Virology
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	Spring, 2004 Lecture Outline 3/4 MINUS-STRAND VIRUSES RHABDOVIRIDAE, PARAMYXOVIRIDAE, ORTHOMYXOVIRIDAE   [-] strand RNA virus introduction: strategy difference in [-] strand vs. [+] strand viruses must make mRNA before translation Rhabdoviridae bullet helical Paramxyoviridae spherical, non-segmented genome Orthomyxoviridae spherical, segmented genome Filoviridae flexible filaments Arenaviridae spherical, ambisense segmented genome Bunyaviridae spherical, segmented genome Rhabdoviridae: simplest of minus-strand grp prototype: vesicular stomatitis virus- cattle, mild Dz structure: lipid rich envelope c peplomers ssRNA minus strand in helical nucleocapsid -UUUUUUUGUCUUCGU 3'} will form panhandle structure -AAAAAAACAGAACCA 5' transcription: VSV RNA 4 x 106 d -> 5 mRNAs codes for 5 proteins transcription req. leader seq., begins at 3'; reads "stop-start" signals- produces 5 mRNA c methylated caps & poly(A) replication: appears to use same enzyme as transcription- forms full-length [+] strand intermediate & progeny minus strands assembly: M protein attaches to inside of fused lipid-G protein complex at cell surface N, L, NS proteins assoc. c M helical nucleocapsid pushes against lipid bilayer, forming bud Rabies: Pasteur developed vaccine from "fixed" virus Negri discovered unique inclusion bodies in nerve cells of infected animals & humans- diagnostic of Dz all strains isolated world wide are of single immunological type transmission & path; epidemiology; vaccines & treatment   Introduction to Paramyxoviridae & Orthomyxoviridae: myxovirus term denotes viral affinity for glycoproteins two major peplomer fxns- hemagglutinin & neuraminidase difference: orthomyxo- has segmented genome [imagine minichromosomes] paramyxo- nonsegmented genome Paramyxoviruses: genus Paramyxovirus: mumps, parainfluenza- human (some paras- other animals); Newcastle Dz (NDV)- chicken genus Morbillivirus: measles- human; distemper- dog; rinderpest- cattle genus Pneumovirus: RSV- human; BRSV- cattle structure: pleomorphic- spheres to filaments, 150-300 nm diameter helical nucleocapsid- protects vs. ribonuclease neuraminidase- cleaves sialic acid from oligosaccharides fusion protein- appears to aid viral-cell fusion p attachment transcription & replication: similar to rhabdovirus; no seq. homology conclusion- both families descended from common ancestor Orthomyxoviruses: influenza (flu) family- many unique features types: serological differences of nucleocapsids many subtypes & strains- internally same, surface protein differences structure: shape- pleomorphic: 100 nm spheres, filaments several 1000 nm majority protein- M forms shell around nucleocapsid c/ envelope 2 types of peplomers: hemagglutinin & neuraminidase RNA: 6 x 106 d total; divided- 8 different RNAs, each for different gene Ag shift: reassortment of segments -> new serotypes responsible for epidemics Ag drift: less dramatic, due to point mutations transcription: occurs in host nucleus instead of cytoplasm like most RNA viruses; 1st transcription- in core progression of translational events occur more in cytoplasm defective interfering particles: interference 1st noted in flu viruses: von Magnus particles lack some, esp. largest, RNA molecules blocks replication of normal particles Influenza pathology Paramyxoviral diseases: replication phases vary greatly, incubation periods vary parainfluenza, measles, mumps, RSV Prevention & control: role of natural exposure & vaccines   Next week: Filoviridae, Arenaviridae, & Bunyaviridae- see CRC, ch 7 & appropriate parts of Wagner, including ch 16, & on-line Midterm 1: Review notes, reading, diagrams, study guide- from beginning through [+] strand ssRNA viruses
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 Updated 1/25/04 by thatcher@sonoma.edu