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Reoviruses. Reoviruses/Reoviridae. Orthoreoviruses Rotaviruses Orbiviruses Coltiviruses. Reoviruses/Reoviridae. Reovirus r espiratory e nteric o rphan. Reoviruses/Reoviridae. Nonenveloped Double-layered protein capsid “10-12 segments” “dsRNA”
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Reoviruses/Reoviridae • Orthoreoviruses • Rotaviruses • Orbiviruses • Coltiviruses
Reoviruses/Reoviridae • Reovirus respiratory enteric orphan
Reoviruses/Reoviridae • Nonenveloped • Double-layered protein capsid • “10-12 segments” • “dsRNA” • Stable over wide pH and temperature ranges • Orbiviruses arboviruses • coltiviruses
Reoviruses/Reoviridae • Orthoreoviruses • Mammalian reoviruses, reoviruses • Cause asymptomatic infections in humans • Rotaviruses • Human infantile gastroenteritis • A very common disease
Reoviruses/Structure & replication • rota Latin word wheel appearence in electron micrographs • dsRNA segmented 10-11 segments • “reassortment of segments” hybrid viruses
Reoviruses/Structure & replication • Replication • Ingestion • Partial digestion of the virion • Production of ISVPs • Attachment to epithelial and other cells • “Transcription”, translation VPs, and • Replication
Reoviruses/Orthoreoviruses • Ubiquitous • 3 serotypes • Do not cause significant disease in humans • Most people are probably infected during childhood (75%of adults)
Rotaviruses • Cause infantile diarrhea • Infection in many mammals and birds • Virions relatively stable @ RT and resistant • Serotypes (VP7, VP4), groups (VP6)(A-G), subgroups • Humans: Group A , B,C
Rotaviruses/Disease mechanisms • Spread: fecal-oral, Respiratory route: possible • Cytolytic and toxin-like action on the intestinal epithelium causes loss of electrolytes and prevents readsorbtion of water • Disease can be significant in infants younger than 24 months but asymptomatic in adults
Rotaviruses/epidemiology • Oneof the most common causes of serious diarrhea in young children worlwide • 600 000 death/year
Rotaviruses/epidemiology • At risk: • Rotavirus type A • <24 months infants • Infantil gastroenteritis with potential dehydration • Older children & adults • Mild diarrhea • Undernourished people in underdeveloped countries diarrhea, dehydration, death
Rotaviruses/epidemiology • At risk: • Rotavirus type B • Infants, older children, and adults in China: • Severe gastroenteritis
Rotaviruses/epidemiology • Geography/Season • Worldwide • More common in autumn, winter, and spring
Rotaviruses/Laboratory diagnosis • Ag • ELISA • Latexaggl • PCR
Prophylaxis • Vaccine • handwashigh
Coltiviruses and Orbiviruses • Coltiviruses • Colorado tick fever • Orbiviruses • Blue tongue disease of sheep • African horse sickness • Epizootic hemorrhagic disease of deer
Colorado tick fever viruses • Infects erythroid precursor cells • cause generally mild or subclinical infection (can cause serious hemorrhagic disease) • Lab. Diagnosis • Ag detection by IF • Treatment • No specific tr.