Influenza Virus: Flu

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Influenza Virus Flu
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As of 1700 GMT, 30 April 2009, 11 countries have
officially reported 257 cases of influenza A
(H1N1) infection. The United States Government
has reported 109 laboratory confirmed human
cases, including one death. Mexico has reported
97 confirmed human cases of infection, including
seven deaths. The following countries have
reported laboratory confirmed cases with no
deaths - Austria (1), Canada (19), Germany (3),
Israel (2), Netherlands (1), New Zealand (3),
Spain (13), Switzerland (1) and the United
Kingdom (8).
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U.S. Human Cases of H1N1 Flu Infection(As of
April 30, 2009, 1030 AM ET)

• States of laboratory confirmed cases
• Arizona 1 
• California 14 
• Indiana 1 
• Kansas 2 
• Massachusetts 2  
• Michigan 1 
• Nevada 1 
• New York 50 
• Ohio1  South Carolina 10 
• Texas 261
• TOTAL COUNTS 109 cases1 death

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Cross-species transmission
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EM of influenza
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Virus Structure
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• The Structure Complexity of Virus Genomes
• more varied than any of those seen in the entire
  bacterial, plant or animal kingdoms
• may be single-stranded or double-stranded,
  linear, circular or segmented
• Single-stranded virus genomes may be
• positive ()sense, i.e. of the same polarity
  (nucleotide sequence) as mRNA
• negative (-)sense
• ambisense - a mixture of the two.
• Virus genomes range in size from approximately
  3,200 nucleotides (nt) (e.g. Hepadnaviruses) to
  approximately 800 kilobase pairs (kbp,
  Mimivirus)

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• Virus genomes may contain in either DNA or RNA.
• Viruses are obligate intracellular parasites
• genome must contain information which can be
  recognized decoded its host cell
• The viral genetic code must match or at least be
  recognized by the host organism.
• Control signals which direct the expression of
  virus genes must be appropriate to the host.

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Figure A-9 Flu Life Cycle
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Figure 5.15 Mechanisms of uptake of
macromolecules
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Figure 5.16 Receptor mediated endocytosis
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Figure 5.20 Flu entry
Globular heads of HA mediate binding which is
followed by endocytosis. Once inside, the
endosome acidifies and HA changes conformation
and the native loop region becomes a coiled coil,
moving the fusion peptide to the cell membrane.
The purple helixes align, moving the globular
heads out to the way so that the fusion peptide
can insert. Hydrogen ions are pumped into the
viral interior by the M2 ion channel and vRNP
dissociates from M1. Released vRNPs are
transported to the nucleus.
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Figure 5.14 Influenza HA receptor--sialic acid
9 (SA?2,6Ga) Different strains prefer different
oligos
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• Sialic acid N-acetylneuraminic acid

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Localization
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Figure 5.31 Nuclear localization signals
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Figure 5.32 Nuclear pore complex
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Figure 5.33 Protein Import Pathway
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Fig. A-8 Orthomyxoviruses (like Flu)
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Cap snatching viral encoded nuclease part of RNA
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Figure 6.9 Flu RNA replication
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Figure 6.9 Cap Snatching (Flu)
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Figure 10.19 Flu M1regulation