Influenza Research Paper

1573 Words4 Pages

Nguyen Le Tam Nhan
10672137
Midterm Assignment
The role of nuclear import for influenza A virus infection
The flu, is characterized as an infection of the respiratory tract caused by influenza viruses. Influenza infection is commonly ranked as one of the most dangerous diseases on Earth because it affects all age groups and can re-occur in any individual. Influenza A, B and C viruses belong to the orthomyxovirus, which is the family of enveloped viruses with segmented, single-stranded, negative-sense RNA genome (Calder et al., 2010; Cox & Subbarao, 1999). Type C cause sporadic mild influenza-like illness in children. Type B are known to cause recurring regional and local epidemic disease, but it is only found in human. Type A virus is the most …show more content…

Each segment is coated with multiple copies of nucleoprotein (NP) to form a nucleocapsid with helical symmetry and the length varies from approximately 30 to 110nm (Ruigrok & Baudin, 1995). Beside RNAs and NPs, the vRNP core is also packed with the RNA polymerase proteins, polymerase basic protein 1 (PB1), polymerase basic protein 2 (PB2) and polymerase acidic protein (PA). Interestingly, some other proteins that are expressed at high level during viral replication but are not structural components of the mature virion, the non-structural protein 1 (NS 1) and nuclear export protein (NEP)/NS2. NS1 is a multi-functional protein with a major role in evasion of the host immune system because it is the interferon α/β antagonist (Hale et al., 2008). NS2 (NEP), plays a crucial role in mediating the export of viral RNPs from the cell nucleus during replication (O'Neill et al., …show more content…

Some viral transcripts require splicing and since influenza virus does not encode splicing machinery, it is dependent on host splicing, an activity related to the cellular DNA-dependent RNA polymerase transcription. Indeed, influenza A virus possesses eight vRNA segments, which have been shown to encode up to 17 proteins. Segment 2 encodes the PB1, PB1-F2, and PB1-N40 by using alternative translation initiation sites (Gibbs et al., 2001; Wise et al., 2009). PB1-F2 can be expressed in many strains of influenza virus, but not all. This protein is found to be involved in the enhancement of apoptosis in host cell (Honda & Ishihama, 1997). Segment 3 encodes the polymerase acidic (PA) proteins PA and PA-X by a ribosomal frameshift, as well as two additional N-terminally truncated forms (PA-N155 and PA-N182) by using alternative translation initiation sites (Jagger et al., 2012; Muramoto et al., 2013). By using alternative mRNA splicing, three proteins, the matrix (M) protein M1 and ion channel proteins M2 and M42, and three other proteins, the NS1 and NS2/NEP are produced from segment 7 and segment 8 respectively. Additionally, previous studies

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