orthomyxovirus (influenza)

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powerpoint presentation - mm 445 lecture 3 chair of microbiology, virology, and immunology orthomyxoviridae paramyxoviridae orthomyxovirus (influenza) family the name myxovirus was originally applied to influenza viruses. it meant virus with an affinity for mucins. now there are 2 main groups – the orthomyxoviruses and the paramyxoviruses differences between orthomyxoviruses and paramyxoviruses feature orthomyxoviruses paramyxoviruses viruses and diseases influenza a,b,c mumps, measles, respiratory syncytial, parainfluenza genome single-stranded rna in 8 pieces, mw 2-4x106 single-stranded rna in single piece, mw 5-8x106 inner ribonucleo-protein helix 9-nm diameter 18-nm diameter influenza “la malatia per l’influenza della stella” (the disease caused by the influence of the stars) in french: grippe, from french verb “agripper” (clinging) influenza severe respiratory disease 20-50 million respiratory illnesses each year in the u.s. 30 million visits to physicians, 200,000 hospitalizations 20,000 deaths new influenza virus strains associated with severe pandemics and high mortality. a severe respiratory disease of humans, …

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orthomyxoviruses. nomenclature human influenza virus influenza a/bangkok/1/79(h3n2) influenza a/singapore/1/57(h2n2) influenza b/ann arbor/1/86 influenza virus a orthomyxoviruses: medium-sized, enveloped, (-) sense that vary in shape from spherical to helical. their genome is segmented into eight pieces influenza virus structure flu viruses currently infecting... humans: h1n1, h1n2, and h3n2 avian flu virus: h5n1 influenza viral genome (-) ssrna 8 segments (pieces) one gene per segment nucleoprotein matrix proteins ns (nonstructural proteins, that are not incorporated into viral particles) gene encodes two different non-structural proteins subunits of rna polymerase spikes (about 500) flu viruses are named by the type of surface proteins hemagglutinin - trimer (ha) helps virus enter cell type a infects humans, birds and pigs type a has ~ 20 different sub types neuraminidase - tetramer (na) helps virus exit cell 9 subtypes orthomyxoviruses m1 protein helical nucleocapsid (rna plus np protein) ha - hemagglutinin polymerase complex lipid bilayer membrane na …

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rna total genome length is 13588 nt the largest segment 2341 nt infect much man and birds. cause human disease but generally not as severe as a types. believed to be epidemiologically important - reassortment with type a leads to epidemics. influenzavirus c virions enveloped many spikes nucleocapsid enclosed within lipoprotein membrane virions contain 7 segments of linear negative-sense single stranded rna total genome length is 12900 nt glycoprotein -hemagglutinin esterase fusion (hef) esterase -> receptor destroying enzyme antigen soluble antigens: include ribonucleoprotein and m protein which are much stable in antigenicity. surface antigens: include ha and na which are much variable in antigenicity. influenza viruses are divided into 3 groups determined by the ribonucleoprotein (rnp) antigen and m antigen type a ++++ yes yes yes shift, drift yes sensitive sensitive 2 severity of illness animal reservoir human pandemics human epidemics antigenic changes segmented genome amantadine, rimantidine zanamivir surface glycoproteins …

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membrane of the cell (aided by the neuraminidase) thus spreading the infection to new cells. single-cell reproductive cycle need to make mrna minus (negative) sense rna genomes (+ve) sense mrna (-ve) sense genomic rna aaa need to make mrna minus (negative) sense rna genomes rna polymerase must be packaged in virion. (+ve) sense mrna (-ve) sense genomic rna if used, rna modifying enzymes are packaged in virion. aaa influenza type a viruses: antigenic shift 1889-1977 year subtype common name type of variation 1889 h2n2 1900 h3n8 1918-1957 h1n1 spanish flu antigenic drift 1957 h2n2 asian flu antigenic shift 1957-1968 h2n2 asian flu antigenic drift 1968 h3n2 hong kong flu antigenic shift 1968-1990 h3n2 hong kong flu antigenic drift 1977-1989 h1n1 russian flu reappearance of viruses from 1918,1950 antigenic drift ukraine to-day а “brisben-1“(h1n1), “brisben-2“(h1n2), “brisben- 1007" (н3n2), b “florida” 1918 influenza epidemic > 20 million died of the flu during …

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uently requires new vaccine every “season” antigenic shift occurs every 8-10 yrs major antigenic change of either h or n antigens or both h and n occurs by gene reassortment after simultaneous infection of a cell with two different viruses three different h proteins and 2 major n proteins have evolved ha ha h1n1 spanish flu h2n2 avian flu h2n2 asian flu na na what is an epidemic? the occurrence of more cases of disease than expected in a given area or among a specific group of people over a particular period of time*. epidemic what is a pandemic? an epidemic occurring over a very wide area (several countries or continents) and usually affecting a large proportion of the population. examples: cholera aids pandemic influenza pandemic where does influenza come from? type a constantly circulates in natural reservoirs birds are the natural reservoir of all subtypes of influenza a viruses …

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powerpoint presentation - mm 445 lecture 3 chair of microbiology, virology, and immunology orthomyxoviridae paramyxoviridae orthomyxovirus (influenza) family the name myxovirus was originally applied to influenza viruses. it meant virus with an affinity for mucins. now there are 2 main groups – the orthomyxoviruses and the paramyxoviruses differences between orthomyxoviruses and paramyxoviruses feature orthomyxoviruses paramyxoviruses viruses and diseases influenza a,b,c mumps, measles, respiratory syncytial, parainfluenza genome single-stranded rna in 8 pieces, mw 2-4x106 single-stranded rna in single piece, mw 5-8x106 inner ribonucleo-protein helix 9-nm diameter 18-nm diameter influenza “la malatia per l’influenza della stella” (the disease caused by the influence of the stars) in french...

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