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RNA Viruses

RNA Viruses. of Animals. Viral Classification. Taxonomy Order (-viridae) Family (-viridae) Subfamily (-virinae) Genus (-virus) Species Group III (ds) IV (+ss) V (-ss). RNA Virions. Cytoplasm: Replication Biosynthesis Helical capsid Most enveloped with spikes NA Double sense

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RNA Viruses

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  1. RNA Viruses of Animals

  2. Viral Classification • Taxonomy • Order (-viridae) • Family (-viridae) • Subfamily (-virinae) • Genus (-virus) • Species • Group • III (ds) • IV (+ss) • V (-ss)

  3. RNA Virions • Cytoplasm: • Replication • Biosynthesis • Helical capsid • Most enveloped with spikes • NA • Double sense • Single sense (+ / -) • 2 single sense (+)

  4. Viral Entry into Cells

  5. Group III: dsRNA Reoviridae

  6. REOVIRIDAE • REO=Respiratory Enteric Orphan Virus • Non-enveloped • Icosahedral • RNA ds • Segmented • Human Diseases • Rotavirus • Coltivirus

  7. Rotavirus • World wide infection • Fecal-oral spread • Incubation: 1-3 days • Diarrhea • Children • Diagnosis • ELISA • Latex Agglutination • Prevention • Hygiene • Water sanitation

  8. Coltivirus • Colorado Tick Fever • Disease • Acute • Myalgia • Photophobia • Rash • Hemorrhage • Tick vector • Rodent reservoir

  9. RNA ss (+); (-); & retro-

  10. Group IV: +ssRNA nonenveloped • Picornavirus • Rhinovirus • Enterovirus • Hepatovirus • Calicivirus • Astrovirus • Hepevirus

  11. Hepevirus (formerly calcivirus) • +ss RNA • nonenveloped • Icosahedral • Fecal-oral • Domestic pig reservoir • Developing countries/sanitation • Hepatitis E (enteric hepatitis)

  12. ASTROVIRIDAE • Astro = Star • Nonenveloped • +ssRNA • 7 Human Serotypes • Diarrhea • Treatment • Supportive

  13. CALICIVIRIDAE • Calicus • Cup shaped • Indentations • Non-enveloped • Icosahedral • Linear ss + RNA • Human Diseases • Norwalk Virus (Norovirus)

  14. Norwalk Virus Summer diarrhea Epidemic Gastroenteritis V/D Institutions ID virus in stool 90% of viral diarrheas Calicivirus

  15. PICORNAVIRIDAE • Pico = small • Nonenveloped • Icosahedral • RNA + ss • Human Diseases • Enterovirus • Polio • Coxsackie A , B • ECHO • Rhinovirus • Hepatovirus

  16. Rhinovirus • Common cold virus: 50% • Transmission: inhalation • Incubation: 1-3 days • Symptoms • Sore throat • Mucopurulent nasal discharge • Complications • predispose to secondary bacterial infections

  17. Hepatovirus: Hepatitis A • Infectious Hepatitis • Milder disease than Hepatitis B • No chronic form • Fecal-oral • Incubation: 2-5 weeks • Virus excreted in stool • Resistant to disinfection • Dx: IgM

  18. Enterovirus • Disease Groups • Poliovirus • Coxsackie A, B • Echovirus • Fecal-oral • Cytolytic • GI mucosa • Lymphatic tissue

  19. Echovirus • ECHO= • Enteric • Cytopathic • Human Orphan • Fecal-oral route • Disease • Meningitis • Paralysis • URTI • Myocarditis • Fever • Rashes • Orchitis

  20. Coxsackie A and B • Fecal-oral • Disease • Coxsackie A • Skin Rashes • Herpangina • Mouth • Pharynx • Hand/Foot/Mouth • Conjunctivitis • +/- DM Type I cause • Coxsackie B • Myocarditis • Meningitis • URTI • Paralysis

  21. Poliomyelitis • 3 serotypes (Type 1 disease) • Transmission: fecal-oral • Throat ->LN->Ileum->Blood-> CNS • Phases • Asymptomatic: 90% • Minor Polio • Non-paralytic • Paralytic: 2-3%, causes 75% of paralysis • Dx: virus in feces, secretions • Prevention: Vaccine • Salk (IPV, killed) • Sabin (OPV, modified live)

  22. Poliovirus Bulbar Poliomyelitis Post Polio syndrome

  23. Togavirus Flavivirus Coronavirus Group IV:+ssRNA enveloped

  24. CORONAVIRIDAE Corona = crown Enveloped Helical Linear RNA + ss Respiratory droplet Human Diseases Common cold (20%) SARS

  25. Severe Acute Respiratory Syndrome (SARS) Respiratory Droplet Direct Indirect 2-10 day incubation Cough->Pneumonia Stable in environment for days Dx: PCR Tx: supportive Prevention avoid contact disinfect

  26. TOGAVIRIDAE • Toga = coat • Spiked envelope • Icosahedral • Linear ss+RNA • ~Arthropod vector • Human diseases • Encephalitis • (VEE, WEE, EEE) • Rubella

  27. Encephalitis: VEE, WEE, EEE all Rodent: VEE

  28. Togavirus: Rubella • Rubella • German Measles • Respiratory Droplet • 2-3 week incubation • Rash: 3 days • Facial • Spreads to body • Changes hourly • Complications • Adults • Arthritis • Encephalitis • Congenital defects • Nervous • Heart • Blindness • Prevention: MMR Rubivirus

  29. FLAVIVIRIDAE • Flavus = yellow • Enveloped • Helical • Linear RNA ss + • Human Diseases • Hepatitis • Encephalitis • Hemorrhagic Fever

  30. Flavivirus • Hepatitis C • HCV • Non A non B • Endemic • Parental • Blood • Needles • Organs • 6-8 week incubation • Mild form • Chronic • Cancer • Liver failure • Dx:IgG, PCR • Tx: Interferon

  31. Hepatitis Yellow Fever Liver / GI Kidneys Heart Hepatitis G Acute Persistent Co-infection with Hepatitis C Parental: blood Encephalitis Japanese Complex Russian spring/summer St. Louis Acute Inflammatory Vector: mosquito 4-21 days incubation Flaviviridae

  32. Flavivirus Encephalitis

  33. Flavivirus • West Nile Virus • Acute • Febrile • Hemorrhagic • Vector: mosquito • 3-14 days incubation • Dx: IgM, ELISA • Tx: Supportive

  34. Flavivirus: Dengue Fever • Tropical • Aedes mosquito • Disease syndromes • Breakbone fever • Rash • Myalgia • Hemorrhagic fever • Reinfection • Hyperimmune response

  35. Bunyvirus Orthomyxovirus Arenavirus Group V: -ssRNA enveloped, segmented

  36. ARENAVIRIDAE • Arenosus = sand (ribosomes) • Enveloped • Helical • Segmented linear ss- RNA • Rodent reservoir • Human Disease • Hemorrhagic fever • Old world • Lassa • Sabia • Junin • Lymphocytic choriomenigitis (LCM) • New world arenavirus

  37. Arenavirus • Hepatitis D • Delta Agent • Defective • Incomplete ss RNA • Viroid • Co-infection with HepB • Satellite virus • Enveloped • Body fluid spread

  38. BUNYAVIRIDAE • Named after location of first viral isolation • Spiked, enveloped • Helical • Circular ss-RNA • Human Disease • Arborvirus • Encephalitis • Respiratory • Hemorrhagic Fever • Rodent • Hanta Virus

  39. Bunyavirus • Hanta virus • Adult Respiratory Disease • 1-3 weeks incubation • Transmission: deer mice • Symptoms • SOB • N/V • pain • Tx: supportive • Prevention: rodent control, disinfect

  40. ORTHOMYXOVIRIDAE • Myxo = mucus • Spiked envelope • HA • hemaggluttinin • attach • Antigen number • NA • neuraminidase • through mucus • antigen number • Helical capsid • 8 Segmented linear ss-RNA • Human Diseases • Influenza A • Influenza B

  41. -ssRNA

  42. Orthomyxovirus • Influenza • Range of symptoms from mild to severe • Droplet • Direct • Indirect • 1-3 days incubation • Reservoir: Humans • Treatments • Vaccination • Drugs • Complications • Recombinant due to segmented RNA • Secondary bacterial infections • Viral super infection with Adenovirus Influenza Treatments Inhibit Neuraminidase Relenza (IN) Tamiflu (PO)

  43. Antigenic drift: HA/NA mutations Antigenic shift: genetic reassortment

  44. Influenza Pandemics

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