Activation of Type I and III Interferon Signalling Pathways Occurs in Lung Epithelial Cells Infected with Low Pathogenic Avian Influenza Viruses

Abstract

The host response to the low pathogenic avian influenza (LPAI) H5N2, H5N3 and H9N2 viruses were examined in A549, MDCK, and CEF cells using a systems-based approach. The H5N2 and H5N3 viruses replicated efficiently in A549 and MDCK cells, while the H9N2 virus replicated least efficiently in these cell types. However, all LPAI viruses exhibited similar and higher replication efficiencies in CEF cells. A comparison of the host responses of these viruses and the H1N1/WSN virus and low passage pH1N1 clinical isolates was performed in A549 cells. The H9N2 and H5N2 virus subtypes exhibited a robust induction of Type I and Type III interferon (IFN) expression, sustained STAT1 activation from between 3 and 6 hpi, which correlated with large increases in IFN-stimulated gene (ISG) expression by 10 hpi. In contrast, cells infected with the pH1N1 or H1N1/WSN virus showed only small increases in Type III IFN signalling, low levels of ISG expression, and down-regulated expression of the IFN type I receptor. JNK activation and increased expression of the pro-apoptotic XAF1 protein was observed in A549 cells infected with all viruses except the H1N1/WSN virus, while MAPK p38 activation was only observed in cells infected with the pH1N1 and the H5 virus subtypes. No IFN expression and low ISG expression levels were generally observed in CEF cells infected with either AIV, while increased IFN and ISG expression was observed in response to the H1N1/WSN infection. These data suggest differences in the replication characteristics and antivirus signalling responses both among the different LPAI viruses, and between these viruses and the H1N1 viruses examined. These virus-specific differences in host cell signalling highlight the importance of examining the host response to avian influenza viruses that have not been extensively adapted to mammalian tissue culture.

Activation of c-jun N-Terminal Kinase upon Influenza A Virus (IAV) Infection Is Independent of Pathogen-Related Receptors but Dependent on Amino Acid Sequence Variations of IAV NS1

“…However, the underlying molecular mechanisms often remain obscure. In accordance with our study, virus-specific differences in host cell signaling, including differential JNK activation, have recently been observed (44). Moreover, NS1 proteins of two avian IAVs differentially inhibit the doublestranded-RNA-induced activation of the AP1 promoter (45).…”

Influenza A Virus Attenuation by Codon Deoptimization of the NS Gene for Vaccine Development

“…Unlike in MDCK cells, the replication capa- bilities of codon-deoptimized influenza viruses were altered in human A549 cells (compare Fig. 4A and 5A), perhaps due to signaling pathways in human A549 cells that are different from those in MDCK cells or absent in MDCK cells (59,60). For instance, since NS1 is an IFN-I antagonist protein, the differences in replication rates observed could correspond with species-specific IFN-I production or be correlated with IFN-I-stimulated gene (ISG) expression (20,21,54).…”

“…To evaluate if the influenza viruses carrying codon-deoptimized NS showed different replication kinetics in a cell line that more accurately represents the cells targeted in a natural human infection, A549 human lung epithelial cells were used (59,60). To that end, human A549 cells were infected with WT NS or codondeoptimized NS viruses (MOI, 0.001), and at 12, 24, 48, and 72 h postinfection, viral titers were evaluated (Fig.…”

“…Due to the delayed growth in human A549 cells, we postulated that NScd and NS1cd viruses would be attenuated in vivo, as A549 cells more accurately reflect the target cells in the respiratory airway (59,60). Thus, we compared the virulence of WT NS and codondeoptimized viruses in mice.…”

Effectiveness of bacterial infection-related cytokine profile (BIRCP) determination for monitoring pathogen infections in children with hemopathy in the bone marrow inhibition phase

“…Other studies, conducted in China and elsewhere, suggested that Grampositive bacterial and fungal infections could cause a mild increase in IL-6 levels (Lehrnbecher et al, 1999), whereas viral infection could cause an increase in IFN-γ (Sutejo et al, 2012), but not in IL-6 or IL-10 levels (Engervall et al, 1995). Therefore, in this study, the high increases of IL-6 and IL-10 levels [>10 times (means ± SD)] in infected children could be considered to indicate Gram-negative bacterial infection.…”