflammatory cytokines/chemokines induction and type I and type II IFN responses. A single dose of 10?U/mL interferon-? (IFN?) pretreatment potently protected both Calu3 and Caco2 against SARS-CoV-2 infection. Interestingly, SARS-CoV-2 was more sensitive to the pretreatment with IFN? and IFN inducer than SARS-CoV in Calu3. CONCLUSIONS:Despite robust infection in both human lung and intestinal epithelial cells, SARS-CoV-2 could attenuate the virus-induced pro-inflammatory response and IFN response. Pre-activation of the type I IFN signaling pathway primed a highly efficient antiviral response in the host against SARS-CoV-2 infection, which could serve as a potential therapeutic and prophylactic maneuver to COVID-19 patients.
Project description:The worldwide outbreak of severe acute respiratory syndrome (SARS) was shown to be associated with a novel coronavirus (CoV) now called SARS CoV. We report here the generation of SARS CoV S protein-pseudotyped murine leukemia virus (MLV) vector particles. The wild-type S protein pseudotyped MLV vectors, although at a low efficiency. Partial deletion of the cytoplasmic tail of S dramatically increased infectivity of pseudotypes, with titers only two- to threefold lower than those of pseudotypes generated in parallel with the vesicular stomatitis virus G protein. S-pseudotyped MLV particles were used to analyze viral tropism. MLV(SARS) pseudotypes and wild-type SARS CoV displayed similar cell types and tissue and host restrictions, indicating that the expression of a functional receptor is the major restraint in permissiveness to SARS CoV infection. Efficient gene transfer could be detected in Vero and CaCo2 cells, whereas the level of gene marking of 293T, HeLa, and HepG2 cells was only slightly above background levels. A cat cell line and a dog cell line were not susceptible. Interestingly, PK-15, a porcine kidney cell line, and primary porcine kidney cells were also highly permissive for SARS S pseudotypes and wild-type SARS CoV. This finding suggests that swine may be susceptible to SARS infection and may be a source for infection of humans. Taken together, these results indicate that MLV(SARS) pseudotypes are highly valuable for functional studies of viral tropism and entry and, in addition, can be a powerful tool for the development of therapeutic entry inhibitors without posing a biohazard to human beings.
Project description:We will use the EMC/2012 strain of the novel beta Coronavirus called Middle East Respiratory Syndrome Coronavirus (MERS-CoV). It was initially passaged on Vero E6 cells in Saudi Arabia before being sequenced at the Erasmus Medical College in Rotterdam, Netherlands by Dr Ron Fouchier. We propose to perform a time course of infection of hCoV-EMC on MRC5 cells (Human Lung origin) and Vero cells (African Green Monkey Kidney cells). Both cell lines readily grow and replicate the virus. Importantly these cell lines show signs of Cytopathic effect (CPE), such as cell rounding and release from the petri dish that coincide with time points high virus replication demonstrating the effects of virus replication on the cells. Transcriptomic analysis will be performed after infection with MERS-CoV and SARS-CoV (Urbani strain) to compare the host gene induction that occurs during infection. MRC5 and Vero E6 cells will be infected at an MOI of 0.1 and 3 and RNA harvested from cells at 24 and 48 post infection. RNA will be processed for library creation and sequenced on an Illumina Hiseq. Sequencing reads will be analyzed and compared across the time course and between each virus to identify common response pathways induced during infection as well as unique pathways specific to each virus.