Week 4/20-4/24

Bird Flu Lecture - 4/21

Control Methods

  • Many Asian countries had vaccinations

  • At least 168 million poultry birds affected in USA in 2025

Tamiflu

  • Could also cure influenza, or bird flu

Neuraminidase Inhibitors

Spanish Flu

Symptoms - hemorrhagic fever

Vaccines

  • Viruses often kill the eggs before growth, now animal culture cells are used

Risk for humans being infected by bird flu is very low.

Sialic Acid and Influenza

  • Birds and humans bind to two different sialic acids

Lung

  • Bronchial cells-upper region of respiratory tract

  • Alveolar cells, lower region of respiratory tract

  • Human viruses bind preferentially to epithelial cells in the bronchi, less to alveolar cells

  • Avian viruses bind preferentially to alveolar cells, but less to bronchial cells

  • Avian viruses would have to mutate

The 2009 pandemic virus has the same amino acids at the tip of HA as the 1918 strain bound to an antibody (red and yellow ribbons)

  • Flu viruses are segmented ssRNA viruses that have the ability to evolve rapidly, particularly when two viral types infect a single host cell

Why are other people less susceptible to H1N1? How would you use this information to design vaccines?

West Nile Virus Lecture 4/24

Flavivirus - a group of RNA viruses that includes Dengue, Zika, and West Nile Virus

Corvid - crow-like birds

Encephalitis - inflammation of the brain

Diaphoresis - sweating

West Nile Virus

  • First isolated from West Nile District of Uganda

  • Emerged 1000 years ago

  • 43 species can carry WNV

Geographical Distribution

  • How Israel passed WNV to New York

    • Possibilities: Migration, mosquitoes, air travel?

  • Lots of cases in 2004

  • Increases more in the summer due to increase in mosquitoes

Disease Risk

  • Amplification

  • Dilution

    • Each tick feeds only once per stage

    • Feedings spent on poorly-competent hosts are “wasted” for the disease

  • Competence - a host acquires and spreads a pathogen

  • American Robins are superspreaders

  • Alala can go extinct if infected

Control and Prevention

  • Mosquito repellent

  • Fix your screens

Classification

  • Flaviviridae

  • Genus - Flavivirus Japanese Encephalitis Antigenic Complex

WNV

  • Mosquito-borne flavivirus; ssRNA

  • + Sense RNA genome that replicate in the cytoplasm of cells

  • Icosahedral, enveloped nucleocapsid

E-protein helps bind to the cell

WNV Replication

  • WNV binds to some receptor protein (DC-SIGN, DC-SIGN-R (Dendritic Cell-Specific ICAM3-Grabbing Nonintegrin-Related Protein), and the integrin αvβ3 in vitro), E protein plays a role.

Symptoms

  • Asymptomatic infection

  • Mild febrile syndrome, fever

  • Neuroinvasive disease - infection or passive transport through the endothelium or choroid plexus epithelial cells

    • Meningitis or encephalitis

Diagnosis

  • IgM antibody detection in serum collected 8—14 days or CSF collected 8 days of illness onset using ELISA

  • Microsphere immunoassays - MOST EFFICIENT

Mechanism

  • Neutralization by the E16 monoclonal antibody that specifically binds DIII region of E protein

Neutralization

  • Large panel of envelope glycoprotein-specific monoclonal antibodies

  • 10/12 potenly neutralizing antibodies (E16) selectively bind DIII of E protein

  • E16 - partially blocks viral attachment yet blocks infection