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26 Cards in this Set

  • Front
  • Back
-spherical or ovoid enveloped
-2 major envelope surface glycoproteins: NA and HA
-ssRNA (-) all within matrix
-helical nucleocapsid made of nucleocapsid protein
-major envelope surface glycoprotein
-used to distinguish subtype of virus within subtype (influenza A H1N1)
-major envelope surface glycoprotein
-used to distinguish subtype of virus within subtype (influenza A H1N1)
Influenza A
-widespread various animals
-genomes into 8 pieces, each for different protein, allowing to recombine when two subtypes co-infect
-13500 nt genome
-most clinically important subtype
-imported and grows into episodic epidemic (Dec-Mar)
-large genetic pool, recombination easier
-highly variable antigenic properties for survival
Influenza B
-only humans
-genomes into 8 pieces, each for different protein
-not much recombination, smaller genomic pool (only humans)
Influenza C
-only humans
-7 segments genome
-not much recombination, smaller genomic pool (only humans)
-not well characterised
-6 segments genome
-composed of matrix protein M1
Mouse tracheal cells experiment
-shows influenza destroys first line of defese against inhaled pathogens (bacteria)
-through desquamation of ciliated epithelium, virus facilitates bacterial entry
-replicating virus in and thus killing round mucous-secreting cells and ciliated upwards beating cells of upper tracheal epithelium
Hemophilus influenzae
-gram negative coccobacillus
-cause of 1918 Spanish flu pandemic
-human experiments show maximal illness at same time maximal viral sheeding
Flu (A) symptoms
-due to produciton of interferon, cytokines and repsonse factros in response to viral replication
-1-4 days after infection
Flu pandemics
-10-50 years irregularly
-1918 Spanish
-1957 Asian
-1967 Hong Kong
Natural Immunity against flu
-against NA and HA
-no cross immunity of subtypes
-protective immunity that is not lifelong since glycoproteins regularly undergo antigenic drift
Antigenic Drift
-mutational antigenicity
-1% change in AA sequence glycoprotines per year through random point mutations in antigenic domains
Antigenic Shift
-every decade or so happens to one glycoprotein
-through genetic recombination with animal influenza subtypes
-potential to be pandemic or epidemic
Antigenic diversity
-increased by virally encoded error-prone RNA dependedent RNA polymerase
-high nucleotide or aa sequence diveristy in WT viral particles
Spanish flu
-20 million deaths
-avian/human recombinant formed in infected swine cell
-cyclic shift allowed influneza to remain pathogenic
-disappeared in 1956 along with appearance H2N2
1880 Flu
-cyclic shift to 1968 but most population in flu from 1880 had died
Asian flu 1
Asian flu 2
Hong Kong flu
-due to antigenic shift
Swine flu scare
-deadly flu containing Hswine thought to be new recombitnant
-actually no recombination
-human-human transmission are low
Cross-specicies infection
-by influenza usualyl does not occur unless large inoculate
-due to host specificity therefore does not occur
Avian flu
-resevoirs, not affected
-humans have partial immunity to N1, no immunity to H5
-although all carry H6 and N1, rest genes are bird genes
-jumped species barrier due to proximity
-66 cases in humans, no human-human transmission
-gets into human respiratory tract, fear of it encoutnering human influenza and recombining making easy spread human to human and therefore pandemic
Influenza A genome
-3 largest segments: polymerase proteins
-4th: hemagglutinin
-5th: nucleoprotein
-6th: neuraminidase
-7th: matrix protein (smaller)
-8th: major non structural protein NS1 (smaller)
-splicing mechanism makes sub genomic mRNA's encoding two small addition proteins