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65 Cards in this Set
- Front
- Back
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Swine Flu
-family -genus |
-orthomyxoviridae
-influenzavirus A |
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Swine flu
-morphological characteristics |
-Enveloped
-linear -segmented - negative sense ssRNA |
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Swine flu
-sensitivity characteristics |
-lipid solvents
-detergents -disinfectants -heat -acid -labile in environment |
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Influenzavirus
-differences between the types based on |
-nuceloprotein
-matrix protein |
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Influenzavirus
-types that infect only humans |
-B
-C |
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Influenzavirus A
-subgroups |
-mammalian
-avian |
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Influenza A
-animals affected |
-humans
-pigs -horses -marine mammals -poultry -dogs |
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Influenzavirus
-type responsible for human pandemics |
-Type A
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Influenzavirus A
-number of genome segments |
-8
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Why is the fact that influenzavirus has a segmented genome important?
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-allows for the reassortment of gene segments
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Influenzavirus
-important surface transmembrane proteins for identification and classification |
-hemagglutinin
-neuraminidase |
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Hemagglutinin
-function |
-binds sialic acid receptors on host cells
-responsible for virus attachment and entry into cells -agglutination of erythrocytes |
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Neuraminidase
-function |
-cleaves sialic acid from sugar residues
-involved in virus release from host cells |
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Hemagglutinin
-subtypes to circulate in waterfowl -subtypes to circulate in humans |
-waterfowl: all
-humans: H1, H2, H3 |
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Classical swine influenza virus
-subtypes |
-H1N1
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Standard nomenclature for classifying influenza viruses
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type/animal of origin/strain number/year of isolation/subtype in parentheses
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Clade
-definition |
-a group of viruses derived from a common ancestor
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Dominant antigen of influenza virus recognized by the immune system
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-hemagglutinin
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Hemagglutinin
-number of different proteins |
16
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Influenza gene with the highest rate of mutation
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-hemagglutinin
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Neuraminidase
-effect of antibodies |
-don't prevent infection
-limit virus spread -shorten duration of illness |
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Neuraminidase
-number of different proteins |
9
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Human influenza subtypes currently in circulation
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-H1N1
-H3N2 -H1N2 |
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Swine influenza subtypes currently in circulation
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-H1N1
-H3N2 -H1N2 |
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Equine influenza subtype currently in circulation
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-H3N8
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Natural host of swine influenza virus
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-swine
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Animals susceptible to swine influenza virus
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-humans
-birds (turkeys) |
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Avian influenza
-natural hosts and reservoir |
-shorebirds
-waterfowl |
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Avian influenza
-type of infection |
-primarily enteric
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Avian influenza
-mode of transmission |
-shed in feces
-persists in water |
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What was the first known direct human-bird transmission of influenza?
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-H5N1 outbreak in Hong Kong
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Swine influenza
-modes of transmission |
-pig-to-pig
-nasopharyngeal secretions -humans -birds -fomites |
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Swine influenza
-most important mode of transmission |
-nasal secretions
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Swine Influenza
-pathogenesis |
-virions attach to and attach epithelial cells in the nasal cavity, trachea, lungs, bronchiolar epithelium
-viral replication within 2 hrs -1-3 days spreads throughout lungs and causes necrosis, loss of epithelium, neutrophil inflammation -spread to lung parenchyma causing interstitial pneumonia |
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Swine Influenza
-cells that are very susceptible to the virus |
-bronchiolar epithelium
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Swine influenza
-how long after infection until replication begins |
-2 hrs
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Swine influenza
-where is the virus normally found |
-nasal epithelium
-tonsils -trachea -lungs -tracheobronchial LNs |
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Swine influenza
-time of virus shedding |
-1 day after infection
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Swine influenza
-how does hemagglutinin work |
-must be cleaved by trypsin-like proteases in the respiratory tract and intestines before it is able to bind to sialic acid receptors
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Why are humans resistant to avian viruses and vice versa?
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-lack of the sialic acid receptor to which avian viruses attach
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Why are pigs susceptible to avian and human viruses?
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-respiratory epithelium has human and avian sialic acid receptors
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What are ways in which new human pandemic strains of the flu emerge?
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-direct transmission from birds to humans
-antigenic shift |
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Antigenic shift
-how does it cause new human pandemic strains of the flu |
-host is infected with 2 viruses
-reassortment of viruses with new hemagglutinin -no immunity develops to the new hemagglutinin -genes from a previous human virus are retained -easy transmission to humans |
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Why does antigenic drift not result in a human flu pandemic?
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-point mutations occur in hemagglutinin and neuraminidase
-antibodies can't fully protect anymore -infection not very severe however because there is some antibody protection -reason behind different seasonal flu vaccines |
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Avian HA
-sialic acid |
-alpha-2,3 sialic acid
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Avian Sialic acid
-located where |
-intestines
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Human HA
-sialic acid |
-alpha-2,6 sialic acid
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Human Sialic Acid
-located where |
-respiratory tract
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Swine influenza
-clinical signs |
-sudden onset
-high morbidity, low mortality -fever -anorexia -huddling -labored & rapid breathing -coughing -nasal discharge -weight loss |
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Swine influenza
-time of recovery |
-5-7 days post-infection (if no secondary infection present)
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Swine influenza
-gross lesions |
-anterior-ventral lung consolidation and edema
-patchy hemorrhages -atelectasis -fibrinous exudate in bronchi |
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Swine influenza
-microscopic lesions |
-bronchointerstitial pneumonia
-bronchial and bronchiolar epithelium necrosis -bronchi, bronchioles, and alveoli plugged with dead cells, fibrin, neutrophils |
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Swine influenza
-clinical signs in pregnant sows |
-abortions, stillbirth
-return to estrus -due to sickness and high fever, not fetal infection |
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Swine influenza
-how long until virus shedding begins |
-1 day
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Swine influenza immunity
-process |
-rapid humoral and cell mediated reponses
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Swine influenza
-neutralizing antibodies |
-antibodies to homologous HA protein
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Swine influenza
-antibodies that limit viral spread |
-antibodies to NA
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Swine influenza
-time until serum antibody appearance |
-3-7 days
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Swine influenza
-antibodies last for how long |
-up to 18 months
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Swine influenza
-how long do colostral antibodies last |
-5-15 wks
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Swine influenza
-vaccines |
-H1N1
-H3N2 -autogenous vaccines commonly used |
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Swine influenza
-methods of antigen detection |
-virus isolation
-ELISA -PCR |
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Swine influenza
-samples used for antigen detection |
-nasal swabs
-tracheobronchial swabs/wash -lung/trachea tissue |
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Swine influenza
-methods of antibody detection |
-hemagglutinin inhibition w/ paired serum samples
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Only constant of the influenza virus
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-it will change
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