G45R on nonstructural protein 1 of influenza A virus contributes to virulence by increasing the expression of proinflammatory cytokines in mice.
Nonstructural protein 1 (NS1) is a multifunctional protein that is a viral replication enhancer and virulence factor. In this study, we investigated the effect of the amino acid substitution G45R on the NS1 of A/Puerto Rico/8/1934 (H1N1) (G45R/NS1) on viral virulence and host gene expression in a mouse model and the human lung cell line A549. The G45R/NS1 virus had increased virulence by inducing an earlier and robust proinflammatory cytokine response in mice. Mice infected with the G45R/NS1 virus lost more body weight and had lower survival rates than mice infected with the wild type (WT/NS1) virus. Replication of the G45R/NS1 virus was higher than that of the WT/NS1 virus in vitro, but the replication of both viruses was similar in mouse lungs. In A549 cells, the majority of G45R/NS1 protein was localized in the cytoplasm whereas the majority of WT/NS1 protein was localized in the nucleus. Microarray analysis revealed that A549 cells infected with the G45R/NS1 virus had higher expression of genes encoding proteins associated with the innate immune response and cytokine activity than cells infected with the WT/NS1 virus. These data agree with cytokine production observed in mouse lungs. Our findings suggest that G45R on NS1 protein contributes to viral virulence by increasing the expression of inflammatory cytokines early in infection.
Interdisciplinary Graduate Program in Genetic Engineering, The Graduate School, Kasetsart University, Bangkok, 10900, Thailand.|Department of Infectious Diseases, MS 330, Division of Virology, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN, 38105-3678, USA.
Challika
C
Kaewborisuth
Department of Infectious Diseases, MS 330, Division of Virology, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN, 38105-3678, USA.
Bryan
B
Kaplan
Department of Infectious Diseases, MS 330, Division of Virology, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN, 38105-3678, USA.
Mark
M
Zanin
Department of Computational Biology, St. Jude Children's Research Hospital, Memphis, TN, 38105-2794, USA.
David
D
Finkelstein
Department of Infectious Diseases, MS 330, Division of Virology, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN, 38105-3678, USA. richard.webby@stjude.org.
Richard J
RJ
Webby
Department of Microbiology and Immunology, Faculty of Veterinary Medicine, Kasetsart University, 50th Ngamwongwan Rd., Chatuchak, Bangkok, 10900, Thailand. fvetptn@ku.ac.th.|Center for Advances Studies in Agriculture and Food, KU Institute for Advanced Studies, Kasetsart University, Bangkok, 10900, Thailand. fvetptn@ku.ac.th.
Porntippa
P
Lekcharoensuk
D000818:Animals; D001835:Body Weight; D002460:Cell Line; D016207:Cytokines / Q000378:metabolism*; D004195:Disease Models, Animal; D004847:Epithelial Cells / Q000276:immunology / Q000821:virology; D005260:Female; D020869:Gene Expression Profiling; D054884:Host-Pathogen Interactions; D006801:Humans; D007155:Immunologic Factors / Q000096:biosynthesis; D053118:Influenza A Virus, H1N1 Subtype / Q000472:pathogenicity*; D008168:Lung / Q000821:virology; D008807:Mice, Inbred BALB C; D020125:Mutation, Missense; D009976:Orthomyxoviridae Infections / Q000473:pathology / Q000821:virology; D016019:Survival Analysis; D019562:Viral Load; D017361:Viral Nonstructural Proteins / Q000235:genetics*; D014774:Virulence; D037521:Virulence Factors / Q000235:genetics*; D014779:Virus Replication
D016207:Cytokines; C085820:INS1 protein, influenza virus; D007155:Immunologic Factors; D017361:Viral Nonstructural Proteins; D037521:Virulence Factors