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Open Access Research

Systems-level comparison of host responses induced by pandemic and seasonal influenza A H1N1 viruses in primary human type I-like alveolar epithelial cells in vitro

Suki MY Lee1, Renee WY Chan12, Jennifer L Gardy3, Cheuk-kin Lo4, Alan DL Sihoe5, Sara SR Kang1, Timothy KW Cheung1, Yi Guan1, Michael CW Chan1, Robert EW Hancock6 and Malik JS Peiris17*

Author Affiliations

1 Department of Microbiology, The University of Hong Kong, Hong Kong SAR, PR China

2 Department of Pathology, The University of Hong Kong, Hong Kong SAR, PR China

3 British Columbia Centre for Disease Control, Vancouver, British Columbia, Canada

4 Department of Cardiothoracic Surgery, Queen Elizabeth Hospital, Kowloon, Hong Kong SAR, PR China

5 Department of Cardiothoracic Surgery, Queen Mary Hospital, Pokfulam, Hong Kong SAR, PR China

6 Centre for Microbial Diseases and Immunity Research, University of British Columbia, Vancouver, British Columbia, Canada

7 The University of Hong Kong-Pasteur Research Centre, Hong Kong SAR, PR China

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Respiratory Research 2010, 11:147  doi:10.1186/1465-9921-11-147

Published: 28 October 2010

Abstract

Background

Pandemic influenza H1N1 (pdmH1N1) virus causes mild disease in humans but occasionally leads to severe complications and even death, especially in those who are pregnant or have underlying disease. Cytokine responses induced by pdmH1N1 viruses in vitro are comparable to other seasonal influenza viruses suggesting the cytokine dysregulation as seen in H5N1 infection is not a feature of the pdmH1N1 virus. However a comprehensive gene expression profile of pdmH1N1 in relevant primary human cells in vitro has not been reported. Type I alveolar epithelial cells are a key target cell in pdmH1N1 pneumonia.

Methods

We carried out a comprehensive gene expression profiling using the Affymetrix microarray platform to compare the transcriptomes of primary human alveolar type I-like alveolar epithelial cells infected with pdmH1N1 or seasonal H1N1 virus.

Results

Overall, we found that most of the genes that induced by the pdmH1N1 were similarly regulated in response to seasonal H1N1 infection with respect to both trend and extent of gene expression. These commonly responsive genes were largely related to the interferon (IFN) response. Expression of the type III IFN IL29 was more prominent than the type I IFN IFN╬▓ and a similar pattern of expression of both IFN genes was seen in pdmH1N1 and seasonal H1N1 infection. Genes that were significantly down-regulated in response to seasonal H1N1 but not in response to pdmH1N1 included the zinc finger proteins and small nucleolar RNAs. Gene Ontology (GO) and pathway over-representation analysis suggested that these genes were associated with DNA binding and transcription/translation related functions.

Conclusions

Both seasonal H1N1 and pdmH1N1 trigger similar host responses including IFN-based antiviral responses and cytokine responses. Unlike the avian H5N1 virus, pdmH1N1 virus does not have an intrinsic capacity for cytokine dysregulation. The differences between pdmH1N1 and seasonal H1N1 viruses lay in the ability of seasonal H1N1 virus to down regulate zinc finger proteins and small nucleolar RNAs, which are possible viral transcriptional suppressors and eukaryotic translation initiation factors respectively. These differences may be biologically relevant and may represent better adaptation of seasonal H1N1 influenza virus to the host.