p53 suppresses the inflammatory response following respiratory syncytial virus infection by inhibiting TLR2.

-Respiratory syncytial virus (RSV) is a pivotal virus leading to acute lower respiratory tract infections in children under 5 years old. This study aimed to explore the correlation between p53 and Toll-like receptors (TLRs) post RSV infection. p53 levels exhibited a substantial decrease in nasopharyngeal aspirates (NPAs) from infants with RSV infection compared to control group. Manipulating p53 expression had no significant impact on RSV replication or interferon signaling pathway. Suppression of p53 expression led to heightened inflammation following RSV infection in A549 cells or airways of BALB/c mice. while stabilizing p53 expression using Nutlin-3a mitigated the inflammatory response in A549 cells. Additionally, Inhibiting p53 expression significantly increased Toll-like receptor 2 (TLR2) expression in RSV-infected epithelial cells and BALB/c mice. Furthermore, the TLR2 inhibitor, C29, effectively reduced inflammation mediated by p53 in A549 cells. Collectively, our results indicate that p53 modulates the inflammatory response after RSV infection through TLR2.

Coronavirus M Protein Trafficking in Epithelial Cells Utilizes a Myosin Vb Splice Variant and Rab10.

The membrane (M) glycoprotein of coronaviruses (CoVs) serves as the nidus for virion assembly. Using a yeast two-hybrid screen, we identified the interaction of the cytosolic tail of Murine Hepatitis Virus (MHV-CoV) M protein with Myosin Vb (MYO5B), specifically with the alternative splice variant of cellular MYO5B including exon D (MYO5B+D), which mediates interaction with Rab10. When co-expressed in human lung epithelial A549 and canine kidney epithelial MDCK cells, MYO5B+D co-localized with the MHV-CoV M protein, as well as with the M proteins from Porcine Epidemic Diarrhea Virus (PEDV-CoV), Middle East Respiratory Syndrome (MERS-CoV) and Severe Acute Respiratory Syndrome 2 (SARS-CoV-2). Co-expressed M proteins and MYO5B+D co-localized with endogenous Rab10 and Rab11a. We identified point mutations in MHV-CoV M that blocked the interaction with MYO5B+D in yeast 2-hybrid assays. One of these point mutations (E121K) was previously shown to block MHV-CoV virion assembly and its interaction with MYO5B+D. The E to K mutation at homologous positions in PEDV-CoV, MERS-CoV and SARS-CoV-2 M proteins also blocked colocalization with MYO5B+D. The knockdown of Rab10 blocked the co-localization of M proteins with MYO5B+D and was rescued by re-expression of CFP-Rab10. Our results suggest that CoV M proteins traffic through Rab10-containing systems, in association with MYO5B+D.

Characteristic of slow growth in cell culture of adenovirus type 54 causing nationwide outbreak epidemic keratoconjunctivitis in Japan.

PURPOSE: To characterize the virological features of adenovirus type 54 (Ad54) causing nationwide outbreak of severe epidemic keratoconjunctivitis (EKC) in Japan, we comparatively analysed the viral propagation phenotype of Ad54 and other Ads: type 37 (Ad37), 64 (Ad64), and 5 (Ad5), in A549 cells quantitatively. STUDY DESIGN: Laboratory investigation. METHODS: We compared the growth rate of Ads using copy numbers and cytopathic effect observation during propagation in A549 cell lines. Expressions of mRNA of E1 gene were also calculated and compared. Phylogenetic analysis of the region, including putative promoter of E1 gene and E1 open reading frame (ORF), were performed. RESULTS: Increases in viral loads, growth rate, and viral propagation were slower for Ad54 than for other Ads. The expression level of the E1 gene per infected cell was lower for Ad54 than for other Ad types on post-infection day 1. Phylogenetic analysis of the E1 gene putative promoter and ORF revealed Ad54 was the closest to Ad type 8. CONCLUSION: The propagation of Ad54 in A549 is slow compared with Ad37, Ad64 and Ad5. This slow propagation could have been caused by slow genomic replication resulting from delayed viral entry or E1 transcription initiation. The EKC caused by Ad54 needs more attention because the slow propagation of Ad54 may contribute to prolonged disease duration.

Metabolomic Analysis of Influenza A Virus A/WSN/1933 (H1N1) Infected A549 Cells during First Cycle of Viral Replication.

Influenza A virus (IAV) has developed strategies to utilize host metabolites which, after identification and isolation, can be used to discover the value of immunometabolism. During this study, to mimic the metabolic processes of influenza virus infection in human cells, we infect A549 cells with H1N1 (WSN) influenza virus and explore the metabolites with altered levels during the first cycle of influenza virus infection using ultra-high-pressure liquid chromatography-quadrupole time-of-flight mass spectrometer (UHPLC-Q-TOF MS) technology. We annotate the metabolites using MetaboAnalyst and the Kyoto Encyclopedia of Genes and Genomes pathway analyses, which reveal that IAV regulates the abundance of the metabolic products of host cells during early infection to provide the energy and metabolites required to efficiently complete its own life cycle. These metabolites are correlated with the tricarboxylic acid (TCA) cycle and mainly are involved in purine, lipid, and glutathione metabolisms. Concurrently, the metabolites interact with signal receptors in A549 cells to participate in cellular energy metabolism signaling pathways. Metabonomic analyses have revealed that, in the first cycle, the virus not only hijacks cell metabolism for its own replication, but also affects innate immunity, indicating a need for further study of the complex relationship between IAV and host cells.

Differential susceptibility & replication potential of Vero E6, BHK-21, RD, A-549, C6/36 cells & Aedes aegypti mosquitoes to three strains of chikungunya virus.

Background & objectives: Chikungunya virus (CHIKV), a mosquito-borne arthritogenic virus causes infections ranging from febrile illness to debilitating polyarthralgia in humans. Re-emergence of the virus has affected millions of people in Africa and Asia since 2004. During the outbreak, a new lineage of the virus has evolved as an adaptation for enhanced replication and transmission by Aedes albopictus mosquito. A study was designed to compare the susceptibility of four vertebrate cell lines, namely Vero E6 (African green monkey kidney), BHK-21 (Baby hamster kidney), RD (human rhabdomyosarcoma), A-549 (human alveolar basal epithelial cell) and C6/36 (Ae. albopictus) to Asian genotype and two lineages of East, Central and South African (E1:A226 and E1:A226V) of CHIKV. Methods: One-step growth kinetics of different CHIKV strains was carried out in the above five cell lines to determine the growth kinetics and virus yield. Virus titre was determined by 50 per cent tissue culture infectious dose assay and titres were calculated by the Reed and Muench formula. Growth and virus yield of the three strains in Ae. aegypti mosquitoes was studied by intrathoracic inoculation and virus titration in Vero E6 cell line. Results: Virus titration showed Vero E6, C6/36 and BHK-21 cell lines are high virus yielding with all the three lineages while RD and A-549 yielded low virus titres. C6/36 cell line was the most sensitive and yielded the maximum titre. Ae. aegypti mosquitoes, when inoculated with high titre virus, yielded an almost equal growth with the three strains while rapid growth of E1:A226V and Asian strain was observed with 1 log virus. Interpretation & conclusions: C6/36 cell line was found to be the most sensitive and high yielding for CHIKV irrespective of lineages while Vero E6 and BHK-21 cell lines yielded high titres and may find application for vaccine/diagnostic development. Infection of Ae. aegypti mosquitoes with the three CHIKV strains gave almost identical pattern of growth.

Transcriptome profiling of influenza A virus-infected lung epithelial (A549) cells with lariciresinol-4-ß-D-glucopyranoside treatment.

The influenza A virus is an acute contagious pathogen that affects the human respiratory system and can cause severe lung disease and even death. Lariciresinol-4-ß-D-glucopyranoside is a lignan that is extracted from Isatis indigotica, which is a medicinal herb plant that was commonly applied to treat infections, the common cold, fever and inflammatory diseases. Our previous study demonstrated that lariciresinol-4-ß-D-glucopyranoside possesses anti-viral and anti-inflammatory properties. However, the comprehensive and detailed mechanisms that underlie the effect of lariciresinol-4-ß-D-glucopyranoside interventions against influenza virus infection remain to be elucidated. In this study, we employed high-throughput RNA sequencing (RNA-seq) to investigate the transcriptomic responses of influenza A virus-infected lung epithelial (A549) cells with lariciresinol-4-ß-D-glucopyranoside treatment. The transcriptome data show that infection with influenza A virus prompted the activation of 368 genes involved in RIG-I signalling, the inflammatory response, interferon α/ß signalling and gene expression that was not affected by lariciresinol-4-ß-D-glucopyranoside treatment. Lariciresinol-4-ß-D-glucopyranoside exerted its pharmacological actions on the immune system, signal transduction, cell cycle and metabolism, which may be an underlying defense mechanism against influenza virus infection. In addition, 166 differentially expressed genes (DEGs) were uniquely expressed in lariciresinol-4-ß-D-glucopyranoside-treated cells, which were concentrated in the cell cycle, DNA repair, chromatin organization, gene expression and biosynthesis domains. Among them, six telomere-associated genes were up-regulated by lariciresinol-4-ß-D-glucopyranoside treatment, which have been implicated in telomere regulation and stability. Collectively, we employed RNA-seq analysis to provide comprehensive insight into the mechanism of lariciresinol-4-ß-D-glucopyranoside against influenza virus infection.

Evaluation of a549 as a new vaccine cell substrate: digging deeper with massively parallel sequencing.

In the past three decades, the use of tumorigenic cell substrates has been the topic of five Vaccine and Related Biological Products Advisory Committee (VRBPAC) meetings, including a review of the A549 cell line in September 2012. Over that period of time, major technological advances in biotechnology have improved our ability to assess the risk associated with using a tumorigenic cell line. As part of the September 2012 review, we assessed the history of A549 cells and evaluated the probable transforming event based on patterns of mutations to cancer genes. In addition, massively parallel sequencing was used to first screen then augment the characterization of A549 cells by searching for the presence of hidden viral threats using sequencing of the entire cellular transcriptome and comparing sequences to a curated viral sequence database. Based upon the combined results of next-generation sequencing technology along with standard cell characterization as outlined in published regulatory guidances, we believe that A549 cells pose no more risk than any other cell substrate for the manufacture of vaccines.