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BioMed Research International
Volume 2013, Article ID 524165, 7 pages
Research Article

Dose- and Time-Dependent Apoptosis Induced by Avian H9N2 Influenza Virus in Human Cells

Razi Vaccine & Serum Research Institute, P.O. Box 31975-148, Karaj 3197619751, Iran

Received 6 April 2013; Revised 17 July 2013; Accepted 12 August 2013

Academic Editor: Pranoti Mandrekar

Copyright © 2013 Shahla Shahsavandi et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


To understand human response to avian H9N2 influenza, we investigated the effects of the viral infection on A549, HepG2, and HeLa cells at low and high MOIs. To identify virus-host interplay, expression of Mx and NP genes was measured in the cells supernatants. Cell viability and apoptosis were evaluated by MTT assay, DNA fragmentation, and florescent staining. The virus titration and NP gene transcript levels indicate lower susceptibility of HeLa cell to H9N2 replication than other cells. Although H9N2 did produce a faster CPE in HepG2, high dose of the virus induced apoptosis within early stage of A549 infection. The DNA laddering was enhanced in the cell correlated with increase in virus transcripts. The undetectable to different regulation levels of Mx gene were observed in response to H9N2 infection suggesting that an insufficient antiviral defense in the noncompetent-IFN HepG2 cell promotes efficient viral replication. These results showed that the permissivity of HepG2 for H9N2 is comparable with A549; however, liver cells are not target tissue respond to the infection. These data revealed that the H9N2 virus induced apoptosis signaling via mitochondrial pathway in human alveolar epithelial cells, indicating that the induction may be associated with a dose-dependent manner.