Avian Influenza Virus

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Avian Influenza Virus

• MDG5101 Advanced Cell BiologyBioinformatics
  Group 6 Presentation
• Liu Ka Po, Gabriel
•  Jayapal Manikandan
•  Annette Shoba Vincent
•  Lee Guan Huei
•  Mok Wei Chuen

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Avian Influenza Virus
To date 186 confirmed human cases. 105 deaths.
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Mechanism of infection and replication
For human influenza viruses, they bind to
receptors that contain terminal 2-6-linked
sialyl-galactosyl residues. PNAS 2004
1014620-4.
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Antigenic Shift
Antigenic Drift
Person infected with virus
Develop Ab against the virus
New viral strain appears
Reinfection occurs

• small changes in the virus that happen
  continually over time.
• Antigenic drift produces new virus strains that
  may not be recognized by the body's immune
  system.

• abrupt, major change in the influenza A viruses
• resulting in new hemagglutinin and/or new
  hemagglutinin and neuraminidase proteins in
  influenza viruses that infect humans

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Avian Influenza Virus Data Search
Avian influenza virus web sites can be searched
via
Information can be obtained by the following data
sources in the following relevant public domains.
For examples
http//www.ncbi.nlm.nih.gov/genomes/FLU/FLU.html
http//www.who.int/csr/disease/avian_influenza/en/
http//www.cdc.gov/flu/avian/
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Avian Influenza Virus Genome Search

• Entrez Genome by NCBI

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Current Diagnostic Test

• Rapid Antigen Detection
• Near-patient tests for influenza
• Immunofluorescence assay
• Enzyme Immunoassay
• Virus Culture
• PCR and Real-time PCR

Recommended laboratory tests to identify avian
influenza A virus in specimens from humans WHO
Geneva June 2005
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RT-PCR Kit for New Mutant Detection

• Primers built on conserved sequences
• H5 (Yuen et al. 1998), N1 (Wright et al. 1995)
  conserved sequences (Genbank)
• Multiple Sequence Alignment (ClustalW)
• Bands detection (Addition/Deletion)
• Expected bands vs. Unexpected bands
• Unexpected bands could indicate possible new
  mutant variants
• PCR-RFLP (Point Mutation)
• Restriction enzymes digestion
• Signatory fragments
• Followed up by sequencing

Yuen KY et al. (1998). Clinical features and
rapid viral diagnosis of human disease associated
with avian influenza A H5N1 virus. Lancet,
351467471. Wright KE et al. (1995). Typing and
subtyping of influenza viruses in clinical
samples by PCR. Journal of Clinical Microbiology,
3311801184.
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Biological Database

• Represent an extraordinarily diverse collection.
  
• Future advances in biology depend critically on
  databases

Definition Large, organized body of persistent
data, associated with computerized software
designed to update, query, and retrieve
components of the data.

• Additional requirements must be met
• Easily accessible via WWW
• A method for extracting (answer a specific
  biological question)

• SQL - access the data and structures within a
  relational database.
• PHP - create dynamic Web pages that are
  generated from information accessed from a MySQL
  database.

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Protein Structure Analysis Visualization
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Present Treatment Options

• Neuraminidase Inhibitors Tamiflu (oseltamivir)
  and Relenza (zanamivir) 1st choice but
  resistant cases reported
• Adamantanes Amantadine and Rimantandine not
  drug of choice due to high resistance rate

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New Drugs in Development Potential Targets

• Proteolytic activation of haemagglutinin, eg
  Camostat
• Attachment of the virus to specific cell-surface
  receptors, eg sialic acid analogs
• Endocytosis and fusion with the endosomal
  membrane, eg Anionic polymers
• Uncoating of the nucleocapsid, eg Bafilomycin
• Multiplication, i.e. synthesis of viral RNA and
  mRNA, eg Flutimide, siRNA

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Speed up drug development

• Traditional vs Rational Drug Design
• Using structural information about drug targets
  or their natural ligands as a basis for the
  design of effective drugs.
• Achieve through proteomics, lipidomics,
  structural biology, bioinformatics
• Computer programmes to search through databases
• Avoid the expense of large-scale screening and
  save time
• Zanamivir is the first successful case

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Vaccines

• Live attenuated vaccines
• Weak or weakened strains of virulent agent
• Closely related species which provide
  cross-protection
• Inert vaccine
• Killed or inactivated
• Recombinant
• Fractionated

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Vaccine design
KNOWLEDGE

• Understanding our immune responses
• Pathogen-host interface
• Antigen processing and presentation
• Immune memory

TECHNOLOGY

• Genome mining as a mean to identify target
  antigens
• New protein expression systems
• Rationally-designed adjuvants and vector systems

TARGET
DEVELOPMENT
Fast mutation rates thus requires constant
reformulation of the vaccine design
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Acknowledgements

• A/P Tan Tin Wee
• A/P Shoba Ranganathan