The influenza virus is humanity's most prolific viral assassin, killing tens of thousands of Americans in a typical year and as many as 20-100 million people worldwide when new a pandemic strain emerges. In order to be infectious, an individual virion must incorporate (package) at least one copy of each of the eight linear RNA segments that make up its genome. Pandemics are thought to arise when an existing strain packages one or more segments from another strain in a dually-infected host, yielding a genetic reassortant with novel immunologic and pathogenic properties. Understanding influenza RNA packaging is therefore critical for understanding and, perhaps, controlling, this lethal re-emerging virus. To date, however, the cis-acting determinants required for packaging (i.e., the packaging signals) have not been fully elucidated for any segment, and the trans-acting factors involved are unknown. Our laboratory has extensive experience in defining the requirements for RNA packaging by HIV. In recent studies, we have localized the signals required for efficient packaging to within discrete 45- to 200-base regions at one or both ends of three influenza RNA segments. We now propose to map the active regions in detail and to determine which specific features of RNA sequence and/or secondary structure are required for packaging of these and the other five segments. We will also pursue our surprising observation that 3'or 5'packaging regions are not simply interchangeable among segments, which implies that as-yet-unknown combinatorial rules govern their interactions in packaging. In addition, we have obtained compelling evidence implicating the influenza PA protein (a component of the trimeric viral RNA polymerase) as a trans-acting factor required for packaging all eight viral RNA segments. We will now investigate the molecular pathway by which PA and other viral proteins recognize the packaging signals in viral RNA segments and directing their incorporation into virions. The studies we propose will help elucidate the linkage between packaging and virion assembly, will extend our understanding of influenza genetics and reassortment, and may reveal vulnerable new targets for antiviral drug development.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Research Project (R01)
Project #
5R01AI067704-04
Application #
7633172
Study Section
Virology - B Study Section (VIRB)
Program Officer
Salomon, Rachelle
Project Start
2006-07-01
Project End
2011-06-30
Budget Start
2009-07-01
Budget End
2010-06-30
Support Year
4
Fiscal Year
2009
Total Cost
$327,916
Indirect Cost
Name
Emory University
Department
Pathology
Type
Schools of Medicine
DUNS #
066469933
City
Atlanta
State
GA
Country
United States
Zip Code
30322
Liang, Yuhong; Danzy, Shamika; Dao, Luan Danh et al. (2012) Mutational analyses of the influenza A virus polymerase subunit PA reveal distinct functions related and unrelated to RNA polymerase activity. PLoS One 7:e29485
Kumar, Naveen; Liang, Yuhong; Parslow, Tristram G et al. (2011) Receptor tyrosine kinase inhibitors block multiple steps of influenza a virus replication. J Virol 85:2818-27
Kumar, Naveen; Sharma, Nishi R; Ly, Hinh et al. (2011) Receptor tyrosine kinase inhibitors that block replication of influenza a and other viruses. Antimicrob Agents Chemother 55:5553-9
Qi, Xiaoxuan; Lan, Shuiyun; Wang, Wenjian et al. (2010) Cap binding and immune evasion revealed by Lassa nucleoprotein structure. Nature 468:779-83